ER: M (Marine)
AB: The seabed is the ultimate sink for virtually every class of marine pollutant. Chlorinated hydrocarbons, petroleum hydrocarbons, metals and radionuclides are deposited in sediments and may persist there long after original sources of contamination are eliminated. This chapter deals with the biological processes that affect the biogeochemical cycling of contaminants in benthic ecosystems. Six processes were selected for discussion: bioaccumulation, trophic transfer, migration, biodegradation, biodeposition and bioturbation. The latter two are examined in the second part of the review (Chapter 29). For review purposes, uptake of pollutants via sediment ingestion is included in the section on bioaccumulation. With the exception of detrital food chains, the discussion of trophic transfer concerns the transport of pollutants from prey to predator. All spatial movements in which animals enter or leave areas of sediment contamination are included in the section on migrations. The discussion of biodegradation is restricted to the metabolism of pollutants by benthic animals.
AN: 0232232

                                                                     255 of 369  
TI: New Data on the Nature of Organic Matter in Oceanic Water and its Energy Resources.
OT: Novye Dannye o Prirode Organicheskogo Veshchestva Okeanskikh vod i Ego Ehnergeticheskie Resursy. 
AU: Skopintsev,-B.A.
AF: Inst. Biol. Vnutr. Vod AN S.S.S.R., Borok, Yarosl. Obl., USSR
SO: OKEANOLOGIYA. 1981. vol. 21, no. 5, pp. 821-830
LA: Russian
ER: M (Marine)
AB: Conditions of humus formation in the ocean are described. New data on the nature of this organic substance are presented: predominance of the organic compounds of the aliphatic (acyclic) structure as compared with the predominance of the aromatic structure in terrestrial humus. For the first time the energy resources of the organic matter in oceanic waters are estimated and compared with similar resources of the terrestrial humus.
AN: 0231810

                                                                     256 of 369  
TI: Carbon and Nitrogen Fluxes During Decomposition of Spartina alterniflora  in a Flow-Through Percolator.
AU: Marinucci,-A.C.
AF: Dept. Biochem. Microbiol., Cook Coll., New Jersey Agric. Exp. Stn., Rutgers State Univ. New Jersey, New Brunswick, NJ 08903, USA
SO: BIOL.-BULL.-MAR.-BIOL.-LAB.,-WOODS-HOLE. 1982. vol. 162, no. 1, pp. 53-69
LA: English
ER: B (Brackish)
AB: The carbon and nitrogen in S. alterniflora  litter were monitored for 4 months during decomposition of 20 degree C in a flow-through percolator that simulates an aerobic, moist marsh. Both the evolution of CO sub(2) and the loss of carbon from the litter followed exponential decay kinetics (0.5% day super(-1) and 1.0% day super(-1)). At first both total organic carbon and total organic nitrogen were lost primarily in dissolved form at high rates, but this leaching ceased rapidly. The NH sub(4) added to the inflow was incorporated into the litter at about 0.25 mg N. g litter super(-1). day super(-1) initially, but the rate declined eventually to about 0.8 mg N.g litter super(-1). day super(-1) after 40 days. Nitrogen enrichment of the litter occurred in two phases with peaks on days 40 and 100. Nitrification started at day 30 and was the main consumer of NH sub(4). The final litter nitrogen concentration was 60% of the initial.
AN: 0228421

                                                                     257 of 369  
TI: Short-Term Starvation Effects on Nitrogen and Phosphorus Excretion by the Chaetognath Sagitta enflata .
AU: Szyper,-J.P.
AF: Oceanic Inst., Waimanalo, HI 96795, USA
SO: ESTUAR.-COAST.-SHELF-SCI. 1981. vol. 13, no. 6, pp. 691-700
LA: English
ER: M (Marine)
AB: Freshly captured Sagitta enflata  exhibited specific excretion rates of ammonium and phosphate (expressed as percentage body content of N or P per hour) that were not significantly related to the size of individual animals. The degree of crowding in experimental vessels was positively correlated with specific excretion rates of ammonium. Excretion rates decreased sharply during the first several hours' incubation time, approaching the rates exhibited by animals starved overnight. Animals captured during the day in Kaneohe Bay, Hawaii, having no food items in their guts, had mean specific excretion rates ( plus or minus S.D.) of 0 multiplied by 81 plus or minus 0 multiplied by 51% body content of N h super(-1) for ammonium, and 1 multiplied by 29 plus or minus 1 multiplied by 24% body content of P h super(-1) for phosphate. Minimal estimates of natural excretion rates, made from the first hour of incubation in further experiments, were 1 multiplied by 19 plus or minus 0 multiplied by 47% h super(-1) for nitrogen and 3 multiplied by 8 plus or minus 3 multiplied by 95% h super(-1) for phosphorus. Sagitta  is not a large contributor to nutrient regeneration in Kaneohe Bay.
AN: 0225005

                                                                     258 of 369  
TI: Distribution of Ionic Cu, Pb, Cd and Zn in the Adriatic Sea.
AU: Branica,-M.
AF: Cent. Mar. Res., Rudjer Boskovic Inst., Zagreb, Jugoslavia
CO: 4. Int. Symp. The Chemistry of the Mediterranean, Rovinj (Yugoslavia), 10 May 1976
SO: PROCEEDINGS-OF-THE-FOURTH-INTERNATIONAL-SYMPOSIUM-THE-CHEMISTRY-OF-THE-MEDITERRANEAN. Commission-Int.-Pour-l'-Exploration-Sci.-de-la-Mer-Mediterrance,-Monaco 1978. vol. 14, no. 1-2 vol. 14, no. 1-2, pp. 151-155
ST: THALASSIA-JUGOSL. vol. 14, no. 1-2
LA: English
ER: M (Marine)
AB: The natural concentration of heavy metals in the marine environment is of great interest for prediction and estimation of pollution. The biogeochemical cycle of a particular pollutant strongly depends on the concentration, degree of actual physicochemical state and reaction pathways of this pollutant in a natural water system. Electrochemical methods, especially polarography and related techniques, have been developed and applied in the determination of trace metals in natural and polluted waters.
AN: 0215628

                                                                     259 of 369  
TI: An Annual Budget of Redox Active Materials in a Lake.
AU: Rich,-P.M.
CA: Connecticut Univ. Storrs (USA)
SO: STORRS,-CT-USA-CU 1980. 13 pp
LA: English
ER: F (Freshwater)
AB: The objectives of this project covered (1) the determination of gross and net flux of iron, nitrogen, and sulfur compounds (redox-active) between interstitial water of surface sediments and overlying lake water, through one annual cycle; (2) the determination of a synoptic material budget for the redox-active compounds in a small bog lake watershed; and (3) correlation of mineral activity in lake water and outflow stream with anaerobic benthic metabolism. It was noted that 50% more reducing power was generated as reduced alternate terminal electron acceptors in the lake (Durham Pond) as seen by reduction of oxygen to water; hence areal hypolimneti carbon dioxide increments better estimated total lake metabolism that areal hypolimnetic oxygen deficits. the watershed supplied more reducing power as dissolved organic matter than it supplied alternate electron acceptors on an annual basis. Finally, alternate electron acceptors were stored in oxidized from in surface sediments during ciruclation and high discharge periods, and used during both summer and winter stratification and low discharge. Hence, current input/output nutrient models accounted for a major biochemical energy transformation entraining redox-active elements and correlated within the lake ecosystem.
AN: 0211568

                                                                     260 of 369  
TI: Annual Oxygen Balance in the World Ocean.
AU: Ivanenkov,-V.N.
AF: Address not stated
SO: OCEANOL.-ACAD.-SCI.-USSR. 1980. vol. 20, no. 4, pp. 419-424
LA: English
ER: M (Marine)
AB: The annual oxygen balance in the World Ocean averages 212.10 super(9) metric tons/years, including: (a) supply: oxygen production through photosynthesis - 154 multiplied by 9 super(9) metric tons/year, oxygen supply to the ocean with rain and river waters - 3 multiplied by 10 super(9) metric tons/year and (b) expenditure: for biochemical oxygen consumption - 151 multiplied by 10 super(9) metric tons/year and for oxygen release from the ocean into the atmosphere - 61 multiplied by 10 super(9) metric tons/year. The resulting annual oxygen exchange between the ocean and the atmosphere (release into the atmosphere) is 6.5 multiplied by 10 super(9) metric tons/year which is  similar to 4% of the annual oxygen production through photosynthesis. The annual oxygen balance is estimated for the Pacific, the Indian, the Atlantic and the Arctic oceans. It is equal to 170 multiplied by 10 super(9) metric tons/year in the Pacific, 97 multiplied by 10 super(9) t/year in the Indian Ocean, 87 multiplied by 10 super(9) metric tons/year in the Atlantic, and 4 multiplied by 10 super(9) metric tons/year in the Arctic Ocean. Oxygen exchange between the oceans is 24, 53, 59 and 80%, respectively, of the above-mentioned annual oxygen balance values in the oceans.
AN: 0182954

                                                                     261 of 369  
TI: Microbial Contribution to the Dynamics of Biological Elements in Marine Environments. April 5, 1980, Tokyo University at Yoyogi, Tokyo.
AU: Seki,-H.
AF: Address Not Stated
CO: Symposium - Microbial Contribution to the Dynamics of Biological Elements in Marine Environments, Tokyo (Japan), 5 Apr. 1980
SO: UMI-MER. 1980. vol. 18, no. 4, pp. 187-228
LA: Japanese
ER: M (Marine)
AB: Contributions cover: Carbon Cycle in the Ocean; Nitrogen Cycling with Special Reference to Ammonia Regeneration and Associated Food Chain; Autotrophic Processes with Special Reference to Microbial Activities; Heterotrophic Processes with Special Reference to Microbial Activities; and Mathematical Model on Dynamics of Biological Elements. A supplement deals with the carbon cycle of brain coral.
AN: 0162495

                                                                     262 of 369  
TI: Organic Matter in Bottom Sediments of the Pos'et Bay (Sea of Japan).
OT: Organicheskoe Veshchestvo v Donnykh Osadkakh Zaliva Pos'eta (Yaponskoe More) 
AU: Andreeva,-N.M.; Agatova,-A.I.
AF: VNIRO, Moscow, USSR
SO: BIOL.-MORYA. 1981. no. 2, pp. 40-49
LA: Russian
ER: M (Marine)
AB: Investigations were carried out in biotopes of natural and artificially cultivated invertebrate populations (at depths of 2-45 m) in August 1977, July - August 1978 and May 1979. Wet samples of the upper 2 cm active layer of bottom sediments consisting of 2 layers differing in color and consistency were analyzed for the content of organic matter (OM), protein, carbohydrates, lipids, nucleic acids, chlorophyll a, b, c and carotenoids, for the protease and lipase activity and photosynthetic rate of phytobenthos. The total OM content in the upper active layer of bottom sediments was found to depend on the season and the metabolic activity of the mollusks in areas of their artificial cultivation. The OM content was lower in sands than in other sediment types. During the period of intensive photosynthesis the OM content in the sediments depended on the OM content in plankton. The qualitative composition of OM in the active layer underwent changes determined by the rate of enzymatic processes in the layer. these processes were more intensive in the upper than in the underlying layer and the upper layer can influence the qualitative composition of the underlying one.
AN: 0162378

                                                                     263 of 369  
TI: Seasonal Transformations and Movements of Iron in a Productive English Lake With Deep-Water Anoxia.
AU: Davison,-W.; Heaney,-S.I.; Talling,-J.F.; Rigg,-E.
AF: Freshwater Biol. Assoc., Ferry House, Ambleside, Cumbria, LA22 OLP, UK
SO: SCHWEIZ.-Z.-HYDROL.-REV.-SUISSE-HYDROL.-SWISS-J.-HYDROL. 1980. vol. 42, no. 2, pp. 196-224
LA: English
ER: F (Freshwater)
AB: The seasonal and depth distributions of the concentrations of total and soluble iron in a seasonally anoxic lake basin are described for two years. Transport of iron is related to hydrodynamics and fluxes of iron both within and to and from the lake are calculated. The results enabled the construction of a schematic model for iron movement; it is critically dependent upon the many rate processes involved.
AN: 0154718

                                                                     264 of 369  
TI: Trace Element Enrichments in Decomposing Litter of Spartina alterniflora .
AU: Breteler,-R.J.; Teal,-J.M.; Giblin,-A.E.; Valiela,-I.
AF: Battelle New England Mar. Res. Lab., 397 Washington Street, Duxbury, MA 02332, USA
SO: AQUAT.-BOT. 1981. vol. 11, no. 2, pp. 111-120
LA: English
ER: B (Brackish)
AB: Concentrations of mercury, copper, zinc, chromium, iron and manganese were measured in Spartina alterniflora  Loisel. during different states of decomposition. Samples were collected from a salt marsh treated with a metal-containing sewage sludge and from a control marsh area. Overall, substantial increases were found in the concentrations of Hg, Cu, Fe, and Zn in all the Spartina  litter samples collected. The trace-metal enrichment in the decaying Spartina  grass was best explained by the adsorption of metal-enriched organic substances during tidal flooding of the marsh surface. No metal adsorption was observed from the sludge-treated marsh soil in spite of an elevation in several of the metals studied.
AN: 0144179

                                                                     265 of 369  
TI: Dissolved Chromium in the Northwest Atlantic Ocean.
AU: Campbell,-J.A.; Yeats,-P.A.
AF: Dept. Oceanogr., The University, Liverpool, L69 3BX, UK
SO: EARTH-PLANET.-SCI.-LETT. 1981. vol. 53, no. 3, pp. 427-433
LA: English
ER: M (Marine)
AB: Total dissolved chromium concentrations have been determined for four vertical profiles from Baffin Bay, the Labrador Sea and the northwest Atlantic Ocean. Chromium concentrations of 3.3 to 5.2nM are found. While the vertical distribution of chromium in the study area is largely controlled by advective processes, the profiles show a small depletion in surface water with increase to a more constant level at depth. Surface depletion and correlations between chromium and nutrients indicate biogeochemical cycling of chromium. At one station, close to the Gibbs fracture zone, a distinct chromium maximum is observed. This feature centred at 3200 m is deeper than the core of the ambient water mass which is advected westward from the Eastern Basin of the Atlantic Ocean through the Gibbs fracture zone.
AN: 0117016

                                                                     266 of 369  
TI: Cadmium, Zinc, Copper, and Barium in Foraminifera Tests.
AU: Boyle,-E.A.
AF: Dept. Earth Planet. Sci., Massachusetts Institute of Technology, Cambridge, MA 02139, USA
SO: EARTH-PLANET.-SCI.-LETT. 1981. vol. 53, no. 1, pp. 11-35
LA: English
AB: The concentrations of cadmium, zinc, copper and barium have been determined on 2-mg samples of single-species foraminifera populations, using North Atlantic core tops, and followed by a detailed downcore study for the last 30,000 years in South Atlantic core V22-174. Improved mechanical and ultrasonic reductive cleaning combined with a mild dissolution in distilled water under 1 atm. P sub(CO2) reduces contaminant levels another order of magnitude. The Cd and Zn concentrations (order 10 super(-8) mole Cd/mole Ca and 10 super(-5) mole Zn/mole Ca) of species with low surface area show an increase with decreasing isotopic temperatures. This increase is consistent with the increasing concentrations of these metals from low values in surface waters to higher values at depth. The variance of Cd and Zn over the last 30,000 years in the central South Atlantic is consistent with the probable variability of the dissolved trace elements at the calcification levels of the species analyzed. Cu and Ba are irreproducible and probably sensitive to residual contaminant phases. The trace element content of the tests differs from levels observed in a recent coprecipitation study. Foraminifera may be a significant vector in zinc cycling in the ocean.
AN: 0114674

                                                                     267 of 369  
TI: Differential Feeding and Fecal Pellet Composition of Salps and Pteropods, and the Possible Origin of the Deep-Water Flora and Olive-Green "Cells".
AU: Silver,-M.W.; Bruland,-K.W.
AF: Ctr. Coast. Mar. Stud., Univ. CA at Santa Cruz, Santa Cruz, CA 95064, USA
SO: MAR.-BIOL. 1981. vol. 62, no. 4, pp. 263-273
LA: English
ER: M (Marine)
AB: Salps (mainly Salpa fusiformis  and, to a lesser extent, Pegea socia ) and a web-building pteropod (Corolla spectabilis ) were studied in epipelagic waters of central California Current. Fecal pellet analysis indicated that their diet differs significantly when they feed together, probably because of differences both in pore sizes of their nets and in feeding methods. Since fecal pellets transport most biogenic material to the deep sea, changes in herbivore species composition at a given geographic location can change the chemistry of materials entering deep water; at the study site, the more salps, the greater the calcite flux, and, the more pteropods, the greater the silica flux. In addition, fecal pellets of both salps and pteropods include partially digested residues of phytoplankton that appear as olive-green spheres, having an ultrastructure identical with that of the so-called olive-green "cells". Presumably, fecal pellets, after sinking into deep water, ultimately disintegrate, releasing both the viable phytoplankton and the olive-green spheres into aphotic waters. Thus the feces of epipelagic herbivores are likely sources of much of the flora of the deep ocean.
AN: 0114042

                                                                     268 of 369  
TI: Hydrochemical Basis of the Primary Production Process in the Coastal Waters of the Sea of Japan.
OT: Gidrokhimicheskie Osnovy Protsessa Pervichnogo Produtsirovaniya v Pribrezhnom Rajone Yaponskogo Morya 
AU: Propp,-M.V.; Propp,-L.N.
AF: Inst. Biol. Morya DVNTs AN S.S.S.R., Vladivostok, USSR
SO: BIOL.-MORYA. 1981. no. 1, pp. 29-37
LA: Russian
ER: M (Marine)
AB: Complex seasonal observations of 19 hydrochemical and production parameters were made at the permanent station in the Vostok Bay of the Sea of Japan. This region is characterized by winter and summer - autumn outbreaks of phytoplankton development. The winter bloom is preceded by nitrate and ortho-phosphate accumulation in water and leads to their almost complete exhaustion. The summer bloom occurs after water temperature increase and acceleration of nitrogen (mainly in ammonia form) and phosphate regeneration at the bottom-water interface. The total nitrogen and phosphorus content, including organic forms, is found to vary approximately 3 times over the year, which points to the important role of the bottom regeneration of the nutrients. The higher productivity of the neritic marine as compared with pelagic ecosystem is believed to be due to accelerate cycles of nutrients.
AN: 0112662

                                                                     269 of 369  
TI: Chemical and Radiochemical Investigations of Surface and Deep Particles of the Indian Ocean.
AU: Krishnaswami,-S.; Sarin,-M.M.; Somayajulu,-B.L.K.
AF: Phys. Res. Lab., Ahmedabad 380009, India
SO: EARTH-PLANET.-SCI.-LETT. 1981. vol. 54, no. 1, pp. 81-96
LA: English
AB: The distribution of "ash" (the non-combustible fraction of marine suspended matter) and concentrations of particulate Al, Ca, Fe, Cr, Ni, Cu, Sr and  super(234)Th in surface waters and of  super(210)Pb,  super(230)Th and  super(234)Th in two vertical profiles (385-4400 m) of the Indian Ocean are reported. The ash concentrations in surface waters follow the primary productivity pattern, with higher abundances in samples south of 40 degree S and lower concentrations in the equatorial and subtropical regions. The high metal/Al ratio in surface particles most likely arises from their involvement in marine biogeochemical cycles. Particulate  super(234)Th activity in surface waters parallels the ash abundance implying that its scavenging efficiency from surface waters depends on the particulate concentration. The particulate  super(230)Th and  super(210)Pb concentration profiles increase monotonously with depth. It is difficult to ascribe this increase to a process other than the in-situ vertical scavenging of  super(230)Th and  super(210)Pb from the water column by settling particles. The geographic distribution of particulate matter, composition and settling velocities in the Atlantic, Pacific and Indian Oceans are similar indicating that they are controlled by quite similar processes in the marine hydrosphere.
AN: 0112585

                                                                     270 of 369  
TI: Dissolved Cyclic Adenosine Monophosphate (cAMP) in the Sea and Uptake of cAMP by Marine Bacteria.
AU: Ammerman,-J.W.; Azam,-F.
AF: Univ. California, Inst. Mar. Resour., A-018, Scripps Inst. Oceanogr., San Diego, La Jolla, CA 92093, USA
SO: MAR.-ECOL.-PROG.-SER.. 1981. vol. 5, no. 1, pp. 85-89
LA: English
ER: M (Marine)
AB: Dissolved cyclic-3',5'-adenosine monophosphate (cAMP) was measured in coastal seawater. Concentrations of cAMP ranged from 1 to 35 x 10 super(-12) M being greatest in nearshore surface samples and from early evening through early morning. Dissolved cAMP was rapidly taken up intact by natural populations of marine bacteria, evidently via high affinity transport systems. Much higher concentrations were found in sediments. Presumed sources of dissolved cAMP are planktonic organisms (bacteria, algae, zooplankton, etc.). cAMP was also measurable in the plankton. Uptake of cAMP from seawater apparently increases the intracellular concentration of cAMP in marine bacteria and thus may play a role in their metabolic regulation.
AN: 0112296

                                                                     271 of 369  
TI: Inventory and origin of sterols in the marine atmosphere in the tropical north-eastern Atlantic.
OT: Inventaire et origine des sterols de l'atmosphere marine en Atlantique tropical nord-est.
AU: Tusseau,D.; Barbier,M.; Marty,J.C.; Saliot,A.-(Inst.-Chim.-Substances-Naturelles,-CNRS,-91190-Gif-sur-Yvette,-France)
SO: Oceanis-Doc.-Oceanogr., 1981 6(2), 167-179
LA: French
ER: M (Marine)
AB: This study was to discover whether the ocean is a source of organic matter, particularly sterols, for the atmosphere. Aerosols, surface microlayer and subsurface water samples have been collected in the tropical north-eastern Atlantic, during the MIDLANTE cruise of the Jean-Charcot-. The lipids have been extracted and the sterols analysed by liquid gas chromatography and mass spectrometry. For sea water and microlayer samples, dissolved and particulate sterols have been analysed separately. The data show that the marine atmosphere sterol content of this area is in the range 2.2-9.ng.mSUP--3, rough sea conditions leading to the highest concentration. The sterol compositions of atmosphere and particulate matter from sea water and the microlayer are very similar, characterized by a large predominance of cholesterol over other compounds, brassicasterol, -siterosterol, and 22-dehydrocholesterol. By comparing these results, it may be inferred that the sterols of the atmosphere are ejected from the ocean microlayer as particulates, at the first stage of the sterol cycle: ocean-atmosphere-continent. These observations emphasize the bio-ecological role of atmospheric sterols coming from the ocean.
AN: 0009180

                                                                     272 of 369  
TI: Data on the exchanges of particulate matter at the air-sea interface: geochemical implicatons.
OT: Donnees sur les echanges de matiere a l'etat particulaire a l'interface air-mer: implications geochimiques.
AU: Morelli,J.-(Minist.-Environ.-et-du-Cadre-de-Vie,-Mission-d'-Etudes-et-Recherche,-14,-Bd.-du-General-Leclerc,-92521-Neuilly-sur-Seine,-France)
SO: Oceanis-Doc.-Oceanogr., 1981 6(2), 109-151
LA: French
ER: M (Marine)
AB: This paper aims to distinguish the fundamental data on air-sea exchanges of particulate matter. It is based to a large extent on a bibliographic synthesis carried out as part of a doctorate thesis on the sea-salts atmospheric cycle, Morelli, 1977. After recalling the nature of the oceanic surface microlayer, attention is given to the oceanic bubbling phenomenon and the production of aerosols from bursting bubbles. Information is given on the composite character of particulate matter suspended in the marine atmosphere and originating not only from the ocean but also from the continental environment. This leads to an examination of the role of the ocean as a sink for this matter. Finally, the complex question of enrichments of marine aerosols components is approached and the geochemical implications are discussed from the point of view of the cyclic atmosphere supply of marine components to continents.
AN: 0009160

                                                                     273 of 369  
TI: Experimental study on metal fixation by a recent sedimentary organic matter of algal origin. 2. In vitro fixation of UO~SUP-2+~~SUB-2~, Cu~SUP-2+~, Ni~SUP-2+~, Zn~SUP-2+~, Pb~SUP-2+~, Co~SUP-2+~, Mn~SUP-2+~, and of VO~SUP--~~SUB-3~, MoO~SUP-2-~~SUB-4~ and GeO~SUP-2-~~SUB-2~.
OT: Etude experimentale de la fixation de metaux par un materiau sedimentaire actuel d'origine algaire _ II. Fixation 'in vitro' de UO~SUP-2+~~SUB-2~, Cu~SUP-2+~, Ni~SUP-2+~, Zn~SUP-2+~, Pb~SUP-2+~, Co~SUP-2+~, Mn~SUP-2+~, ainsi que de VO~SUB-3~~SUP--~, MoO~SUP-2-~~SUB-4~ et GeO~SUP-2-~~SUB-3~.
AU: Disnar,J-R.-(Bur.-Rech.-Geol.-Minieres,-Dep.-Mineral.,-Geochim.,-Analyses,-B.P.-6009-45060-Orleans-Cedex,-France)
SO: Geochim.-Cosmochim.-Acta, 1981 45(3), 363-379
LA: French
AB: The 'in vitro' metal fixation ability of a recent sedimentary organic matter of algal origin has been investigated with seven divalent cations (UOSUP-2+SUB-2, NiSUP-2+, MnSUP-2+, ZnSUP-2+, CoSUP-2+, PbSUP-2+, CuSUP-2+) and three anionic species (VOSUP--SUB-3, MoOSUP-2-SUB-4, GeOSUP-2-SUB-3). In the case of the cations, the great selectivity of the fixation, the independence of the amounts of metal fixed with regard to the cation exchange capacity of the organic matter and the existence of a 'pH effect', suggest the fixation mechanism to be a complexation chelation process. The similarities between the cation fixation capacity vs pH curves [in the 2 to (4-7) pH range] emphasize the existence of a common and determining step in the chelation mechanism for all the cationic species. This phenomenon is assessed to be an interaction between the cationic species and anionic carboxylate groupings. This first, non-selective, interaction is supposed to be followed by the formation of selective linkages between the metal and various organic functional groups.
AN: 1087920

                                                                     274 of 369  
TI: Experimental study in metal fixation by a recent sedimentary organic matter of algal origin. 1. Isolation, purification and characterization of the organic matter.
OT: Etude experimentale de la fixation de metaux par un materiau sedimentaire actuel d'origine algaire _ 1. Isolement, purification et caracterisation de la matiere organique.
AU: Disnar,J.-R.; Trichet,J.-(Bur.-Rech.-Geol.-Minieres,-Dep.-Mineral.,-Geochim.,-Analyses,-B.P.-6009-45060-Orleans-Cedex,-France)
SO: Geochim.-Cosmochim.-Acta, 1981 45(3), 353-362
LA: French
AB: In order to study the 'in vitro' fixation of metal ion species on algal and bacterial sedimentary organic matter, two algal mat samples have been studied. The main interest of this organic matter is its specific cyanobacterial origin. After isolation and purification, the organic matter was characterized by elemental and functional analysis, infrared spectroscopy, carbohydrates and amino-acid titration. These analyses indicate the richness of this type of organic matter in amino acids and carbohydrates, its poverty in aromatic structures, and to ascertain the types of bacteriological and chemical transformations undergone by the original biological compounds in the first steps of the diagenesis.
AN: 1087900

                                                                     275 of 369  
TI: Variations in the biological activity of the surface film in the course of the day.
OT: Variations de l'activite biologique du film superficiel au cours de la journee.
AU: Souza-Lima,Y.de; Daumas,R.-(Stn.-Mar.-d'-Endoume,-rue-de-la-Batterie-des-Lions,-13007-Marseille-Cedex,-France)
SO: Oceanis-Doc.-Oceanogr., 1981 6(2), 193-204
LA: French
ER: M (Marine)
AB: The presence of a great number of microorganisms at the surface film of sea water involves a great biological activity, either autotrophic or heterotrophic. Fluctuation in this biological activity during daytime is due mainly to special physical conditions such as solar radiation and the state of the sea. Measurements of the activity of the respiratory electron transport system (ETC), chlorophyll a concentrations and photosynthetic carbon fixation compared to biomass, suggest the migration of an important fraction of the biomass towards deeper layers, taking place mostly in the mid-afternoon, during summer.
AN: 0009200

                                                                     276 of 369  
TI: Excretion of dissolved organic phosphorus in tropical brackish waters.
AU: Lemasson,L.; Pages,J.-(Antenne-ORSTOM,-Station-INRA,-Avenue-de-Corzent,-74203-Thonon,-France)
SO: Estuar.-Coast.-Shelf-Sci., 1981 12(5), 511-523
LA: English
ER: B (Brackish)
AB: Dissolved organic phosphorus (DOP) release was measured on natural populations of a brackisk lagoon in the Ivory Coast (West Africa). DOP mean excretion is 8% of net phosphorus absorption, and represents 1.7% hSUP--1 of the biomass. Only 28% of biomass is involved in rapid uptake and excretion. Release of P is inversely proportional to the CSUB-p:NSUB-p ratio of the seston and the dissolved inorganic phosphorus concentration.
AN: 1087340

                                                                     277 of 369  
TI: Nutrient relationships in shallow water in an African lake, Lake Naivasha.
AU: Gaudet,J.J.; Muthuri,F.M.-(Univ.-Nairobi,-Dep.-Bot.,-PO-Box-30197,-Kenya)
SO: Oecologia, ISSN:-0029-8549 1981 49(1), 109-118
LA: English
ER: F (Freshwater)
AB: In the littoral zone of a shallow, tropical lake (Lake Naivasha, Kenya), average nutrient composition of emergent macrophytes along a permanent transect (0-2m depth) on a dry weight basis was: P 0.23%; N 0.96%; and S 0.11%. In the hydrosoil the average composition was much lower, sediments were: P 0.03%; N 0.24%; and S 0.05%. The water depth varied, with lake edge being exposed during the annual drawdown for a part of the year and subsequently being inundated. Water quality varied considerably during the year (temperature 19-28 C; pH 7.0-8.0; conductivity 282-975  ScmSUP--1). Of the three nutrients in the water of the littoral zone, N had the highest mean concentration (4.25 mg.lSUP--1) while P was intermediate (1.90) and sulphur had the least (0.99). The distribution of nutrients followed a decreasing gradient from shore to open water. High levels of nutrients were recorded in September following the inundation of drawdown soil and plant material. The large stock of nutrients generated in the littoral zone helps to replenish nutrients in the open lake where low concentrations are typical.
AN: 1010710

                                                                     278 of 369  
TI: Pathways of manganese in an open estuarine system.
AU: Sundby,B.; Silverberg,N.; Chesselet,R.-(Dep.-Oceanogr.,-Univ.-Quebec,-Rimouski,-Que.-G5L-3A1,-Canada)
SO: Geochim.-Cosmochim.-Acta, 1981 45(3), 293-307
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: The distribution of Mn was examined in the bottom sediments and water column (suspended particulate matter) of the Laurentian Trough, Gulf of St. Lawrence. A characteristic profile of Mn with depth in the sediment consisted of a Mn-enriched surface oxidized zone, less than 20 mm thick, and a Mn-depleted subsurface reducing zone. A subsurface Mn maximum occurred within the oxidized zone. Below this maximum the concentration dropped sharply to nearly constant residual levels in the reducing zone. The accumulating estuarine sediments are deficient in Mn compared to the river input of suspended matter and are definitely not the ultimate sink for manganese. Manganese escapes from the sediment by diffusion and resuspension, forming Mn-enriched, fine-grained particles which are flushed out in the estuarine circulation, 5.0 x 10SUP-9 g/yr of Mn, or 50% more than the river input of dissolved Mn, are exported to the open ocean. In spite of the efficient mobilization and export of Mn, the quantity exported is a small fraction (0.2%) of the total flux to the deep-sea sediments. This is related to the low levels of particulate matter transported by the St. Lawrence River. The export phenomenon, however, is probably true of many coastal regions of muddy sediments and thus has interesting implications for the oceanic budget of Mn.
AN: 1083800

                                                                     279 of 369  
TI: Microbial control of organic carbon in marine sediments: coupled chemoautotrophy and heterotrophy.
AU: Kepkay,P.E.; Novitsky,J.A.-(Dep.-Oceanogr.,-Dalhousie-Univ.,-Halifax,-NS,-B3H-4J1,-Canada)
SO: Mar.-Biol., 1980 55(4), 261-266
LA: English
ER: M (Marine)
AB: The chemoautotrophic fixation of carbon dioxide is responsible for an appreciable component of the organic matter apparent as a carbon-rich peak at 40 cm sub-bottom in the marine muds of Halifax Harbour, Nova Scotia, Canada. Dissolved oxygen and sulfide profiles show that the 40 cm horizon represents a transitional environment from aerobic to underlying anaerobic conditions. A dissolved sulfate maximum and pH minimum at 40 cm indicate that sulfur-oxidizing chemoautotrophs are associated with the organic carbon production at this horizon. The stimulation of COSUB-2-fixation by thiosulfate and inhibition by anaerobic conditions, ammonia, nitrate and nitrite further support the contention that sulfur-oxidizers are primary producers at this horizon. Heterotrophic activity data show that both aerobic and anaerobic heterotrophs are active in the sediments. These data, in conjunction with the measurement of COSUB-2-fixation and the calculation of organic carbon accumulation over time, show that the peak of organic carbon observed is residual carbon that is not heterotrophically recycled to COSUB-2 at the 40 cm horizon.
AN: 1006400

                                                                     280 of 369  
TI: Studies on calcium, magnesium and sulphate in the Mandovi and Zuari River Systems (Goa).
AU: Sen-Gupta,R.; Naik,S.-(Natl.-Inst.-Oceanogr.,-Dona-Paula,-Goa-403-004,-India)
SO: Indian-J.-Mar.-Sci., 1981 10(1), 24-34
LA: English
ER: B (Brackish)
AB: Distribution of calcium, magnesium and sulphate have been examined in the tide-dominated Mandovi and Zuari river systems. Calcium and magnesium appears to take some part in the bio-geochemical cycles of the rivers and behave as semi-conservative parameters. Sulphate, however, behaves in a purely conservative manner and remains in a steady state in the rivers. A 'Simple mixture' relationship is applied to calculate the dilution and mixing processes in the rivers using calcium, magnesium and sulphate as indicators, it has been observed that the percentages of sea water in the estuarine region of Mandovi vary from 88-92 during premonsoon, 12-23 during monsoon and 78-79 during postmonsoon. Similar figures for Zuari are 94-99, 27-43 and 79-91 during the 3 seasons. The possibility of loss of calcium and magnesium due to precipitation as their insoluble phosphates in the upper reaches of the rivers is discussed.
AN: 1006350

                                                                     281 of 369  
TI: Denitrification and formation of extreme concentrations of nitrate and nitrite nitrogen in the Peruvian Upwelling Zone.
AU: Sapozhnikov,V.V.; Sviridova,I.V.-(Address-not-stated)
SO: Oceanol.-Acad.-Sci.-USSR, 1979 19(3), 273-275
LA: English
ER: M (Marine)
AB: Processes involving the transformation of nitrogen compounds under anaerobic conditions in a layer of sharp oxygen minimum (<0.1 ml OSUB-2/l) are examined in the Peruvian upwellng zone. It is shown that bacterial nitrate reduction or denitrification result in an accumulation of nitrites and in an associated reduction in the amount of nitrates. According to the denitrification equation, an increase in the ammonium nitrogen stocks (reserves) should take place, but this does not occur. It is assumed that ammonium N is accumulated by nitrobacteria during the reduction of nitrates. A new denitrification equation without ammonium N in the right-hand part is presented.
AN: 1061100

                                                                     282 of 369  
TI: Methane oxidation in Lake Tanganyika (East Africa).
AU: Rudd,J.W.M.-(Dep.-Fish.-Oceans-Freshwater-Inst.,-501-University-Crescent,-Winnipeg,-Manitoba-R3T-2N6,-Canada)
SO: Limnol.-Oceanogr., 1980 25(5), 958-963
LA: English
ER: F (Freshwater)
AB: Methane oxidation rates were measured at 5 stations on Lake Tanganyika. Oxidation occurred mainly within a narrow zone at the bondary of the seasonally mixed layer and the permanently anoxic monimolimnion. Whole lake methane oxidation rates were estimated to have varied seasonally from 3.8 to 5.8 mmol CHSUB-4.mSUP-2.dSUP--1. The annual rate was tentatively estimated to be about 3.1 mmol CHSUB-4.mSUP--2.yrSUP--1, equivalent to at least 10% of annual primary productivity. Certain differences and similarities of methane cycling in Lakes Tanganyika and Kivu are compared to those in lakes of other types.
AN: 1057600

                                                                     283 of 369  
TI: Variations of stable hydrogen isotopes in plankton from a freshwater lake.
AU: Stiller,M.; Nissenbaum,A.-(Isot.-Dep.,-Weizmann-Inst.-Sci.,-Rehovot,-Israel)
SO: Geochim.-Cosmochim.-Acta, 1980 44(8), 1099-1101
LA: English
ER: F (Freshwater)
AB: The isotopic composition of the organically bonded hydrogen in microplankton and zooplankton samples collected monthly from Lake Kinneret during 1972 and 1973 ranges between -90 and -130o/oo. The temporal variations which have been observed in the deuterium content of the plankton samples, seem to be controlled by metabolic processes and not by variations in the temperature and in the deuterium content of the lake water. The organic material of the zooplankton is consistently enriched in deuterium, by about 20o/oo as copared to that of the phytoplankton.
AN: 1056790

                                                                     284 of 369  
TI: Polychlorinated biphenyls in sediments of the tidal Hudson River, New York.
AU: Bopp,R.F.; Simpson,H.J.; Olsen,C.R.; Kostyk,N.-(Lamont-Doherty-Geol.-Obs.,-Columbia-Univ.,-Palisades,-NY-10964,-USA)
SO: Environ.-Sci.-Technol., 1981 15(2), 210-216
LA: English
ER: B (Brackish); F (Freshwater)
AB: As the result of discharges of PBCs from two manufacturing facilities on the upper Hudson River between ca 1950 and 1976, recent sediments of the tidal Hudson have been contaminated to an average level of 10 ppm. This is 1-2 orders of magnitude higher than levels in a number of other large rivers and estuaries that have been studied. The degree of contamination decreases regularly with distance downstream from the source. Downstream changes in PCB composition along the axis of the Hudson can be understood qualitatively in terms of suspended matter-water partitioning of PCB components. The presence of SUP-137Cs in the sediments can be used as an independent indication of sediment deposition since the era of atmospheric testing of nuclear weapons. SUP-137Cs and PCB depth profiles in cores are used to determine a first-order PCB budget for sediments of the tidal Hudson and to indicate regional levels of PCB contamination prior to the large point-source discharges to the upper Hudson.
AN: 1050650

                                                                     285 of 369  
TI: Formation of C~SUB-4~-C~SUB-7~ hydrocarbons from bacterial degradation of naturally occurring terpenoids.
AU: Hunt,J.M.; Miller,R.J.; Whelan,J.K.-(Woods-Hole-Oceanogr.-Inst.,-Woods-Hole,-MA-02543,-USA)
SO: Nature, 1980 288(5791), 577-578
LA: English
ER: M (Marine)
AB: The authors found many light hydrocarbons, both alkanes and alkenes, in trace amounts (ng compound per g sediment) in recent marine sediments. These hydrocarbons are believed to originate from both biological and low-temperature reactions in the sediments. Understanding their mechanism of formation may allow use of these compounds to decipher the past biological and thermal history of the sediments. To investigate biological origins the authors cultivated mixed populations of bacteria on natural terpenoids and found, as degradation products, both alkanes and alkenes in the CSUB-1-CSUB-7 range; this is the first report of CSUB-4-CSUB-7 hydrocarbons being formed from microbial activities. Aerobic followed by anaerobic degradation yielded mainly small amounts of straight-chain alkenes. No such products resulted from blanks or controls. The results are consistent with products observed in natural environments.
AN: 1039240

                                                                     286 of 369  
TI: Transportation and enrichment of chlorinated phenolic compounds in different aquatic food chains.
AU: Paasivirta,J.; Sarkka,J.; Leskijarvi,T.; Roos,A.-(Dep.-Chem.,-Univ.-Jyvaskyla,-Kyllikinkatu-1-3,-40100-Jyvaskyla-10,-Finland)
SO: Chemosphere, 1980 9(7-8), 441-456
LA: English
ER: F (Freshwater)
AB: Food chain and sediment samples of 3 lake areas in Middle Finland were analyzed for their chlorophenol contamination using 12 model compounds which are main residues of chlorobleaching and wood preservation. Six of these compounds were commonly found. Statistical treatment of the analysis results indicate that tetrachloroguaiacol is the most potent biocide of the compounds studied.
AN: 1045470

                                                                     287 of 369  
TI: Phosphorus and nitrogen in the Mediterranean Sea, budgets and potential fertility. /
OT:  Le phosphore et l'azote en mer Mediterranee, bilans et fertilite potentielle.
AU: Bethoux,J.P.-(Lab.-Phys.-Chim.-Mar.,-Univ.-Paris-6,-ERA-CNRS,-Stn.-Mar.-BP8,-06230-Villefranche-sur-mer,-France)
SO: Mar.-Chem., 1981 10(2), 141-158
LA: French
ER: M (Marine)
AB: Owing to the P concentrations in the deep waters and the terrestrial discharges, the balance of this element requires low concentrations in the surface layers (<0.1 g P/l) which appear to be in agreement with the measured phosphate concentrations in the Strait of Gibraltar and in the Strait of Sicily. The P cycle in the Mediterranean Sea is characterised by the transfer of the terrestrial and Atlantic influxes from the surface layer to the intermediate and deep layers. The geographic distribution of the terrestrial discharges is highly asymmetric, and the vertical movements of the water masses in certain regions induce an important hydrologic recycling of P. The potential fertility is estimated from the local surface P flows and from the hydrologic recycling. Its values range, in the Western basin, between 9 and 86 g C/m/y in the Southern and Northern parts of this basin, respectively. In addition to biological reasons, the N budget in the Mediterranean Sea should be comparable to that of P because the geographical variations of the nitrate concentrations in the deep waters and the distribution of terrestrial discharges are similar to those of P. However, the relatively low values of terrestrial discharges of N proposed by UNEP do not allow a balance of this nutrient unless a high concentration in the Atlantic surface waters is introduced.
AN: 1049550

                                                                     288 of 369  
TI: Physico-chemical processes of silicates in the estuarial region. 4. An analysis of the mechanism of removal of reactive silicate in the estuarial region.
AU: Li,F.-(Dep.-Oceanogr.,-Xiamen-Univ.,-China)
SO: Acta-Oceanol.-Sin., 1980 2(1), 43-56
LA: Chinese
ER: B (Brackish)
AB: The controversy among recent investigators on the problem whether there is any extent of inorganic removal of reactive silicate in the estuarial regions is reviewed and discussed on appropriate theoretical, experimental, and in situ observational bases. A mathematical model based on mixing ratios of different water sources has been proposed, and theoretical equations for reactive silicate vs chlorosity relations for various cases have been derived, assuming reactive silicate to be a conservative constituent. The extent of silicate removal may then be estimated. Arguments have been admitted about the inference drawn by Wollast and De Broeu, and also by Fanning and Pilson, that the silicate removal is mostly biological. It is suspected whether the results of the laboratory experiments by the above authors can ever rule out the possibility of significant inorganic removal. As in parts II and III of this series of papers, the simulation experiments showing the occurrence of chemical adsorption of soluble silicate on colloidal Fe(OH)SUB-3 and Al(OH)SUB-3 precipitates, and the analytical data of the suspended matter in the estuarial waters showing the stoichiometric ratios between the 'authigenic' Si, Fe and Al contents and the smaller amount of organic Si than that of 'authigenic' inorganic Si in the suspended matter, have given good evidence for the occurrence of inorganic removal of reactive silicate and also the possibility of transforming into certain kinds of more stable silicate compounds of Al and or Fe after removal.
AN: 1004790

                                                                     289 of 369  
TI: Methylmercury production in the marine water column.
AU: Topping,G.; Davies,I.M.-(Dep.-Agric.-Fish.-Scotland,-Mar.-Lab.,-Victoria-Rd.,-Aberdeen-AB9-8DB,-UK)
SO: Nature, 1981 290(5803), 243-244
LA: English
AB: Although the biosynthesis of methylmercury in sediments is well established, this is not necessarily the exclusive natural source of methylmercury entering the marine food chain, particularly commercial fish and shellfish species for human consumption. An examination of mercury levels in freshwater fish, collected from a lake with a history of industrial mercury contamination, suggested that levels in fish are controlled in part by mercury in suspension and it followed that methylation should occur in the water column. Although methylmercury is present in seawater in coastal areas receiving discharges of waste containing either inorganic mercury or methylmercury there is no evidence that methylmercury is actually formed in the water column. The authors present data which demonstrate that inorganic mercury can be methylated in the water column and compare this production with that known to occur in marine sediments.
AN: 1055330

                                                                     290 of 369  
TI: Inorganic lead complexation in natural seawater determined by UV spectroscopy.
AU: Byrne,R.H.-(Dep.-Mar.-Sci.,-Univ.-South-Florida,-St-Petersburg,-FL-33701,-USA)
SO: Nature, 1981 290(5806), 487-489
LA: English
ER: M (Marine)
AB: Recent effort to construct trace metal complexation models in natural media is a mark of the importance of chemical form in the biogeochemical behaviour of trace metals. Unfortunately such chemical modelling is difficult in many ways. Chemical speciation models of trace metals in complex natural media such as seawater are usually constructed using stability constants determined in simple media. The authors describe an alternative procedure which can reduce the errors inherent in this approach. Using UV spectroscopy, lead speciation in seawater is examined. The method is a means of describing metal speciation in seawater quantitatively using stability constants determined exclusively in seawater. Preliminary experiments indicate that the same approach can be used for other metals including copper.
AN: 1055320

                                                                     291 of 369  
TI: Arsenic cycling in marine systems.
AU: Sanders,J.G.-(Woods-Hole-Oceanogr.-Inst.,-Woods-Hole,-MA-02543,-USA)
SO: Mar.-Environ.-Res., 1980 3(4), 257-266
LA: English
ER: M (Marine)
AB: The arsenic cycle in productive, near-shore marine systems is complex, involving both geochemical inputs and outflows and biological mediation. The major input to the Georgia Bight is intrusion of subsurface Gulf Stream water; in other marine systems, river run-off and atmospheric deposition may provide a large percentage of the arsenic input. Indiscriminate biological uptake is responsible for changes in arsenic speciation, involving approximately 20% of the dissolved arsenate pool and resulting in measurable concentrations of reduced and methylated arsenic species. The overall cycle is similar to the phosphate cycle; however, regeneration time for arsenic is much slower.
AN: 0009740

                                                                     292 of 369  
TI: Pathways and mechanisms for removal of dissolved organic carbon from leaf leachate in streams.
AU: Dahm,C.N.-(Dep.-Fish.-Wildl.,-Oregon-State-Univ.,-Corvallis,-OR-97331,-USA)
SO: Can.-J.-Fish.-Aquat.-Sci., 1981 38(1), 68-76
NT: Incl. bibliogr.: 51 ref.
LA: English
ER: F (Freshwater)
AB: Removal of dissolved organic carbon (DOC) from water resulting from adsorption and microbial uptake was examined to determine the importance of biotic and abiotic pathways. Physical-chemical adsorption to components of the stream sediment or water and biotic assimilation associated with the microbial population was determined in recirculating chambers utilizing leachate from alder (Alnus rubra-). Adsorptive mechanisms were further separated into interactions involving (1) specific clay minerals, (2) amorphous solid phases of hydrous aluminum and iron oxides; and (3) fine particulate organic matter. Physical-chemical adsorptive mechanisms for alder leachate removal exhibited rapid kinetic equilibration between the DOC and solid phases, but only a specific fraction of the DOC, likely containing certain chemical functional groups, was adsorbed. The amorphous aluminum and iron oxides possessed a much higher potential capacity than the clay minerals or fine particulate organics for DOC adsorption,. Microbial uptake of DOC from the alder leachate was kinetically slower than adsorptive uptake. However, microbial activity was overall much more effective in the removal and degradation of the total DOC pool leached from alder leaves. Over a 48-h period, 97% of added U1SUP-4C labeled leachate was removed from solution by adsorption (ca. 20%) and microbial utilization (ca. 77%). The rate of microbial uptake was 45 g C/g sediment C/h or 14 mg C/mSUP-2/h.
AN: 1000090

                                                                     293 of 369  
TI: Adenosine triphosphate and adenylate energy charge in marine sediments.
AU: Christensen,J.P.; Devol,A.H.-(Univ.-Washington,-Coll.-Fish.,-WH-10,-Seattle,-WA-98195,-USA)
SO: Mar.-Biol., ISSN:-0025-3162. 1980 56(3), 175-182
LA: English
ER: M (Marine)
AB: The determination of adenosine triphoshate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP) concentrations in sediments from both Puget Sound and the Washington State continental shelf (USA) has been investigated. Major losses during the extracton procedure included sediment sorption, coprecipitation, and unreactivity of the soluble adenylates presumably through irreversible binding to solubilized sediment organics. Addition of phosphoric acid and the non-ionic detergent Triton X-100 to cold sulfuric acid significantly increased the extraction efficiency and sensitivity over that of sulfuric acid alone, although both methods yielded similar results when corrected for losses. Vertical profiles of ATP, total adenylates (ASUB-T), and adenylate energy charge (EC) in sediments from both areas are presented. Profiles of ASUB-T are similar in both areas, but EC values in the shelf sediments are significantly lower, which suggests a depressed physiological condition in the shelf population relative to that in Puget Sound.
AN: 1005280

                                                                     294 of 369  
TI: Concentration and microbiological utilization of small organic molecules in the Scheldt estuary, the Belgian coastal zone of the North Sea and the English Channel.
AU: Billen,G.; Joiris,C.; Wijnant,J.; Gillain,G.-(Lab.-Oceanogr.,-Univ.-Bruxelles,-Brussels,-Belgium)
SO: Estuar.-Coast.-Mar.-Sci., 1980 11(3), 279-294
LA: English
ER: M (Marine); B (Brackish)
AB: Concentrations and utilization rates of alanine, aspartate, lysine, glucose, glycollic, acetic and lactic acids have been determined on 6 occasions at least, during a full seasonal cycle in the water column of 3 stations (Scheldt estuary, coastal North Sea and English Channel) with greatly differing biological characteristics. No significant differences in substrate concentration could be detected between the 3 stations, although the rate of utilization of all substrates differed greatly, decreasing in the order estuarine > coastal > open sea environment. This apparent paradox is explained by aid of a simple model showing that the steady state concentration of a particular substrate is independent of its rate of production (and thus of consumption) and depends only on purely physiological characteristics of the bacteria. Using published data for the pertinent physiological parameters of marine bacteria, the model accounts for at least the order of magnitude of substrate concentrations observed, and the absence of important seasonal variations.
AN: 1038060

                                                                     295 of 369  
TI: Phosphate uptake by phytoplankton in the central North Pacific Ocean.
AU: Perry,M.J.; Eppley,R.W.-(Oceanogr.-Dep.,-Washington-Univ.,-Seattle,-WA-98195,-USA)
SO: Deep-Sea-Res., 1981 28(1A), 39-49
LA: English
ER: M (Marine)
AB: The central North Pacific Ocean (CNP) is an oligotrophic environment characterized by low concentrations of plankton biomass and of dissolved nitrogen and phosphorus compounds. The dynamics of phosphorus utilization was examined to test the hypothesis that phosphorus controlled phytoplankton growth rates. Rates of phosphate uptake were measured in natural assemblages using SUP-33P-phosphorus and were compared with rates of SUP-15N-nitrogen and SUP-14C-carbon assimilation. Phosphate uptake was linear over 24 h. Turnover times for phosphate averaged 28 d in Feb, 19 d in June, and 31 d in Dec. Zooplankton regeneration accounted for 55 to 183% of the daily phytoplankton phosphate requirement. Growth rates of phytoplankton in the mixed layer, calculated from SUP-33P-phosphorus uptake, were 9% of the maximum rate at ambient central North Pacific temperatures and averaged 0.14 doublings/d. Assimilation ratios of C, N, and P suggested nitrogen-limited, rather than phosphorus-limited, growth. Physiological adaptions, such as low KSUB-m for phosphate uptake, light-independence of uptake, and derepressible alkaline phosphatase, may prevent the onset of phosphorus stress.
AN: 1004610

                                                                     296 of 369  
TI: The mean residence time of plankton-derived carbon in a Long Island Sound sediment core: a correction.
AU: Turekian,K.K.; Benoit,G.J.; Benninger,L.K.-(Dep.-Geol.-Geophys.,-Yale-Univ.,-New-Haven,-CT-06520,-USA)
SO: Estuar.-Coast.-Mar.-Sci., 1980 11(5), 583
LA: English
ER: M (Marine)
AB: An error is reported and corrected with reference to a recent paper by the authors (Estuarine and Coastal Mar. Sci. 10, p. 178 (1979)). The value of 28 days for the mean residence time relative to metabolic regeneration of plankton-derived carbon in the top 5 cm of a Long Island Sound sediment core is now corrected to 2.2 years, and a revised equation is given.
AN: 1047700

                                                                     297 of 369  
TI: Removal of 'soluble' iron in the Potomac River Estuary: a reply.
AU: Eaton,A.-(J.M.-Montgomery,-Inc.-555-E.-Walnut-St.,-Pasadena,-CA-91101,-USA)
SO: Estuar.-Coast.-Mar.-Sci., 1980 11(5), 589-591
LA: English
ER: M (Marine); B (Brackish)
AB: Sholkovitz (1980) states that the observations of Eaton (1979) on freshwater removal of soluble Fe in the Potomac River actually represent cation coagulation at very low salinities. It is shown here that the salinity does not change over the region of Fe removal and thus the original hypotheses of Eaton (1979) are a better explanation in this case.
AN: 1038020

                                                                     298 of 369  
TI: Removal of 'soluble' iron in the Potomac River Estuary: comments.
AU: Sholkovitz,E.R.-(Univ.-Edinburgh,-Grant-Inst.-Geology,-West-Mains-Rd.,-Edinburgh-EH9-3JW,-UK)
SO: Estuar.-Coast.-Mar.-Sci., 1980 11(5), 585-587
LA: English
ER: M (Marine); B (Brackish)
AB: Eaton (1979) states that the removal of soluble Fe in the Potomac River estuary does not result from the coagulation of Fe-colloids by seawater cations but rather by the destabilizing action of 'bacterial polymers'. The data of Eaton are used to demonstrate that the removal mechanism is cation coagulation, the same process as observed in other estuaries.
AN: 1038010

                                                                     299 of 369  
TI: Annual oxygen balance in the World Ocean.
OT: Godovoj balans kisloroda v Mirovom okeane.
AU: Ivanenkov,V.N.-(Inst.-Okeanol.-AN-SSSR.,-Moscow,-USSR)
SO: Okeanologiya, ISSN-0030-1574 1980 (no. 4), 637-644
NT: Incl. bibliogr.: 39 ref.
LA: Russian
ER: M (Marine)
AB: The annual oxygen balance in the World Ocean averages 212.10SUP-9t/year made up of (a) supply: 154.10SUP-9t/year produced through photosynthesis, 55.10SUP-9t/year absorbed from the atmosphere, 3.10SUP-9t/year arriving with rain and river water and (b) expenditure: 151.10SUP-9t/year for biochemical oxygen consumption and 61.10SUP-9t/year for release to the atmosphere. These oxygen balance components have a 10-15% error. The resultant of the annual ocean-atmosphere oxygen exchange (release to the atmosphere) amounts to 6.510SUP-9t/year which is ca. 4% of the annual oxygen production through photosynthesis. The annual oxygen balance is 170.10SUP-9t/year for the Atlantic and 4.10SUP-9t/year in the Arctic Ocean, the oxygen exchange between the oceans (which is not taken into account in estimating the annual oxygen balance in the World Ocean) being 24, 53, 59 and 80% respectively of the above annual oxygen balance values in the oceans.
AN: 1000940

                                                                     300 of 369  
TI: Biogeochemical investigations of some continental water systems in Yugoslavia by instrumental activation analysis.
AU: Draskovic,R.J.; Draskovic,R.S.-(Boris-Kidric-Inst.-Nucl.-Sci.,-Vinca,-Lab.-Radioisotopes,-Beograd,-POB-522,-Yugoslavia)
SO: J.-Radioanal.-Chem., 1980 58(1-2), 275-280
LA: English
ER: F (Freshwater)
AB: The theoretical approaches to the biogeochemical examination of continental water systems in Yugoslavia are discussed. These water systems have been characterized by the parameters (partial and integral contents of elements CSUB-X) of the components of these systems, vir. living and non-living matter (non-living matter: materials dissolved in water CSUB-W, suspended and bed materials CSUB-sm and CSUB-bm, soil in the rivers basin CSUB-s; living matter CSUB-vivo; plankton CSUB-p, alga CSUB-al, benthos CSUB-b, shells and crustacea CSUB-sc, fish CSUB-f). The values of the integral contents of Cr, Sb, Sc, Fe, Co, La and Na in the components of the rivers Danube, Sava, V. Morava, Tisa and Karas are presented and discussed.
AN: 1025860

                                                                     301 of 369  
TI: The behavior of ~SUP-14~C and ~SUP-13~C in estuarine water: effects of in situ CO~SUB-2~ production and atmospheric exchange. /[Proceedings of:- 10. International Radiocarbon Conference; Heidelberg (GFR); 19 Aug 1979].
AU: Spiker,E.C.-(US-Geol.-Surv.,-Reston,-VA-22092,-USA)
CO: /[Proceedings of:- 10. International Radiocarbon Conference  Heidelberg (GFR)  19 Aug 1979].
SO: Radiocarbon, 1980 22(3), 647-654
LA: English
ER: B (Brackish)
AB: The effects of nonconservative sources (inputs) and sinks (outputs) of carbon are indicated by the behavior of SUP-14C and SUP-13C of the total dissolved inorganic carbon (|COSUB-2) in San Francisco Bay and Chesapeake Bay. Isotopic distributions and model calculations indicate that in North San Francisco Bay the net COSUB-2 flux to the atmosphere and carbon utilization in the water column are balanced by benthic production. Municipal waste appears to be a dominant source in South San Francisco Bay. In Chesapeake Bay, atmospheric exchange has increased the SUP-14C and SUP-13C in the surface water. Decomposition of organic matter in the water column is indicated to be the dominant source of excess |COSUB-2 in the deep water.
AN: 1024510

                                                                     302 of 369  
TI: Biogeochemical cycling in an organic rich coastal marine basin. II. Nutrient sediment-water exchange processes.
AU: Val-Klump,J.; Martens,C.S.-(Cent.-Great-Lakes-Stud.,-Univ.-Wisconsin-Milwaukee,-Milwaukee,-WI-53201,-USA)
SO: Geochim.-Cosmochim.-Acta, 1981 45(1), 101-121
LA: English
ER: M (Marine)
AB: The release of remineralized N and P from the organic-rich anoxic sediments of Cape Lookout Bight is controlled by processes occurring within the sediment column and at the sediment-water interface. The relatively rapid rates of temperature dependent microbial degradation of organic matter support seasonally varying nutrient fluxes ranging from 20 to 1200 mol/mSUP-2/h for dissolved ammonium and from -20 to 120 mol/mSUP-2/h for total dissolved phosphate (measured in situ over the period Oct, 1976 to Oct 1978). Gradients for ammonium and phosphate ranged from 0.33 to 1.10 and from 0 to 0.29 mol/cmSUB-pwSUP-3/cmSUB-s, respectively. These high summertime fluxes appear to result from increased sediment-water transport associated with bubble tubes created and maintained by low-tide methane gas bubble ebullition. When these tubes are present, apparent bulk sediment diffusivities calculated from concurrent studies of methane and radon-222 sediment-water exchange are 1.0-3.1 times greater than molecular diffusivities. Nutrient fluxes calculated via Fick's first law indicate that removal by aerobic adsorption and/or biological uptake at the sediment-water interface plays an important role in controlling nutrient exchange in these sediments.
AN: 1038200

                                                                     303 of 369  
TI: A hydrogeochemical survey of the chalk groundwater of the Banstead area, Surrey, with particular reference to nitrate.
AU: Young,G.P.; Morgan-Jones,M.-(Resour.-Div.,-Water-Res.-Cent.)
SO: J.-Inst.-Water-Eng.-Sci., 1980 34(3), 213-236
LA: English
ER: F (Freshwater)
AB: Concentrations of nitrate close to, or exceeding WHO's recommended European standard (11.3 mg N/L) have been measured in groundwater from a number of chalk sources in the UK in the last decade. A research programme was initiated in 1974 by the Water Research Centre with the objectives of (1) determining the extent of nitrate pollution in main UK aquifers; and (2) identifying and, if possible, quantifying the factors responsible for the accumulation, convection, and dispersion of nitrate within the aquifers. This paper records investigtions west of Central London in the Sutton District Water Co. supply catchment. The groundwater was shown to be of typical CaHCOSUB-3 type. A seasonal variation in the concentrations of certain solutes indicates that a proportion of the recharge moves rapidly from the surface to the water table. With the exception of Pb trace metals showed no significant variations. Evidence suggests nitrate rich groundwater is generally restricted to the upper layers of the water table. Two possible sources of nitrate were identified as mineralization of soil organic material arising from urbanization of the northern part of the area and the increase in arable farming, with more extensive use of fertilizers after World War 2.
AN: 1013520

                                                                     304 of 369  
TI: Biogeochemical processes affecting metal concentrations in lake sediments (IJsselmeer, The Netherlands).
AU: Salomons,W.; Mook,W.G.-(Delft-Hydraulics-Lab.,-Haven-Branch,-Oosterweg-92,-9751-PK-Haren,-Gr.,-Netherlands)
SO: Sci.-Total-Environ., 1980 16(3), 217-229
LA: English
ER: F (Freshwater)
AB: The IJsselmeer originated in 1932 when a former coastal lagoon was shut off from the North Sea. Its main source of water and sediments is from the highly polluted river Rhine. The lake acts as a sink not only for particulate trace metals, but also for the dissolved metals; especially dissolved zinc, chromium and cadmium are held back in the lake. For these metals field and laboratory experiments revealed a correlation between pH and element concentrations where adsorption strongly depends on the pH within the range 7-9 observed in the IJsselmeer. Algae account for about 4-14% of the removal cadmium, chromium, zinc and copper. In the mouthing area of the river IJssel, metal concentrations in the sediments are determined by physical (mixing of lake and river sediments) and by chemical processes (adsorption). Mixing of the sediments has been quantitatively studied with the aid of natural stable isotope tracers. Between 1932 and 1974 trace metal concentrations in the sediments show increases between 25% (chromium) and 600% (cadmium). Organic matter concentrations increased by 140%, calcium carbonate by300% and phosphorus by 600%.
AN: 1012530

                                                                     305 of 369  
TI: Marsh plants as vectors in trace metal transport in Oregon tidal marshes.
AU: Gallagher,J.L.; Kibby,H.V.-(Coll.-Mar.-Stud.,-Univ.-Delaware,-Lewes,-DE-19958,-USA)
SO: Am.-J.-Bot., 1980 67(7), 1069-1074
LA: English
ER: B (Brackish)
AB: The role of Pacific coast marsh plants as vectors in the flux of trace metals was studied in natural and perturbated situations. The flux of Cr, Cu, Fe, Mg, Sr, and Zn were studied in natural stands of Carex lyngbyei, Distichlis spicata, Potentilla pacifica-, and Salicornia virginica-. Seasonal fluxes of trace metals into the shoots of the living plants were measured as was their transfer to the dead plant community through mortality. Disappearance from the latter community (through fragmentation, leaching and excretion) was calculated. Seasonal data were summed to produce annual input-output budgets. The flux varied from 3 mg/mSUP-2 for Cr in a stand of Potentilla pacifica- to 15000 mg/mSUP-2 for Fe in Carex lyngbyei-). The uptake of trace metals from contaminated dredged material was compared with that from natural soils using modified buckets placed in the marsh. Four plants (C. lyngbyei, D. spicata, Deschampsia cespitosa-, and S. virginica-) were tested for Cd, Cr, Cu, Pb and Zn. Copper was the only metal accumulated from contaminated soils in the situations tested.
AN: 1008250

                                                                     306 of 369  
TI: Relationships between microbial distributions and the anaerobic decomposition of organic matter in surface sediments of Long Island Sound, USA.
AU: Aller,R.C.; Yingst,J.Y.-(Dep.-Geophys.-Sci.,-Univ.-Chicago,-5734-South-Ellis-Ave.,-Il-60367,-USA)
SO: Mar.-Biol., 1980 56(1), 29-42
LA: English
ER: M (Marine)
AB: Relative rates of the anaerobic decomposition of organic matter in the upper 10 cm of sediment from two stations in central Long Island Sound, USA, were compared. Sediment samples from discrete depth intervals were incubated anoxically and changes in SOSUB-4SUP-2-, NHSUB-4SUP-+, bacterial numbers, extractable adenosine triphosphate (ATP), organic matter, and organic carbon were measured as a function of time and temperature. At both stations (15 and 34 m water-depths, respectively), the calculated rates of SOSUB-4SUP-2- reduction and NHSUB-4SUP-+ production decreased exponentially with depth. Over the same depth interval, ATP concentrations dropped by a factor of 6-7 and bacterial numbers were lower by a factor of 2-3. These decreases reflect a change in the physiological state of microbial populations with depth in the sediment and are consistent with the conclusions that the quantity of easily utilizable organic matter changes rapidly below the sediment surface and that food limitation controls the basic depth distribution of microbial activity. The average rates of SOSUB-4SUP-2- reduction, 29-39 mM/yr (22 C), in the top 10 cm are similar at both stations studied here, as well as at an additional station from a previous study. In contrast, average NHSUB-4SUP-+ production differs by a factor of 2 at the two stations, reflecting differences in the C:N ratio of the organic matter supplied to the sediment surface and differences in particle reworking by macrofauna at each site.
AN: 0010380

                                                                     307 of 369  
TI: Inorganic transformation of applied phosphorus in brackishwater fish pond soil under different water salinity levels.
AU: Chattopadhyay,G.N.; Mandal,L.N.-(Central-Inland-Fish.-Res.-Inst.,-Barrackpore,-West-Bengal,-India)
SO: Hydrobiologia, 1980 71(1-2), 125-130
LA: English
ER: B (Brackish)
AB: Transformation of applied P was studied as occurring in such ponds, in presence and in absence of added organic matter. Added P disappeared rapidly from the water phase with some variations under different water salinities. The amount of added P in saloid-bound form increased with increase in water salinity but the same in Bray's (No. 2) extractable form showed a reverse trend. Applied P was transformed mostly into insoluble calcium phosphate form which increased with increase in water salinity. Transformation was intermediate into iron phosphate and the least into aluminium phosphate form. Application of organic matter reduced the fixation of added P into the iron phosphate form during the initial period ofstudy and thus increased availability of P both in water as well as soil phases.
AN: 0133460

                                                                     308 of 369  
TI: Bacterial catalysis of the oxidation of manganous manganese in natural waters. Geochemical implications.
OT: Catalyse bacterienne de l'oxydation du manganese manganeux dans les eaux. Consequences geochimiques.
AU: Boulegue,J.; Renard,D.-(Lab.-Geochim.-Eaux,-CNRS-LA-no-196,-Univ.-Paris-VII,-2,-place-Jussieu,-75221-Paris-Cedex-05,-France)
SO: C.-R.-Hebd.-Seances-Acad.-Sci.,-Paris,-Ser.-D, 1980 290(17), 1165-1168
LA: French
ER: M (Marine)
AB: The kinetics of oxidation of manganous manganese in some natural waters is increased 10,000 times as compared with chemical oxidation under abiotic conditions. This is due to bacteria which catalyse the oxidation. The possibility of the presence of such bacteria in the vicinity of mid-oceanic ridges may explain the high deposit rates observed.
AN: 0110420

                                                                     309 of 369  
TI: The geochemical and paleoecological significance of silicon accumulator plants in southeastern salt marshes. /[Presented at:- 44. Annual meeting of the Academy; Tampa, FL (USA); 23 Mar 1980].
AU: Andrejko,M.J.; Cohen,A.D.-(Dep.-Geol.,-Univ.-South-Carolina,-Columbia,-SC-29208,-USA)
CO: /[Presented at:- 44. Annual meeting of the Academy  Tampa, FL (USA)  23 Mar 1980].
SO: Fla.-Sci., 1980 43(suppl. 1), 43
NT: Summary only.
LA: English
ER: B (Brackish)
AB: The coastal salt marshes of the southeastern U.S. are basically dominated by two main plants, Spartina alterniflora- in the low marsh, and Juncus roemerianus- in the high marsh. Earlier studies have shown that tidal creek waters in the low marsh become enriched in dissolved silica during low tide discharge. This may be possibly due to the decomposition of plant organic matter and the dissolution of biogenic silicates on the marsh surface. With this in mind, the purpose of this study was to determine the extent to which both Spartina- and Juncus- might behave as reservoirs for future silicon recycling from the decomposition of both in-situ and storm transported plant debris. In addition, the silicon bodies (phytoliths) deposited within the plants themselves were isolated and identified so as to be useful for environmental interpretation of Holocene clayey sediments associated with buried and exposed peat bodies on the Southeastern Coastal Plain.
AN: 0141800

                                                                     310 of 369  
TI: MELIMEX, an experimental heavy metal pollution study: regulation of trace metal concentrations in limno-corrals.
AU: Baccini,P.; Ruchti,J.; Wanner,O.; Frieder,E.-(EAWAG/ETH,-CH-6047-Kastanienbaum,-Switzerland)
SO: Schweiz.-Z.-Hydrol.-Rev.-Suisse-Hydrol.-Swiss-J.-Hydrol., 1979 41(2), 202-227
LA: English
ER: F (Freshwater)
AB: In three limno-corrals of the MELIMEX project the transport paths of the trace metals Cu, Zn, Cd, Hg and Pb and the reaction of the systems on increased metal loads were investigated. The metal balances lead to the conclusion that the biomass is the main factor responsible for the regulation of trace metal concentration. The observed sequence of relative residence times of the trace metals can be described with a steady-state model. Additional metal load decreases the ability of the limnic system to lower the metal concentration. The production of phytoplankton and its assimilation capacity for metals are reduced leading to relatively higher metal concentrations in the lake.
AN: 0005640

                                                                     311 of 369  
TI: Hydrographic features of the deep water of the Bering Sea _ the Sea of Silica.
AU: Tsunogai,S.; Kusakabe,M.; Iizumi,H.; Koike,I.; Hattori,A.-(Hokkaido-Univ.,-Chem.-Dep.,-Hakodata,-Japan)
SO: Deep-Sea-Res., 1979 26(6A), 641-659
LA: English
ER: M (Marine)
AB: The deep water of the Bering Sea contains concentrations of dissolved silicate up to 240 g at. Si/l. Nitrate concentrations are less than in the North Pacific at the depths with the same oxygen contents. The rate of chemical and biochemical reactions occurring in the deep water (below 2 km) were estimated from hydrographic data by applying a modified one-dimensional model. Oxidation of organic matter in the oxygenated water column of the Bering Sea was twice that of the North Pacific. Silicate regeneration, or dissolution of biogenic opal and denitrification, or bacterial nitrate reduction to gaseous nitrogen, on and in the bottom sediments of the deep Bering Sea basin were calculated to be 212 and 20 mg at/mSUP-2/yr, respectively. These values are consistent with the ones estimated from vertical profiles of dissolved silicate and nitrate in the interstitial water of the sediments. The chemical anomaly observed in the deep water of the Bering Sea can be produced by these reactions in the bottom sediments. The decomposition of organic matter in anoxic sediments accounts for about 8% of the total organic matter decomposing in the water column below 2 km and in the sediments.
AN: 0007230

                                                                     312 of 369  
TI: Specificities of the distribution and dynamics of nitrate nitrogen in the waters of the Bulgarian sector of the Black Sea.
AU: Rojdestvensky,A.V.-(Address-not-stated)
SO: Okeanologiya-Oceanology,-Sofia, 1980 vol. 6, 30-36
LA: Bu
ER: M (Marine)
AB: The mean distribution of nitrate nitrogen in the surface waters is presented on the basis of investigtions over many years. The general tendency is decrease of the content with increasing the distance to the shore, though local zones of increased or reduced content are observed depending on hydrological and biological factors. The characteristic seasonal patterns of the distribution are outlined along the vertical. In winter there is deep wedging of the nitrate-containing near-shelf waters in the region of the shore slope and upward pushing of the deep waters containing hydrogen sulphide and contaning no nitrates in the regions situated closer to the central part of the sea. In spring considerable nitrate uptake is observed in the upper photic layers, while the isolines of nitrate nitrogen show a tendency towards sloping position; the denitrification process is intensified in the deep-water layers. In summer the two processes are intensified, especially in the deep-water part remote from the shelf. In autumn there is again an increase of the nitrate content and downward movement of the near-shelf waters. On the basis of the data about the nitrate distribution it may be concluded that the autumn-winter descent and wedging of the near-shelf waters in different depth horizons plays a considerable role in the total vertical circulation of the Black Sea waters.
AN: 0134830

                                                                     313 of 369  
TI: Removal of ~SUP-234~Th from a coastal sea: Funka Bay, Japan.
AU: Minagawa,M.; Tsunogai,S.-(Mitsubishi-Kasei-Inst.-Life-Sci.,-Minami-Ohya,-Machida,-Tokyo-194,-Japan)
SO: Earth-Planet.-Sci.-Lett., 1980 47(1), 51-64
LA: English
ER: M (Marine)
AB: In Funka Bay of Hokkaido, Japan, seawater, suspended matter and settling matter were collected once every month in the summer of 1974. These samples were analyzed for SUP-234Th, a short-lived daughter of dissolved SUP-238U. A pronounced disequilibrium between SUP-234Th and SUP-238U, and a highly variable concentration of SUP-234Th were found. Positive correlation, however, exist among the deficiency of SUP-234Th relative to SUP-238U in seawater, the concentration of particulate SUP-2U3SUP-4Th, the fraction of particulate SUP-234Th to total SUP-234Th in seawater, the total dry weight of suspended matter, and the primary productivity during the month previous to sampling. The specific activity of SUP-234Th for the settling particles (620  170 dpm/g) was nearly equal to that for suspended particles (720  600 dpm/g) but much greater than that for plankton (47  24 dpm/g). These facts suggest that suspended particles are somehow closely related to the removal of heavy metals from seawater, in spite of the negligibly small settling flux of suspended matter. The residence time of thorium in Funka Bay (mean depth: 60 m) is found to be about 60 days, which is nearly equal to those of SUP-210Pb and SUP-210Po.
AN: 0114670

                                                                     314 of 369  
TI: The seasonal variation in the nutrient chemistry of the surface microlayer of Galway Bay, Ireland.
AU: Berry-Lyons,W.; Pybus,M.J.S.; Coyne,J.-(Dep.-Oceanogr.,-Univ.-College,-Galway,-Eire)
SO: Oceanol.-Acta, 1980 3(2), 151-155
LA: English
ER: M (Marine)
AB: Surface microlayer samples and bulk water samples 50 cm below the surface were collected over a 20 month period at three regular stations in Galway Bay, Ireland. Phosphate enrichments coincided with spring phytoplankton blooms while reactive silicate and nitrate enrichments were associated with high chlorophyll a values in the sub-surface water. The data suggest that in Galway Bay, the largest nutrient enrichments in the surface microlayer are caused by biological activity.
AN: 0004970

                                                                     315 of 369  
TI: Biotic and abiotic parameters affecting diversity in modern and ancient benthic diatom assemblages of Florida. /[Presented at:- 43. Annual Meeting of the Florida Academy of Sciences; Miami, FL (USA); 22 Mar 1979].
AU: Defelice,D.; Lynts,G.-(Dep.-Geology,-FSU,-Tallahassee,-FL-32306,-USA)
CO: /[Presented at:- 43. Annual Meeting of the Florida Academy of Sciences  Miami, FL (USA)  22 Mar 1979].
SO: Fla.-Sci., 1979 42(1, suppl.), 44
NT: Summary only.
LA: English
ER: M (Marine)
AB: Study of benthic diatom communities in Florida Bay reveals that diversity in living diatom populations is a function of several biotic and abiotic parameters. Among the most important of these parameters is substrate, light quality, sediment particle size, and distance from land. Examination of a core recovered from Florida Bay shows that although diatoms are quite common in surface sediment, they are absent immediately below the surface horizon, leaving sponge spicules as the only siliceous biogenic components in the sediment. Florida Bay, as a shallow water carbonate environment, is extremely undersaturated with respect to silica in the water column and at the sediment-water interface. It is believed that diatoms dissolve almost immediately after death, allowing for quick recycling and reutilization of silica in a silica starved environment. Rapid dissolution and recycling would subsequently impede any accumulation of dissolved silica in interstitial pore waters.
AN: 0129160

                                                                     316 of 369  
TI: Oceanographic distributions of cadmium, zinc, nickel, and copper in the North Pacific.
AU: Bruland,K.W.-(Cent.-Coast.-Mar.-Stud.,-Div.-Nat.-Sci.,-Univ.-California,-Santa-Cruz,-CA-95064,-USA)
SO: Eart-Planet-Sci.-Lett., 1980 47(2), 176-198
LA: English
ER: M (Marine)
AB: Vertical profiles of Cd, Zn, Ni, and Cu have been determined at three stations in the North Pacific and in the surface waters on a transect from Hawaii to Monterey, California. The distributions found are oceanographically consistent and provide a needed confirmation and extension of several recent studies on the marine geochemistries of these metals. Cadmium concentrations average 1.4 pmol/kg in surface waters of the central North Pacific and show a strong correlation with the labile nutrients, phosphate and nitrate, increasing to values of 1.1 nmol/kg at depths corresponding to the phosphate maximum. Zinc is depleted in surface waters of the central gyre to an average value of 0.07 nmol/kg and increases to a deep maximum of 9 nmol/kg exhibiting a strong correlation with the nutrient silicate. Nickel concentrations average 2.1 nmol/kg in surface central gyre waters and increase to a deep maximum of 11 nmol/kg. Nickel is best correlated with a combination of phosphate and silicate. Copper averages less than 0.5 nmol/kg in surface waters of the central North Pacific and increases gradually to values of 5 nmol/kg in bottom waters. The Cu profiles show evidence of intermediate and deep water scavenging. The involvement of these metals in the internal biogeochemical cycles of the sea is responsible for their distributions which are predictable on the basis of oceanographic parameters.
AN: 0115580

                                                                     317 of 369  
TI: [Changes in the salt and biogenic composition of water caused by phenol introduction (an experimental study)].
OT: Izmenenie solevogo i biogennogo sostava vod pri vnesenii fenola (v ehksperimente).
AU: Sinel'-nikov,V.E.; Kudryavtsrva,N.A.; Yagodka,N.L.-(Inst.-Biol.-Vnutr.-Vod.-AN-SSSR,-Borok,-Yaroslav,-Obl.,-USSR)
SO: Gidrobiol.-Zh., 1979 15(6), 101-106
LA: Russian
AB: The formation of the composition of bottom water layers under conditions of continuous introduction of large quantities of phenol (5 mg/l) is analyzed. If the abundance and the species diversity of hydrobionts are not large (sand bottom) the products of the transformation and synthesis of new phenol-based organic substances participate in leaching out the components of the mineral composition of bottom sediments. In the case of a high species diversity of hydrobionts the phenol breaks down to final mineral products.
AN: 0006040

                                                                     318 of 369  
TI: [Experimental approach to the ecological rating of harmful compounds in water bodies].
OT: Ehksperimental'nyj podkhod k ehkologicheskomu normirovaniyu vrednykh veshchestv v vodoemakh.
AU: Kamshilov,M.M.; Yagodka,N.L.-(Inst.-Vnutr.-Vod.-AN-SSSR,-Borok,-USSR)
SO: Gidrobiol.-Zh., 1979 15(6), 85-91
LA: Russian
AB: Studies of the phenol destruction processes in the presence of lead showed that the rate of phenol destruction in the ecosystems of different types was dependent on the concentration of lead. A new approach to the biotesting of pollutants is proposed based on the evaluation of the phenol destruction rate under the influence of toxicants.
AN: 0006010

                                                                     319 of 369  
TI: [On the compensation of anthropogenic CO~SUB-2~ emissions by water and woodland].
OT: Zur Kompensation der anthropogenen CO~SUB-2~-Emission durch Wasser und Wald.
AU: Paucke,H.-(Akad.-Wissenschaft.-DDR,-Inst.-Geogr.-Geooekol.,-Bereich-Oekol.-Oekon.-Syst.,-DDR-1199-Berlin,-Rudower-Chaussee-5,-GDR)
SO: Acta-Hydrophys., 1979 24(1-2), 35-96
LA: German
AB: The paper deals with the question of how far woodland and aquatic ecosystems are able to compensate for anthropogenic COSUB-2-emissions and utilize them for organic matter production. The natural contents of COSUB-2 in air and water and anthropogenic COSUB-2-formation are discussed to show the complicated character and complexity of the problem. Information is given on primary production in terrestrial and aquatic ecosystems and on the multiplicity of interrelations existing between COSUB-2 and primary production. The COSUB-2 cycle is also discussed.
AN: 0088380

                                                                     320 of 369  
TI: Microelements in the Japan Sea ecosystem.
OT: Mikroehlementy v ehkosisteme Yaponskogo morya.
AU: Patin,S.A.; Morosov,N.P.; Romanteeva,A.S.; Mel'-nikova,R.M.; Borisenko,G.S.-(VNIRO,-Moscow,-USSR)
SO: Geokhimiya, ISSN:-0016-7525 1980 (no. 3), 423-429
LA: Russian
ER: M (Marine)
AB: The content and distribution of microelements (Fe, Mn, Zn, Cu, Ni, Pb, Cd and Sr) in water suspension, plankton, fish and phyto- and zoobenthos from the Sea of Japan are considered. Preliminary estimates of average concentrations of microelements are given for separate components of the marine ecosystem.
AN: 0004250

                                                                     321 of 369  
TI: Investigations on the sedimentation in the Darss-Zingst Bodden waters. A contribution to the establishment of an energy and matter balance in the ecosystem. Part 1: Determination of the rate of sedimentation and of production-biologically important parameters of the sedimented material.
OT: Untersuchungen zur Sedimentation in den Darss-Zingster Boddengewaessern _ ein Beitrag zur Aufstellung einer Energie- und Stoffbilanz im Oekosystem. Teil 1: Die Bestimmung der Sedimentationsrate und die Erfassung produktionsbiologisch wichtiger Parameter des sedimentierten Materials.
AU: Nausch-Stengl,M.; *Schlungbaum,G.; Oertzen,J.A.v.-(Sekt.-Biol.,-Fachber.-Meeres-u.-Fischereibiol.,-Wilhelm-Pieck-Univ.-Rostock,-25-Rostock-1,-Freiligrathstr.-7/8,-GDR)
SO: Acta-Hydrochim.-Hydrobiol., 1980 8(1), 59-69
LA: German
ER: M (Marine); B (Brackish)
AB: The sedimented material is characterized by its contents of P and Fe, loss on ignition, chemical oxygen consumption and caloric value. The increase of sediment is estimated at 2.3 cm/s, corresponding to about 1% of the energy of global radiation. The P sedimentation is 3.14 g/mSUP-3a POSUB-4-P, 75% being released again and 0.8 g being retained in the sediment. The oxygen consumption for the reduction from 60 to 30% of substance within the dry matter is 380 mg OSUB-2/g dry matter.
AN: 0103660

                                                                     322 of 369  
TI: The nutrient distribution in sediments of North-German lakes and remarks about the exchange between sediment and pelagic region.
OT: Die Naehrstoffverteilung in Sedimenten norddeutscher Seen und Hinweise auf den Austausch Sediment-Pelagial.
AU: Mothes,G.-(Inst.-Geogr.-und-Geooekol.,-Akad.-Wiss.-DDR,-Bereich-Hydrol.,-1162-Berlin,-Mueggelseedamm-260,-GDR)
SO: Acta-Hydrochim.-Hydrobiol., 1980 8(1), 35-46
LA: German
ER: F (Freshwater)
AB: Nutrient and carbon concentrations in the superficial sediment layers of eight stations in five lakes and in a pond in the Stechlin lake region are discussed. The indicator value of P distribution in the sediment is demonstrated by a comparison between oligotrophic and eutrophic, low-production, high-production and overfertilized waters. Data concerning sedimentation, release and retention of C, N and P yield information concerning the effects of sanitation measures, the reduction of the C:P-ratio and carbon oxidation in the sediment.
AN: 0103650

                                                                     323 of 369  
TI: Geochemistry of sulphur in the bottom sediments of Lake Baikal.
OT: Geokhimiya sery v donnykh otlozheniyakh ozera Bajkal.
AU: Lazo,F.I.-(Limnol.-Inst.-Sibirsk.-Otd.-AN-SSSR,-Listvennichnoe-na-Bajkale,-USSR)
SO: Geokhimiya, ISSN-0016-7525. 1980 (no. 1), 109-115
LA: Russian
ER: F (Freshwater)
AB: Original data on the content of sulphur forms (sulphate, free, sulphide, pyrite and organic) in the sediments are presented and discussed. The data point to a fairly high rate of exchange reactions determined by microbiological processes of sulphate reduction and formation of reduced S forms.
AN: 0004230

                                                                     324 of 369  
TI: A model of amorphous silica accumulation in the bottom sediments of the Pacific Ocean.
OT: Model' nakopleniya amorfnogo kremnezema v donnykh osadkakh Tikhogo okeana.
AU: Bogdanov,Yu.A.; Gurvich,E.G.; Lisitsyn,A.P.-(Inst.-Okeanol.-AN-SSSR,-Moscow,-USSR)
SO: Geokhimiya, ISSN-0016-7525. 1980 (no. 1), 84-92
LA: Russian
ER: M (Marine)
AB: Amorphous silica together with organic carbon in the bottom sediments of the Pacific Ocean is fairly informative for quantitative characterization of the environmental conditions of sedimentation. Accumulation of amorphous silica as well as the amorphous silica-organic carbon ratio in recent bottom sediments of the Pacific Ocean are quantitatively interrelated with the biologic productivity of surface waters and with the ocean depth. A model is proposed which describes well the acumulation of amorphous silica in the areas of the pelagic zone where there is no redeposition of sedimentary material on the bottom.
AN: 0004210

                                                                     325 of 369  
TI: The major-element chemistry of suspended matter in the Amazon Estuary.
AU: Sholkovitz,E.R.; Price,N.B.-(Grant-Inst.-Geol.,-West-Mains-Road,-Edinburgh-EH9-3JW,-UK)
SO: Geochim.-Cosmochim.-Acta, 1980 44(2), 163-171
LA: English
ER: B (Brackish)
AB: Suspended matter from the surface waters of the Amazon Estuary were collected during May and June 1976 on the 'R/V Alpha Helix-', and their major-element compositions (Al, Si, Ti, K, Mg, Ca, P, Fe and Mn) were measured. Between salinities of 0 and 10 o/oo, the suspended material, predominantly terrigenous in derivation, decreases in load from 500 to 3 mg/l, but has a chemical composition which remains essentially constant. With the onset of a large amount of biological productivity at approximately 10 o/oo salinity, there are large increases in the ratios of Si/Al, P/Al, Ca/Al, Mg/Al, Ti/Al and Mn/Al which are maintained at higher salinities. Calculations of 'excess' concentrations of elements held in the non-terrigenous components of the suspended material further support the main conclusion that Si, P, Ca, Mg, Ti and Mn are incorporated into the skeletal and organic phases of marine phytoplankton (predominantly diatoms) of the Amazon Estuary. The data suggest, but with less certainty, that Fe and K follow the above elements. This study has demonstrated that the chemical composition of river-introduced suspended matter can be significantly altered by bioloical activity within estuarine waters as can be the geochemical cycle of inorganic elements.
AN: 0081030

                                                                     326 of 369  
TI: Migration of ~SUP-90~Sr and ~SUP-137~Cs within water - freshwater plant and water - soil systems.
AU: Kulikov,N.V.; Chebotina,M.Ya.; Lyubimova,S.A.-(Inst.-Plant-and-Anim.-Ecol.,-Ural-Sci.-Cent.,-USSR-Acad.-Sci.,-Sverdlovsk,-USSR)
SO: Radiobiologiya, 1980 20(1), 146-148
LA: Russian
ER: F (Freshwater)
AB: Strontium-90 is fixed in stonewort more firmly than in higher aquatic plants: for cesium-137, there is no difference between stonewort and other freshwater plants. Both radioisotopes are sorbed by sapropel and peaty soil better than by sand-silty and lime soils. The poorest isotope fixation was registered in sandy soil.
AN: 0073830

                                                                     327 of 369  
TI: Water column anomalies in dissolved silica over opaline pelagic sediments and the origin of the deep silica maximum.
AU: Edmond,J.M.; Jacobs,S.S.; Gordon,A.L.; Mantyla,A.W.; Weiss,R.F.-(Dep.-Earth-Planet.-Sci.,-Massachusetts-Inst.-Technol.,-Cambridge,-MA-02139,-USA)
SO: J.-Geophys.-Res., 1979 84(C12), 7809-7826
LA: English
ER: M (Marine)
AB: Recent estimates based on pore water studies and mass balance considerations put the average flux of dissolved silica from the sediments into the deep water at about 3 mol cmSUP--2 yrSUP--1. This flux, if mixed uniformly in a bottom layer 100 m thick, results in an anomaly increment of 0.3 mol kgSUP--1 yrSUP--1. In basins of restricted circulation containing opaline sediments the residence time of the bottom waters should be long enough that the resulting anomaly be easily resolvable using existing data. Examination of the many hundreds of detailed, precise silica profiles presently available in unpublished reports shows that this is indeed the case.dian Ocean. The flux of dissolved silica from the sea floor is generally unaccompanied by any resolvable oxygen consumption, indicating that relatively minor amount of organic material reach the sediments in these regions. However, in the north Indian Ocean there are pronounced effects on all the nutrients, oxygen, and alkalinity, with regeneration approximating the Redfield prediction. In the northern Indian Ocean and the extreme northeast Pacific (northeast of 45N, 160W) the silica profiles increase to the bottom. This is a strong indication that the deep silica maximum observed over much of these oceans may have a large adv                                                   ective component, the feature itself being induced by the northward flow of the underlying low-silica bottom waters. In the Indian Ocean the data coverage is sufficient to demontrate unequivocally the dominance of this effect.
AN: 0080890

                                                                     328 of 369  
TI: Biogeochemical cycling in an organic-rich coastal marine basine. _ 1. Methane sediment-water exchange processes.
AU: Martens,C.S.; Klump,J.V.-(Mar.-Sci.-Prog.-and-Dep.-Geol.,-Univ.-North-Carolina,-Chapel-Hill,-NC-27514,-USA)
SO: Geochim.-Cosmochim.-Acta, 1980 44(3), 471-490
LA: English
ER: M (Marine)
AB: Methane produced in anoxic organic-rich sediments of Cape Lookout Bight, North Carolina, enters the water column via two seasonally dependent mechansisms: diffusion and bubble ebullition. Diffusive transport measured in situ with benthic chambers averages 49 and 163 mol.mSUP--2.hrSUP--1 during November-May and June-October respectively. High summer sediment methane production causes saturation concentrations and formation of bubbles near the sediment-water interface. Subsequent bubble ebullition is triggered by low-tide hydrostatic pressure release. June-October sediment-water gas fluxes at the surface average 411 ml (377 ml STP; 16.8 mmol).mSUP--2 per low tide. Bubbling maintains open bubble tubes which apparently enhance diffusive transport. When tubes are present, apparent sediment diffusivities are 1.2-3.1-fold higher than theoretical molecular values reaching a peak value of 5.2 x 10SUP--5 cmSUP-2.secSUP--1. Dissolution of 15% of the rising bubble flux containing 86% methane supplies 170 mol.mSUP--2.hrSUP--1 of methane to the bight water column during summer months; the remainder is lost to the troposphere. Bottom water methane concentration increases observed during bubbling can be predicted using a 5-15 m stagnant boundary layer dissolution model. Advective transport to surrounding waters is the major dissolved methane sink; aerobic oxidation and diffusive atmospheric evasion losses are minor within the bight.
AN: 0074300

                                                                     329 of 369  
TI: Modelling sedimentary systems and their vertical exchanges. /[Presented at:- Society for General Microbiology Symposium on the Microbiology of Sediments; Cambridge (UK); 27 Mar 1980].
AU: Billen,G.-(Lab.-Oceanogr.,-Univ.-Brussels,-Belgium)
CO: /[Presented at:- Society for General Microbiology Symposium on the Microbiology of Sediments  Cambridge (UK)  27 Mar 1980].
SO: Soc.-Gen.-Microbiol.-Q., 1980 7(2), 67
NT: Summary only.
LA: English
AB: Evaluating the rates of microbiological processes in biogeochemical cycles and understanding the factors controlling them, are often the final aims of ecological studies of the microbiology of sediments. For these two purposes, mathematical modelling in combination with other methods for determining rates of microbial activities, can be very helpful. Modelling the vertical distribution of the concentration of some chemical species within the sedimentary column allows one to use this kind of statical data for deducing dynamical information such as rates of production or consumption of this species and exchange flux across the sediment-water interface. When some particular regulation mechanism is postulated or experimentally demonstrated, diagenetic models can be used for simulating its overall effect on the whole sedimentary system and their vertical exchanges. This contribution gives a general presentation of the techniques commonly used in such models, along with several illustrations of the usefulness of this approach in studying nitrogen recycling in North Sea sediments.
AN: 0046940

                                                                     330 of 369  
TI: [Preface to special issue on geobiochemical investigations in the Zaire river, estuary and plume].
AU: Eisma,D.-(Netherlands-Inst.-Sea-Res.,-Texel,-The-Netherlands)
SO: Neth.-J.-Sea-Res., 1979 12(3-4), 253-254
NT: Special issue: geobiochemical investigations in the Zaire river, estuary and plume.
LA: English
ER: M (Marine); B (Brackish)
AB: In November 1976 a research programme was carried out in the Zaire (Congo) river estuary and the adjacent ocean. This was the first part of a project to investigate the contribution of the Zaire river to the ocean, to study its outflow and the physical and chemical processes involved, and to study the deposition of Zaire river material on the floor of the Angola Basin. The Zaire was selected as it is the second largest river in the world, and because little was known about the river and its chemistry. A second programme was carried out in April and May 1978 and a third programme, mainly concerning the ocean bottom deposits, will be carried out in 1980. In this issue the results of the November 1976 programme are presented together with the salinity, temperature and nutrient data obtained in April and May 1978 which became available while this issue was in preparation. The project, sponsored by the Committee on Oceanic Research of the Netherlands Academy of Sciences, was made possible by the financial support of the Netherlands Ministry of Education and Sciences and by the cooperation of the Zairean Government which gave permission to carry it out within the territorial waters of Zaire. Contributions are catalogued separately in ASFA 1 and 2.
AN: 0008830

                                                                     331 of 369  
TI: Marine biota, nearshore sediments, and the global carbon balance.
AU: Deuser,W.G.-(Woods-Hole-Oceanogr.-Inst.,-Woods-Hole,-MA-02543,-USA)
SO: Org.-Geochem., 1979 1(4), 243-247
LA: English
ER: M (Marine)
AB: Nearshore waters to a depth of 200 m constitute only 0.2% of the volume of the world's oceans, but they receive and process 25% of the oceans' input of organic carbon, between 6 and 7 x 10SUP-15 g C per year. Man's activities during the past century have significantly increased both the supply of nutrients from land to coastal waters and the total sediment load carried by rivers and deposited in nearshore waters. The combination of increased primary productivity, due to increased supply of nutrients, and increased burial of organic matter, due to increased sedimentation, could sequester a significant fraction of the carbon released into the atmosphere by man as organic carbon in recent shallow-water sediments.
AN: 0038280

                                                                     332 of 369  
TI: Volatile organic sulfides from freshwater algae.
AU: Bechard,M.J.; *Rayburn,W.R.-(Dep.-Bot.,-Washington-State-Univ.,-Pullman,-WA-99164,-USA)
SO: J.-Phycol., 1979 15(4), 379-383
LA: English
ER: F (Freshwater)
AB: Dimethyl sulfide (DMS) was found to be the principle biogenic sulfur compound in a freshwater environment. Endemic and non-endemic algae were cultured under axenic and nonaxenic conditions in defined media. Sulfur gas analysis of culture fluids indicated that Cyanophyta were probable sources of DMS whereas representatives of Chlorophyta, Xanthophyta and Bacillariophyta apparently did not produce this compound. Comparison of gaseous contents of young and old nonaxenic cultures of filamentous Chlorophyta and Xanthophyta showed DMS occurred only in aged cultures and was probably produced by bacteria utilizing substances from senescent algal cells. Data suggest that the composition of the algal community determines whether DMS is algal and/or bacterial in origin.
AN: 0044620

                                                                     333 of 369  
TI: Kinetics of nutrient regeneration in anoxic marine sediments.
AU: Berner,R.A.-(Dep.-Geol.-Geophys.,-Yale-Univ.,-New-Haven,-CT-06520,-USA)
SO: Phys.-Chem.-Earth, 1979 11, 279-292
LA: English
ER: M (Marine)
AB: Anoxic sediments undergoing bacterial sulfate reduction, because of the buildup in them of dissolved ammonia and phosphate from the decomposition of organic matter, may serve as important sources of these nutrients for the oceans. This paper demonstrates how pore water concentration-vs-depth data, along with laboratory measurements, can be combined with theoretical models to deduce rates and rate laws for nutrient release and bacterial sulfate reduction in sediments. Further application of the models enables determination of the stoichiometric C:N:P composition of the organic matter undergoing decomposition and the fraction of liberated nutrient which is returned to the overlying water. For an anoxic sediment from Long Island Sound, USA, diagenetic modeling of pore water data showed that rates of organic N and P decomposition and of microbial sulfate reduction, below the top few cm of sediment, is first order with respect to the organic matter being decomposed. Application of the first-order rate law to a variety of other sediments reviewed a direct proportionality between the rate constant for sulfate reduction and the square of the rate of deposition. Also, decomposition rates calculated from modeling are in good agreement with rates measured in the laboratory using the same sediment. In the upper portion of anoxic sediments overlain by oxygenated water, higher concentrations of more readily metabolized organic matter are found, and migration of dissolved constituents is enhanced due to irrigatin and other modes of mixing by benthic organisms (bioturbation).
AN: 0023500

                                                                     334 of 369  
TI: [Preface to special issue on geobiochemical investigations in the Zaire river, estuary and plume].
AU: Eisma,D.-(Netherlands-Inst.-Sea-Res.,-Texel,-Netherlands)
SO: Neth.-J.-Sea-Res., 1979 12(3-4), 253-254
NT: Special issue: Geobiochemical investigations in the Zaire river, estuary and plume.
LA: English
ER: M (Marine); B (Brackish)
AB: In November 1976 a research programme was carried out in the Zaire (Congo) river estuary and the adjacent ocean. This was the first part of a project to investigate the contribution of the Zaire river to the ocean, to study its outflow and the physical and chemical processes involved, and to study the deposition of Zaire river material on the floor of the Angola Basin. The Zaire was selected as it is the second largest river in the world, and because little was known about the river and its chemistry. A second programme was carried out in April and May 1978 and a third programme, mainly concerning the ocean bottom deposits, will be carried out in 1980. In this issue the results of the November 1976 programme are presented together with the salinity, temperature and nutrient data obtained in April and May 1978 which became available while this issue was in preparation. The project, sponsored by the Committee on Oceanic Research of the Nethelands Academy of Sciences, was made possible by the financial support of the Netherlands Ministry of Education and Sciences and by the cooperation of the Zairean Government which gave permission to carry it out within the territorial waters of Zaire. Contributions are catalogues separately in ASFA 1 and 2.
AN: 0008830

                                                                     335 of 369  
TI: Atmospheric contributions to stream water chemistry in the North Cascade Range, Washington.
AU: Dethier,D.P.-(U.S.-Geol.-Surv.,-Seattle,-WA-98105,-USA)
SO: Water-Resour.-Res., 1979 15(4), 787-794
LA: English
ER: F (Freshwater)
AB: Bulk precipitation contributes significant quantities of cations and trace metals to a subalpine catchment located in the North Cascade Range of Washington. Precipitation loadings accounts for 30% of the major and >50% of the minor element export from the catchment. Preliminary data from larger basins in the North Cascades suggest similar values. Calcium and potassium measured in bulk precipitation are largely derived from continental dusts, while sodium and magnesium originate as marine aerosols. Lead, copper, and arsenic, products of anthropogenic activity in the Puget Lowland, are deposited downwind in the Cascade Mountains; mean precipitation pH at the study site was 4.85 during 1974 and 1975. Elements contributed by precipitation become part of complex upland biogeochemical cycles. With the exception of highly mobile ions like sodium, elemental levels in streamflow reflect biologic and pedogenic cycling processes rather than direct precipitation influence.
AN: 0007290

                                                                     336 of 369  
TI: The coordinated Mediterranean Pollution Monitoring and Research Program.
AU: Keckes,S.-(UNEP,-Palais-de-Nations,-CH-1211-Geneva-10,-Switzerland)
SO: Ambio, 1977 6(6), 327-328
LA: English
ER: M (Marine)
AB: Seven pilot projects were originally approved at the 1975 Intergovernmental Meeting in Barcelona as part of the Mediterranean Pollution Monitoring and Research Program (MED POL). Four of them are basically monitoring activities, although all have a strong research orientation. The monitoring is based on very precise sampling and analytical procedures as well as on permanent intercalibration techniques. This leads to comparable data from the whole Mediterranean. The original seven pilot projects of the MED POL deal mainly with the coastal waters of the Mediterranean, and therefore an additional pilot project dealing with pollution levels of the open waters and the biogeochemical cycles of the most important pollutants was later initiated in cooperation with IAEA and IOC.
AN: 9177270

                                                                     337 of 369  
TI: [Data on the atmospheric cycle of marine salts].
OT: Donnees sur le cycle atmospherique des sels marins.
AU: Morelli,J.-(Mission-Rech.,-Ministere-Environ.-Cadre-de-Vie,-14-Bd-General-Leclerc,-92521-Neuilly-sur-Seine,-France)
SO: J.-Rech.-Oceanogr., 1978 3(4), 27-50
LA: French
ER: M (Marine)
AB: This paper uses results presented in a thesis (Morelli, 1977). Although investigations concern generally four components of atmospheric aerosol which are the most abundant cations in sea water _ Na, K, Ca, Mg _, attention is focused on the case of potassium, element of a great interest for biosphere. Research was carried out in a large scale view. It has taken into account observations at different levels of the atmospheric link of considered elements biogeochemical cycle: injection into air by oceanic bubbling, study of their distribution close to the sea surface in various marine regions and of their vertical distribution, deposition on ocean and continents. An estimation of potassium fluxes magnitude injected in the atmospheric reservoir from different natural and anthropogenic sources is given. The question of cyclic supply of marine potassium to continents and its geochemical implications is discussed.
AN: 9005130

                                                                     338 of 369  
TI: Mechanisms for detrital cycling in nearshore waters at Bermuda.
AU: Welsh,B.L.; Bessette,D.; Herring,J.P.; Read,L.M.-(Mar.-Sci.-Inst.,-Univ.-Connecticut,-Avery-Point,-Groton,-CT-06340,-USA)
SO: Bull.-Mar.-Sci., 1979 29(2), 125-139
LA: English
ER: M (Marine)
AB: The detrital cycle in Whalebone Bay and adjacent coastal waters at Bermuda was investigated to determine how such a relatively open system of exchanges of nutrients and carbon could be maintained in the highly oligotrophic waters which bathe the island. The shore zone and particularly the beach wrack were found to provide a source of materials, and a stranding cycle is described whereby detrital seagrasses and algae are insolated, desiccated, and leached, accelerating the release of dissolved constituents and fine particulates to the water column. Three conservative processes associated with the embayment were noted: tidal recycling of nearshore water, the delaying effects of oscillatory wave motion, and biological uptake by benthic plants which served to reduce exports and retain both nutrients and organic carbon within the Bay, thereby perpetuating the cycle. Little if any particulate material left the Bay. In fact, substantial quantities of C, N, and P were imported from the Sargasso Sea in the form of Sargassum- which more than compensated for any exports. Thus a relatively open detrital system does operate in Bermuda, maintained and perpetuated by a combination of physical, chemical, and biological processes and subsidized from the open ocean, but its influence is confined to a narrow band near shore.
AN: 9113500

                                                                     339 of 369  
TI: Balance of biogenous elements in the Caspian Sea during the period of regulated streamflow runoff.
AU: Maksimova,M.P.; Katunin,D.N.; Yeletskiy,B.D.-(Address-not-stated)
SO: Oceanol.-Acad.-Sci.-USSR, 1978 18(3), 295-297
LA: English
ER: M (Marine)
AB: Calculations of the balance of biogenous elements in the Caspian Sea during th period of regulated streamflow show that their main source is continental runoff (about 70% of nitrogen, 90% of phosphorus, 95% of silicon), that submarine ground-water runoff accounts for about 15% of nitrogen, 10% of phosphorus, and 5% of silicon, and that about 15% of the nitrogen are supplied from the atmosphere. The long-period mean total supply of these elements to the Caspian is: 40,700 metric tons of total phosphorus, 607,000 metric tons of total nitrogen (including about 20% dissolved mineral phosphorus and 50% dissolved mineral nitrogen); and 750,000 metric tons of dissolved silicon. The annual supply varies within 26,300-55,100 metric tons of total phosphorus, 389,000-904,000 metric tons of total nitrogen, and 400,000-1,230,000 metric tons of phosphorus, 590,000 metric tons of nitrogen, and 730,000 metric tons of silicon. The losses due to fishery amount to about 4% of phosphorus and 2% of nitrogen.
AN: 9118460

                                                                     340 of 369  
TI: Uptake of americium-241 by algae and bacteria.
AU: Giesy,J.P.,Jr.; Paine,D.-(Savannah-River-Ecol.-Lab.,-Drawer-E,-Aiken,-SC-29801,-USA)
SO: Prog.-Water-Technol., 1977 9(4), 845-857
LA: English
AB: The availability of SUP-241Am to algae and bacteria was studied to elucidate their role in determining the ultimate fate of SUP-241Am released into the environment. It was found that both algae and bacteria concentrate SUP-241Am to a high degree, which makes them potentially important in biomagnification, as well as cycling the element in the water column and mobilisation from the sediments. Chemical fixation of algal cells caused an increased uptake of SUP-241Am, which indicates that uptake is by passive diffusion. Increased uptake, after fixation, is probably due to chemical alteration of surface binding sites. This problem may be eliminated by killing algal cells used in uptake studies by u.v. light.
AN: 9091810

                                                                     341 of 369  
TI: Biological release and recycling of toxic metals from lake and river sediments.
AU: Nicholas,W.L.; Thomas,M.-(Dep.-Zool.,-Australian-Natl.-Univ.,-Canberra,-2600-ACT,-Australia)
SO: Aust.-Water-Resour.-Counc.-Tech., 1978 (no. 33), 1-99
LA: English
ER: F (Freshwater)
AB: The Molonglo River, NSW, Australia, has been polluted with heavy metal wastes from mines, now abandoned, on the banks of the river. Pollution has almost eliminated animals and plants from the river bed for many kilometres downstream. Great quantities of zinc are present in the river system. Organic detritus has firmly bound very high concentrations of zinc and animals and plants have very high concentrations of zinc in their tissues. Microbial films accumulated high concentrations of heavy metals and microscopic nodules rich in zinc and copper or iron, manganese, with lesser amounts of other metals have developed on substrates over several months. Bullrushes and willows take up zinc from the river sediments, and their dead leaves retain zinc until they disintegrate. Dead bullrush leaves continue to absorb zinc from the river water and from the river sediments. Microorganisms, predominately algae, also absorb zinc from river water and retain zinc in zinc-free water. Invertebrates feeding on the detritus and microorganisms ingest zinc in their food, retaining some in their tissues, but excrete much with their faeces.
AN: 9079820

                                                                     342 of 369  
TI: Copper in the marine environment _ Part 2.
AU: Schmidt,R.L.-(Battelle-Mem.-Inst.,-Richland,-WA-99352,-USA)
SO: C.R.C.-Crit.-Rev.-Environ.-Control, 1978 8(3), 247-291
LA: English
ER: M (Marine)
AB: Adsorption appears to have the strongest influence on Cu added to the sea from freshwater sources. Freshly formed hydrous oxides of Mn and Fe and organic matter form thin films on clay particles and may play a dominant role in adsorption. Precipitation may be an important process only in anoxic waters. The accumulation of Cu in sediments appears to be a two-component process. Copper associated with lithic materials is sedimented in proportion to clay deposition. The second component consists of Cu adsorbed from the water column during transport or Cu associated with biotic debris. The uptake of soluble Cu by plankton is the principal pathway for entry of the metal into the food web, although ingestion of Cu-containing nonbiotic particulates may also lead to Cu accumulation by marine organisms. Mobilization of Cu from suspended matter and sediments occurs when Cu-containing organic matter of CuS is oxidized or Cu is desorbed due to dilution or is complexed to form soluble compounds with inorganic and organic ligands. Sediment microbiota affect the biogeochemistry of Cu by influencing the kinetics and thermodynamics of reactions, releasing metabolites that bond with Cu, and catalyzing the oxidation-reduction of metals in sediments.
AN: 9070950

                                                                     343 of 369  
TI: Carbon dioxide - a global environmental problem into the future.
AU: Wong,C.S.-(Ocean-Chem.-Div.,-Inst.-Ocean-Sci.,-Sidney,-British-Columbia,-Canada)
SO: Mar.-Pollut.-Bull., 1978 9(10), 257-264
LA: English
ER: M (Marine)
AB: The author believes that all other forms of pollution are dwarfed by the scale of the invisible pollutant, carbon dioxide, resulting from energy use pattern. Given the considerable climatic effects of COSUB-2 increase in the atmosphere there has not been sufficient resources addressed to this problem. The relationship between COSUB-2 in the atmosphere with wood and fossil fuel burning, changes in soil and land (eg. agriculture, desertification), and natural biological processes (eg. respiration of ocean biota) are discussed. Necessary future remedies are outlined. The author recommends: (1) Techniques of observing oceanic partial pressure of COSUB-2 and other carbonate chemistry parameters should be improved; (2) Efforts to man available open ocean platforms to establish COSUB-2 increase should be intensified; (3) An intensification in the effort to understand oceanic processes of COSUB-2 uptake and release through controlled experiments; and (4) An intensification of work on the physical circulation in the ocean.
AN: 9066170

                                                                     344 of 369  
TI: On the role of the atmosphere in biogeochemical cycles.
AU: Bolin,B.-(Dep.-Meteorol.,-Univ.-Stockholm,-Stockholm,-Sweden)
SO: Quart.-J.-R.-Meteorol.-Soc., 1979 105, 25-42
LA: English
ER: M (Marine)
AB: Of particular concern is an understanding of the basic biogeochemical mechanisms that maintain a quasi-equilibrium; of the extent to which the system may be sensitive to disturbances; and of the way in which the equilibrium may then change. This presentation attempts to emphasize some important general principles and to discuss also some specific questions, such as the likely further increase of carbon dioxide in the atmosphere, the sulphur cycle and the acidity of rain, and the nitrogen cycle and agriculture, since they are much debated at this time.
AN: 9069300

                                                                     345 of 369  
TI: Biological control of dissolved aluminium in seawater: experimental evidence.
AU: Stoffyn,M.-(Bedford-Inst.-Oceanogr.,-Dartmouth,-N.S.-B27-4A2,-Canada)
SO: Science-Wash., 1979 203(4381), 651-653
LA: English
ER: M (Marine)
AB: Experimental evidence supports the hypothesis that the concentration and distribution of dissolved aluminium in ocean water are controlled by biological activity in the surface waters. The growth of the diatom Skeletonema costatum- in artificial seawater media spiked with aluminium reduced the aluminium concentration to that actually found in surface open ocean waters (about 0.5 micrograms per liter). Furthermore, aluminium had a catalytic and limiting effect on the growth of the diatoms.
AN: 9051350

                                                                     346 of 369  
TI: Distribution of stable organic molecules in the marine environment: physical chemical aspects. Chlorinated hydrocarbons.
AU: Dexter,R.N.; Pavlou,S.P.-(URS-Company,-Seattle,-WA-98121,-USA)
SO: Mar.-Chem., 1978 7(1), 67-84
LA: English
ER: M (Marine)
AB: The relative concentrations of non-polar organic compounds in seawater and suspended particulate matter can be explained by an equilibrium sorption mechanism. The value of the quasi-equilibrium constant, K, was calculated with reasonable accuracy for polychlorinated biphenyls from a relatively simple equation which relies on both measurable physical parameters and a number of molecular terms estimated from fundamental physical chemical considerations. This model represents an approach to defining the accumulation of stable organic molecules on marine particulate interfaces within a coherent theoretical framework. As such, it provides a guide for selecting appropriate ecosystem parameters which influence the distribution and accumulation potential of these chemicals in the marine environment.
AN: 9031150

                                                                     347 of 369  
TI: Chemical exchange across sediment-water interface.
AU: Lerman,A.-(Dep.-Geol.-Sci.,-Northwestern-Univ.,-Evanston,-IL-60201,-USA)
SO: Ann.-Rev.-Earth-Planet.-Sci., 1978 6, 281-303
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: Fluxes of chemical species across the sediment-water interface are generated by (a) deposition of sediments, (b) growth of the sediment-pore-water column taking place in the course of deposition, and (c) diffusion in pore waters. For different chemical species, the relative importance of each of the three fluxes depends on the nature and type of chemical reactions between solids and solution. When uptake or adsorption from solution is strong, the flux on solids usually predominates over the two other modes of transport. When the rate of sedimentation is slow, then the diffusional fluxes (provided concentration gradients exist) can be the main transport mechanism upward or downward across the sediment-water interface. For those chemical species, concentrations of which in sediment pore waters are affected by biochemical reactions (sulfate, bicarbonate, phosphate, and nitrogen species), the fluxes into or out of sediments are approximately directly related to the sedimentation rates. A global geochemical role of the oeanic sediment-water interface is reflected in the amount of materials, such as biogenic calcium carbonate and silica, that are being regenerated to ocean water during their residence time at the interface. Of the total of biogenic skeletal materials reaching the ocean bottom, significant fractions dissolved before burial in sediments. In general, regeneration of biogenic materials at the sediment-water interface can significantly affect the chemical composition of overlying water and it can be, in human terms, environmentally harmful when relatively large quantities of material dissolve, oxidize, or decay in a relatively small volume of water, such as in seasonally stratified eutrophic lakes.
AN: 9037590

                                                                     348 of 369  
TI: Lead in the environment.
AU: Swaine,D.J.-(CSIRO-Fuel-Geosci.-Unit,-North-Ryde,-N.S.W.-2113,-Australia)
SO: J.-Proc.-R.-Soc.-NSW, 1978 111(1-2), 41-47
LA: English
AB: Various aspects of the geochemistry of lead are discussed in terms of the geochemical cycle. Values are given for concentrations of lead in rocks, soils, water, vegetation, coals, and fertilisers. Lead tends to be concentrated in surface soils, probably because of the insolubility of the common lead minerals and of the lead complexed with some forms of organic matter. The same properties also govern the general unavailability of lead to plants and the low concentrations of lead in natural waters. Lead in solution in waters and lakes also depends on reactions at the sediment-water interface and on the pH and oxidation-reduction potential. The mean content of lead in coal is about 10 ppm Pb, and most of this is retained with fly-ash after the combustion of pulverised coal. The sources of lead in the body are also discussed. Pollution is seen as something imposed on a natural background; the proper assessment of the effects of lead and other heavy metals depends on reliable geochemical data and on careful interpretation.
AN: 9035840

                                                                     349 of 369  
TI: Props and actors on a massive stage.
AU: Mortimer,C.H.-(Center-for-Great-Lakes-Studies,-Univ.-Wisconsin-Milwaukee,-3203-N-Downer,-WI-53201,-USA)
SO: Nat.-Hist.-N.Y., 1978 87(7), 51-58
LA: English
ER: F (Freshwater)
AB: The geochemical characteristics of the Great Lakes basin is outlined, and the seasonal cycle described in detail. During winter the waters are well stirred by wind and wave action and cool down to several degrees below the 40 F temperature of maximum density. As the water warms up in the early spring however thermal stratification develops and terminates the mixing. Illuminated by spring sunshine, microscopic algae photosynthesize to become the initial crop of 'grass' which then nourishes a community of zooplankton. The rate of photosynthetic production is largely controlled by the ratio of 2 depths: the depth from the surface to which photosynthetically usable light energy penetrates and the depth from the surface to which active turbulent stirring is maintained by winds and currents. Soon after stratification has become fully established across the open waters of the lakes essential nutrients in surface offshore waters become progressively depleted because algal growth is limited to the surface illuminated layer and nutrient replenishment from below is impeded at the thermocline. Production continues until late September when the thermocline has sunk below the level at which sufficient light remains. All parts of the food chain interact concurrently. In addition detritus of the living matter is recycled. Aquatic cycles often have some degree of vertical separation of the phases of production and breakdown, due to the combined effects of stratification gravity and vertical variation in intensity of turbulent transport and confinement of most primary production to surface illuminated layers. It is concluded that in general, the Great Lakes ecosystem has survived quite well despite the various and sometimes conflicting uses humans have made of the lakes' resources. Recommendations for future management of these resources is discussed.
AN: 9029200

                                                                     350 of 369  
TI: Hydrocarbons and petroleum in the marine ecosystem - a review./[Presented at-: Petroleum hydrocarbons in the marine environment (ICES Workshop); Aberdeen (UK); 9 Sep 1975].
AU: Hardy,R.; Mackie,P.R.; Whittle,K.J.-(Torry-Res.-Stn.,-P.O.Box-31,-135-Abbey-Road,-Aberdeen-AB9-8DG,-UK)
CO: /[Presented at-: Petroleum hydrocarbons in the marine environment (ICES Workshop)  Aberdeen (UK)  9 Sep 1975].
SO: Rapp.-P.-V.-Reun.-Cons.-Int.-Explor.-Mer. 1977 171, 17-26
LA: English
ER: M (Marine)
AB: Various aspects concerning the presence of petroleum in the marine ecosystem are discussed. It is clear from a review of the literature that there is no simple method of determining accurately the amount of petroleum in the ecosystem, especially in the open seas where the concentrations are low. The subsequent fate of the petroleum components is not known although studies have shown that they may be removed or converted into other components by physical, chemical and biological (biochemical) means. Nevertheless, the amounts of petroleum compounds present in the environment appear to exceed the estimated annual input by several orders of magnitude. This may be a reflection of the size of other non-petroleum inputs, erroneous calculations of the size of the petroleum input and/or a greater stability of the petroleum-like components in the ecosystem. The effects caused by petroleum vary not only with the composition and concentration of the petroleum but also with the interacting component. Such effects can be observed most readily where large spillages have occurred. At lower input levels, especially at concentrations found in the open sea, the effects caused by the various petroleum components are not well known and merit a more detailed study.
AN: 8185230

                                                                     351 of 369  
TI: Application of four input-output models for nutrients in Lake Okeechobee, Florida.
AU: Miller,R.L.-(US-Geol.-Surv.,-Denver,-CO,-USA)
SO: J.-Res.-US-Geol.-Surv., 1978 6(6), 821-828
LA: English
AB: R.A. Vollenweider's (1975) nonconservative model described concentrations of nitrogen and phosphorus for 1969-70 in Lake Okeechobee, Florida, better than the models of F. Biffi in 1963, R.H. Rainey in 1967, and R. Piontelli and V. Tonolli in 1964. Vollenweider's model predicted concentrations of 1-.-4 mg/L of total nitrogen and 0-.-09 mg/L of total phosphorus in the lake. The concentration of nitrogen could be approximated with conservative models but phosphorus required a nonconservative model. Unless variations in input concentrations and flow rate of the tributaries are modeled, only short-term predictions of lake concentrations can be made because of variations in inflow concentrations and because of the short time required (400 days) for the lake to be flushed by its inflow.
AN: 9008180

                                                                     352 of 369  
TI: [On the problem of the formation of natural waters chemical composition].
OT: K probleme formirovaniya rhimicheskogo sostava prirodnykh vod.
AU: Samarina,V.S.-(Address-not-stated)
SO: Vesn.-Leningr.-Univ.,-Ser.-Biol., 1977 (no. 18), 63-70
LA: Russian
ER: M (Marine); F (Freshwater)
AB: The main process of formation of the chemical composition of natural water is examined on the basis of circulation of natural waters. The discussional character of the problem of the formation of deep chloride-calcic brines is stated. The conclusion about the genetic non-uniformity of brines and the necessity of detailed studies to understand the natural system : rock-water-gas-living substance is also made.
AN: 9008360

                                                                     353 of 369  
TI: Future research problems in marine organic chemistry.
AU: Gagosian,R.B.; Ahmed,S.I.; Farrington,J.W.; Lee,R.F.; Mantoura,R.F.C.; Nealson,K.H.; Packard,T.T.; Reinhart,K.L.,Jr.-(Dep.-Chem.,-Woods-Hole-Oceanogr.-Inst.,-Woods-Hole,-MA-02543,-USA)
SO: Mar.-Chem., 1978 6(4), 375-382
LA: English
ER: M (Marine)
AB: In June 1977, several marine scientists participated in a workshop sponsored by the National Science Foundation Office for the International Decade of Ocean Exploration. The objective of this meeting was to identify promising opportunities in chemical oceanographic research of the 1980's. The workshop was divided into subsections, one of which was 'Marine Organic Chemistry and Associated Biochemical Problems'. Although some of the recommendations of this subsection were included in an overall report, a more detailed, unified report dealing solely with this topic was deemed necessary and is discussed as follows: (A) Production (1) pelagic; (2) benthic; (B) Transport (1) circulation; (2) vertical flux and resuspension; (C) Transformations (1) environmental effects; (2) upwelling zones; (3) oxygen minimum zones; (4) organic-metallic complexes in the sea; (5) organic mineral phase interactions; and (6) macromolecular compound formation.
AN: 9002080

                                                                     354 of 369  
TI: The dissolved mineral composition of the water flowing into and out of the Hartbeespoort Dam.
AU: Toerien,D.F.; Walmsley,R.D.-(Inst.-Environ.-Sci.,-Univ.-Orange-Free-State,-Bloemfontein,-9301,-South-Africa)
SO: Water-S.A., 1978 4(1), 25-38
LA: English
ER: F (Freshwater)
AB: A two year analytical survey was conducted of the waters flowing into and out of the Hartbeespoort Dam. The Crocodile River was the main source of water and chemical input to the dam, contributing from 88 to 99% of the dissolved mineral input. The concentrations of dissolved minerals in the inflowing waters were highest during the winter dry weather flow and lowest during the summer rainfall period. The mineral content of waters from the outflow of the dam was not subject to the same variation. Considerable quantities of dissolved nitrogenous and phosphate compounds disappear from the water in the dam either through biological or chemical conversions.
AN: 8007860

                                                                     355 of 369  
TI: Experimental measurements of nitrogen remineraliztion in coastal waters.
AU: Harrison,W.G.-(Mar.-Ecol.-Lab.,-Bedford-Inst.-Oceanogr.,-Dartmouth,-NS-B2Y-4A2,-Canada)
SO: Limnol.-Oceanogr., 1978 23(4), 684-694
LA: English
ER: M (Marine)
AB: Ammonium remineralization was measured in the euphotic zone of two coastal areas using a -SUP-15-N isotope dilution technique. Remineralization fluxes were high in both areas and often exceeded assimilation fluxes. A strong positive correlation between ammonium remineralization and ammonium and carbon dioxide assimilation suggests a close coupling of photo-synthesis and nitrogen recycling. Regenerative fluxes decreased with depth and with distance offshore, but to a relatively lesser extent than did assimilative fluxes. Turnover times for remineralization of utilizable organic nirogen were estimated to be from 3 to 16 days. Size fractionation experiments and estimates from the literature suggest that microplankton (<183 -mu-m) may have been the primary nitrogen remineralizers.
AN: 8171430

                                                                     356 of 369  
TI: Studies of Hawaiian freshwater and soil algae. 2. Algal colonization and succession on a dated volanic substrate.
AU: Carson,J.L.; Brown,R.M.,-Jr.-(Dep.-Bot.,-Univ.-North-Carolina,-Chapel-Hill,-NC-27514,-USA)
SO: J.-Phycol., 1978 14(2), 171-178
LA: English
ER: F (Freshwater)
AB: Spatial studies of colonization and succession of soil algae and chemical analyses of the various soils on the cinder cone of Kilauea Iki in Hawaii Volcanoes National Park, Hawaii are outlined. There is a positive correlation between the diversity and quantity of soil algae with nutrient levels and organic matter accumulation in each locale. Three distinct edaphic-biotic zones existing in this area are differently revealed by the soil chemical composition, quantity and diversity of soil algae, and as evident variations in higher plant growth and colonization. Varying colonization and successional phases of higher plant growth around standing and fallen tree snags killed by volcanic activity also reflect variations in the soil algal flora. These variations appear largely as a function of differential water interception, absorption, and retention as well as differential accumulation of organic matter, and the initiation of various biogeochemical cycles.
AN: 8174600

                                                                     357 of 369  
TI: Some observations on the stable carbon isotope composition of dissolved and particulate organic carbon in the marine environment.
AU: Eadie,-B.J.; Jeffrey,-L.M.; Sackett,-W.M.-(Dep.-Oceanogr.,-Texas-A-and-M-Univ.,-College-Station,-TX-77843,-USA)
SO: Geochim.-Cosmochim.-Acta, 1978 42(8), 1265-1269
LA: English
ER: M (Marine)
AB: -delta--SUP-13-C-SUB-PDB- compositions for 39 samples of dissolved organic carbon (DOC) from the Gulf of Mexico-Caribbean Sea-Atlantic Ocean system, the South Pacific and Ross Sea are reported. Deep water values are similar with a mean of -21-.-8-SUP-o-/-SUB-oo- attesting to the homogeneity of the oceanic DOC pool. In Antarctic waters, a 5-SUP-o-/-SUB-oo- difference between DOC and particulate organic carbon (POC), with POC having values similar to modern plankton (-delta--SUP-13-C-SUB-PDB- approx -27-SUP-o-/-SUB-oo-) supports the idea of the transient nature of POC as compared to DOC. Total, lipid, acid hydrolyzed, amino acid and residue fractions of POC are about 5, 3, 7, 5 and 3-SUP-o-/-SUB-oo- respectively, more negative in 2000 m water as compared to surface water samples from the Gulf of Mexico.
AN: 8160460

                                                                     358 of 369  
TI: Cadmium in northeast Pacific waters.
AU: Bruland,-K.W.; Knauer,-G.A.; Martin,-J.H.-(Cent.-Coastal-Mar.-Stud.,-Div.-Nat.-Sci.,-Univ.-California,-Santa-Cruz,-CA-95064,-USA)
SO: Limnol.-Oceanogr., 1978 23(4), 618-625
LA: English
ER: M (Marine)
AB: Northeast Pacific water was collected by five different methods and the Cd in it was preconcentrated by both chelex-ion exchange and chelation-organic extraction techniques. All sampling and preconcentration methods yielded essentially the same data. Cadmium was very significantly correlated with phosphate and nitrate at all depths and it appears that the resulting equations, ng Cd-.-liter-SUP--1- = -3-.-6 + 34-.-9 (-mu-mol PO-SUB-4--.-liter-SUP--1-) and ng Cd-.-liter-SUP--1- = 5-.-1 + 2-.-45 (-mu-mol NO-SUB-3--.-liter-SUP--1-), can be used to predict oceanic Cd values. Cadmium concentrations are lowest in nutrient-depleted surface waters (4-.-5  0-.-4 ng-.-liter-SUP--1-) and greatest (125 ng Cd-.- liter-SUP--1-) at the depths of the PO-SUB-4- and NO-SUB-3- maxima. Hence, Cd has one of the highest deep enrichment:surface depletion ratios (equal to approximately 30) yet observed. Cadmium and phosphorus are also correlated in microplankton, and it is apparent that these organisms and their organic remains are a dominant factor in the biogeochemical cycling of this element.
AN: 8171410

                                                                     359 of 369  
TI: On the barium data from the Atlantic GEOSECS Expedition.
AU: Chan,-L.H.; Drummond,-D.; Edmond,-J.M.; Grant,-B.-(Dep.-Geol.,-Louisiana-State-Univ.,-Baton-Rouge,-LA-70803,-USA)
SO: Deep-Sea-Res., 1977 24(7), 613-649
LA: English
ER: M (Marine)
AB: Barium profiles at the Atlantic stations of the Geochemical Ocean Sections (GEOSECS) Program are remarkably similar to those for silicate and alkalinity. In nutrient depleted surface waters barium ranges between 36 and 44 nm kg-SUP--1-: the Arctic overflows have values between 44 and 49 nm kg-SUP--1- and the Antarctic Bottom Water 100 to 106 nm kg-SUP--1-. Both barium and silica behave non-conservatively in basins with restricted circulation - the Greenland and Norwegian seas and the Angola Basin - with anomalies of up to 1, 2 and 7 nm Ba kg-SUP--1-, respectively. There is extensive in situ production of silica and barium in the bottom waters of the Weddell Sea Basin, the silica anomaly ranging up to 35 -mu-m kg-SUP--1- and that for barium to 15 nm kg-SUP--1-. Barium behaves uniquely only in the upper waters. At tropical and temperate latitudes there is commonly a minimum of several nannomoles per kilogram in the uppermost thermocline, often associated with the high salinity core of the Sub-Tropical Underwater. In the Circumpolar Current the depletion in surface silica is associated with only a minor reduction in barium. The values at <5 -mu-m Si kg-SUP--1- are about 30 nm kg-SUP--1- higher than those at lower latitudes. The important question of the removal mechanism is not resolved from the profile data.
AN: 8006960

                                                                     360 of 369  
TI: An assessment of the environment impact of mining of the continental shelf.
AU: Owen,-R.M.-(Dep.-Atomos.-and-Ocean.-Sci.,-Univ.-Michigan,-Ann-Arbor,-MI-48104,-USA)
SO: Mar.-Min., 1977 1(1-2), 85-102
LA: English
ER: M (Marine)
AB: The ocean is a complex system and oceanographers have a limited understanding of the potential impact of mining on the marine environment. However, this lack of knowledge probably will not deter developed nations from commencing marine mining in the near future, because these nations are hard pressed to obtan critical minerals. This study is focused on an assessment of possible environmental disturbances associated with mining on the continental shelf, because a variety of political, economic, and technological factors suggest that the initial large-scale marine mining efforts will occur here. Mining activites on the continental shelf can disrupt the sediment budget and interfere with sediment dispersal patterns, resulting in coastal erosion and the formation of navigation hazards. The biogeochemical processes involved in photosynthesis and primary productivity, secondary productivity, and detoxification are also susceptible to environmental impacts caused by mining. The consequences of altering these processes may include the destruction of organisms and habitats, oxygen depletion, and the release of toxic substances from the sediments. Pre-mining baseline data and continuous monitoring of certain critical parameters at each mining site will be necessary to minimize adverse effects. Certain shelf environments will require special attention. These include fishing grounds, semi-enclosed embayments, and coral reefs.
AN: 8146840

                                                                     361 of 369  
TI: Production of methane and carbon dioxide from methane thiol and dimethyl sulphide by anaerobic lake sediments.
AU: Zinder,-S.H.; Brock,-T.D.-(Dep.-Earth-and-Space-Sci.,-UCLA,-Los-Angeles,-CA-90024,-USA)
SO: Nature, 1978 273(5659), 226-228
LA: English
ER: F (Freshwater)
AB: Methane thiol (methyl mercaptan, MeSH), its oxidation product, dimethyl disulphide (DMDS), and dimethyl sulphide (DMS) are naturally occurring metabolites. They are also produced by paper mills using the kraft pulp process and cause an industrial odour problem because of their low odour threshold. Although the biological production of these compounds is fairly well understood, little is known about their biological decomposition. The authors report that microbial populations present in anaerobic freshwater sediments and in anaerobic sewage digestor sludge are capable of metabolising the carbon in these volatile organic sulphur compound to methane and carbon dioxide. Therefore, anaerobic habitats may serve as sinks in the biogeochemical cycling of these compounds.
AN: 8109850

                                                                     362 of 369  
TI: Applications of polarography and voltammetry to marine and aquatic chemistry: 4. A new voltammetric method for the study of mercury traces in sea water and inland waters.
AU: Sipos,-L.; Valenta,-P.; Nurnberg,-H.W.; Branica,-M.-(Cent.-Mar.-Res.,-Inst.-'-Rudjer-Boskovic'-,-Zagreb,-Croatia,-Yugoslavia)
SO: J.-Electroanal.-Chem.-and-Interfacial-Electrochem., 1977 (77), 263-266
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: Mercury is well known as one of the most toxic metals in the environment. In sea water and inland waters mercury is dissolved usually at the ultra trace level (typically 0-.-1-0-.-01 -mu-gl-SUP--1-). Nevertheless the dissolved state is an important stage in the biogeochemical cycle of toxic metals as from there they interact with sediments and they also enter the marine and aquatic food chain due to accumulation by aquatic organisms. A reliable voltammetric approach to the determination of Hg is thus of particular importance for aquatic environmental trace chemistry. A series of preliminary tests convinced us that gold is the preferable electrode material and that the combination of several methodological principles of advanced polarography and voltammetry would provide an optimal performance with respect to accuracy and precision at the required high sensitivity level. The method developed consists of differential pulse anodic stripping in the subtractive mode (DPASV-S) at a twin disc gold electrode rotating with 1500 rpm during the cathodic deposition stage where a particular program of polarization is applied.
AN: 8135280

                                                                     363 of 369  
TI: Biogeochemical studies in the sea: studies on primary production and its relationship to the metabolism of organic matter in the marine and lacustrine environment.
AU: Saijo,-Y.-(Water-Res.-Inst.,-Nagoya-Univ.,-Chikusa,-Nagoya-464,-Japan)
SO: J.-Oceanogr.-Soc.-Jap., 1977 33(5), 290-296
LA: Japanese
AB: The studies on metabolism of organic matter in aquatic environments first involved research on the sedimentation process of organic matter in lacustrine environments. Subsequent measures of primary production in lake and sea water were undertaken to know the organic substance supply into the metabolism. After establishing the routine technique of productivity measurement in aquatic environment, the primary production and the photosynthetic characteristics in waters in the northwestern Pacific, the western Indian Ocean and the Antarctic Sea were studied. Following the development of new methods to determine the organic substances in the dissolved and particulate forms and chlorophyll pigment in seawater, their distributions in both horizontal and vertical directions were determined. The author has also been interested in the mechanism producing a subsurface chlorophyll maximum in the ocean. In addition, interest has been directed to the coastal waters. The nitrogen cycle was studied in oyster beds and the research on eutrophication processes in a shallow bay is being carried out from the aspect of production and decomposition of organic matter.
AN: 8125000

                                                                     364 of 369  
TI: High molecular weight organic matter in seawater. [Presented at: NATO/ONR Symposium on 'Concepts in Marine Organic Chemistry'; Edinburgh (UK); 6 Sep 1977].
AU: Ogura,-N.-(Dep.-Environ.-Sci.-Conserv.,-Tokyo-Univ.-Agric.-and-Technol.,-Fuchu,-Tokyo-183,-Japan)
CO: [Presented at: NATO/ONR Symposium on 'Concepts in Marine Organic Chemistry'  Edinburgh (UK)  6 Sep 1977].
SO: Mar.-Chem., 1977 5(4-6), 535-549
LA: English
ER: M (Marine)
AB: The presence and nature of high molecular weight organic matter in seawater was critically reviewed and its biogeochemical cycle was discussed. Organic matter that passes through a filter of 0-.-5-1 -mu-m pore size is called dissolved and that which does not pass through such a filter is defined as particulate. The size of colloidal particles ranges from 0-.-001 to 1 -mu-m, and therefore, they are included in the dissolved fraction having high molecular weight. High molecular weight organic matter greater than 100 000 molecular weight was found in the seawater of Tokyo Bay. The values ranged from 0-.-1 to 1-.-5 mgC/l, and accounted for 8-45% of the total dissolved organic matter. Decomposition experiments on dissolved organic matter showed that macromolecular organic matter is refractory to bacterial attack. However, macromolecular organic materials tend to aggregate or adsorb on small particles to a sufficient size for precipitation. Organic aggregates thus formed sink to the bottom of the sea and bioelements included in them are removed from water column. High molecular weight organic materials are, therefore, considered to play an important role in transportation and distribution of matter in seawater. In order to elucidate the chemical and biological properties of macromolecular organic matter, concentration and isolation of this material are important, using methods such as adsorption on organic adsorbents or ultrafiltration.
AN: 8089380

                                                                     365 of 369  
TI: Biokinetics of neptunium-237 in mussels and shrimp.
AU: Guary,-J.C.; Fowler,-S.W.-(Internatl.-Lab.-Mar.-Radioactivity,-IAEA,-Mus.-Oceanogr.,-Monaco)
SO: Mar.-Sci.-Commun., 1977 3(3), 211-229
LA: English
ER: M (Marine)
AB: Neptunium-237 kinetics were studied in marine shrimp and mussels using a thick source alpha counting technique. Bioaccumulation of -SUP-237-Np from water was relatively slow in both species, reaching whole body concentration factors of only 15 to 20 after three months. Surface adsorption was implicated in the initial uptake. Both uptake and loss of the radioisotope were not significantly affected by temperature; this may be a reflection of the physical nature of the uptake. By virtue of the large amounts of accumulated -SUP-237-Np associated with the exoskeleton of shrimp, molting will play an important role in the biogeochemical cycling of this transuranic in the marine environment. Rapid growth of organisms like mussels acts to reduce the -SUP-237-Np concentration in tissues during a period of decontamination.
AN: 8025060

                                                                     366 of 369  
TI: The chemical composition of Central Amazonian aquatic macrophytes with special reference to their role in the ecosystem.
AU: Howard-Williams,-C.; Junk,-W.J.-(Inst.-Freshwater-Stud.,-Rhodes-Univ.,-Grahamstown,-South-Africa)
SO: Arch.-Hydrobiol., 1977 79(4), 446-464
LA: English
ER: F (Freshwater)
AB: Levels of ash, Na, K, Ca, Mg, Si, N, P, dry matter, polyphenols, potential energy (calories) and cell wall material were determined from 23 species of aquatic plants from the Central Amazon. Levels of P and K were particularly high in the aquatic plants when compared with the amounts of these elements in the soils and waters of the area, although Ca was extremly low in the macrophytes. The role of the macrophytes as nutrient reservoirs and in the biogeochemical cycle of the varzea lakes of the Central Amazon is discussed.
AN: 8056320

                                                                     367 of 369  
TI: Biokinetics of neptunium-237 in mussels and shrimp
AU: Guary,-J.C.; Fowler,-S.W.-(Internatl.-Lab.-Mar.-Radioactivity-IAEA,-Mus.-Oceanogr.,-Monaco)
SO: Mar.-Sci.-Commun., 1977 3(3), 211-229
LA: English
ER: M (Marine)
AB: Neptunium-237 kinetics were studied in marine shrimp and mussels using a thick source alpha counting technique. Bioaccumulation of -SUP-237-Np from water was relatively slow in both species, reaching whole body concentration factors of only 15 to 20 after three months. Surface adsorption was implicated in the initial uptake. Both uptake and loss of the radioisotope were not significantly affected by temperature; this may be a reflection of the physical nature of the uptake. By virtue of the large amounts of accumulated -SUP-237-Np associated with the exoskeleton of shrimp, molting will play an important role in the biogeochemical cycling of this transuranic in the marine environment. Rapid growth of organisms like mussels acts to reduce the -SUP-237-Np concentration in tissues during a period of decontamination.
AN: 8025060

                                                                     368 of 369  
TI: Processes of organic production on coral reefs
AU: Lewis,-J.B.-(Redpath-Mus.-Mar.-Sci.-Cent.,-McGill-Univ.,-Montreal,-Quebec,-Canada)
SO: Biol.-Rev.-Camb.-Philos.-Soc., 1977 52(3), 305-347
LA: English
ER: M (Marine)
AB: Rates of gross primary production on reefs vary between 300-5000 gC/m-SUP-2-/yr. These rates are higher than general oceanic values and as high as those of the most productive marine communities. Sources of primary production include fleshy macrophytes, calcareous algae, filamentous algae on the coral skeletons or calcareous rock, marine grasses and the zooxanthellae within coral tissue. Production values from the various sources fall within the range of production of reefs as a whole. There is evidence to suggest that nitrogen and phosphorus are recycled rapidly on the reef and that nitrogen is fixed by bacteria and primary producers. The weight of evidence suggests that while there is a removal of zooplankton by benthic organisms, the total biomass carried over the reef is too small to support the energy needs of secondary production. Bacteria are a potential source of energy for secondary production on reefs and are implicated in nitrogen fixation, decomposition and biogeochemical cycling. Estimates of reef growth have been made from measurements of coral growth and from the flux of calcium carbonate. Hydrographic factors influence growth and form of reefs and their is some evidence to show that production is enhanced by conservation of water in lagoonal areas.
AN: 8029540

                                                                     369 of 369  
TI: The chemical composition of central Amazonian aquatic macrophytes with special reference to their role in the ecosystem
AU: Howard-Williams,-C.; Junk,-W.J.-(Max-Planck-Inst.-Limnol.,-Ploen,-GFR)
SO: Arch.-Hydrobiol., 1977 79(4), 446-464
NT: 47 ref
LA: English
ER: F (Freshwater)
AB: Levels of ash, Na, K, Ca, Mg, Si, N, P, dry matter, polyphenols, potential energy (calories) and cell wall material were determined from 23 species of aquatic plants from the Central Amazon. Levels of P and K were particularly high in the aquatic plants when compared with the amounts of these elements in the soils andn waters of the area, although Ca was extremely low in the macrophytes. The role of the macrophytes as nutrient reservoirs and in the biogeochemical cycle of the varzea lakes of the Central Amazon is discussed.
AN: 7010080


No.    Records  Request

1:        504   BIOGEOCHEMICAL
2:      >8530   CYCL*
3:        369   BIOGEOCHEMICAL CYCL*
                Searches and records above from: ASFA 1978-1987
5:       1521   #3


                                                                      1 of 1521  
TI: Biogeochemical transformations of nitrogen and phosphorus in the marine environment -- coupling hydrodynamic and biogeochemical processes in models for the Baltic proper
AU: Savchuk,-O.; Wulff,-F.
AF: State Oceanographic Inst., St Petersburg Branch, 23d Line, 2A, 199026, St Petersburg, Russia
SO: SYST.-ECOL.-CONTRIB. 1996 no. 2, 79 pp
LA: English
ER: M (Marine)
AB: Numerical models explicitly simulating complex interactions between physical and biogeochemical processes are an important tool to study these phenomena at the ecosystem level. This technical report describes the continued development of a coupled hydrodynamic-biogeochemical model, originally presented by Stigebrandt & Wulff. The further developments of this model have followed the strategy adopted for a research program on the large-scale effects of pollution of the Baltic Sea, funded by the Swedish Environmental Protection Agency. For model development, a cooperation was initiated with the Russian 'Project Baltica' where similar models have been developed. A sub-model that couples the nitrogen and phosphorus pelagic cycles in the upper layers of the water column was described in Savchuk & Wulff. Here we present some results from the development of the biochemical sub-models with descriptions of nitrogen fixation and of sediment-water interactions which has been coupled with the hydrodynamic sub-model and implemented for the Baltic Proper. We have also verified the model results in an extensive analysis of observations from the Baltic and other marine areas.
AN: 3971280

                                                                      2 of 1521  
TI: Phosphorus metabolism in anthropogenically transformed lagoon ecosystems: The Comacchio lagoons (Ferrara, Italy)
AU: Sorokin,-Y.I.; Dallocchio,-F.; Gelli,-F.; Pregnolato,-L.
AF: Dipto. di Biochimica e Biol. Molecolare, via Borsari 46, 44100 Ferrara, Italy
SO: J.-SEA-RES. 1996 vol. 35, no. 4, pp. 243-250
LA: English
ER: B (Brackish)
AB: Inorganic phosphorus dynamics were investigated with the use of  super(32)P in the hypertrophic Comacchio lagoons (NE Adriatic) during an extremely dense, quasi-permanent bloom of picocyanobacteria. Concentrations of dissolved inorganic phosphate (DIP) in waters of the blooming lagoons were usually near the detection limit (0.01  mu moles/dm super(3)). DIP uptake rates by microplankton at near-ambient concentrations (0.01 to 0.1  mu moles/dm super(3)) were in the range of 9.6 to 16.1 nmoles P/dm super(3)/min, and turnover times were 1.5 to 3 min. The turnover time was >40 h in the eutrophic coastal waters of the adjacent Adriatic Sea. The uptake rate of DIP depended on its initial concentration. In water samples artificially enriched with DIP, the uptake rate rose to its maximum of 0.10 to 0.13  mu moles P/dm super(3)/min (or  similar to 6 to 7  mu moles/dm super(3)/h) when the initial concentration of DIP was elevated to 10 to 20  mu moles/dm super(3). The potential capacity of microplankton in the water samples to consume and retain DIP was estimated at  similar to 25  mu moles/dm super(3). Specific features are discussed of phosphorus metabolism in the anthropogenically transformed lagoon ecosystem with an anomalous food web with few animals.
AN: 3970980

                                                                      3 of 1521  
TI: Some aspects of iron cycling in maritime Antarctic lakes
AU: Ellis-Evans,-J.C.; Lemon,-E.C.G.
AF: Bri. Antarc. Surv., Nat. Environ. Res. Counc., High Cross, Madingley Rd., Cambridge, CB3 OET, UK
CO: 23. Cong. of the Societas Internationalis Limnolgiae Hamilton (New Zealand) [nd]
SO: HIGH-LATITUDE-LIMNOLOGY. Vincent,-W.F.;Ellis-Evans,-J.C.-eds. 1989 vol. 172 pp. 149-164
ST: HYDROBIOLOGIA vol. 172
LA: English
ER: F (Freshwater)
AB: Iron occurs in extremely high concentrations in certain maritime Antarctic freshwater lakes which seasonally develop an anoxic zone. In oligotrophic Sombre Lake the data show that Fe(II) precipitates as Fe(III) oxyhydroxides which bind phosphorus and return it to the sediments. In nutrient-enriched Amos Lake, significant quantities of sulphide are also produced and this binds a proportion of the released Fe(II) so reducing the ratio of total iron to phosphorus at the redox boundary where the oxyhydroxides are formed. A proportion of the sediment-released phosphorus therefore reaches the upper waters of this lake (unlike in Sombre Lake) and provides the initial nutrient source for under-ice phytoplankton development in spring. Iron-reducing bacteria have been isolated, from Sombre Lake sediments, which apparently utilise the abundant Fe(III) oxyhydroxides. From thermodynamic considerations (assuming Fe(III) is not limiting) these should outcompete sulphate reducers and methanogens (both previously reported from Sombre and Amos Lakes) and could therefore constitute an important component of the anaerobic mineralisation of organic carbon in such lakes (DBO).
AN: 3969753

                                                                      4 of 1521  
TI: A 420,000-year record of cyclicity in oceanic and atmospheric processes from the eastern Equatorial Pacific
AU: Rea,-D.K.; Chambers,-L.W.; Chuey,-J.M.; Janecek,-T.R.; Leinen,-M.; Pisias,-N.G.
AF: Oceanogr. Program, Dep. Atmos. and Ocean. Sci., Univ. Michigan, Ann Arbor, MI, USA
SO: PALEOCEANOGRAPHY 1986 vol. 1, no. 4, pp. 577-586
NT: Special issue: Milankovitch cycles through geologic time.
LA: English
ER: M (Marine)
AB: (DBO).
AN: 3969648

                                                                      5 of 1521  
TI: Cyclic patterns in the Paleozoic and Mesozoic: Implications for time scale calibrations
AU: Bayer,-U.; McGhee,-G.R.,Jr.
AF: Dep. Geol. Sci., Wright Geol. Lab., Rutgers Univ., New Brunswick, NJ, USA
SO: PALEOCEANOGRAPHY 1986 vol. 1, no. 4, pp. 383-402
NT: Special issue: Milankovitch cycles through geologic time.
LA: English
ER: M (Marine)
AB: (DBO).
AN: 3969634

                                                                      6 of 1521  
TI: Cyclicity in the Milankovitch band through geologic time: An introduction
AU: Arthur,-M.A.; Garrison,-R.E.
AF: Grad. Sch. Oceanog., Univ. Rhode Island, Narragansett, RI, USA
SO: PALEOCEANOGRAPHY 1986 vol. 1, no. 4, pp. 369-372
NT: Special issue: M: lankovitch cycles through geologic time.
LA: English
ER: M (Marine)
AB: (DBO).
AN: 3969632

                                                                      7 of 1521  
TI: Tectonic cycles and the history of the earth's biogeochemical and paleoceanographic record
AU: Worsley,-T.R.; Nance,-R.D.; Moody,-J.B.
AF: Dep. Geol. Sci. Ohio Univ., Athens, OH, USA
SO: PALEOCEANOGRAPHY 1986 vol. 1, no. 3, pp. 233-263
LA: English
ER: M (Marine)
AB: (DBO).
AN: 3969624

                                                                      8 of 1521  
TI: The effect of phosphate status on the kinetics of cyanophage infection in the oceanic cyanobacterium Synechococcus sp. WH7803
AU: Wilson,-W.H.; Carr,-N.G.; Mann,-N.H.
AF: Dep. Biol. Sci., Univ. Warwick, Coventry CV4 7AL, UK
SO: J.-PHYCOL. 1996 vol. 32, no. 4, pp. 506-516
LA: English
ER: M (Marine)
AB: Phycoerythrin-containing Synechococcus species are considered to be major primarily producers in nutrient-limited gyres of subtropical and tropical oceanic provinces, and the cyanophages that infect them are thought to influence marine biogeochemical cycles. This study begins an examination of the effects of nutrient limitation on the dynamics of cyanophage/Synechococcus interactions in oligotrophic environments by analyzing the infection kinetics of cyanophage strain S-PM2 (Cyanomyoviridae isolated from coastal water off Plymouth, UK) propagated on Synechococcus sp. WH7803 grown in either phosphate-deplete or phosphate-replete conditions. When the growth of Synechococcus sp. WH7803 in phosphate-deplete medium was followed after infection with cyanophage, an 18-h delay in cell lysis was observed when compared to a phosphate-replete control. Synechococcus sp. WH7803 cultures grown at two different rates (in the same nutritional conditions) both lysed 24 h postinfection, ruling out growth rate itself as a factor in the delay of cell lysis. One-step growth kinetics of S-PM2 propagated on host Synechococcus sp. WH7803, grown in phosphate-deplete and-replete media, revealed an apparent 80% decrease in burst size in phosphate-deplete growth conditions, but phage adsorption kinetics of S-PM2 under these conditions showed no differences. These results suggested that the cyanophages established lysogeny in response to phosphate-deplete growth of host cells. This suggestion was supported by comparison of the proportion of infected cells that lysed under phosphate-replete and-deplete conditions, which revealed that only 9.3% of phosphate-deplete infected cells lysed in contrast to 100% of infected phosphate-replete cells. Further studies with two independent cyanophage strains also revealed that only approximately 10% of infected phosphate-deplete host cells released progeny cyanophages. These data strongly support the concept that the phosphate status of the Synechococcus cell will have a profound effect on the eventual outcome of phage-host interactions and will therefore exert a similarly extensive effect on the dynamics of carbon flow in the marine environment.
AN: 3969472

                                                                      9 of 1521  
TI: Interannual variability of a salt-marsh ecosystem
AU: Teal,-J.M.; Howes,-B.L.
AF: Woods Hole Oceanographic Inst., Woods Hole, MA 02543, USA
SO: LIMNOL.-OCEANOGR. 1996 vol. 41, no. 4, pp. 802-809
LA: English
ER: B (Brackish)
AB: Data from Great Sippewissett Salt Marsh are used to gauge the extent of change of Spartina alterniflora marsh during periods of several to 22 yr. Our data all relate to plant production: from aboveground, maximum plant biomass measured over the entire period; from belowground, live root and rhizome biomass measured in 1974 and 1983, CO sub(2) evolution from the sediments for 7 yr, and pore-water concentrations of dissolved sulfide for 6 yr. All the measures indicated a relatively low degree of interannual change in salt-marsh areas vegetated by tall- and short-form S. alterniflora. The similarity in both plant and biogeochemical parameters between years is likely related to the regular, high-frequency tidal flooding of grass stands. These interannual comparisons of each quantified parameter support the contention that measurements made in any single year can be applied to other years with suitable precautions to account for seasonal cycles. Our data also illustrate the importance of long time series for establishing sound correlations in environmental data.
AN: 3968891

                                                                     10 of 1521  
TI: Biogeochemistry of N, P and Si in Baltic Sea sediments: Response to a simulated deposition of a spring diatom bloom
AU: Conley,-D.J.; Johnstone,-R.W.
AF: National Environmental Research Institute, Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark
SO: MAR.-ECOL.-PROG.-SER. 1995 vol. 122, no. 1-3, pp. 265-276
NT: Bibliogr.: 68 ref.
LA: English
ER: M (Marine)
AB: Experimental studies of intact cores from the Baltic Sea were conducted to determine the response of sediment nutrient recycling processes to varied inputs of organic matter. A 2 mo enrichment experiment was carried out in the laboratory on sediment cores held at 4 degree C using a flow-through system where overlying waters were continuously replaced at a rate of 1 d super(1) The experiments were designed to simulate the deposition of organic matter that occurs during a typical spring diatom bloom (1x) and under enriched conditions with eutrophication at approximately 3 times (3x) a normal spring bloom utilizing added organic matter from a natural phytoplankton assemblage collected in a eutrophic coastal fjord during the spring diatom bloom. Low and constant sediment-water fluxes were observed throughout the duration of the experiment in control cores with no added organic matter. In all cases an immediate response was noted when a single pulsed addition of algal material was added to the sediment surface. Sediment-water fluxes of ammonium (NH sub(4) super(+)), and dissolved inorganic phosphate (DIP) increased significantly (ANOVA, p <0.01). For nitrite + nitrate (NO sub(2) super(-) + NO sub(3) super(-)) and dissolved silicate (DSi) sediment-water fluxes, differences were initially observed; however, only the NO sub(2) super(-) + NO sub(3) super(-) fluxes were significantly different over time (ANOVA, p <0.01). Fluxes of NO sub(2) super(-) + NO sub(3) super(-) were into the sediment for 3 to 10 d after addition of organic material, followed by small fluxes out of the sediment. The addition of algal material proportionate to a normal spring bloom (1x) had only a minor effect on porewater nutrient concentrations, whereas the 3x treatment substantially modified both the short- and long-term response of sediments. A greater proportion of anaerobic decomposition products, e.g. NH sub(4) super(+) and DIP, were observed with an expansion of more reducing conditions resulting from the addition of organic matter. The percentage of Si remineralized decreased as the flux of material to the sediment increased. Deposition rates similar to a typical spring bloom did not have long-term effects on the nutrient recycling processes; however, increases in the present level of deposition (as simulated in this study), which are forecasted with further eutrophication in the Baltic Sea, may have a significant impact on nutrient biogeochemical cycles.
AN: 3967434

                                                                     11 of 1521  
TI: Modelling areal hypolimnetic oxygen demand in lakes
AU: Chapra,-S.C.; Bachmann,-R.W.; Jones,-J.R.; Peters,-R.H.; Soballe,-D.M.-(eds.)
AF: Univ. Colorado, Boulder, CO 80309-0428, USA
CO: 15. Annual International Symposium of the North American Lake Management Society, Toronto, ON (Canada), 6-11 Nov 1995
SO: LAKE-RESERV.-MANAGE. 1995 vol. 11, no. 2, p. 125
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: After a brief review of empirical AHOD models, a new mechanistic approach is described. The approach employs a mass balance for the hypolimnion that can be solved for temporal changes in oxygen concentration as a function of time. Thermocline fluxes include settling of particulate organic carbon (POC) and diffusion of both POC and oxygen. Hypolimnetic oxygen sinks include carbon decomposition and nitrification in the water and sediment oxygen demand (SOI). The latter is linked to settling POC using Di Toro's estuary SOD modelling framework. This framework is modified to apply to freshwater systems. In particular, methanogenesis and methane bubble formation are included. The approach is demonstrated by applying it to Cascade Reservoir in Idaho. Finally, a comparison between the mechanistic model and empirical approaches is presented.
AN: 3966922

                                                                     12 of 1521  
TI: Seasonal and interannual variability in primary production and particle flux at Station ALOHA
AU: Karl,-D.M.; Christian,-J.R.; Dore,-J.E.; Hebel,-D.V.; Letelier,-R.M.; Tupas,-L.M.; Winn,-C.D.
AF: Dep. Oceanogr., Sch. Ocean and Earth Sci. and Technol., Univ. Hawaii, 1000 Pope Rd., Honolulu, HI 96822, USA
SO: DEEP-SEA-RES.-2-TOP.-STUD.-OCEANOGR. 1996 vol. 43, no. 2-3, pp. 539-568
NT: Special issue: Ocean time-series: Results from the Hawaii and Bermuda research programs.
LA: English
ER: M (Marine)
AB: A 5-year time-series study of primary production and euphotic-zone particle export in the subtropical North Pacific Ocean near Hawaii (Sta. ALOHA, 22 degree 45'N, 158 degree W) with measurements collected at approximately monthly intervals has revealed significant variability in both ecosystem processes. Depth-integrated (0-200 m) primary production averaged 463 mg C m super(-2) day super(-1) (s = 156, n = 54) or 14.1 mol C m super(-2) year super(-1). This mean value is greater than estimates for the North Pacific Ocean gyre made prior to 1984, but conforms to data obtained since the advent of trace metal-clean techniques. Daily rates of primary productivity at Sta. ALOHA exhibited interannual variability including a nearly 3-year sustained increase during the period 1990-1992 that coincided with a prolonged El Nino-Southern Oscillation (ENSO) event. Export production, defined as the particulate carbon (PC) flux measured at the 150 m reference depth, also varied considerably during the initial 5 years of the ongoing field experiment. The PC flux averaged 29 mg C m super(-2) day super(-1) (s = 11, n = 43) or 0.88 mol C m super(-2) year super(-1). A 5-fold variation between the minimum and maximum fluxes, measured in any given year, was observed. During the first 3 years of this program (1989-1991), a pattern was resolved that included two major export events per annum one centered in late winter and the other in late summer. After 1991, export production exhibited a systematic decrease with time during the prolonged ENSO event. When expressed as a percentage of the contemporaneous primary production, PC export ranged from 2 to 16.9%, with a 5-year mean of 6.7% (s = 3.3, n = 40). Contrary to existing empirical models, contemporaneous primary production and PC flux were poorly correlated, and during the ENSO period they exhibited a significant inverse correlation. This unexpected decoupling of particle production and flux has numerous implications for oceanic biogeochemical cycles and for the response of the ocean to environmental perturbations.
AN: 3965261

                                                                     13 of 1521  
TI: Cost-effective lake analysis: 20-20 Hind sight
AU: Welch,-E.B.; Jacoby,-J.M.; Bachmann,-R.W.; Jones,-J.R.; Peters,-R.H.; Soballe,-D.M.-(eds.)
AF: Dep. Civ. Eng., Univ. Washington, Seattle, WA 98195, USA
CO: 15. Annual International Symposium of the North American Lake Management Society, Toronto, ON (Canada), 6-11 Nov 1995
SO: LAKE-RESERV.-MANAGE. 1995 vol. 11, no. 2, pp. 201-202
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Water and nutrient budgets and trophic assessment are recommended and often required in Phase I diagnostic prerestoration studies (Cooke et al., 1993; USEPA, 1990). Annual water and nutrient budgets are costly, may be inaccurate and are often of minor importance in assessing the cause(s) for summer algal and macrophyte problems. If internal phosphorus (P) loading is suspected as the major cause for summer algal problems, a more cost-effective approach is to directly determine internal P loading from lake data and calculate external nonpoint loading with a mass balance model (Cooke et al., 1993) during summer when algal problems are usually most prevalent. Surface inflows are usually low, but internal loading is highest during that period. If macrophytes are the main problem, water and nutrient budgets are of minor importance in subsequent management schemes. Costly nitrogen analyses would probably be eliminated, because reduction in N would rarely be recommended to control algae. In 11 of 14 cases in Washington State, corrective action could have been recommended without expensive, time consuming water and nutrient budgets. For future protection of lakes of low trophic state or if knowledge of the relative contribution of P from subwatersheds is important, then complete water and P budgets would be necessary. However, the prevailing approach to start with complete water and P budgets for all lakes, or that inlake treatments should occur only after external loads are controlled may not be cost-effective, especially if external loads are nonpoint and of minor importance during summer when algal problems usually occur.
AN: 3964127

                                                                     14 of 1521  
TI: Bacterial populations and processes in sediments containing gas hydrates (ODP Leg 146: Cascadia Margin)
AU: Cragg,-B.A.; Parkes,-R.J.; Fry,-J.C.; Weightman,-A.J.; Rochelle,-P.A.; Maxwell,-J.R.
AF: Dep. Geol., Univ. Bristol, Bristol BS8 1RJ, UK
SO: EARTH-PLANET.-SCI.-LETT. 1996 vol. 139, no. 3-4, pp. 497-507
LA: English
ER: M (Marine)
AB: Bacterial populations and activity were quantified at three sites in the Cascadia Margin accretionary wedge, off the West Canadian/American coast (ODP Leg 146). At two sites sediments contained gas hydrates, Site 889/890 had a discrete zone of hydrate approximately 10 m above a bottom simulating reflector (BSR) at 225 m below sea floor (mbsf) and Site 892 had disseminated hydrate in the upper 20 mbsf and a BSR at 74 mbsf. Site 888 was a control site without gas hydrates. The control site (888) and top approximately 90 mbsf of Site 889/890 had bacterial distributions similar to previous Pacific Ocean sites. In the upper approximately 30 m of Site 892, however, bacterial populations were much lower, suggesting inhibition by the high concentrations of H sub(2)S within the hydrate zone. Below this depth bacterial populations rose to concentrations consistent with other sites. The control site was dominated by SO sub(4) reduction and rates of CH sub(4) oxidation in the top 90 m were low (0.002-0.033 nmol cm super(-3) d super(-1)). At Site 889/890 bacterial populations and activity were stimulated in the discrete hydrate zone. CH sub(4) oxidation rates increased in the middle of this zone to 134.5 nmol cm super(-3) d super(-1) (ca. 9 times the average rate at other depths), resulting in a significant (x 10) increase in the total bacterial population. The anaerobic process(es) responsible for this oxidation remain unclear, despite SO sub(4)-reducing bacteria, previously associated with CH sub(4) oxidation, also being stimulated in this zone. Fluid flux into accretionary wedge sediments may be an important process in providing electron acceptors to maintain these relatively high rates of CH sub(4) oxidation. This first microbiological study of gas hydrates indicates that bacterial processes are influenced by gas and fluid venting, and they play a major role in geochemical changes within these deep (> 200 mbsf) sediments.
AN: 3964064

                                                                     15 of 1521  
TI: Production of methanethiol from dimethylsulfoniopropionate in marine surface waters
AU: Kiene,-R.P.
AF: Department of Marine Sciences, University of South Alabama, LSCB 25, Mobile, AL 36688-0002, USA
SO: MAR.-CHEM. 1996 vol. 54, no. 1, pp. 69-83
LA: English
AB: Degradation of nM levels of dissolved dimethylsulfoniopropionate [DMSP(d)] in surface water samples from the Gulf of Mexico and Gulf of Maine was accompanied by the accumulation of both dimethylsulfide (DMS) and methanethiol (MeSH). The mean net yields for DMS and MeSH, in terms of sulfur from DMSP, were 32% (range 12-66%) and 22 % (range 3-64%), respectively. In six out of seventeen experiments, maximum net accumulations of MeSH were equivalent to, or greater than, those obtained for DMS. No relationship between net DMS and MeSH accumulations was found when all mseventeen experiments were considered. Inhibition of DMSP(d) degradation with 50  mu M glycine betaine substantially lowered production of both MeSH and DMS, indicating that degradation of DMSP was required to produce these sulfur gases. The most likely route for MeSH formation is from demethiolation of 3-methiolpropionate (MMPA), a product of DMSP demethylation. Experimental additions of MMPA confirmed that MeSH could be produced from this compound. The MeSH produced from DMSP was rapidly lost in all water samples tested, much more rapidly than DMS. Direct determinations of MeSH loss rate constants showed these to fall in the range of 0.14-1.4 h-1 in different water samples. Filtration of water through 0.2- mu m membrane filters resulted in a 1.3-4.5-fold decrease in the whole water loss rate constants, suggesting biological or particle sinks for MeSH. Addition of Suwannee River humic acid accelerated the loss of MeSH from filtered water, suggesting a possible interaction between MeSH and DOM. The results of this study indicate that a substantial fraction of the DMSP(d) degraded in aerobic seawater is converted to MeSH. The diversion of DMSP-sulfur to MeSH represents an important biogeochemical control on the production of climatically active DMS. In addition, the production of highly reactive MeSH suggests that the degradation of DMSP may have a more important impact on the chemistry of marine surface waters than previously recognized.
AN: 3961419

                                                                     16 of 1521  
TI: The biogenic silica production in the ocean: From the Weddel Sea to the Antarctic Ocean
OT: La production de silice biogenique dans l'ocean: de la mer de Weddel a l'ocean antarctique
AU: Leynaert,-A.
CA: Paris 6 Univ., (France)
SO: PARIS-FRANCE UNIV.-PARIS-6 1993 93 pp
LA: French
ER: M (Marine)
AB: The aim of the study was to establish the level of the biogenic silica production in the surface waters of the Antarctic Ocean, to assess the question of the silica paradox: how can a region of the world ocean account for less than 5% of the world's primary production, when it is the site of the 2/3 of the global accumulation of modern biogenic siliceous sediment? Within a framework of international co-operation we developed and improved a new method of determination of biogenic silica production. This method is based upon the use of radioactive isotope of silicon, whose radioactive daughter can be readily radioassay in waters by means of its Cerenkov radiations. This new technique presents several advantages: it can be use in oligotrophic areas, it doesn't require any samples preparation and preliminary silicic uptake rates can be determined aboard ship. In the meanwhile, we measured stocks and fluxes of biogenic silica in two regions of the Antarctic Ocean: the Weddel Sea and the Ross Sea. The results, along with previously collected data, are the support for a new estimate of the biogenic silica annual production in the Antarctic ocean. Limited to the area south of the Polar front, this estimate ranges between eleven and thirty two tera-moles of silicium per year, significantly lower than previously published values. When referring to the global marine silica production of the World ocean, the Antarctic contribution would account for no more than 4 to 21%.
AN: 3960989

                                                                     17 of 1521  
TI: Use of fluorogenic model substrates for extracellular bacterial enzyme activity (EEA)
OT: Utilisation d'un substrat modele fluorogene pour mesurer l'activite enzymatique extracellulaire (AEE) bacterienne
AU: Talbot,-V.; Bianchi,-M.
AF: Microbiologie marine CNRS UPR 223, Campus de Luminy, case 907, 13288 Marseille cedex 9, France
CA: Ecole thematique du CNRS, Banyuls-sur-Mer (France)
CO: Ecologie Bacterienne des Milieux Aquatiques, Banyuls-sur-Mer, 15-27 Oct 1995
SO: BACTERIAL-ECOLOGY-OF-THE-AQUATIC-ENVIRONMENTS.-ECOLOGIE-BACTERIENNE-DES-MILIEUX-AQUATIQUES. Lebaron,-P.-ed. PARIS-FRANCE INSTITUT-OCEANOGRAPHIQUE 1995 vol. 21, no. 1 pp. 247-260
ST: OCEANIS-DOC.-OCEANOGR. vol. 21, no. 1
LA: French
ER: M (Marine)
AB: Most of organic compounds produced in natural waters have a polymeric structure and have to be hydrolysed by extracellular enzymes before incorporation into the bacterial cell. Use of fluorogenic model substrates for extracellular enzyme activity (EEA) measurement of bacteria is a rapid and sensitive method. These substrates contain an artificial fluorescent molecule the methylumbelliferone (MUF) or the 4-methylcoumarinyl-7-amide (MCA) linked by a specific binding to a natural molecule (e.g. amino acids glucose). The fluorescence is observed after enzymatic splitting of the complex molecule and is measured by spectrofluorometry. Several model substrates are available and permit the measurement of the EEA of most of enzymes (e.g. aminopeptidase glucosidase phosphotase galactosidase sulfatase). Different concentrations have to be used to approach the in situ activity and maximum activity, or to determine the kinetic parameters (Vm and Km). Moreover ectoenzyme activity could provide an indication of the organic matter flux crossing through the microbial loop as well as the quantity and quality of the organic matter in the environment. Therefore EEA plays a key role in the organic matter flux and in the biogeochemical cycles.
AN: 3960888

                                                                     18 of 1521  
TI: Estimate of state variables of a trophic web model in the Bay of Brest
OT: Estimation des variables d'etat d'un modele de reseau trophique benthique en Rade de Brest
AU: Jean,-F.; Thouzeau,-G.
AF: URA 1513 CNRS, UFR Sciences et Techniques, 6 Av. Le gorgeu, BP 809, 29285 Brest Cedex, France
SO: C.-R.-ACAD.-SCI.-SER.-3-SCI.-VIE-LIFE-SCI. 1995 vol. 318, no. 1, pp. 145-154
LA: French
ER: M (Marine)
AB: Winter biomasses of the benthic fauna in the Brest Roadsted were estimated to model carbon fluxes through the benthic food web. Total biomass (9.59 g C m super(-2)) is dominated by macrofaunal suspension feeders (53%) and carnivores (25%). Macrofaunal deposit feeders and herbivores, meiofauna, bacteria and demersal fishes accounted for 22% of total biomass. Most of the biomass was found on coarse coralline algae bottoms in relation to environmental and biotic factors. Mean macrofaunal biomass is significantly higher in the Bay of Brest than in many other temperate coastal ecosystems. The proliferation of suspension feeders in the Bay would correspond to the first perturbation level of the ecosystem due to organic enrichment. Suspension feeders would prevent eutrophication 6y controlling phytoplankton biomass.
AN: 3960874

                                                                     19 of 1521  
TI: Modeling the diurnal cycle of carbon monoxide: Sensitivity to physics, chemistry, biology, and optics
AU: Gnanadesikan,-A.
AF: Prog. in Atmos. and Oceanic Sci., Princeton Univ., Princeton, NJ 08540, USA
SO: J.-GEOPHYS.-RES.-C-OCEANS 1996 vol. 101, no. C5, pp. 12,177-12,191
LA: English
ER: M (Marine)
AB: As carbon monoxide within the oceanic surface layer is produced by solar radiation, diluted by mixing, consumed by biota, and outgassed to the atmosphere, it exhibits a diurnal cycle. The effect of dilution and mixing on this cycle is examined using a simple model for production and consumption coupled to three different mixed layer models. The magnitude and timing of the peak concentration, the magnitude of the average concentration, and the air-sea flux are considered. The models are run through a range of heating and wind stress and compared to experimental data reported by Kettle [1994]. The models are run to simulate a single day of observations. The mixing parameterization is shown to be very important, with a model which mixes using small-scale diffusion producing markedly larger surface concentrations than models which homogenize the mixed layer completely and instantaneously.
AN: 3960073

                                                                     20 of 1521  
TI: Biogeochemical cycling in the global ocean. 2. New production, Redfield ratios, and remineralization in the organic pump
AU: Shaffer,-G.
AF: Dep. Geophys., Niels Bohr Inst. for Astronomy, Phys., and Geophys. Univ. Copenhagen, Copenhagen, Denmark
SO: J.-GEOPHYS.-RES.-C-OCEANS 1996 vol. 101, no. C2, pp. 3723-3745
LA: English
ER: M (Marine)
AB: Analytic solutions for global ocean distributions of phosphate, nitrate, and dissolved oxygen are presented for the high-latitude exchange/interior diffusion-advection (HILDA) model. The organic pump, which together with ocean physics controls nutrient and oxygen cycling in the ocean, is characterized in the model by parameters representing element (Redfield) ratios of organic matter exported from the lighted surface layer of the ocean and by parameters representing depth scales of remineralization for each element. A critical reassessment of recent work on determining Redfield ratios in new production and remineralization ratios is presented. From this reassessment and from the more robust results of this paper, the following conclusions are reached: (1) Total ocean new production is probably at least 5 Gt C yr super(-1). (2) The best estimate for ocean mean -O sub(2):C:N:P mole ratios in new production is about 148:105:15:1. (3) Significant vertical fractionation of organic matter occurs in the upper kilometer or so of the ocean; nutrients are released in the mean faster than carbon dioxide. Mean remineralization ratios for -O sub(2):P (C:P) increase from about 130  plus or minus  15 (90  plus or minus  15) at the base of the euphotic zone to about 170  plus or minus  10 (125  plus or minus  10) at 1000- to 1500-m depth and remain so deeper down. (4) The organic matter exported out of the surface layer of the high-latitude oceans is relatively poor in nitrogen but relatively rich in hydrogen.
AN: 3960053

                                                                     21 of 1521  
TI: Atmospheric sulfur cycling in the Tropical Pacific marine boundary layer (12 degree S, 135 degree W): A comparison of field data and model results. 2. Sulfur dioxide
AU: Yvon,-S.A.; Saltzman,-E.S.
AF: Natl. Oceanic and Atmos. Admin., Climate Monitoring and Diagnostics Lab., Boulder, CO, USA
SO: J.-GEOPHYS.-RES.-D-ATMOS. 1996 vol. 101, no. D3, pp. 6911-6918
NT: Special section: GEWEX Continental-scale International Project (GCIP).
LA: English
ER: M (Marine)
AB: The atmospheric chemistry of sulfur dioxide over the tropical South Pacific Ocean is investigated by using results from field measurements and numerical models. Simultaneous real time measurements of sulfur dioxide and its biogenic precursor dimethylsulfide were made at 12 degree S, 135 degree W for a 6-day period from March 3 through March 9, 1992. The mean SO sub(2) and DMS mole fractions were 71  plus or minus  56 pmol mol super(-1) (1 sigma ) and 453  plus or minus  93 pmol/mol (1 sigma ) respectively. These concentrations are compared to those predicted by a time-dependent photochemical box model of the marine boundary layer. Model estimates of the yield of SO sub(2) from DMS oxidation range from 27% to 54%. Even with low yields, DMS is the dominant source of SO sub(2) in this region. Estimates of vertical entrainment velocities based on the tropospheric ozone budget suggest that vertical entrainment is a minor source of SO sub(2). The relative rates of various loss mechanisms for SO sub(2) are dry deposition to the sea surface (58%), in-cloud oxidation (9%), OH oxidation (5%), and uptake by sea-salt aerosols (28%).
AN: 3953816

                                                                     22 of 1521  
TI: Atmospheric sulfur cycling in the Tropical Pacific marine boundary layer (12 degree S, 135 degree W): A comparison of field data and model results. 1. Dimethylsulfide
AU: Yvon,-S.A.; Saltzman,-E.S.; Cooper,-D.J.; Bates,-T.S.; Thompson,-A.M.
AF: Rosenstiel Sch. Mar. and Atmos. Sci., Univ. Miami, Miami, FL, USA
SO: J.-GEOPHYS.-RES.-D-ATMOS. 1996 vol. 101, no. D3, pp. 6899-6909
NT: Special section: GEWEX Continental-scale International Project (GCIP).
LA: English
ER: M (Marine)
AB: Shipboard measurements of atmospheric and seawater DMS were made at 12 degree S, 135 degree W for 6 days during March 1992. The mean seawater DMS concentration during this period was 4.1  plus or minus  0.45 nM (1 sigma , n = 260) and the mean atmospheric DMS mole fraction was 453  plus or minus  93 pmol/mol (l sigma , n = 843). Consistent atmospheric diel cycles were observed, with a nighttime maximum and daytime minimum and an amplitude of approximately 85 pmol/mol. Photochemical box model calculations were made to test the sensitivity of atmospheric DMS concentrations to the following parameters: 1) sea-to-air flux, 2) boundary layer height, 3) oxidation rate, and 4) vertical entrainment velocities. The observed relationship between the mean oceanic and atmospheric DMS levels require the use of an air-sea exchange coefficient which is at the upper limit end of the range of commonly used parameterizations. The amplitude of the diel cycle in atmospheric DMS is significantly larger than that predicted by a photochemical model. This suggests that the sea-to-air DMS flux is higher than was previously thought, and the rate of daytime oxidation of DMS is substantially underestimated by current photochemical models of DMS oxidation.
AN: 3953815

                                                                     23 of 1521  
TI: Biogeochemical cycles of selenium in Antarctic water
AU: Weiping,-Xia; Haishen,-Zhang; Jianan,-Tan
AF: Dep. Oceanogr., Old Dominion Univ., Norfolk, VA 23529, USA
SO: J.-ENVIRON.-SCI.-CHINA 1996 vol. 8, no. 1, pp. 120-126
LA: English
ER: M (Marine)
AB: Both vertical and horizontal profiles of total dissolved selenium, dissolved organic and inorganic selenium, including Se(IV) and Se(VI), as well as particulate selenium in seawater were obtained on a basis of newly developed separation technique form Antarctic Ocean, where the production of deep waters occurs. The results exhibited that the concentrations of Se(IV) and Se(VI) were elevated and the total concentration in the surface of the high latitude waters (1.31 nmol/L) was above those at lower latitudes (1.09 nmol/L) and also that previously reported from the Southern Ocean (1.18 nmol/L, Suzuki, 1987). Preliminary investigation using specifically designed microlayer-sampler, that was first employed to identify the main biogeochemical processes, revealed Antarctic Ocean being functioning as a potential source as selenium in sea-air exchange. The mean life time of the selenium, detected as Se(IV) in deep water, was also estimated rather shorter than the residence time of the water mass, based on the samples collected from the cruise of China's Sixth Scientific Expedition.
AN: 3952281

                                                                     24 of 1521  
TI: Metazooplankton distribution in the Pomeranian Bay (southern Baltic) -- species composition, biomass and respiration
AU: Postel,-L.; Mumm,-N.; Krajewska-Soltys,-A.
AF: Institute of Baltic Sea Research Rostock-Warnemuende, Seestrasse 15, D 18119 Rostock-Warnemuende, Germany
SO: BIUL.-MORSK.-INST.-RYBACK.-GDYNIA-BULL.-SEA-FISH.-INST.-GDYNIA 1995 vol. 136, no. 3, pp. 61-73
LA: English
ER: M (Marine)
AB: The major objective of this study was to assess the importance of metazooplankton for organic matter transformations under the influence of spatial gradients in environmental conditions between the Odra River estuary and the open Baltic Sea. Zooplankton was collected in the fall of 1993, and net samples were sieved into size fractions for determinations of dry weight, species composition, and respiration. Cluster analysis revealed 4 major zooplankton assemblages: 1) a river plume, where limnetic rotifers, cladocerans, and cyclopoids acquired a high numerical importance, 2) a coastal transition zone characterized by a frequent occurrence of meroplankton larvae, 3) an outer transition zone dominated by copepods and cladocerans, and 4) an assemblage typical of open Arkona Sea conditions, almost exclusively consisting of copepods. In general, the biomass tended to decline with increasing distance from the river outlet, from 140 mg/m super(3) to open sea levels of about 40 mg/m super(3). However, a sharp drop in the biomass to 10 mg/m super(3) was observed near the border of fresh water influence, reflecting the disappearance of limnetic species. The average dry mass specific respiration rate decreased with increasing size class from 3.62 to 1.79  mu l O sub(2)/mg/h. Due to the low biomass of the smallest size class, in situ respiration was mainly a function of dry mass concentration. Total respiration in 55-500  mu m decreased from about 10 to 3 ml O sub(2)/m super(3)/day with increasing distance to the river mouth. This tendency was superimposed by a strong decline to 1 ml O sub(2)/m super(3)/day near the front of the river plume. In terms of carbon utilization, in situ respiration corresponds to 1-2% of primary production. This low percentage, which is rather typical of spring bloom conditions, results mainly from low dry mass specific respiration, despite high primary production, chlorophyll a concentration, and temperature. One possible explanation for this obvious inconsistency would be that seasonal variations in metabolic activity are not controlled by temperature and/or food conditions alone, but also by the biological constitution of plankton organisms.
AN: 3950799

                                                                     25 of 1521  
TI: Confirmation of iron limitation of phytoplankton photosynthesis in the Equatorial Pacific Ocean
AU: Behrenfeld,-M.J.; Bale,-A.J.; Kolber,-Z.S.; Aiken,-J.; Falkowski,-P.G.
AF: Oceanogr. and Atmos. Sci. Div., Brookhaven Natl. Lab., Upton, NY 11973-5000, USA
SO: NATURE 1996 vol. 383, no. 6600, pp. 508-511
LA: English
ER: M (Marine)
AB: The eastern Equatorial Pacific Ocean is one of only three open-ocean regions where low phytoplankton chlorophyll biomass persists despite perennially high nitrate and phosphate nutrient concentrations. In 1993, an area within this region was artificially enriched with a single dose of soluble iron to test whether phytoplankton are physiologically prevented from utilizing the available nutrients by the low natural iron concentrations. Although photosynthesis was stimulated, the observed lack of a bloom or a significant decrease in nutrient concentrations could not be attributed unequivocally to zooplankton grazing, further iron limitation or secondary nutrient limitation. In 1995, a second iron-enrichment experiment (IronEx II) was conducted in which the same total dosage of iron was added, but over eight days. A massive phytoplankton bloom developed, significantly reducing surface-water nutrient and CO sub(2) concentrations. Here we report in situ measurements of fluorescence during IronEx II, which show that the iron enrichment triggered biophysical alterations of the phytoplankton's photosynthetic apparatus, resulting in increased photosynthetic capacities throughout the experiment and, hence, the observed bloom. These results unequivocally establish physiological limitation of phytoplankton by iron as the cause of the high-nitrate, low-chlorophyll phenomenon in this ocean region.
AN: 3950484

                                                                     26 of 1521  
TI: Large decrease in ocean-surface CO sub(2) fugacity in response to in situ iron fertilization
AU: Cooper,-D.J.; Watson,-A.J.; Nightingale,-P.D.
AF: Dep. Atmos. and Oceanic Sci., Univ. Wisconsin, 1225 West Dayton St., Madison, WI 53706, USA
SO: NATURE 1996 vol. 383, no. 6600, pp. 511-513
LA: English
ER: M (Marine)
AB: The Equatorial Pacific Ocean is a "high-nitrate, low-chlorophyll" region where nitrate and phosphate are abundant all year round. These nutrients cannot therefore be limiting to phytoplankton production. It has been suggested that the bioavailability of iron--a micronutrient--may be preventing full biological utilization of the major nutrients. The results of a previous in situ iron fertilization experiment in this region provided support for this hypothesis, but the observed biological response resulted in only a small decrease in surface-water CO sub(2) fugacity. Here we report a much larger, biologically induced uptake of surface-water CO sub(2) that occurred during a second study. The fugacity of CO sub(2) in the centre of the (iron-fertilized) patch of surface ocean fell from a background value near 510  mu atm to approximately 420  mu atm, corresponding to a transient 60% decrease in the natural ocean-to-atmosphere CO sub(2) flux. We conclude that iron supply to this ocean region can strongly modulate the local short-term source of CO sub(2) to the atmosphere, but has little long-term influence on atmospheric CO sub(2) partial pressure. However, if such a modulation also occurs in the Southern Ocean, then iron bioavailability at high southern latitudes could have a significant effect on atmospheric CO sub(2) partial pressure, for example over glacial-interglacial periods.
AN: 3950482

                                                                     27 of 1521  
TI: Increased dimethyl sulphide concentrations in sea water from in situ iron enrichment
AU: Turner,-S.M.; Nightingale,-P.D.; Spokes,-L.J.; Liddicoat,-M.I.; Liss,-P.S.
AF: Sch. Environ. Sci., Univ. East Anglia, Norwich NR4 7TJ, UK
SO: NATURE 1996 vol. 383, no. 6600, pp. 513-517
LA: English
ER: M (Marine)
AB: The concentrations of bioavailable iron in the surface waters of some ocean regions may indirectly modulate climate by controlling phytoplankton productivity and thus the amounts of carbon dioxide and dimethyl sulphide (DMS) that are exchanged with the atmosphere. Oxidation of DMS is involved in the formation of atmospheric sulphate particles, which can exert a climate cooling effect directly (by scattering and absorbing solar radiation), and indirectly (by affecting cloudiness and hence global albedo). But direct evidence supporting the hypothesis that DMS production in the ocean is affected by iron availability is lacking. Here we report changes in the concentrations of DMS in response to in situ iron-enrichment during two ecosystem-scale experiments designed to investigate the biological and chemical effects of iron fertilization of under-productive surface ocean waters. The first such experiment revealed a limited overall biological response and no significant changes in DMS concentrations, although the concentrations of its biochemical precursor doubled. The second experiment, designed to better mimic the natural process of iron enrichment, elicited a much stronger biological response, and DMS concentrations increased by a factor of 3.5. This result provides direct support for an important link in the iron--DMS--climate hypothesis.
AN: 3950481

                                                                     28 of 1521  
TI: A massive phytoplankton bloom induced by an ecosystem-scale iron fertilization experiment in the Equatorial Pacific Ocean
AU: Coale,-K.H.; Johnson,-K.S.; Fitzwater,-S.E.; Gordon,-R.M.; Tanner,-S.; Chavez,-F.P.; Ferioli,-L.; Sakamoto,-C.; Rogers,-P.; Millero,-F.; Steinberg,-P.; Nightingale,-P.; Cooper,-D.; Cochlan,-W.P.; Kudela,-R.
AF: Moss Landing Lab., P.O. Box 450, Moss Landing, CA 95039-0450, USA
SO: NATURE 1996 vol. 383, no. 6600, pp. 495-501
LA: English
ER: M (Marine)
AB: The seeding of an expanse of surface waters in the Equatorial Pacific Ocean with low concentrations of dissolved iron triggered a massive phytoplankton bloom which consumed large quantities of carbon dioxide and nitrate that these microscopic plants cannot fully utilize under natural conditions. These and other observations provide unequivocal support for the hypothesis that phytoplankton growth in this oceanic region is limited by iron bioavailability.
AN: 3950479

                                                                     29 of 1521  
TI: Global carbon exchange and methane emissions from natural wetlands: Application of a process-based model
AU: Cao,-M.; Marshall,-S.; Gregson,-K.
AF: Dep. Physiol. and Environ. Sci., Univ. Nottingham, Loughborough, England, UK
SO: J.-GEOPHYS.-RES.-D-ATMOS. 1996 vol. 101, no. D9, pp. 14,399-14,414
LA: English
ER: F (Freshwater)
AB: Wetlands are one of the most important sources of atmospheric methane (CH sub(4)), but the strength of this source is still highly uncertain. To improve estimates of CH sub(4) emission at the regional and global scales and predict future variation requires a process-based model integrating the controls of climatic and edaphic factors and complex biological processes over CH sub(4) flux rates. This study used a methane emission model based on the hypothesis that plant primary production and soil organic matter decomposition act to control the supply of substrate needed by methanogens; the rate of substrate supply and environmental factors, in turn, control the rate of CH sub(4) production, and the balance between CH sub(4) production and methanotrophic oxidation determines the rate of CH sub(4) emission into the atmosphere. Coupled to data sets for climate, vegetation, soil, and wetland distribution, the model was used to calculate spatial and seasonal distributions of CH sub(4) emissions at a resolution of 1 degree  latitude x 1 degree  longitude. The calculated net primary production (NPP) of wetlands ranged from 45 g C m super(-2) yr super(-1) for northern bogs to 820 g C m super(-2) yr super(-1) for tropical swamps. CH sub(4) emission rates from individual gridcells ranged from 0.0 to 661 mg CH sub(4) m super(-2) d super(-1), with a mean of 40 mg CH sub(4) m super(-2) d super(-1) for northern wetland, 150 mg CH sub(4) m super(-2) d super(-1) for temperate wetland, and 199 mg CH sub(4) m super(-2) d super(-1) for tropical wetland. Total CH sub(4) emission was 92 Tg yr super(-1). Sensitivity analysis showed that the response of CH sub(4) emission to climate change depends upon the combined effects of soil carbon storage, rate of decomposition, soil moisture and activity of methanogens.
AN: 3950389

                                                                     30 of 1521  
TI: Global forest systems: An uncertain response to atmospheric pollutants and global climate change?
AU: Dixon,-R.K.; Wisniewski,-J.
AF: U.S. Support for Country Stud. to Address Climate Change, PO-63, 100 Independence Ave., SW, Washington, DC 20585, USA
CO: 5. Int. Conf. on Acidic Deposition: Science and Policy, Goteborg (Sweden), 26-30 Jun 1995
SO: ACID-REIGN-'-95?-PROCEEDINGS-FROM-THE-5TH-INTERNATIONAL-CONFERENCE-ON-ACIDIC-DEPOSITION:-SCIENCE-AND-POLICY-HELD-IN-GOTEBORG,-SWEDEN,-26-30-JUNE-1995. Grennfelt,-P.;Rodhe,-H.;Thoerneloef,-E.;Wisniewski,-J.-eds. 1995 vol. 85, no. 1 pp. 101-110
ST: WATER,-AIR,-SOIL-POLLUT. vol. 85, no. 1
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: Forest systems cover more than 4.1 x 10 super(9) ha of the Earth's land area. The future response and feedbacks of forest systems to atmospheric pollutants and projected climate change may be significant. Boreal, temperate and tropical forest systems play a prominent role in carbon (C), nitrogen (N) and sulfur (S) biogeochemical cycles at regional and global scales. The timing and magnitude of future changes in forest systems will depend on environmental factors such as a changing global climate, an accumulation of CO sub(2) in the atmosphere, and increase global mineralization of nutrients such as N and S. The interactive effects of all these factors on the world's forest regions are complex and not intuitively obvious and are likely to differ among geographic regions. Although the potential effects of some atmospheric pollutants on forest systems have been observed or simulated, large uncertainty exists in our ability to project future forest distribution, composition and productivity under transient or nontransient global climate change scenarios. The potential to manage and adapt forests to future global environmental conditions varies widely among nations. Mitigation practices, such as liming or fertilization to ameliorate excess NO sub(x) or SO sub(x) or forest management to sequester CO sub(2) are now being applied in selected nations worldwide.
AN: 3950128

                                                                     31 of 1521  
TI: Methane budget from paddy fields in India
AU: Parashar,-D.C.; Mitra,-A.P.; Gupta,-P.K.; Rai,-J.; Sharma,-R.C.; Singh,-N.; Koul,-S.; Ray,-H.S.; Das,-S.N.; Parida,-K.M.; Rao,-S.B.; Kanungo,-S.P.; Ramasami,-T.; Nair,-B.U.; et-al.
AF: Natl. Phys. Lab. (NPL), Dr. K.S. Krishnan Rd., New Delhi-110012, India
SO: CHEMOSPHERE 1996 vol. 33, no. 4, pp. 737-757
LA: English
AB: Results of national methane campaign launched in 1991 to assess methane budget from Indian paddy fields are reported. The campaign involved a number of scientific institutions and universities with National Physical Laboratory at Delhi operating as a nodal agency and covered most of the major rice growing regions of India. Methane emission rates ranged between -0.64 and 84.1 mg m super(-2)h super(-1). The methane budget from Indian paddies has been estimated to be around 4.0 TgY super(-1) with a range between 2.7 to 5.4 TgY super(-1).
AN: 3948300

                                                                     32 of 1521  
TI: Redfield ratios and regeneration rates of particulate matter in the Sea of Japan as a model of closed system
AU: Chen,-C.-T.A.; Gong,-Gwo-Ching; Wang,-Shu-Lun; Bychkov,-A.S.
AF: Inst. Mar. Geol. and Chem., Natl. Sun Yat-Sen Univ., Kaohsiung, Taiwan
SO: GEOPHYS.-RES.-LETT. 1996 vol. 23, no. 14, pp. 1785-1788
LA: English
ER: M (Marine)
AN: 3945802

                                                                     33 of 1521  
TI: Bio-optical modeling of photosynthetic production in coastal waters
AU: Smith,-R.C.; Prezelin,-B.B.; Bidigare,-R.R.; Baker,-K.S.
AF: CSL/Cent. Remote Sensing and Environ. Opt, UCMBO Geogr. Dep., Univ. California at Santa Barbara, Santa Barbara, CA 93106, USA
SO: LIMNOL.-OCEANOGR. 1989 vol. 34, no. 8, pp. 1524-1544
NT: Special issue: Hydrologic optics.
LA: English
ER: M (Marine)
AB: A physiological-based bio-optical model is used to estimate vertical profiles of instantaneous, diurnal, and integrated daily rates of in situ primary production throughout the water column at three stations across a coastal front. The model makes use of an empirical relationship between photosynthesis, quantum yield, and photosynthetically absorbed radiation and is a full spectral model with all relevant parameters determined as a function of wavelength. In the prior application of this bio-optical model, parameters used to estimate quantum yield as a function of irradiance were wavelength-independent and held constant. Here, the model is recast so that quantum yield is estimated with wavelength-dependent photosynthesis-irradiance (P-I) parameters, P sub(max) the maximum rate of phytoplankton photosynthesis, and I sub(k) the P-I saturation parameter, which are allowed to vary with depth and time of day. Both P sub(max)-dependent (assumed to be  lambda -independent) and I sub(k)-dependent (known to be  lambda -dependent) estimates of temporal/spatial changes in quantum yield were assessed. The model was tested in water masses where a net-to-nanoplankton transition was occurring in phytoplankton communities dominated by diatoms and prymnesiophytes. At each station there is close agreement between  super(14)C productivity estimates derived from knowledge of diurnal patterns in P-I parameters and productivity estimates derived from two variants of the bio-optical model based on knowledge of spectral irradiance and phytoplankton pigmentation. The  super(14)C and bio-optical estimates of primary production also show similar vertical patterns for either instantaneous or daily integrated values. When compared with  super(14)C estimates, I sub(k)-dependent bio-optical estimates of photosynthetic rates give a closer match than bio-optical estimates that are P sub(max)-dependent. The model permits calculation of primary production from shipboard observations and may be useful for predicting production rates from bio-optical data provided by untended buoys. (DBO)
AN: 3945026

                                                                     34 of 1521  
TI: The role of heterotrophic bacteria in iron-limited ocean ecosystems
AU: Tortell,-P.D.; Maldonado,-M.T.; Price,-N.M.
AF: Dep. Ecol. and Evol. Biol., Princeton Univ., Princeton, NJ 08544, USA
SO: NATURE 1996 vol. 383, no. 6598, pp. 330-332
LA: English
ER: M (Marine)
AB: Iron availability limits phytoplankton growth in large areas of the world's oceans and may influence the strength of the biological carbon pump. Very little is known of the iron requirements of oceanic heterotrophic bacteria, which constitute up to 50% of the total particulate organic carbon in open ocean waters and are important in carbon cycling as remineralizers of dissolved organic matter and hence producers of CO sub(2). Here we report that oceanic bacteria contain more iron per biomass than phytoplankton. In the subarctic Pacific, they constitute a large fraction of biogenic iron and account for 20-45% of biological iron uptake. Bacterial iron quotas in the field are similar to those of iron-deficient laboratory cultures, which exhibit reduced electron transport, slow growth, and low carbon growth efficiency. Heterotrophic bacteria therefore play a major role in the biogeochemical cycling of iron. In situ iron limitation of heterotrophic metabolism may have profound effects on carbon flux in the ocean.
AN: 3944722

                                                                     35 of 1521  
TI: TAG hydrothermal field
AU: Humphris,-S.E.; Herzig,-P.M.; Miller,-J.
AF: Dep. Geol. and Geophysics, Woods Hole Oceanogr. Inst., Woods Hole, MA 02543, USA
SO: JOIDES-J. 1995 vol. 21, no. 2, pp. 8-15
LA: English
ER: M (Marine)
AB: Leg 158 investigated the fluid flow, geochemical fluxes and associated alteration and mineralization, microbiological processes, and the subsurface nature of an active hydrothermal system on a slow-spreading sediment-free mid-ocean ridge. The active mound within the Trans-Atlantic Geotraverse (TAG) hydrothermal field at 26 degree N latitude on the Mid-Atlantic Ridge (MAR) is a large, mature deposit of varying mineralogy with emanating fluids displaying a wide range of temperatures and two distinct, but related, chemistries. At Site 957, a northwest-southeast transect of holes in three major, distinct areas of the mound was drilled: the upper terrace east of the Black Smoker Complex (proposed TAG-1 area), the white smoker Kremlin area (proposed TAG-2 area), and the upper terrace west of the Black Smoker Complex (proposed TAG-4 area). Based on the sequence of rock types recovered from each area, four major lithologic types can be distinguished, all of which may or may not be present at a given location. Massive pyrites and pyrite breccias dominate the upper 10-20 m. This is followed by an anhydrite-rich zone, which is composed of matrix-supported pyrite- anhydrite breccias and pyrite-anhydrite-silica breccias. At depths of about 40-45 mbsf, the amount of quartz-pyrite mineralization and quartz veining increases and represents the top of the quartz-sulfide stockwork zone, which typically includes pyrite-silica breccias overlying silicified wall-rock breccias. A quartz-chlorite stockwork zone was sampled at depths greater than 100 mbsf in Hole 957E. This complex assemblage of rock types is a product of the multistage development of the mound, and is reflected in the sequences of alteration and veining events that can be distinguished both in the sulfide breccias and in the silicified wall-rock and chloritized basalt breccias.
AN: 3943060

                                                                     36 of 1521  
TI: Preface to tropical coastal sedimentary environments
AU: Nittrouer,-C.; Figueiredo,-A.
SO: GEO-MAR.-LETT. 1996 vol. 16, no. 1, pp. 1-2
NT: Special issue: Tropical coastal sedimentary environments.
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: Coastal oceanographers around the world need to recognize the importance of tropical settings to the global ocean and articulate this to organizations that support international scientific research. Major research studies should be designed for tropical coastal environments, similar to those studies being undertaken in higher latitude coastal settings and in deep-sea equatorial settings. The wet tropics, in particular, have a significant influence on the world ocean; unfortunately, geopolitical circumstances deny them a powerful voice to bring about concerted efforts for scientific investigation. Therefore, we urge the international scientific community not to forget the wet tropics. This volume is an example of the international community at work. It is an outgrowth of two meetings convened in 1993. One was held at Universidade Federal Fluminense (A. G. Figueiredo and C. A. Nittrouer, conveners) and focused on the Brazilian coastal ocean at the mouth of the Amazon River. The other meeting was held at the Australian Institute of Marine Science (G. J. Brunskill and C. A. Nittrouer, conveners) and primarily considered the Gulf of Papua (southern coast of Papua New Guinea) with contrasts to the Amazon coastal area. This collection of papers represents contributions from both meetings. Unfortunately, the length of the volume required it to be split into two parts, appearing in Geo-Marine Letters as a final double issue of 1995 (v. 15) and the first issue of 1996 (v. 16).
AN: 3941050

                                                                     37 of 1521  
TI: Decomposition along a bog to rich fen gradient in central Alberta, Canada
AU: Szumigalski,-A.R.; Bayley,-S.E.
AF: Dep. Biol. Sci., CW405 Biol. Sci. Bldg., Univ. Alberta, Edmonton, AB T6G 2E9, Canada
SO: CAN.-J.-BOT.-REV.-CAN.-BOT. 1996 vol. 74, no. 4, pp. 573-581
LA: English
ER: F (Freshwater)
AB: The carbon (C) and nitrogen (N) contents and decomposition rates of the aboveground litter were measured in five peatlands (bog, poor fen, open moderately rich fen, wooded moderately rich fen, and lacustrine sedge fen) in central Alberta, Canada, over a period of 2 years. Decay rates and C and N content of the dominant species were measured at each site. Weight losses after 1 and 2 years were negatively correlated with initial and final C/N ratios. Weight losses were positively correlated with initial and final %N, with the fastest weight losses in the species with the highest N content. Rates of decay within sites differed according to litter types, with Carex > Betula > mosses. Decay rates and C and N content were also determined for a standard litter type (Carex lasiocarpa), to make cross-site comparisons. Standard litter weight losses differed between sites after 1 and 2 years of decay. The sites ranked poor fen > wooded-rich fen > bog > open-rich fen > sedge fen in order of greatest to smallest percent weight loss after 2 years. After 1 year, weight loss of the standard litter was negatively correlated with water level and pH-related parameters and positively correlated with total dissolved P. Decomposition was correlated with both substrate quality and environmental parameters, but the former may be more important than the latter in controlling decomposition in these peatlands.
AN: 3940642

                                                                     38 of 1521  
TI: Aspects of the biogeochemistry of sulphur in glacial melt water ponds on the McMurdo Ice Shelf, Antarctic
AU: De-Mora,-S.J.; Lee,-P.A.; Grout,-A.; Schall,-C.; Heumann,-K.G.
AF: Dep. Oceanographie, Univ. Quebec a Rimouski, 300 allee des Ursulines, Rimouski, Quebec, Canada
SO: ANTARCT.-SCI. 1996 vol. 8, no. 1, pp. 15-22
LA: English
ER: F (Freshwater)
AB: The distribution of dimethylsulphide (DMS), together with the precursor dimethylsulphonio-propionate (DMSP) and the oxidation product dimethylsulphoxide (DMSO), was measured in melt waters on the McMurdo Ice Shelf in the immediate vicinity of Bratina Island. Conductivity in these sulphate dominated ponds was extremely variable, ranging from 0.106-52.3 mS cm super(-1). Similarly, chlorophyll a concentrations in the pond waters (1-150  mu g l super(-1)) and mats (1.4-33  mu g cm super(-2)) differed considerably. The biomass was dominated by benthic felts of phototrophic cyanobacteria, which might act as a source of biogenic sulphur compounds in the ponds. The mean (and ranges) of concentrations of dissolved sulphur compounds (nmol l super(-1)) were: CS sub(2) 0.16 (<0.04-1.20); DMSP sub(d) 0.6 (<0.07-8.4); DMS 3.5 (<0.07-183); DMSO 27.9 (15.5-184.5). Very high concentrations of DMSO were ubiquitous in the ponds in the ice-cored moraine region of the ice shelf, with dissolved concentrations having been 1-2 orders of magnitude greater than those of DMS or DMSP sub(d). It is difficult to ascribe the formation of DMSO solely to the conventionally accepted pathways of DMS oxidation by either bacterial activity or photochemical reactions. A direct biosynthetic production from phytoplankton or bacteria might be involved which means that DMSO in aquatic environments could act as a significant source of DMS rather than as a sink as generally supposed.
AN: 3938807

                                                                     39 of 1521  
TI: [Modelling the biogeochemical cycle of the elements limiting the primary production in the English Channel (N, P, Si).]
OT: Modelisation du cycle biogeochimique des elements limitant la production primaire en Manche (N, P, Si)
AU: Hoch,-T.
CA: Univ. Paris 7, (France)
SO: PARIS-FRANCE UNIV.-PARIS-7 1995 213 pp
LA: French
ER: M (Marine)
AB: This work presents a model of organic matter cycle in the English Channel, through the nitrogen, phosphorous and silicium cycles. These elements were chosen for that they are limitant factors for the primary production in the Channel. In a first approach, a physical sub-model in boxes has been retained. The "ELISE" logiciel cutted the Channel into 71 boxes between which water fluxes were automatically calculated. This model has been associated to a two-layer vertical thermo-haline model, that simule temperature and salinity in the surface, also in the bottom layers. A biogeochemical model considers nitrogen, phosphorus and silicium into their mineral forms, also into their organic (phytoplanktonic), detritic in the water column, and organic benthic forms. Results of the coupling of the two models show influence of the stratification, of thermal origin in the Western Channel, and haline in the Bay of Seine upon phytoplankton distribution. Phytoplankton grow better in shallow water zones and in the surface layer of stratified zones, where the low thickness of the water let light penetrate at the best. The spring bloom is determined by these criteria, but the strengh of the bloom depends on the chemical richness of the environment. High concentration are also remarked at the opening of the Seine Estuary and along the french coast of the Eastern Channel. Raw annual primary production is strongly influenced by vertical structure, but in a quasi-opposite pattern as the spring bloom. The higher productions are recorded in the middle of the Eastern Channel that are depth mixed depth zones. The "ELISE" model was used to make a sensiblity analysis of the ecological processes at their limits, and of the forcing variables. Terrigenous nutriments inputs to the sea show that rivers have a little but remarkable role. The Seine river is by far the most important of these inputs. Nitrogen and phosphorous were analysed separately, and it is shown that the primary production is dependant of the nitrogen input. A long-term meteorological simulation (1978-1992) was initiated, and show strong dependance of the ecosystem towards meteorological conditions. They determine not only temperature and solar radiation used by phytoplankton, but also the vertical structure and possible stratification. Multi-years variations of the Seine inputs are only sensible upon the Picardie coastal zone. An assay of coupling this biological model with a physical fine model show the results of a pseudo-3D simulation. Such results are more precise as in the preceding conditions, but confirm the general conclusions.
AN: 3938628

                                                                     40 of 1521  
TI: The estimation of current state of Lake Ladoga using mathematical models
AU: Leonov,-A.V.; Filatov,-N.N.; Titov,-V.S.
AF: Water Problems Inst., Russian Acad. Sci., N. Basmannay Str. 10, 107078, Moscow, Russia
CO: 1. Int. Lake Ladoga Symp., St. Petersburg (Russia), 22-26 Nov 1993
SO: PROCEEDINGS-OF-THE-FIRST-INTERNATIONAL-LAKE-LADOGA-SYMPOSIUM:-ECOLOGICAL-PROBLEMS-OF-LAKE-LADOGA-HELD-IN-ST.-PETERSBURG,-RUSSIA,-22-26-NOVEMBER-1993. Simola,-H.;Viljanen,-M.;Slepukhina,-T.;Murthy,-R.-eds. 1996 vol. 322, no. 1-3 pp. 103-108
ST: HYDROBIOLOGIA vol. 322, no. 1-3
LA: English
ER: F (Freshwater)
AB: This paper describes a mathematical simulation model of the transformation of organic matter and biogenic compounds. The model is validated with observations made on Lake Ladoga. Despite the approximate nature of the biogenic load data, a good agreement is obtained between the calculated substance concentrations and available observations made during individual seasons for different areas of the lake. The model was developed by the author Leonov and this paper presents new model results with accurate formulations for nitrogen and carbon components. Comparison with observational data base collected during 1976-1979 shows that the model results provide good simulation of the annual seasonal changes in material concentrations in the identified regions of the lake.
AN: 3932181

                                                                     41 of 1521  
TI: The biogeochemical cycling of Zn, Cu, Fe, Mn, and dissolved organic C in a seasonally anoxic lake
AU: Hamilton-Taylor,-J.; Davison,-W.; Morfett,-K.
AF: Inst. Environ. and Biol. Sci., Lancaster Univ., Lancaster LA1 4YQ, UK
SO: LIMNOL.-OCEANOGR. 1996 vol. 41, no. 3, pp. 408-418
LA: English
ER: F (Freshwater)
AB: Detailed time-depth distributions of dissolved Zn, Cu, Fe, Mn, and dissolved organic C (DOC), together with pH, were obtained for the water column and near-surface sediment pore waters of a seasonally anoxic lake (Esthwaite Water, U.K.) over a 1-yr period. Dissolved Fe and Mn followed well-known patterns linked to redox recycling. The variation in DOC resulted mostly from its coupling with Fe, DOC being coprecipitated with Fe oxide and released into solution on the reductive remobilization of the oxide. This process produced a >7-fold seasonal variation in DOC concentrations in the pore waters, with a maximum of  similar to 7 mg/liter. Dissolved Zn and Cu exhibited coherent and similar distribution patterns unrelated in any simple way to the distributions of dissolved Fe and Mn, pH, and DOC. The most ubiquitous feature of the distribution of dissolved Zn, and to a lesser degree that of dissolved Cu, was a concentrations maximum at the sediment-water interface, which disappeared completely only when anoxia was maximal in mid- and late summer. The interfacial maxima were attributed to rapid release from freshly deposited particles allied to sulfide precipitation in the sediments. The timing of events, associated with an increase in interfacial dissolved Cu and Zn concentrations before and during a period of ice cover, indicated that the Cu was derived from Fe and possibly Mn oxides and Zn from planktonic algae. The cumulative downward diffusive fluxes of Zn and Cu from the interfacial maxima were unimportant ( similar to 1% of total) compared to total metal sedimentation rates. Chemical equilibrium calculations indicated that Zn- and Cu-sulfide complexes dominated in the pore waters under reducing conditions, with humic binding being insignificant, and that precipitation as pure sulfides or coprecipitation with FeS were likely major removal processes for Zn and Cu under anoxic conditions.
AN: 3931599

                                                                     42 of 1521  
TI: Loading and utilization of dissolved organic carbon from emergent macrophytes
AU: Mann,-C.J.; Wetzel,-R.G.*
AF: Dep. Biol. Sci., Univ. Alabama, Tuscaloosa, AL 35487-0206, USA
SO: AQUAT.-BOT. 1996 vol. 53, no. 1-2, pp. 61-72
LA: English
ER: F (Freshwater)
AB: The very high productivity of emergent macrophytes can provide major sources of dissolved organic matter to recipient aquatic ecosystems. Leachate was collected from live and senescent tissues of Juncus effusus L. and Typha latifolia L. and analyzed for dissolved organic carbon (DOC; mg C/l/cm super(2) surface area) and its availability to wetland bacteria. Leachate DOC ranged from 1.9 to 5.2 mg C/l cm super(2) across a gradient of fully photosynthetic to fully senescent culms. In culms 1/4 to 3/4 senescent, there was no significant difference (P > 0.05) in leachate DOC concentrations between the photosynthetic and senescent portions of culms. DOC in the leachate of J. effusus culms decreased significantly (P < 0.05) from an average of 336.8 mg C/l cm super(2) in January 1994 to 68.3 mg C/l/cm super(2) in July 1994. Bacterial growth efficiencies (ratio of bacterial biomass produced, measured by [ super(3)H] leucine incorporation, to leachate DOC utilized) on the leachate of J. effusus ranged from 16 to 34%. DOC concentrations in the leachate from T. latifolia were 1.4 (photosynthetic leaves) and 145.3 (senescent leaves) mg C/l cm super(2) and supported bacterial efficiencies of 45% (photosynthetic leaves) and 4% (senescent leaves), respectively.
AN: 3931575

                                                                     43 of 1521  
TI: The biogeochemistry of lipids in rivers of the Orinoco Basin
AU: Jaffe,-R.; Wolff,-G.A.; Cabrera,-A.C.; Chitty,-H.C.
AF: Florida Intl. Univ., Drinking Water Res. Cent., University Park, Miami, FL 33199, USA
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 21, pp. 4507-4522
LA: English
ER: F (Freshwater)
AB: Water samples from rivers in the Orinoco Basin were examined in order to assess the biogeochemistry of particle-associated and dissolved lipids. Lipid fractions were characterised so as to determine their origin, speciation, variability in individual rivers, and their flux to the lower Orinoco River. Aliphatic hydrocarbons, ketones, alcohols, triterpenoids, and fatty acids were ubiquitous in the rivers, and a large proportion of these compounds were found to be autochthonous in origin. The relative loadings of particle-associated and dissolved lipids were of the same order of magnitude in most of the rivers, indicating the importance of the dissolved phase. Apparently, true equilibria between water and particulate phases were not reached, probably as a result of the high amounts of colloidal and humic materials associated with the dissolved phase in most of the rivers. Preliminary data indicate that there were considerable seasonal variabilities in the distributions and concentrations of lipids in some of the rivers, but that each of these showed different behaviour.
AN: 3931547

                                                                     44 of 1521  
TI: The role of phytoplankton cells on the control of heavy metal concentration in seawater
AU: Gonzalez-Davila,-M.
AF: Dep. Quimica, Fac. Cienc. del Mar, Univ. Palmas de Gran Canaria, 35017 Palmas de Gran Canaria, Spain
SO: MAR.-CHEM. 1995 vol. 48, no. 3-4, pp. 215-236
LA: English
ER: M (Marine)
AB: An overview is presented of the ability of phytoplankton to passively adsorb and actively assimilate heavy metals from their aqueous environment and to release into the environment organic ligands capable of complexing metals. The uptake of all necessary trace metals by phytoplankton occurs via binding to a surface ligand and subsequent transfer across the cell membrane. This sorptive process can be explained by using surface complex formation equilibria; due to the heterogeneity of the algal surface, multi-site binding models must be developed. The production of extracellular organic matter with metal complexing properties plays an important role in decreasing the concentration of free metal ions and thus mitigating the potential toxic effects on organisms. However, while much research has been carried out on the uptake of single species of metal ions, little attention seems to have been given to the study of multimetal ion systems. Synergistic and antagonistic interactions between multiple trace metals are expected and could be very important in the oceans. These types of behaviours are extremely complex, influencing uptake and release of natural ligands and limiting plankton production and plankton species composition in the oceans. Future investigations should be carried out in order to gain understanding how the combinations of metal ions affect the physiological, biochemical and ecological processes of phytoplankton in seawater.
AN: 3931544

                                                                     45 of 1521  
TI: Processes controlling the chemistry of two snowmelt-dominated streams in the Rocky Mountains
AU: Campbell,-D.H.; Clow,-D.W.; Ingersoll,-G.P.; Mast,-M.A.; Spahr,-N.E.; Turk,-J.T.
AF: U.S. Geological Surv., Lakewood, CO, USA
SO: WATER-RESOUR.-RES. 1995 vol. 31, no. 11, pp. 2811-2821
LA: English
ER: F (Freshwater)
AN: 3930730

                                                                     46 of 1521  
TI: Biogeochemical influences on the determination of water chemistry in a temperate forest basin: Factors determining the pH value
AU: Ohte,-N.; Tokuchi,-N.; Suzuki,-M.
AF: Dep. Forest., Fac. Agric., Kyoto Univ., Kyoto, Japan
SO: WATER-RESOUR.-RES. 1995 vol. 31, no. 11, pp. 2823-2834
LA: English
ER: F (Freshwater)
AN: 3930729

                                                                     47 of 1521  
TI: Part 2. Nutrients, particulate organic matter, and planktonic and benthic production of the Tikehau Atoll (Tuamotu Archipelago, French Polynesia)
AU: Charpy-Roubaud,-C.J.; Charpy,-L.
AF: ORSTOM-Tahiti, BP 529, Papeete, French Polynesia
SO: ATOLL-RES.-BULL. 1994 v.p.
LA: English
ER: M (Marine)
AB: Matter and energy budgets for coral reefs, their components, and the world around them can, do, and must balance in a theorical context (Smith and Kinsey, 1988). In this paper, we will try to establish nitrogen, phosphorus and silica budgets between ocean and lagoon waters of Tikehau atoll in the purpose to learn more about the functioning of coral reef lagoons. Nutrient concentrations (dissolved components and particulate organic matter) were measured in the lagoon and in the surrounding oceanic surface waters between 1983 and 1987.
AN: 3930690

                                                                     48 of 1521  
TI: Sulphur and nitrogen compounds in variable marine/continental air masses at the southwest European coast
AU: Pio,-C.A.; Cerqueira,-M.A.; Castro,-L.M.; Salgueiro,-M.L.
AF: Departamento de Ambiente e Ordenamento, Universidade de Aveiro, 3810 Aveiro, Portugal
SO: ATMOS.-ENVIRON. 1996 vol. 30, no. 18, pp. 3115-3127
LA: English
AB: Measurements of atmospheric sulphur and nitrogen species were made on the west coast of Portugal, within the framework of BMCAPE project. Four research intensive campaigns took place between November 1993 and August 1994 and revealed pronounced seasonal cycles for DMS and MSA. Surprisingly high levels of DMS were detected during autumn (mean concentration: 776 ng S m super(-3)), possibly as a consequence of a later algae bloom or local marsh emissions. COS displayed a slight seasonal variation with mean concentrations ranging from 741 ng S m super(-3) in autumn up to 903 ng S m super(-3) in summer. On the basis of backward air mass trajectories and local meteorological data, samples were assigned into different classes of air masses. The lowest concentrations of SO sub(2), nssSO sub(4) super(2-), NH sub(3), NH sub(4) super(+), HNO sub(3), NO sub(3) super(-) and NO sub(2) were found in air masses transported over the Atlantic Ocean and were about 3-10 times lower than those recorded in air masses from continental origin. Nevertheless, for many of the species, the mean concentrations in maritime air were still significantly higher than those previously recorded in remote marine sites, presumably owing to long-range transport of pollutants or contamination induced by mesoscale wind circulation.
AN: 3930604

                                                                     49 of 1521  
TI: Horizontal and vertical profiles of light hydrocarbons in sea water related to biological, chemical and physical parameters
AU: Ratte,-M.; Plass-Duelmer,-C.; Koppmann,-R.; Rudolph,-J.
AF: Institut Atmosphaerische Chemie, Forschungszentrum Juelich, 52425 Juelich, FRG
SO: TELLUS-B-CHEM.-PHYS.-METEOROL. 1995 vol. 47B, no. 5, pp. 607-623
LA: English
ER: M (Marine)
AB: In situ-measurements of light (C sub(2)-C sub(4)) nonmethane hydrocarbons (NMHC) in sea water were performed during a ship cruise in spring 1991 in the Mediterranean, the Atlantic and the North Sea. The investigated regions were characterized with respect to biological (phytoplankton density, chlorophyll concentration), chemical (concentration of dissolved organic carbon, DOC) and physical parameters (irradiation intensity, wind velocities). These data were analysed for possible correlations with NMHC concentrations. An anticorrelation was found between NMHC concentrations and wind velocity. During periods of very low wind velocities, i.e., low mixing in the ocean surface layer and low emission rates, the concentrations of alkenes in surface water exhibited a distinct diurnal pattern with the concentrations increasing during day time and remaining constant at night.
AN: 3927296

                                                                     50 of 1521  
TI: Oxygen isotope analyses of chemically and microbially produced manganese oxides and manganates
AU: Mandernack,-K.W.; Fogel,-M.L.; Tebo,-B.M.; Usui,-A.
AF: Earth System Sci., Phys. Sci. Res. Facility, Univ. California, Irvine, CA 92717-3100, USA
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 21, pp. 4409-4425
LA: English
ER: M (Marine)
AB: Understanding the formation of metal deposition in the geological record depends in part on understanding some of the basic reactions that could have occurred when those ore deposits were formed. For manganese oxides and manganates, the  delta  super(18)O value might reflect the conditions that influenced the oxidation pathway during deposition, which include temperature, the  delta  super(18)O values of H sub(2)O or dissolved O sub(2), and microbial catalysis. Mn(IV) 10 angstrom manganates were, therefore, prepared by three different procedures with different sources of water having distinct  delta  super(18)O-H sub(2)O values, while keeping the  delta  super(18)O-O sub(2) constant. Application of the results to natural deposits of manganese oxides indicates a microbial origin for a freshwater manganese nodule from Oneida Lake, NY, USA, as well as a 50% dissolved oxygen signal. Oxygen isotopic values of Mn(IV) manganates from the Kaikata seamount, however, appear to reflect the  delta  super(18)O value of seawater exclusively. Therefore, Mn(IV) manganates in nature may not always contain a dissolved oxygen signal, presumably a result of different oxidation pathways or postdepositional alteration.
AN: 3927277

                                                                     51 of 1521  
TI: Manganese mineral formation by bacterial spores of the marine Bacillus, strain SG-1: Evidence for the direct oxidation of Mn (II) to Mn (IV)
AU: Mandernack,-K.W.; Post,-J.; Tebo,-B.M.
AF: Earth System Sci., Phys. Sci. Res. Facility, Univ. California, Irvine, CA 92717-3100, USA
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 21, pp. 4393-4408
LA: English
ER: M (Marine)
AB: The spores of a marine Bacillus bacterium, strain SG-1, are able to oxidize Mn (II) over a wide range of temperatures (0-80 degree C) and Mn (II) concentrations (<1 nM to >25 mM), in both low ionic strength N-(2-hydroxyethyl) piperazine-N'-ethanesulfonic acid (HEPES) buffer (HB) and in HEPES-buffered seawater (SW). The observed differences between SW and HB may have resulted from differences in the chemical milieu, or because of the marine adapted physiology of the bacterial spores. Under a variety of conditions (HB and SW, 3-55 degree C) Mn(IV) mineral formation often occurred at pH and Mn(II) concentrations too high to be favorable for the disproportionation of Mn sub(3)O sub(4), or  beta MnOOH to Mn (IV). The results strongly suggest direct oxidation of Mn(II) to Mn(IV) by SG-1 spores without lower valence intermediates. Considering the environmental relevance of these experiments, direct oxidation of Mn(II) to Mn(IV) by microbes is probably a common process in natural environments.
AN: 3927276

                                                                     52 of 1521  
TI: Seasonal cycles of pelagic production and consumption
AU: Longhurst,-A.
AF: Place de l'Eglise, 46160 Cajarc, France
SO: PROG.-OCEANOGR. 1995 vol. 36, no. 2, pp. 77-167
LA: English
ER: M (Marine)
AB: Comprehensive seasonal cycles of production and consumption in the pelagial require the ocean to be partitioned. This can be done rationally at two levels: into four primary ecological domains (three oceanic and one coastal), or about fifty biogeochemical provinces. The domains differ in their characteristic seasonal cycles of stability, nutrient supply and illumination, while provinces are defined by ocean currents, fronts, topography and recurrent features in the sea surface chlorophyll field. For each of these compartments, seasonal cycles of photic depth, primary production and accumulation (or loss) of algal biomass were obtained from the climatological CZCS chlorophyll field and other data and these, together with mixed layer depths, rendered characteristic seasonal cycles of production and consumption, which can be grouped into eight models: i - polar irradiance-mediated production peak; ii - nutrient-limited spring production peak; iii - winter-spring production with nutrient limitation; iv - small amplitude response to trade wind seasonality; v - large amplitude response to monsoon reversal; vi - canonical spring-fall blooms of mid-latitude continental shelves; vii - topography-forced summer production; viii - intermittent production at coastal divergences. For higher latitudes, these models suggest that the observed late-summer 'blooms' result not from a renewal of primary production rate, but from a relaxation of grazing pressure; in mid-latitudes, the observed 'winter' bloom represents chlorophyll accumulation at a season when loss terms are apparently smaller than during the period of peak primary production rate which occurs later, in spring. Where an episodic seasonal increase in rate of primary production occurs, as in the Arabian Sea, algal biomass accumulation may brief, lasting only until consumption is fully re-established. Only in the low latitude oligotrophic ocean are production and consumption perennially and closely coupled.
AN: 3926609

                                                                     53 of 1521  
TI: Carbon cycling in mesohaline Chesapeake Bay sediments 2: Kinetics of particulate and dissolved organic carbon turnover
AU: Roden,-E.E.; Tuttle,-J.H.
AF: Univ. Alabama, Dep. Biol. Sci., Box 870206, Tuscaloosa, AL 35487-0206, USA
SO: J.-MAR.-RES. 1996 vol. 54, no. 2, pp. 343-383
LA: English
ER: B (Brackish)
AB: Temporal and depth variations in benthic carbon metabolism rates were examined in relation to particulate organic carbon (POC) deposition rates and particulate and dissolved organic carbon degradation kinetics in two sediments from the mesohaline region of Chesapeake Bay. The depth distribution of a single pool of metabolizable POC (MPOC) in mid-Bay sediments was estimated by curve-fitting of dry weight POC profiles ("I-G" approach). Estimated MPOC pools accounted for 3-4% of total POC content in the upper 10 cm of sediment. First-order MPOC decay constants of  approximately  10 yr super(-1) during the warm season were estimated from the ratio of MPOC pool size to weighted-average MPOC deposition rate derived from mid-water column sediment trap deployments. These results indicated that the MPOC pool defined by the 1-G approach corresponded to the most readily degradable component of coastal marine phytoplankton detritus. Transient-state kinetic models of MPOC turnover, based on observed MPOC deposition rates and temperature-dependent mineralization, predicted MPOC accumulation in sediments during the spring followed by depletion during the summer. The models also predicted an early summer maximum in MPOC mineralization rate associated with the degradation of MPOC accumulated during the spring, in agreement with the seasonal pattern of sulfate reduction rates in mid-Bay sediments. Model results suggested that MPOC deposition during the summer is important in maintaining high rates of benthic carbon metabolism throughout the warm season.
AN: 3926606

                                                                     54 of 1521  
TI: Effects of eucalyptus afforestation on leaf litter dynamics and macroinvertebrate community structure of streams in Central Portugal
AU: Abelho,-M.; Graca,-M.A.S.
AF: Dep. Zoologia, Univ. Coimbra, 3049 Coimbra Codex, Portugal
SO: HYDROBIOLOGIA 1996 vol. 324, no. 3, pp. 195-204
LA: English
ER: F (Freshwater)
AB: To test the hypothesis whether afforestation with Eucalyptus globulus affects litter dynamics in streams and the structure of macroinvertebrate aquatic communities, we compared streams flowing through eucalyptus and deciduous forests, paying attention to: (i) litterfall dynamics, (ii) accumulation of organic matter, (iii) processing rates of two dominant leaf species: eucalyptus and chestnut, and (iv) macroinvertebrate community structure. The amount of allochthonous inputs was similar in both vegetation types, but the seasonality of litter inputs differed between eucalyptus and natural deciduous forests. Eucalyptus forest streams accumulated more organic matter than deciduous forest streams. Decomposition of both eucalyptus and chestnut leaf litter was higher in streams flowing through deciduous forests. The eucalyptus forest soils were highly hydrophobic resulting in strong seasonal fluctuations in discharge. In autumn the communities of benthic macroinvertebrates of the two stream types were significantly different. Deciduous forest streams contained higher numbers of invertebrates and more taxa than eucalyptus forest streams. Mixed forest streams (streams flowing through eucalyptus forests but bordered by deciduous vegetation) were intermediate between the two other vegetation types in all studied characteristics (accumulation of benthic organic matter, density and diversity of aquatic invertebrates). These results suggest that monocultures of eucalyptus affect low order stream communities. However, the impact may be attenuated if riparian corridors of original vegetation are kept in plantation forestry.
AN: 3926530

                                                                     55 of 1521  
TI: Effects of drying-out on the biogeochemical cycle of nitrogenous nutrients in oyster ponds: Preferential ammonification
OT: Effets de l'assechement des bassins ostreicoles sur le cycle biogeochimique de nutrienets azotes: Ammonification preferentielle
AU: Gouleau,-D.; Feuillet-Girard,-M.; Germaneau,-J.; Robert,-S.
AF: CNRS-IFREMER, Centre de Recherche en Ecologie Marine et Aquaculture de L'Houmeau, BP 5, 17137 L'Houmeau, France
SO: OCEANOL.-ACTA 1996 vol. 19, no. 2, pp. 101-115
LA: French
ER: M (Marine)
AB: Oyster ponds behave as organic matter accumulators, unlike wetlands which export a large part of their natural productivity towards the ocean as well as inorganic nitrogen towards the atmosphere through denitrification. Thus, to prevent eutrophication temporary drying-out is necessary, the physical effects of which are well known but whose biogeochemical processes are still poorly documented. The aim of the present study was to perform a drying-out operation in an oyster pond, and to describe the modifications which occurred within the nitrogen cycle: i. e. mineralization processes within the top 5 cm of the sediment; changes in nutrient pore-water concentrations; and fluxes through the water/sediment interface. Prior to the operation, ammonia was the major nitrogen form in the water column and in pore waters (top 5 cm); concentrations of free NH sub(4)  super(+) increased as a function of depth, whereas exchangeable NH sub(4)  super(+) decreased. At the end of drying-out, when salt precipitation first occurred at the water/sediment interface, the sediment remained reduced despite a slight oxidation around des s icati on cracks, thus preventing nitrification. In consequence, ammonification was the prevailing process within the sediment. At the surface of the sediment, concentrations of free NH sub(4)  super(+) in pore waters were 45 times as high as at the beginning of the drying-out, whereas they remained constant at 5 cm depth; exchangeable NH sub(4)  super(+) did not increase accordingly, but tended, rather, to decrease. Strong increases of free ammonia were correlated to those of pore-water salinity. The non-adsorption of NH sub(4)  super(+) on sediment and the concomitant defixing of NH sub(4)  super(+) from illitic clays were due to increasing quantities of K super(+), as a consequence of the high salinities induced by drying. The flooding carried out a few days after the occurrence of salt precipitation had the following effects: (i) maximum ammonia fluxes through the water/sediment interface which persisted for a long time after flooding; (ii) restoration of reduced conditions which prevented nitrogen loss due to the coupling of nitrification and denitrification; (iii) disappearance of high salinities in pore waters, thus eliminating the effect of K super(+) on clays, and allowing NH sub(4)  super(+) fixing and adsorption on sediments. In conclusion, drying-out might help physically to control ammonia production, independently of the biological production (bacterial mineralization) which is controlled bv temperature.
AN: 3921797

                                                                     56 of 1521  
TI: Is DOC the main source of organic matter remineralization in the ocean water column?
AU: Lefevre,-D.; Denis,-M.*; Lambert,-C.E.; Miquel,-J.-C.
AF: Cent. d'Oceanologie de Marseille, CNRS URA 041, Universite d'Aix-Marseille II, Parc Scientifique et Technologique de Luminy, Case 901, 13288 Marseille Cedex 09, France
CO: 1994 International Liege Colloquium on Ocean Hydrodynamics, Liege (Belgium), 2-6 May 1994
SO: THE-COASTAL-OCEAN-IN-A-GLOBAL-CHANGE-PERSPECTIVE. Djenidi,-S.-ed. 1996 vol. 7, no. 2-4 pp. 281-291
ST: J.-MAR.-SYST. vol. 7, no. 2-4
LA: English
ER: M (Marine)
AB: Recent interpretations of carbon flux data and deep-sea processes have led to a reconsideration of the role of dissolved organic carbon (DOC) in supporting water column remineralization and other mid-water biogeochemical transformations. To date, there have been no direct comparisons of particulate carbon flux data with water column metabolic rates. Here, for the first time, particulate carbon flux and respiratory electron transport activity (from which metabolic CO sub(2) production is derived), have been monitored simultaneously for one year in the same area of the northwestern Mediterranean Sea. In the aphotic layer (200-1000 m), particulate organic carbon (POC) can support only 20% of the overall organic matter remineralization. Remineralization rates are consistent with recent calculations of DOC exported from the euphotic layer in this area, confirming the vital importance of DOC in maintaining deep-water metabolism. This finding would apply to other regions of mesotrophic and oligotrophic production and thus affect our understanding of carbon recycling in the water column, new production and O sub(2) utilization.
AN: 3920080

                                                                     57 of 1521  
TI: Spatial and temporal variability of phytoplankton biomass in upwelling areas of the northwestern Mediterranean: A coupled physical and biogeochemical modelling approach
AU: Pinazo,-C.; Marsaleix,-P.; Millet,-B.; Estournel,-C.; Vehil,-R.
AF: Cent. Oceanol. Marseille, URA CNRS 41, Univ. Aix-Marseille II, Campus Luminy, F-13288 Marseille Cedex 09, France
CO: 1994 International Liege Colloquium on Ocean Hydrodynamics, Liege (Belgium), 2-6 May 1994
SO: THE-COASTAL-OCEAN-IN-A-GLOBAL-CHANGE-PERSPECTIVE. Djenidi,-S.-ed. 1996 vol. 7, no. 2-4 pp. 161-191
ST: J.-MAR.-SYST. vol. 7, no. 2-4
LA: English
ER: M (Marine)
AB: The coupling of a 3-D hydrodynamic model and the biogeochemical algorithms of phytoplankton biomass production was performed at the meso scale of the northwestern Mediterranean shelf. This study, which was part of the French Programme National d'Oceanographie Cotiere, represented a theoretical approach to study the phytoplankton dynamics at mesoscale, according to upwelling processes induced by both the general circulation (LPC) and the typical northwestern wind that prevail in the Gulf of Lions. The coupling task consisted in writing the equations of nitrogen and carbon cycles form both the algorithms describing the biogeochemical gain and loss terms, and the advective-diffusive numerical scheme of the physical model, according to the same spatial grid. This approach allowed fine 3-D spatial descriptions of the biogeochemical processes during 20-day periods. The physical parameters used in the advective-diffusive numerical scheme, such as velocities and coefficients of vertical eddy diffusivity, were first calculated by the hydrodynamic model, averaged over one inertial period (17.6 h), and then introduced into the biogeochemical coupled model as constant forcing variables.
AN: 3920077

                                                                     58 of 1521  
TI: Chemical fractionation of phosphorus and cadmium in the marine diatom Phaeodactylum tricornutum
AU: Kudo,-Isao; Kokubun,-Haruyo; Matsunaga,-Katsuhiko
AF: Department of Oceanography, Faculty of Fisheries, Hokkaido University, Hakodate 041, Japan
SO: MAR.-CHEM. 1996 vol. 52, no. 3-4, pp. 221-231
LA: English
AB: Fractionation of P and Cd within the cell of Phaeodactylum tricornutum grown by semi-continuous cultures in natural low concentrations of dissolved phosphate and cadmium was examined by the chemical separation method. Cellular Cd content increased with the concentration of Cd in the medium and was independent of growth rate, but it was present only in the acid-soluble fraction and no growth inhibition was observed even at 90 nM. Cellular P content in the acid-soluble fraction varied with both growth rate and concentration in the medium. The residue fraction (acid-insoluble) depended on concentration in the medium. Proportion of these fractions, however, changed only as a function of growth rate. As a consequence of these changes, cellular Cd/P ratio decreased with growth rate. The distributions of Cd and P in the phytoplankton cells were not always the same portion. The Cd/P ratio in phytoplankton cells is affected by the physiological state of the cells and ambient Cd/PO4 ratio in the medium. Thus, biological activity would influence the biogeochemical cycling of Cd and PO4 and the Cd/PO4 ratio in the ocean.
AN: 3915447

                                                                     59 of 1521  
TI: Trends in eutrophication research and control
AU: Rast,-W.; Thornton,-J.A.
AF: Freshwater Programme, United Nations Environ. Programme, PO Box 30552, Nairobi, Kenya
SO: HYDROL.-PROCESS. 1996 vol. 10, no. 2, pp. 295-313
LA: English
ER: F (Freshwater)
AB: Eutrophication is the natural process of lakes. It is characterized by a geologically slow shift from in-lake biological production driven by allochthonous (external to the water body) loading of nutrients, to production driven by autochthonous (in-lake) processes. This shift typically is accompanied by changes in species and biotic community composition, as an aquatic ecosystem is ultimately transformed into a terrestrial biome. However, this typically slow process can be greatly accelerated by human intervention in the natural biogeochemical cycling of nutrients within a watershed; the resulting cultural eutrophication can create conditions inimical to the continued use of the water body for human-driven economic purposes. Excessive algal and rooted plant growth, degraded water quality, extensive deoxygenation of the bottom water layers and increased fish biomass accompanied by decreased harvest quality, are some features of this process.
AN: 3914315

                                                                     60 of 1521  
TI: The sulfur cycle in the chemocline of a meromictic salt lake
AU: Overmann,-J.; Beatty,-J.T.; Krouse,-H.R.; Hall,-K.J.
AF: Inst. fuer Chemie und Biologie des Meeres, Univ. Oldenburg, Postfach 2503, D-26111 Oldenburg, Germany
SO: LIMNOL.-OCEANOGR. 1996 vol. 41, no. 1, pp. 147-156
LA: English
ER: F (Freshwater)
AB: An extremely dense layer of the purple sulfur bacterium Amoebobacter purpureus in the chemocline of meromictic Mahoney Lake (British Columbia) was investigated over a 2-yr period. Within this layer, sulfide, elemental sulfur, and polysulfides were the main species of reduced sulfur. The oxidative part of the sulfur cycle was dominated by anoxygenic photosynthesis of A. purpureus. During summer, when sulfide concentrations in the layer were limiting, intracellular sulfur became the main electron donor for photosynthesis.  delta  super(34)S determinations revealed that the intracellular sulfur reacts chemically with dissolved sulfide to form polysulfides. Polysulfide concentrations decreased over summer, accompanied by an increase in numbers of sulfur-reducing bacteria. Sulfate reduction was the major pathway of sulfide formation. The annual carbon requirement of sulfate-reducing bacteria in the chemocline (22.5 g C m super(-2) yr super(-1)) was met by the photosynthetic C fixation of A. purpureus (33.5 g C m super(-2) yr super(-1)). Carbon demand exceeded the concomitant C fixation temporarily in summer, however. The activities of biomass-degrading enzymes and the formation of volatile fatty acids were sufficient to provide the carbon substrates. Our data indicate that in Mahoney Lake, anoxygenic photosynthesis and sulfate reduction are only indirectly coupled via degradation and autolysis of photosynthetically formed biomass.
AN: 3913682

                                                                     61 of 1521  
TI: Marine scavenging: The relative importance of mass transfer and reaction rates
AU: Jannasch,-H.W.; Honeyman,-B.D.; Murray,-J.W.
AF: Monterey Bay Aquarium Res. Inst., POB 628, 7700 Sandholdt Rd., Moss Landing, CA 95039, USA
SO: LIMNOL.-OCEANOGR. 1996 vol. 41, no. 1, pp. 82-88
LA: English
ER: M (Marine)
AB: We present an analysis of factors regulating the scavenging rate of trace elements and nutrients by settling particles in the ocean. The overall process limiting marine scavenging rates is determined by comparing the relative kinetics of dissolved phase mass transfer and particle-associated sorption rates. Measured scavenging and uptake rates of a variety of marine particle types are then compared to theoretically calculated mass transfer rate constants. Our calculations show that for most marine environments, sorption rates are much slower than external mass transfer of dissolved species. External mass transfer is therefore not the limiting process. Particle-associated processes such as adsorption, intraparticle reactions, and particle repackaging must control the overall scavenging rates observed in the ocean.
AN: 3913679

                                                                     62 of 1521  
TI: Microbial cycling of DMSP and DMS in coastal and oligotrophic seawater
AU: Ledyard,-K.M.; Dacey,-J.W.H.
AF: Mar. Sci. Inst., Univ. California, Santa Barbara, CA 93106, USA
SO: LIMNOL.-OCEANOGR. 1996 vol. 41, no. 1, pp. 33-40
LA: English
ER: M (Marine)
AB: The rates and concentration dependence of microbial dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) cycling were assessed in Vineyard Sound, Massachusetts, and the Sargasso Sea. Net rates of dissolved DMSP loss, DMS production from DMSP, and DMS consumption were measured at ambient and near-ambient substrate levels. Turnover times of dissolved DMSP, based on loss rates, were short, usually ranging from 1.5 d to several hours. However, the specific process of DMSP cleavage to form DMS accounted for only a portion of total DMSP turnover. Short-term variability obscured possible regional or seasonal trends in these data. Dissolved DMSP removal and cleavage exhibited saturable kinetics in spring in Vineyard Sound and in winter in the Sargasso Sea. In fall and spring in the Sargasso Sea, where dissolved DMSP levels ranged from 2 to 9 nM, DMSP cleavage did not saturate at DMSP levels as high as 1  mu M. Kinetic parameters of DMSP uptake appeared to increase with proximity to summer, as did the proportion of DMSP uptake resulting in DMS production.
AN: 3913674

                                                                     63 of 1521  
TI: A preliminary study on the bioactivity of dissolved organic phosphorus in marine environment
AU: Wang,-Haili; Hong,-Huasheng; Huang,-Bangqin
AF: Res. Cent. Environ. Sci., Xiamen Univ., Xiamen 361005, People's Rep. China
SO: J.-XIAMEN-UNIV.-NAT.-SCI.-XIAMEN-DAXUE-XUEBAO 1995 vol. 34, no. 3, pp. 416-420
LA: Chinese
ER: M (Marine)
AB: Results from batch culture experiments indicated that adenosine triphosphate, sodium glycerophosphate (GP) and ribose-5-phosphate could be utilized by phytoplankton. The availability of dissolved organic phosphorus (DOP) was comparable to that of dissolved inorganic phosphorus (DIP). It seemed that although algae preferred DIP when DIP and DOP co-existed, DOP could also be uptaken right after the depletation of DIP. The uptake of DOP was relatively quicker under lower ambient concentration, implicating its potential environmental effects.
AN: 3911549

                                                                     64 of 1521  
TI: Aerobic and anaerobic decomposition of organic matter in marine sediment: Which is fastest?
AU: Kristensen,-E.; Ahmed,-S.I.; Devol,-A.H.
AF: Inst. Biol., Odense Univ., DK-5230 Odense M, Denmark
SO: LIMNOL.-OCEANOGR. 1995 vol. 40, no. 8, pp. 1430-1437
LA: English
ER: M (Marine)
AB: The enigma of aerobic vs. anaerobic decomposition in marine sediments was addressed by means of a thin-layer incubation technique. Two different  super(14)C-labeled plant materials, aged diatoms (Skeletonema costatum) and fresh barley hay, were each mixed into intertidal sediment and spread in a 1.5-mm layer on the bottom of oxic and anoxic chambers. After a 27-d incubation, conditions in all chambers were switched from aerobic to anaerobic and vice versa for 11 d. Rates of  super(14)CO sub(2) evolution in diatom chambers showed that aerobic carbon mineralization was  similar to 10 times faster than anaerobic both before and after the switch. Low rates of [ super(14)C]DOC release suggested that the limiting step of anaerobic decay was the initial hydrolytic and fermentative enzymatic attack on the predecomposed diatoms. Initial carbon mineralization of barley hay was not affected by the presence or absence of oxygen. Leaching of DOC from the fresh barley hay supplied anaerobic respirers with labile substrates. When leaching ceased and after the aerobic-anaerobic switch, the rate of anaerobic mineralization was reduced. Mineralization of leachable and easily hydrolyzable compounds from fresh plant detritus is equally fast under aerobic and anaerobic conditions. When structural components dominate the particulate remains, anaerobic processes are hampered by inefficient and slow bacterial hydrolysis of structurally complex macromolecules.
AN: 3907920

                                                                     65 of 1521  
TI: Redox stabilization of the atmosphere and oceans by phosphorus-limited marine productivity
AU: van-Cappellen,-P.; Ingall,-E.D.
AF: Sch. Earth and Atmos. Sci., Georgia Inst. Technol., Atlanta, GA 30332-0340, USA
SO: SCIENCE-WASH. 1996 vol. 271, no. 5248, pp. 493-496
LA: English
ER: M (Marine)
AB: Data from modern and ancient marine sediments demonstrate that burial of the limiting nutrient phosphorus is less efficient when bottom waters are low in oxygen. Mass-balance calculations using a coupled model of the biogeochemical cycles of carbon, phosphorus, oxygen, and iron indicate that the redox dependence of phosphorus burial in the oceans provides a powerful forcing mechanism for balancing production and consumption of atmospheric oxygen over geologic time. The oxygen-phosphorus coupling further guards against runaway ocean anoxia. Phosphorus-mediated redox stabilization of the atmosphere and oceans may have been crucial to the radiation of higher life forms during the Phanerozoic.
AN: 3907143

                                                                     66 of 1521  
TI: Variability in removal of dissolved organic carbon in hyporheic sediments
AU: Findlay,-S.; Sobczak,-W.V.
AF: Inst. Ecosystem Stud., PO Box AB, Millbrook, NY 12545, USA
SO: J.-N.-AM.-BENTHOL.-SOC. 1996 vol. 15, no. 1, pp. 35-41
LA: English
ER: F (Freshwater)
AB: Dissolved organic carbon (DOC) is consumed by microbial metabolism as streamwater perfuses through a lateral gravel bar of the East Branch of the Wappinger Creek. The rate of DOC removal was estimated from the decline in DOC and travel time through the bar. Variability in DOC removal together with potential regulatory factors was determined for 14 dates spanning more than a 2-y period. DOC removal was not correlated with temperature, availability of oxygen, or residence time within hyporheic sediments. Hyporheic DOC could be predicted (r super(2) = 0.68) from streamwater DOC concentrations, with a surprisingly constant 57% ( plus or minus 9% [1 SD]) removal of DOC. This pattern suggests an initial concentration-dependent adsorption of DOC onto surfaces. This mechanism allows for efficient retention of DOC within hyporheic sediments even under conditions (low temperature, high interstitial velocity) that might be expected to minimize biotic consumption of DOC.
AN: 3906298

                                                                     67 of 1521  
TI: Seasonal and storm dynamics of the hyporheic zone of a 4th-order mountain stream. 2: Nitrogen cycling
AU: Wondzell,-S.M.; Swanson,-F.J.
AF: Dep. Forest Sci., Oregon State Univ., Corvallis, OR 97331, USA
SO: J.-N.-AM.-BENTHOL.-SOC. 1996 vol. 15, no. 1, pp. 20-34
LA: English
ER: F (Freshwater)
AB: The objective of this study was to quantify subsurface nitrogen fluxes between a riparian forest and a 4th-order mountain stream, McRae Creek, for each season of the year and during storms. A network of wells was installed on a gravel bar and a portion of the adjacent floodplain between 1989 and 1992. Water samples were collected to monitor dissolved nitrogen concentrations. Advected channel water and ground water were enriched in nitrogen relative to the stream; thus, subsurface flow was a net source of nitrogen to the stream in all seasons of the year and during both base-flow periods and storms. Estimates of the flux of advected channel water and the discharge of ground water were combined with changes in mean nitrogen concentrations along subsurface flow paths to estimate nitrogen inputs to the stream. Discharge or ground water from the conifer-dominated floodplain was the largest source of nitrogen added to the stream; however, more than 50% of this nitrogen was dissolved organic nitrogen. In contrast, two-thirds of the nitrogen from the alder-dominated gravel bar was inorganic. Net nitrogen fluxes from the gravel bar to the stream were lowest during the summer when water table elevations were low. Net fluxes of nitrogen from the gravel bar to the stream were largest during the fall, especially at peak flow during storms when interstitial water in the gravel bar was enriched in NO sub(3) super(-). The estimated annual flux of nitrogen from the riparian forest to McRae Creek was 1.9 g/m super(2) of streambed, of which 1.0 g/m super(2) was inorganic. Estimated net annual flux was large relative to the estimated input of nitrogen in litterfall, or the nitrogen required to support estimated rates of primary productivity.
AN: 3906297

                                                                     68 of 1521  
TI: Patterns of differential digestion of sedimentary bacteria by the deposit feeder, Arenicola marina
AU: Goldfinch,-A.; Plante,-C.
AF: Dep. Biol., Univ. Charleston, Charleston, SC 29412, USA
CO: 24. Annu. Benthic Ecology Meeting, Columbia, SC (USA), 7-10 Mar 1996
SO: TWENTY-FOURTH-ANNUAL-BENTHIC-ECOLOGY-MEETING,-HELD-IN-COLUMBIA,-SOUTH-CAROLINA,-MARCH-7-10,-1996. Woodin,-S.A.;Allen,-D.M.;Stancyk,-S.E.;Williams-Howze,-J.;Feller,-R.J.;Wethey,-D.S.;Pentcheff,-N.D.;Chandler,-G.T.;Decho,-A.W.;Coull,-B.C.-eds. 1996 p. 42
NT: Abstract only
LA: English
ER: M (Marine)
AB: Sedimentary bacteria are consumed and digested by deposit-feeding macrofauna. This predator-prey relationship may markedly influence biogeochemical cycling and food web dynamics. Bacterial community compositions, for instance, may be altered by selective digestion of diverse strains, thus influencing rates of geochemical reactions. We used a turbidimetric assay to compare the lytic susceptibilities of bacteria when exposed to the digestive fluids collected from the deposit-feeding polychaete, Arenicola marina. Over two dozen environmental isolates were tested under identical conditions. Significantly different bacteriolytic rates were observed; 75% of strains were completely resistant to lysis, while the remaining strains exhibited varied rates of digestion. Potentially important differences among these strains, such as cell wall type (gram-positive v. gram-negative), and exopolymer secretions, were examined in an effort to identify mechanisms for differential digestion.
AN: 3904787

                                                                     69 of 1521  
TI: Regeneration of trace metals from picoplankton by nanoflagellate grazing
AU: Twiss,-M.R.; Campbell,-P.G.C.*
AF: INRS-Eau, Universite du Quebec, C.P. 7500, Ste-Foy, PQ G1V 4C7, Canada
SO: LIMNOL.-OCEANOGR. 1995 vol. 40, no. 8, pp. 1418-1429
LA: English
AB: Rapid regeneration of trace metals from the particulate to the dissolved phase (<0.2  mu m) was observed in the laboratory with a simplified microbial food web composed of mixotrophic chrysophycean nanoflagellates (Ochromonas danica) grazing on picocyanobacteria (Synechococcus leopoliensis) that had been previously exposed to the radionuclides  super(153)Gd(III),  super(65)Zn(II),  super(109)Cd(II), and  super(137)Cs(I). These trace metals were chosen to represent a range of surface reactivities with particles (Gd>Zn, Cd greater than or equal to Cs). Grazing experiments and the appropriate nongrazing controls were carried out in batch cultures over 43-49 h in defined, inorganic freshwater medium; metal partitioning among the consumer, prey, and dissolved phases was determined by sequential filtration (3  mu m, 0.2  mu m) at timed intervals. Most of the trace metals consumed as radioactive prey were regenerated into the dissolved phase. Regenerated Gd, Zn, and Cd present in the dissolved phase were less available for resorption by plankton than were the same radionuclides added in inorganic form to fresh growth medium. Our suggest that where this grazing activity exists, it will serve to increase trace metal residence times in the water column.
AN: 3902390

                                                                     70 of 1521  
TI: Spreading of water masses and regeneration of silica and  super(226)Ra in the Indian Ocean
AU: Kumar,-M.D.; Li,-Y.-H.
AF: Natl. Inst. Oceanogr., Dona Paula, Goa 403 004, India
SO: DEEP-SEA-RES.-2-TOP.-STUD.-OCEANOGR. 1996 vol. 43, no. 1, pp. 83-110
LA: English
ER: M (Marine)
AB: The magnitudes of silica and  super(226)Ra inputs to water (through particle regeneration, in situ, and from sediments) and the validity of observed Si and  super(226)Ra as tracers of water masses and advective processes were examined in the Indian Ocean using the GEOSECS data. The regenerated quantities of these two parameters were calculated as the difference between the observed and the expected concentrations; the latter were estimated from a three end-member mixing model employing potential temperature and salinity as conservative tracers. Here we present results on the quantitative spreading of the Antarctic Bottom Water (AABW); the Modified North Atlantic Deep Water (MNADW, also known as the Circumpolar Water) and the North Indian Deep Water (NIDW)-both these were represented together as High Salinity Deep Waters (HSDW); the Antarctic Intermediate Water (AAIW); the North Indian Intermediate Water (NIIW) and the Central Indian Water (CIW). Our results concur with recent results in the literature. Briefly, the northward flow of the AABW is uneven; the MNADW core layer is found to be closer to the Antarctic that spreads to the north, and AAIW is largely restricted to the Indian Ocean south of 10 degree S. Our results also reveal that: roughly 10% more AABW enters the Bay of Bengal than the Arabian Sea; there is greater possibility for deep waters to enter the Central Indian Basin from the Bay of Bengal; CIW occupies a larger part of the Bay of Bengal than of the Arabian Sea; and 10% of the NIIW reaches 30 degree S in the western Indian Ocean. The regenerations of Si and  super(226)Ra are mainly from the underlying sediments rather than through the dissolution of particles in the water column. The sediments in the northern parts seem to supply  super(226)Ra and Si to the rest of the Indian Ocean. At 10 degree S there is a subsurface ( similar to 600 m) maximum in regenerated Si, which is possibly connected to the advection of particles by Indonesian waters. The maxima in regenerated  super(226)Ra and Si contribute about 50% and 30%, respectively, to the observed abundances, suggesting that the observed Si is a more useful tracer of water masses and mixing processes than  super(226)Ra. Linear relationships were found between regenerated Si and  super(226)Ra, but departures noticed for  super(226)Ra in the eastern Indian Ocean may be attributed to its release from particles transported by the Indian rivers. Diverse regimes with respect to the extent of sources and dissolution of opal were noted in the Indian Ocean: high diatom abundance but low Si regeneration in the Antarctic, high diatom abundance and high regenerated Si in the Arabian Sea, and low diatom abundance but high regenerated Si in the Bay of Bengal.
AN: 3899160

                                                                     71 of 1521  
TI: Chemotaxis links the marine microbial loop to atmospheric sulfur production
AU: Zimmer-Faust,-R.; De-Souza,-M.; Yoch,-D.
AF: Dep. Biol. and Mar. Sci. Cent., Univ. California, Los Angeles, CA 90095-1606, USA
CO: 24. Annu. Benthic Ecology Meeting, Columbia, SC (USA), 7-10 Mar 1996
SO: TWENTY-FOURTH-ANNUAL-BENTHIC-ECOLOGY-MEETING,-HELD-IN-COLUMBIA,-SOUTH-CAROLINA,-MARCH-7-10,-1996. Woodin,-S.A.;Allen,-D.M.;Stancyk,-S.E.;Williams-Howze,-J.;Feller,-R.J.;Wethey,-D.S.;Pentcheff,-N.D.;Chandler,-G.T.;Decho,-A.W.;Coull,-B.C.-eds. 1996 p. 90
NT: Abstract only
LA: English
ER: M (Marine)
AB: Dimethylsulfide (DMS) gas comprises 90% of biogenic sulfur emissions from oceans and is an important agent in climate regulation. DMS arises primarily via lyase degradation of dimethylsulfoniopropionate (DMSP), an osmolyte produced in high concentrations by marine phytoplankton. DMSP lyase producing bacteria (Alcaligenes strain M3A) significantly reduce their tumbling frequency and are attracted to DMSP at levels found near senescing phytoplankton cells (10 super(-8) to 10 super(-6) M). In contrast, genetically identical bacteria without the induced lyase are not attracted to DMSP. Combined with lyase activity, microbial chemotaxis to DMSP should increase the rate of DMS production and, therefore, play a critical role in biogeochemical sulfur cycling between dissolved organic matter in seawater and earth's atmosphere.
AN: 3899005

                                                                     72 of 1521  
TI: Microbial production, enzyme activity, and carbon turnover in surface sediments of the Hudson River estuary
AU: Sinsabaugh,-R.L.; Findlay,-S.
AF: Biol. Dep., Univ. Toledo, Toledo, OH 43606, USA
SO: MICROB.-ECOL. 1995 vol. 30, no. 2, pp. 127-141
LA: English
ER: F (Freshwater)
AB: The authors investigated variability in microbial abundance and activities within the tidal freshwater estuary of the Hudson River. Surface sediments were collected from four contrasting sites: a mid-channel shoal, two types of wetlands, and a tributary confluence. These samples, collected in June to August 1992, were sorted into two to four size fractions, depending on the particle size distribution at each site. Each fraction was analyzed for bacterial biomass, bacterial production, fungal biomass, fungal production, and the potential activities of seven extracellular enzymes involved in degradation. Decomposition rates for particulate organic carbon (POC) were estimated from a statistical model relating mass loss rates to endocellulase activity. Within samples, bacterial biomass and productivity were negatively correlated with particle size. Conversely, fungal biomass was positively correlated with particle size. Extracellular enzyme activities also differed significantly among size classes, with high carbohydrase activities associated with the largest particles, while oxidative activities predominated in the smallest size classes.
AN: 3898779

                                                                     73 of 1521  
TI: Uptake of fenvalerate by the ostracod Chrissia halyi (Ferguson)
AU: Zeba,-M.; Khan,-M.A.; Rao,-B.N.
AF: H. No. 142-B Class, Mallapally, Hyderabad-500 007, India
SO: BULL.-ENVIRON.-CONTAM.-TOXICOL. 1996 vol. 56, no. 3, pp. 483-485
LA: English
ER: F (Freshwater)
AB: Once a pesticide is introduced into the environment there is a reasonable chance that it will eventually find its way into water. Therefore aquatic systems probably represent one of the most important complex environment as far as describing the fate and behaviour of pesticides. Zooplankton comprise a large portion of the living matter in natural waters and play an important role in biogeochemical cycles. Ostracods are one of the important zooplanktonic groups and constitute a significant percentage of the benthic fauna in a number of fresh water basins. The abundance of these organisms provide a very good food to the fish and other invertebrates. Being benthic in nature it is assumed that these ostracods can accumulate the toxicants at a higher level, at the same time being primary consumers they are assumed to be important organisms transferring the toxicants to higher trophic levels. In the present study an attempt has been made to see the accumulation of fenvalerate, a synthetic pyrethroid in the ostracod Chrissia halyi.
AN: 3898288

                                                                     74 of 1521  
TI: Seasonal biogeochemical patterns in surface water, subsurface hyporheic, and riparian ground water in a temperate stream ecosystem
AU: Hendricks,-S.P.; White,-D.S.
AF: Hancock Biological Station, Route 3, Box 288M, Murray, KY 42071, USA
SO: ARCH.-HYDROBIOL. 1995 vol. 134, no. 4, pp. 459-490
NT: Bibliogr.: 58 ref.
LA: English
ER: F (Freshwater)
AB: Relationships among stream surface water (9-km reach), substream hyporheic water ( 10-m pool-riffle-pool reach), and riparian groundwater (single site) biogeochemical patterns were examined in four seasons (1989-1990) in a temperate stream ecosystem (Michigan, USA). Surface water concentrations of chloride, dissolved organic carbon (DOC), and chlorophyll-a exceeded those of groundwater during most sampling periods. Groundwater and hyporheic concentrations of silica (SiO sub(2)), soluble reactive phosphorus (SRP), nitrate+nitrite (NO sub(3)-N), and ammonium (NH sub(4)-N) were generally higher than in surface water, particularly during summer. Hyporheic temperatures exhibited sharpest gradients with depth and distance downstream beneath a study riffle during summer and winter. Biologically reactive solutes (SRP, NO sub(3)-N, NH sub(4)-N, and DOC) generally decreased with depth and increased with distance beneath the riffle during summer and winter as well. Hyporheic patterns were indistinct or more variable during spring and fall and were attributed, in part, to the breakdown of thermal gradients within the bed, similar to seasonal lake turnover (mixis). Similarities between longitudinal/depth gradients in hyporheic patterns and longitudinal stream channel patterns for SiO sub(2) and Cl (the more conservative solutes) indicated potential cumulative groundwater discharge effects through successive hyporheic zones over stream distance. Relationships between hyporheic patterns, stream channel patterns, and the biologically reactive solutes (SRP, NO sub(3)-N, NH sub(4)-N, DOC) were less clear because of potential biotic or abiotic uptake at the sediment-water interface. Groundwater-surface water interaction within a hyporheic zone forms a complex system structured not only by hydrologic forces but also by seasonal changes in temperature and discharge.
AN: 3897613

                                                                     75 of 1521  
TI: Size-distribution analysis of sub-micron colloidal particles in river water
AU: Kim,-J.P.; Lemmon,-J.; Hunter,-K.A.*
AF: Dep. Chem., Univ. Otago, Dunedin, New Zealand
SO: ENVIRON.-TECHNOL. 1995 vol. 16, no. 9, pp. 861-868
LA: English
ER: F (Freshwater)
AB: The particle size spectra of sub-micron colloidal particles collected from a river water, the Water of Leith in Dunedin, New Zealand, have been determined by transmission electron microscopy (TEM). Particles were isolated onto hydrophilic carbon films by ultracentrifugation at 300,000 g for 1 hr. Size spectra were found to conform to a power-law size distribution dn/dr = A r super(- beta ), behaviour also found for much larger-sized particles in natural waters and marine colloids. Values of the exponent  beta  for unfiltered samples were in the range 2.3-2.9, consistent with Brownian aggregation as the principal mechanism maintaining the size spectrum. Comparison with spectra obtained from sampled prefiltered through Nuclepore 0.4 mu m filters showed clear evidence of particle removal down to 100-120 nm radius by filtration. Particles exhibited a range of electron densities under TEM, indicating a mixture of inorganic minerals and organic matter in the colloidal size range. Examples of fractal aggregates were also found.
AN: 3887090

                                                                     76 of 1521  
TI: Palmer LTER: Hydrogen peroxide in the Palmer LTER region: 3. Local sources and sinks
AU: Tien,-G.; Karl,-D.M.
AF: Sch. Ocean and Earth Sci. and Technol., Univ. Hawaii, Honolulu, HI 96822, USA
SO: ANTARCT.-J.-U.S. 1993 vol. 28, no. 5, pp. 229-230
LA: English
ER: M (Marine)
AB: During the austral spring and autumn long-term ecological research (LTER) cruises aboard the R/V Polar Duke (PD92-09, November 1992) and R/V Nathaniel B. Palmer (NBP93-02, March through May 1993), we had an opportunity to investigate selected sources and sinks of hydrogen peroxide (H sub(2)O sub(2)) in a variety of antarctic coastal habitats. These measurements constituted one component of our comprehensive study of H sub(2)O sub(2) dynamics. The potential source terms we evaluated were wet deposition (snow), glacial ice meltwater and land runoff, and in situ biological processes; photochemical processes are discussed in a companion paper. The primary H sub(2)O sub(2) sink we investigated was bacterial enzymatic activity.
AN: 3885198

                                                                     77 of 1521  
TI: RACER: Nitrogen remineralization within Antarctic sea ice during the 1992 austral winter
AU: Dore,-J.E.; Houlihan,-T.; Karl,-D.M.
AF: Sch. Ocean and Earth Sci. and Technol., Univ. Hawaii, Honolulu, HI 96822, USA
SO: ANTARCT.-J.-U.S. 1993 vol. 28, no. 5, pp. 167-169
LA: English
ER: M (Marine)
AB: Antarctic sea ice provides a number of habitats for thriving microbial communities. Such communities play important roles in the overall ecology of the southern oceans. Although a number of investigations have been made of the sea-ice microbial communities of the Weddell and the McMurdo Sound and Ross Ice Shelf regions, comparatively few data exist on the sea-ice biota of the western Antarctic Peninsula, particularly during the winter. During the final expedition of the Research on Antarctic Coastal Ecosystem Rates program (RACER IV, July and August 1992), several stations along the Antarctic Peninsula were occupied in coastal waters completely covered by the winter ice pack. We describe here data on ammonium distributions and microbial nitrification rates within and below the ice at three of these stations.
AN: 3885179

                                                                     78 of 1521  
TI: RACER: Methane enrichments in Port Foster, Deception Island
AU: Tilbrook,-B.D.; Karl,-D.M.
AF: Commonwealth Scientific and Ind. Res. Organization, Div. Oceanogr., Hobart, Tasmania, 7001, Australia
SO: ANTARCT.-J.-U.S. 1993 vol. 28, no. 5, pp. 165-166
LA: English
ER: M (Marine)
AB: During the research on antarctic coastal ecosystem rates (RACER) program, methane distributions in antarctic coastal waters of the Bransfield Strait, the Gerlache Strait, and in the southern oceans waters of the Drake Passage were examined. The objectives of the study were to identify the factors controlling methane distributions in antarctic shelf and open ocean environments and to evaluate the contribution these regions make to the sea-air flux of methane. As one small component of this larger study, we also occupied a single hydrostation in Port Foster, Deception Island. In this report, we present the water-column methane distribution from this unique, partially submerged volcanic caldera and compare these values with samples collected in surrounding surface waters.
AN: 3885168

                                                                     79 of 1521  
TI: The dynamic of benthic nutrient pools and fluxes in tropical mangrove forests
AU: Alongi,-D.M.
AF: Australian Inst. Mar. Sci., PMB No. 3, Townsville, M.C., Qld. 4810, Australia
SO: J.-MAR.-RES. 1996 vol. 54, no. 1, pp. 123-148
LA: English
ER: M (Marine); B (Brackish)
AB: Variations in benthic nutrient pools and rates of dissolved nutrient exchange between the forest floor and tidal waters were examined over a 5-yr period in mixed Rhizophora forests lining Coral Creek on Hinchinbrook Island in Queensland, Australia. Seasonal and spatial changes in redox status, porewater and solid-phase nutrients, and in exchange rates were not consistent and did not correlate with temperature. Below-ground roots, on average, accounted for  similar to 79%, 37% and 26% of bulk sediment TOC, total N and total P pools, respectively. Porewater nutrient concentrations were dominated by Si(OH) sub(4) super(+) and DON with consistently low levels of NO sub(2) super(-) + NO sub(3) super(-). At most sampling periods, porewater NH sub(4) super(+) and PO sub(4) super(3) super(-) concentrations were higher in creek bank sediments than in mangrove sediments indicating uptake by trees. These sediments have low absorption capacity (K = 0.17-0.47) for NH sub(4) super(+), but a moderate capacity (K = 0.8-4.8) for PO sub(4) super(3) super(-) adsorption. Most measured benthic fluxes of dissolved nitrogen and phosphorus showed uptake by sediments, prop roots and timber lying on the forest floor. Mangrove forests are a very efficient sink of dissolved nitrogen, phosphorus and silicon in this tidally-driven coastal ecosystem. This import may be driven by the consistently high rates of microbial and plant growth and productivity within the forests.
AN: 3883421

                                                                     80 of 1521  
TI: On migration, accumulation and circulation of total mercury and methylmercury in ecosystem in the Songhua River
AU: Yu,-Changrong; He,-Ying; Liang,-Dongmei
AF: Environ. Prot. Res. Inst., Jilin Prov., Changchun 130012, People's Rep. China
SO: SHANDONG-FISH.-QILU-YUYE 1995 vol. 12, no. 2, pp. 39-42
LA: Chinese
ER: F (Freshwater)
AB: The total mercury and methylmercury in the Songhua River and its deposits are passed and accumulated in the body of the aquatic animals through the food chain of the aquatic living things which took in the food at each layer of nutrient class. The longer the food chain of the aquatic living things, the more the mercury and methylmercury is accumulated in the body of the aquatic animals. If people eat the polluted fish and chickens, ducks of geese, the total mercury and methylmercury are migrated and deposited in the people's body, thus potentially endangering their health.
AN: 3883354

                                                                     81 of 1521  
TI: Microbiological gas formation altering top sediment composition and its relation to the internal nutrient load in eutrophic lakes
AU: Matinvesi,-J.
AF: Helsinki Univ. Technol., Espoo, Finland
SO: HELSINKI-UNIV.-TECHNOL.,-LAB.-ENVIRON.-PROT.-TECHNOL. 1995 vol. 970, no. 1, 37 pp.
NT: Dissertation for degree of Doctor of Technology.
LA: English
ER: F (Freshwater)
AB: The aim of this investigation was to gain more information on the biological processes taking place in the lake sediments and to find measures to improve the condition of eutrophic lakes. In six central Finnish lakes representing different trophic states, the phosphatase enzyme activity, the number of acetic acid-, ferricphosphate-, and tricalcium-phosphate-utilizing bacteria, and the levels of organic substances were the highest in the top layer of every sediment profile. The top sediments reveal to a great extent a fixed relation of carbon to nitrogen and phosphorus so that biological processes, degradation and deformation, have probably affected the distribution of organic substances and nutrients in the top sediments of these Finnish lakes. This suggests that a part of the organic substances may be mobile within the "reactive zone" and may move to the uppermost sediment layer in the course of time in undisturbed lake sediments. Mixing of organic substances into the water phase will take place in anaerobic conditions when aerobic bacteria are not capable of consuming methane in the sediment-water interface. A lake restoration method is proposed based on an old incident in eastern Finland. In 1859, the level of Lake Hoeytiaeinen was accidentally lowered by 9.5 m. The event is marked by a 2-3 cm dense interlayer of clay and fine silt of deep-water sediments. The layer prevented microbiological interaction between sediment and water. The amounts of LI, BOD sub(7) and tot. N below the clay horizon are comparable to typical undisturbed top sediments in oligotrophic central Finnish lakes. During the 133 years since then, little mineralization in the buried sediment has occurred. Covering bottom deposits with silt and clay (5 to 10 cm) may offer a useful lake restoration method in cases where inner load of nutrients is the main cause for lake eutrophication and where gas formation is not too vigorous in the bottom and where lake morphometry is suitable. BOD analyses give good information of the activity of microbiological processes in top sediment.
AN: 3882982

                                                                     82 of 1521  
TI: Dissolved and particulate nutrient transport through a coastal watershed-estuary system
AU: Smith,-S.V.; Chambers,-R.M.; Hollibaugh,-J.T.
AF: De. Oceanogr., Univ. Hawaii, Honolulu, HI 96822, USA
SO: J.-HYDROL.-AMST. 1996 vol. 176, no. 1-4, pp. 181-203
LA: English
ER: B (Brackish)
AB: Tomales Bay and its adjacent watershed are the location of integrated research on the C-N-P-Si biogeochemical coupling between the land and coastal ocean and cycling of these materials within the bay. In the present paper, budgets have been constructed to describe the rainfall delivery of dissolved nutrients to the watershed and export of dissolved and particulate nutrients from the watershed, mostly in runoff. The quantity of dissolved materials, especially dissolved organic materials, delivered to the watershed by rainfall is about the same as the export: Suspended load transport represents the major net removal of C, N, and P from the watershed, and this flux shows large interannual variation. Runoff-adjusted particle flux from the watershed is small at present in comparison with estimates based on sedimentation rate in the bay over the past 130 years. This difference apparently cannot be explained by natural or managed interannual variation in runoff or by other obvious aspects of water management. We believe that changes in agricultural land use have led to recent decreases in erosion and removal of particulate materials from the watershed. Even though the watershed has been disturbed by agricultural practices over the past 130 years, the system as a whole appears largely to have recovered to steady-state conditions.
AN: 3881216

                                                                     83 of 1521  
TI: Biofilm development and invertebrate colonization of wood in four New Zealand streams of contrasting pH
AU: Tank,-J.L.
AF: Dep. Biol., Virginia Polytech. Inst. and State Univ., Blacksburg, VA 24061, USA
SO: FRESHWAT.-BIOL. 1995 vol. 34, no. 2, pp. 303-315
LA: English
ER: F (Freshwater)
AB: Biofilm development and activity on wood substrata (Nothofagus menziesii) were examined at four forested sites in a South Island, New Zealand, river catchment over a period of 6 months. Two of the sites had brown waters and mean pH of 3.7 and 4.5, whereas the other two had clear waters and mean pH of 6.3 and 6.8. Fungi and other filamentous heterotrophs were the dominant colonizers of wood at all sites; few algal cells were present. Incorporation of  super(14)C-glucose by biofilms was greatest in all four streams after 3 months, whereas endocellulase activity fluctuated. Radiotracer experiments with a grazing amphipod (Paraleptamphopus sp.) demonstrated that biofilms on wood from all four sites could be ingested and at least partially assimilated. Chironomid larvae and harpacticoid copepods were the most abundant invertebrates colonizing wood substrata at all sites.
AN: 3880603

                                                                     84 of 1521  
TI: Biogeochemical studies in the Cauvery Estuary, east coast of India
AU: Ramanathan,-A.L.; Subramanian,-V.; Das,-B.K.
AF: Department of Geology, Annamalai University, Chidambaram 608 002, India
SO: INDIAN-J.-MAR.-SCI. 1996 vol. 25, no. 1, pp. 71-73
LA: English
ER: B (Brackish)
AB: Particulate organic carbon and particulate organic nitrogen show a decreasing trend towards the sea. Dissolved silica and phosphorus showed an erratic variation in the Cauvery Estuary. The  delta  super(13)C shows a marginal conservative behaviour in the Cauvery Estuary. Reduction in the dissolved P and Si concentrations are accompanied by enhanced levels in particulates. Phosphorus in sediments occurred in all the size fractions and possibly exist as a ferric and/or calcium phosphate.
AN: 3880432

                                                                     85 of 1521  
TI: Carbon dioxide and nitrous oxide in the north Indian Ocean
AU: Dileepkumar,-M.; Naqvi,-S.W.A.; Jayakumar,-D.A.; George,-M.D.; Narvekar,-P.V.; deSousa,-S.N.
AF: NIO, Dona Paula, Goa 403 004, India
SO: CURR.-SCI. 1995 vol. 69, no. 8, pp. 672-678
LA: English
ER: M (Marine)
AB: The understanding of biogeochemical cycling of carbon dioxide and nitrous oxide in the oceans is essential for predicting the fate of anthropogenically emitted components. The North Indian Ocean, with its diverse regimes, provides us with a natural laboratory that can unravel the mechanisms controlling these gases with implications for the global aquatic bodies. The anthropogenically impinged global budgets for these gases, largely collected under the Global Change Programme from the North Indian Ocean are reviewed and the contributions from this region to the global sea-to-air fluxes.
AN: 3880169

                                                                     86 of 1521  
TI: Electrochemical study of sulfur species in seawater and marine phytoplankton cultures
AU: Ciglenecki,-I.; Cosovic,-B.
AF: Cent. Marine Res. Zagreb, Rudjer Boskovic Inst., POB 1016, 41001 Zagreb, Croatia
SO: MAR.-CHEM. 1996 vol. 52, no. 1, pp. 87-97
LA: English
AB: Using a direct voltammetric method in seawater samples from the northern Adriatic Sea we have observed a peak at -0.6 V which belongs to sulfur species. The levels of sulfur (expressed as equivalent to sulfide concentrations) ranged between 10 and 50 nM, depending on the season. Maximum concentrations (appr. 500 nM) were found in the surface water during an intensive phytoplankton bloom. Experiments with different phytoplankton cultures (Phaeodactylum tricornutum, Emiliana huxleyi, Tetraselmis suecica, Isochrysis galbana, Prorocentrum micans, Thalassiosira weissflogii and a mixed culture from the Adriatic Sea) incubated with dimethylsulfoniopropionate (DMSP) suggested that this sulfur peak is, in addition to other possible sources, closely connected with degradation processes of DMSP which is a direct or indirect precursor of several marine sulfur species: dimethyl sulfide (DMS), methanethiol (MSH), 3-methiolpropionate (MMPA), 3-mercaptopropionate (MPA), carbonyl sulfide (COS), dimethyl disulfide (DMDS), H2S, S0. The observed voltammetric peak at -0.6 V was stable on acidification and purging procedure, followed by a readjustment of the solution pH to 8-10. The characterization of the electroactive sulfur species responsible for this peak was made by comparison with model substances. No inorganic or organic sulfur species alone revealed completely the voltammetric behaviour of natural samples. We concluded that in seawater and in phytoplankton cultures sulfur is very probably bound and stabilized with organic matter assuming that some of the bound sulfurs are electrochemically active. Our results do not rule out the possibility that some metal sulfides stabilize sulfide in oxic waters too.
AN: 3880094

                                                                     87 of 1521  
TI: Model of carbon cycling in planktonic food webs
AU: Connolly,-J.P.; Coffin,-R.B.
SO: J.-ENVIRON.-ENG. 1995 vol. 121, no. 10, pp. 682-690
LA: English
AB: A mathematical model of carbon fluxes through the heterotrophic microbial food web is developed from a synthesis of laboratory and field research. The basis of the model is the segregation of organic carbon into lability classes that are defined by bioassay experiments. Bacteria, phytoplankton, three trophic levels of zooplankton, and dissolved organic carbon (DOC) and particulate organic carbon (POC) are modeled. The descriptions of bacterial growth and utilization of the various classes of substrate were treated as "universal constants" in the application of the model to three distinct ecosystems, ranging from oligotrophic to highly eutrophic. The successful application of the model to these diverse ecosystems supports the basic validity of the description of the microbial food web and the dynamics of carbon flux. The model indicates that the dynamics of bacteria and protozoan zooplankton production govern the rates of oxidation of carbon entering the water column. Explicit consideration of these groups would improve the capability of eutrophication models to predict dissolved oxygen dynamics, particularly when projecting responses to loading changes.
AN: 3878396

                                                                     88 of 1521  
TI: Evidence for a winter sink of atmospheric carbonyl sulfide in the northeast Atlantic Ocean
AU: Ulshoefer,-V.S.; Uher,-G.; Andreae,-M.O.
SO: GEOPHYS.-RES.-LETT. 1995 vol. 22, no. 19, pp. 2601-2604
LA: English
ER: M (Marine)
AN: 3878377

                                                                     89 of 1521  
TI: Anaerobic methane oxidation on the Amazon shelf
AU: Blair,-N.E.; Aller,-R.C.
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 18, pp. 3707-3715
LA: English
ER: M (Marine)
AB: Anaerobic methane oxidation on the Amazon shelf is strongly controlled by dynamic physical sedimentation processes. Rapidly accumulating, physically reworked deltaic sediments characteristic of much of the shelf typically support what appear to be low rates of steady state anaerobic methane oxidation at depths of 5-8 m below the sediment-water interface. Methane oxidation in these cases is responsible for <  similar to  10% of the  capital sigma CO sub(2) inventory in the oxidation zone and is limited largely by the steady-state diffusive flux of methane into the overlying sulfate reduction zone. In contrast, a large area of the shelf has been extensively eroded, reexposing once deeply buried (> 10 m) methane-charged sediment directly to sea-water. In this nonsteady-state situation, methane is a major source of recently produced  capital sigma CO sub(2) and an important reductant for sulfate. These observations suggest that authigenic sedimentary carbonates derived from anaerobic methane oxidation may sometimes reflect physically enhanced nonsteady-state exposure of methane to sulfate in otherwise biogeochemically unreactive deposits. The concentration profiles of CH sub(4), SO sub(4) super(=), and  capital sigma CO sub(2) in the eroded deposit were reproduced by a coupled reaction-transport model. This area of the shelf was reexposed to seawater approximately 5-10 years ago based on the model results and the assumption that the erosion of the deposit occurred as a single event that has now ceased. The necessary second order rate constant for anaerobic methane oxidation was  greater than or equal to 0.1 mM/d.
AN: 3878370

                                                                     90 of 1521  
TI: CO sub(2) transfer at the air-sea interface: Numerical tests of the dual-tracer method
AU: Phillips,-L.F.
AF: Chem. Dep., Univ. Canterbury, Christchurch, New Zealand
SO: GEOPHYS.-RES.-LETT. 1995 vol. 22, no. 19, pp. 2597-2600
LA: English
ER: M (Marine)
AB: Gas-water fluxes of CO sub(2), O sub(2), He, SF sub(6) and NH sub(3) have been calculated for conditions corresponding to the measurements of Liss et al for O sub(2) exchange and of Smith and coworkers for CO sub(2) exchange. For each experimental run, the best value of surface temperature was selected by matching the calculated transfer velocity to the measured value for O sub(2) or CO sub(2), and fluxes of the other gases were then calculated for steady state, boundary layer, surface renewal and eddy diffusion models. The results indicate that the dual tracer method should work well for sparingly soluble gases under conditions where a surface renewal model applies, and moderately well under conditions where the boundary layer model is appropriate, but they leave open the question of when such models should apply.
AN: 3878369

                                                                     91 of 1521  
TI: The labyrinth of nutrient cycles and buffers in wetlands: Results based on research in the Camargue (southern France)
AU: Golterman,-H.L.
AF: Association 'Leiden-Camargue', Stn. Biologique de la Tour du Valat, Le Sambuc, F-13200 Arles, France
SO: HYDROBIOLOGIA 1995 vol. 315, no. 1, pp. 39-58
NT: Special issue: Nutrient cycles.
LA: English
ER: F (Freshwater)
AB: In this article different aspects of nutrient cycles are discussed in view of approaching a sufficiently precise quantification. The nutrient input balance of the Camargue was therefore measured which showed that the input of nutrients with the irrigation water, taken from the River Rhone, roughly equals the quantity of fertilizers added. Phytoplankton growth can be approached reasonably with the Monod model, although there are still many practical problems, such as the influence of the pH on P uptake and the problem of measuring P uptake in the field. The situation is worse for macrophyte growth; quantitative data are scarce and studies have often been carried out with unrealistic nutrient concentrations or without addressing the influence of the sediment. This influence can also include negative factors, such as high concentrations of Fe super(2+), H sub(2)S or FeS, but cannot yet be quantified. The nitrogen cycle in wetlands is dominated by denitrification. Most wetlands have sediments with high concentrations of organic matter, therefore with a large reducing capacity. Besides this process, we have shown that denitrification can also be controlled by FeS. In the Camargue sediments this denitrification is mediated by bacteria from the sulfur cycle; this appeared to be the major pathway.
AN: 3878334

                                                                     92 of 1521  
TI: Phytoplankton as an increasingly compound photosynthetic system: A historical perspective
AU: Talling,-J.F.
AF: Freshwater Biol. Association, Ambleside, Cumbria LA22 0LP, UK
SO: HYDROBIOLOGIA 1995 vol. 315, no. 1, pp. 9-14
NT: Special issue: Nutrient cycles.
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: The original suggestion that phytoplankton can be viewed and modelled as a compound photosynthetic system combined light gradients with depth and biological plus chemical homogeneity. Subsequent experience often involved biological and chemical differentiation in depth and time. Such differentiation is surveyed; it can add to the compound structure, and modify the kinetics of depth-integrated photosynthetic production. Further compounding possibilities are introduced by alternatives in carbon input, output and storage; also, conceptually, by the level of approach adopted. These features are discussed in historical perspective.
AN: 3878331

                                                                     93 of 1521  
TI: The carbonic system distribution and fluxes in the NE Atlantic during spring 1991
AU: Rios,-A.F.; Anderson,-T.R.; Perez,-F.F.
AF: Instituto de Investigaciones Marinas, Consejo Superior de Investigaciones Cientificas (CSIC), Eduardo Cabello, 6, 36208 Vigo, Spain
SO: PROG.-OCEANOGR. 1995 vol. 35, no. 4, pp. 295-314
LA: English
ER: M (Marine)
AB: The potential of the North Atlantic as a sink for atmospheric CO sub(2) was investigated by studying the carbonic system using data obtained during the spring of 1991. The air-sea flux of CO sub(2) was related to chlorophyll and other environmental variables, and the regeneration of carbon in the mid-ocean studied by examining vertical sections representative of the study area. Poor correlations were found between pCO sub(2) and chlorophyll throughout much of the study area, although a good correlation was found along 16 degree W. The highest air-sea fluxes of CO sub(2) were calculated for areas where chlorophyll was highest (45 degree 13'N, 16 degree 04'W), and where the greatest wind speeds occurred (47 degree 51'N, 28 degree 18'W). The mean CO sub(2) flux from the atmosphere to the ocean during the study period (May) was calculated as 0.65mmol m super(-2)d super(-1), which compares well with other studies. Regression equations were developed to predict total inorganic carbon from nutrients; errors were typically less than 1  mu mol kg super(-1). Regeneration of carbon in the mid-ocean occurred in two principal stages: 0-1000m and >2300m. Regeneration in the upper zone was dominated by soft tissue carbon (86%), with skeletal carbon (calcite) contributing only 14%. The fraction of regenerated carbon of skeletal origin increased to 51% in the >2300m zone.
AN: 3877855

                                                                     94 of 1521  
TI: Carbon and phosphorus transport by the major Indian rivers
AU: Ramesh,-R.; Purvaja,-G.R.; Subramanian,-V.
AF: Cent. for Water Resour., Anna Univ., Madras, India
CO: 1. GCTE Science Conference, Woods Hole, MA (USA), 23-27 May 1994
SO: J.-BIOGEOGR. 1995 vol. 22, no. 2-3, pp. 409-415
LA: English
ER: F (Freshwater)
AB: Riverine systems play a major role in the transport of nutrients from the land masses and atmosphere to the oceans and frequently serve as reservoirs for numerous compounds. The biogeochemical cycling of elements is significantly affected by man's activities. With the growing awareness of human impact on quality of rivers, emphasis is given more towards a holistic treatment of a river as an ecosystem. In the present study, an attempt is made to estimate the organic carbon transport from the Himalayan rivers. The transfer of dissolved organic carbon (DOC) and particulate organic carbon (POC) from the Himalayan rivers is estimated to be about 7.6 and 9 million tons per year. High concentrations of P-PO sub(4) are found in all the Indian rivers, which may be due to human interference. Pronounced temporal and seasonal variation for DOC and P-PO sub(4) have been reported. The flux of P-PO sub(4) and particulate inorganic phosphorus (PIP) from the Indian rivers to the ocean is 19.5 x 10 super(10) g yr super(-1) and 1.5 x 10 super(12) g yr super(-1) respectively. Comparisons were made with the prominent world rivers.
AN: 3874423

                                                                     95 of 1521  
TI: Structure and productivity of a 20-year-old stand of Rhizophora apiculata Bl. mangrove forest
AU: Jin-Eong,-O.; Khoon,-G.W.; Clough,-B.F.
AF: Cent. for Marine and Coastal Studies, Universiti Sains Malaysia, 11800 Penang, Malaysia
CO: 1. GCTE Science Conference, Woods Hole, MA (USA), 23-27 May 1994
SO: J.-BIOGEOGR. 1995 vol. 22, no. 2-3, pp. 417-424
LA: English
ER: B (Brackish)
AB: Mangroves are dominant interface ecosystems between the land and the sea in the tropics, and are of importance in the economy of many of these regions in terms of mangrove-linked fisheries and forestry. Recently, mangroves have been of particular interest in relation to global change both because of the possible high carbon sequestration as well as being in the 'forefront' of any sea-level change, because of their location. To understand the impact of global change on these ecosystems (considered terrestrial and aquatic at the same time) and vice versa, it is necessary to obtain 'a more comprehensive and realistic picture of the terrestrial carbon cycle', which is one of the aims of the GCTE Programme. We therefore present here some of the results of our long-term study (started in the mid-1970s) on the carbon and nutrient budget of a mangrove ecosystem as a basis for further studies, including the proposed large-scale biogeochemical transects and climate models proposed by GCTE. The tree density of the 20 m X 40 m plot in the 20-year-old stand was equivalent to 2425 stems per hectare (1975 live trees per hectare). Size (girth at breast height) of Rhizophora apiculata trees ranged from 9 to 75.5 cm with a mean at 39 cm. The smallest live tree weighed 10 kg and the biggest weighed 510 kg with a mean biomass of 122 kg. About 70% of the trees were below 100 kg but the 30% of the bigger trees contributed to slightly more than half of the total biomass of the plot. The canopy had an average height of 21 m. The total standing biomass was 114 t C ha super(-1); 74% of the biomass was in the trunk, 15% in the roots (10% in stilts and 5% below-ground) and 10.6% in the canopy (only 2.6% in leaves). Using allometric regressions, we obtained a net productivity (root turnover and loss through leaching were not measured but only approximated as equal to small litter production) of 17 plus or minus 5 t C ha super(-1) yr super(-1). If greater accuracy (than plus or minus 30%) is needed, direct measurements of root turnover and leaching from roots would be needed. Using the gas exchange method and using the mean value for a whole day's net photosynthesis measurements (averaged at 6  mu mol m super(-2) s super(-1)), 1.5  mu mol m super(-2) s super(-1) for leaf respiration, a leaf area index of 4, and assuming respiration of the non-leaf tissues to be the same as for leaves, we estimated net productivity to be 11.35 t ha super(-1) yr super(-1), almost at the lower limit of the allometric estimate. Use of leaf to tree to stand models may improve the accuracy of this method. The main gaps are in fine root turnover and possible loss of carbon through leaching from the roots.
AN: 3870303

                                                                     96 of 1521  
TI: The role of microorganisms in biosorption of toxic metals and radionuclides
AU: White,-C.; Wilkinson,-S.C.; Gadd,-G.M.*
AF: Dep. Biol. Sci., Univ. Dundee, Dundee DD1 4HN, UK
CO: Symposioum on Biosorption and Bioremediation, Madrid (Spain), 17-19 Oct 1993
SO: BIOSORPTION-AND-BIOREMEDIATION. Laborda,-F.;Beech,-I.B.;Sylvestre,-M.-eds. 1995 vol. 35, no. 1-3 pp. 17-40
ST: INT.-BIODETERIOR.-BIODEGRAD. vol. 35, no. 1-3
LA: English
AB: A multiplicity of physico-chemical and biological mechanisms determine the removal of toxic metals, metalloids and radionuclides from contaminated wastes. Physico-chemical mechanisms of removal, which may be encompassed by the general term "biosorption", include adsorption, ion exchange and entrapment which are features of living and dead biomass as well as derived products. In living cells, biosorption can be directly and indirectly influenced by metabolism. Metabolism, dependent mechanisms of metal removal which occur in living microorganisms include metal precipitation as sulphides, complexation by siderophores and other metabolites, sequestration by metal-binding proteins and peptides, transport and intracellular compartmentation. In addition, transformations of metal species can occur resulting in oxidation, reduction or methylation. For metalloids such as selenium, two main transformation mechanisms are the reduction of oxyanions to elemental forms, and methylation to methylated derivatives which are volatilized. Such mechanisms are important components of natural biogeochemical cycles for metals and metalloids as well as being potential application for bioremediation.
AN: 3868598

                                                                     97 of 1521  
TI: Distribution of biological activity in the lower St Lawrence Estuary as determined by multivariate analysis
AU: Savenkoff,-C.; Chanut,-J.-P.; Vezina,-A.F.; Gratton,-Y.
AF: Dep. Fish. and Oceans, Maurice-Lamontagne Inst., P.O. Box 1000, Mont-Joli, PQ G5H 3Z4, Canada
SO: ESTUAR.-COAST.-SHELF-SCI. 1995 vol. 40, no. 6, pp. 647-664
LA: English
ER: M (Marine)
AB: Three stations located in the Laurentian Trough were investigated three times during the summer production maximum (in June-July 1990; COUPPB90-1 cruise). A range of multivariate analyses was carried out to extract major physical-biological features in a large data set covering the whole cruise. This study presents the advantages of combining conventional principal component analysis (PCA) with a three-way data analysis. PCA provides the centre of gravity of the different locations for each variable and each sample during the cruise without temporal information. Three-way data analysis produces the trajectory of the different site/time locations for each variable and each sample, and clarifies spatial and temporal relationships between variables. The results reproduce the main patterns of the lower St Lawrence Estuary during the summer plankton bloom and indicate an upstream movement of warm and less saline waters associated with surface production. Apparently these large changes at the surface are not reflected in the deeper layers. Cluster analysis suggests that autotrophic and heterotrophic activities are decoupled when production is low and are correlated only when production increases.
AN: 3865608

                                                                     98 of 1521  
TI: Effects of zooplankton on sedimentation in pelagic ecosystems: Theory and test in two lakes of the Canadian shield
AU: Elser,-J.J.; Foster,-D.K.; Hecky,-R.E.
AF: Dep. Zool., Arizona State Univ., Tempe, AZ 85287-1501, USA
SO: BIOGEOCHEMISTRY 1995 vol. 30, no. 3, pp. 143-170
LA: English
ER: F (Freshwater)
AB: A simple heuristic theory based on conservation of matter and describing the fate of autotrophic production in pelagic ecosystems was developed to assist in conceptualizing how zooplankton affect sedimentation processes in lakes and oceans. The theory predicted that effects of zooplankton on the fraction of autotrophic incorporation that sediments (the "export ratio") will be a function of factors related both to zooplankton digestion and egestion and to tendencies of particulate matter to sediment directly prior to mineralization. As a result, effects of zooplankton grazing on the export ratio were predicted to be site-dependent, a function of physical conditions and zooplankton communities characterizing an ecosystem. The theory was tested by monitoring autotrophic production of C, N, and P, sedimentation of C, N, and P, and zooplankton biomass in two lakes of the Canadian shield characterized by contrasting morphometry and food-web structure. In Lake 110, a small elongate lake protected from wind exposure, export ratios of C, N, and P declined strongly with zooplankton biomass. In contrast, in L240, a larger lake with considerably greater wind exposure, export ratios increased with zooplankton biomass. These results were consistent with predictions of our theory that effects of zooplankton on sedimentation processes will depend on the tendency of particulate matter to directly sediment relative to the tendency of egested materials to sediment. However, no significant differences in relationships between export ratios for C, N, and P and zooplankton biomass were found.
AN: 3865603

                                                                     99 of 1521  
TI: Seasonal sedimentation of autochthonous material from the euphotic zone of a coastal system
AU: Olesen,-M.; Lundsgaard,-C.
AF: Mar. Biol. Lab., Univ. Copenhagen, DK-3000 Helsinger, Denmark
SO: ESTUAR.-COAST.-SHELF-SCI. 1995 vol. 41, no. 4, pp. 475-490
LA: English
ER: M (Marine)
AB: The seasonal sedimentation of particulate matter across the pycnocline was recorded in the Kattegat during the period of stratification (March-October 1989). The proportion of viable phytoplankton cells of the total carbon flux (63 g C/m super(2)) was low (18%). Faecal pellets contributed on average less than 5%. The major component of the sinking matter consisted of detrital material (amorphous particles with few recognizable components) which was estimated mainly to originate from the activity of microzooplankton. The average C/N ratio of the particulate biogenic matter trapped at the pycnocline was 8.6, but only 6.4 for the suspended particulate organic matter in the mixed layer indicating that nitrogen is more effectively recycled than carbon in the euphotic zone. This mechanism allows for an additional new organic carbon production of 33% compared to that which can be estimated from the external loading of nitrogen. Over the entire period the average daily vertical flux of carbon corresponded to 14% of the phytoplankton biomass indicating a high efficiency in the transport of organic material from the euphotic zone to the bottom.
AN: 3863766

                                                                    100 of 1521  
TI: Predictive model of the effects on lake metabolism of decreased airborne litterfall through riparian deforestation
AU: France,-R.L.; Peters,-R.H.
AF: Dep. Biol., McGill Univ., 1205 Ave. Dr. Penfield, Montreal, PQ H3A 1B1, Canada
SO: CONSERV.-BIOL. 1995 vol. 9, no. 6, pp. 1578-1586
LA: English
ER: F (Freshwater)
AB: The importance of airborne allochthonous litter to the carbon and nutrient budgets of lakes has been seldom studied. We compiled data on the input of terrestrial litter to develop a simple and speculative model to predict the potential consequences of riparian deforestation on one aspect of lake metabolism, specifically the balance between phytoplankton production and plankton respiration. During the autumn of 1992, 56 litter traps were deployed around the littoral zones of four oligotrophic lakes in a densely forested region of northwestern Ontario, Canada. The airborne litter input was estimated to be 32 g dry weight per meter of forested shoreline per year. Allochthonous litter input per unit offshore distance was related to the size of riparian trees, their proximity to the shoreline, and the elevation of their canopy. Combining our data with those from other studies suggests that terrestrial litter can contribute up to 15% of the total carbon supply to oligotrophic lakes and up to 10% of the total phosphorus supply to lakes with a large surface area relative to that of their drainage basin. These results were incorporated into a simple model that predicts that removal of shoreline trees could increase the ratio of plankton production to respiration in oligotrophic lakes situated within small drainage basins. Such lakes may therefore shift from allotrophy to increasing autotropy (energy self-sustenance) following riparian deforestation.
AN: 3863225

                                                                    101 of 1521  
TI: Organic carbon transport from the Southern Ocean and bacterial growth in the Antarctic intermediate water masses of the Tasman Sea
AU: Moriarty,-D.J.W.; O'-Donohue,-M.J.
AF: ARDA-Tek, 315 Main Rd. Wellington Point, Qld. 4160, Australia
SO: MAR.-ECOL.-PROG.-SER. 1995 vol. 119, no. 1-3, pp. 291-297
LA: English
ER: M (Marine)
AB: The concept that organic carbon is transported to the equatorial region at intermediate water depths from subantarctic frontal zones has been re-investigated using the tritiated thymidine method to determine rates of bacterial DNA synthesis in water masses of the Tasman Sea. There was a higher bacterial growth rate and thus a higher flux of organic carbon through bacteria in the Antarctic Intermediate Water (900 to 1000 m depth) than in the water masses immediately above or below in the Tasman Sea east and south of Tasmania. Values for bacterial production were 4 to 8  mu g C/m super(3)/d, which are equivalent to a consumption of about 3 to 6  mu l O sub(2)/l/yr. In the deeper layer at 1200 to 1500 m, rates were 3 to 4 times lower. These rates are compatible with other data on oxygen utilisation. Our results support the concept that organic matter sinks with downwelling water in the zone between the Subtropical Convergence and the Polar Front in the Southern Ocean and is advected towards the equator below the photic zone.
AN: 3862994

                                                                    102 of 1521  
TI: Role of a dense bed of Ophiothrix fragilis (Abildgaard) in the transfer of heavy metals at the water-sediment interface
AU: Gounin,-F.; Davoult,-D.; Richard,-A.
AF: Stn. Mar. (URA-CNRS 1363), Wimereux, France
SO: MAR.-POLLUT.-BULL. 1995 vol. 30, no. 11, pp. 736-741
LA: English
ER: M (Marine)
AB: The role of a dense bed of suspension-feeders (Ophiothrix fragilis) on the biogeochemical cycle of five major metals has been studied in the English Channel (Fe, Mn, Pb, Cu, Cd). Metal concentrations in ophiurids, their food (=suspended matter) and their faeces did not show any significant time variation. After their transit between food, organisms and faeces, metal concentrations were poorly modified, but relations between them changed. A lot of trace elements have been detected in the stomach, some of them typical of the waste inputs above the site. So, the ophiurid O. fragilis can be considered as a biological indicator of the elemental composition of the water mass entering the North Sea.
AN: 3862287

                                                                    103 of 1521  
TI: The formation of surface-active organic complexes of copper in coastal marine waters
AU: Shine,-J.P.; Wallace,-G.T.
AF: Environ. Sci. Program, Univ. Massachusetts at Boston, 100 Morrissey Blvd., Boston, MA 02125, USA
SO: MAR.-CHEM. 1995 vol. 51, no. 2, pp. 145-157
LA: English
ER: M (Marine)
AB: The importance of surface-active organic matter on the speciation of copper in coastal seawater was examined over a 22 month period in Massachusetts Bay. Concentrations of copper associated with dissolved surface-active organic matter ranged from 15 pmol/kg during winter (0.67% of total dissolved copper) to 850 pmol/kg (18% of total dissolved copper) at the peak of primary production during a spring bloom and, following a spring bloom, accounted for 36% of the total dissolved copper concentration. Association of copper with surface-active organic matter may have occurred by direct complexation with surface-active organic ligands or indirectly via organic-organic interactions with non-surface-active organic complexes of copper. Although total dissolved copper at the site was inversely related to salinity, indicative of freshwater/continental sources, the amount of copper bound to surface-active organic matter was significantly correlated with estimated rates of phytoplankton primary production (r super(2) = 0.78). The primary source of surface-active organically bound copper in Massachusetts Bay is apparently in-situ biological production and not export of anthropogenic/freshwater ligands from continental sources. Although they represent a small but significant fraction of the total copper species present in coastal seawater, surface-active forms of copper assume added importance due to their active role in the transport and biogeochemical cycling of this element.
AN: 3861713

                                                                    104 of 1521  
TI: A discussion on vertical profiles of dissolved Cu, Cd and Ni in the northwestern Pacific, South of Japan
AU: Wang,-Zhengfang; Junichi,-O.
AF: 2nd Inst. Oceanogr., SOA, Hangzhou 310012, People's Rep. China
SO: ACTA-OCEANOL.-SIN.-HAIYANG-XUEBAO 1993 vol. 12, no. 4, pp. 597-603
LA: English
ER: M (Marine)
AB: Some of the results about vertical profile of heavy metals of seawater to the South of Japan in Oct. 1990 are presented and discussed in relation to the concentration of dissolved Cu, Cd and Ni to biogeochemical environments. It points out that the distribution of dissolved Cu is higher in surface water than that in/upper 500 m layer, and maxima value attains the 8.2 n mol/dm super(3) in depth of 4 000 m. The concentrations of dissolved Ni ranges from 3.4 n mol/dm super(3) in surface seawater to 8.5 n mol/dm super(3) in the deep seawater to the South of Japan. The highest values are observed in the colder waters. This paper shows also that the vertical profile of dissolved Cd is perfect nutrient-type distribution. Dissolved Cd and phosphate are linearly correlated by the regression equation.
AN: 3860125

                                                                    105 of 1521  
TI: Seasonal flooding, nitrogen mineralization and nitrogen utilization in a prairie marsh
AU: Neill,-C.
AF: Ecosyst. Cent., Mar. Biol. Lab., Woods Hole, MA 02543, USA
SO: BIOGEOCHEMISTRY 1995 vol. 30, no. 3, pp. 171-189
LA: English
ER: F (Freshwater)
AB: Flooding can be an important control of nitrogen (N) biogeochemistry in wetland ecosystems. In North American prairie marshes, spring flooding is a dominant feature of the physical environment that increases emergent plant production and could influence N cycling. I investigated how spring flooding affects N availability and plant N utilization in whitetop (Scolochloa festucacea) marshes in Manitoba, Canada by comparing experimentally spring-flooded marsh inside an impoundment with adjacent nonflooded marsh. The spring-flooded marsh had net N mineralization rates up to 4 times greater than nonflooded marsh. Total growing season net N mineralization was 124 kg N ha super(-1) in the spring-flooded marsh compared with 62 kg N ha super(-1) in the nonflooded marsh. Summer water level drawdown in the spring-flooded marsh decreased net N mineralization rates. Net nitrification rates increased in the nonflooded marsh following a lowering of the water table during mid summer. Growing season net nitrification was 33 kg N ha super(-1) in the nonflooded marsh but <1 kg N ha super(-1) in the spring-flooded marsh. Added No sub(3) super(-) induced nitrate reductase (NRA) activity in whitetop grown in pot culture. Field-collected plants showed higher NRA in the nonflooded marsh. Nitrate comprised 40% of total plant N uptake in the nonflooded marsh but <1% of total N uptake in the spring-flooded marsh. Higher plant N demand caused by higher whitetop production in the spring-flooded marsh approximately balanced greater net N mineralization. A close association between the presence of spring flooding and net N mineralization and net nitrification rates indicated that modifications to prairie marshes that change the pattern of spring inundation will lead to rapid and significant changes in marsh N cycling patterns.
AN: 3860017

                                                                    106 of 1521  
TI: Role of benthic communities in organic contaminant (PAH, PCB) transport and fate. 2. Bioaccumulation and biotransformation
AU: Lay,-P.W.; Dickhut,-R.M.; Schaffner,-L.C.; Mitra,-S.
AF: Sch. Mar. Sci., Coll. William and Mary, Virginia Inst. Mar. Sci., Gloucester Point, VA 23062, USA
CO: 37. Conference of the International Association of Great Lakes Research and Estuarine Research Federation, Windsor, ON (Canada), 5-9 Jun 1994
SO: 37TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH-AND-ESTUARINE-RESEARCH-FEDERATION:-PROGRAM-AND-ABSTRACTS. International-Assoc.-for-Great-Lakes-Research,-Buffalo,-NY-USA BUFFALO,-NY-USA IAGLR 1994 166
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Numerous macrobenthic organisms from lower Chesapeake Bay have been observed to rapidly accumulate and transform a series of organic contaminants (OCs). Bioaccumulation and biotransformation vary both within and among major taxa, and with the OC physical-chemical properties (e.g., desorption rate, diffusivity, octanol/water partition coefficient - K sub(OW)). Nonetheless, bioaccumulation of OCs is rapid for various organisms regardless of feeding behavior (e.g., surface and head-down deposit feeders, predators) indicating that uptake of contaminants from the dissolved phase may be important. Comparison of OC and metabolite body burdens to those in the corresponding sediment indicate three types of behavior for OC fluxes through the organisms over 56 days of exposure to contaminated sediments: [1] steady state between contaminant uptake and elimination, [2] faster uptake than elimination corresponding to increasing bioaccumulation, and [3] rapid loss relative to uptake, with decreasing bioaccumulation factors with time. OC loss mechanisms from operationally defined detectable pools in the benthic biota may include: elimination of parent or metabolites, and binding of reactive metabolites to cellular structures. OC fate and transport pathways within benthic organisms are of importance in determining both the direct and indirect effects of organic pollutants on aquatic ecosystems including trophic transfer of parent compounds and toxic metabolites.
AN: 3859635

                                                                    107 of 1521  
TI: Modeling hydrophobic organic contaminant trophic transfer in the mesohaline Chesapeake Bay
AU: Kucklick,-J.R.; Madden,-J.; Baker,-J.E.; Kemp,-W.M.; Cheng,-Chung-Chi; Ko,-F.C.
AF: Chesapeake Biol. Lab., Univ. Maryland Syst., P.O. Box 38, Solomons, MD 20688, USA
CO: 37. Conference of the International Association of Great Lakes Research and Estuarine Research Federation, Windsor, ON (Canada), 5-9 Jun 1994
SO: 37TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH-AND-ESTUARINE-RESEARCH-FEDERATION:-PROGRAM-AND-ABSTRACTS. International-Assoc.-for-Great-Lakes-Research,-Buffalo,-NY-USA BUFFALO,-NY-USA IAGLR 1994 166
NT: Summary only.
LA: English
ER: B (Brackish)
AB: A simulation model was constructed to help elucidate processes influencing the trophic transfer of hydrophobic organic contaminants in Chesapeake Bay. The model differs from other trophic transfer models by focusing on lower trophic levels, such as phytoplankton and zooplankton, and incorporating a fairly sophisticated trophic carbon flow model for the mesohaline bay. Contaminants are introduced into the food web by passive diffusion, which is affected by exchange area and water-organism mass transfer coefficients, and feeding. The model was calibrated using a data set on seasonal PCB (congener specific) concentrations and distributions in size fractioned particles and water from the mesohaline Chesapeake Bay at two depths. This data set contains PCB congener concentrations in 2-10  mu m, 10-64  mu m, 64-202  mu m, and >202  mu m particles, which in the model represent ciliates and nanophytoplankton, phytoplankton and microheterotrophs, larger phytoplankton, and zooplankton, respectively. Lipid and carbon concentrations for each of the size classes are also contained in the data set and are used in the model. This talk presents the overall model structure as well as results from seasonal simulations and a sensitivity analysis on HOC transfer parameters.
AN: 3859633

                                                                    108 of 1521  
TI: Chemical correlates of Hg and methyl-Hg in northern Wisconsin lake waters under ice-cover
AU: Watras,-C.J.; Morrison,-K.A.; Bloom,-N.S.
AF: WI Dep. Nat. Resour., Univ. Wisconsin, Trout Lake Stn., 10810 CTY N, Boulder Junction, WI 54512, USA
SO: WATER,-AIR,-SOIL-POLLUT. 1995 vol. 84, no. 3-4, pp. 253-267
LA: English
ER: F (Freshwater)
AB: Total and dissolved concentrations of Hg and methyl-Hg (MeHg) were determined in the surface waters of 19 northern Wisconsin lakes under ice-cover when differences due to temperature, hydrology, productivity, and atmospheric exchange were minimal. Measured concentrations ranged from 0.3 to 5.3 ng/L for HgT and from 0.01 to 2.8 ng/L for MeHgT. Dissolved species comprised 30% to 95% of the HgT and MeHgT. MeHg was strongly correlated with Hg for both total and dissolved fractions. Thirteen ancillary constituents were measured in conjunction with the Hg determinations (pH, DOC, DIC, DO sub(2), conductivity, suspended particulate matter (SPM), Ca, Mg, Mn, Fe, Na, SO sub(4), Cl). Simple linear regressions indicated that DOC explained 87% of the variability in HgT and 79% of the variability in MeHgT. Of the other measured variables, pH, DO sub(2), Fe and Mn showed weak but significant simple correlations with Hg and MeHg (p < 0.05). Multiple regression models containing two independent variables, (DOC and pH), explained 92% of the variability in HgT and 83% of the variability in MeHgT. Models containing DOC alone fit the dissolved Hg data well. We conclude that organic carbon concentrations have a strong effect on the concentrations of Hg and MeHg in these lakewaters.
AN: 3857836

                                                                    109 of 1521  
TI: Winter-summer differences of carbon dioxide and oxygen in the Weddell Sea surface layer
AU: Hoppema,-M.; Fahrbach,-E.; Schroeder,-M.; Wisotzki,-A.; De-Baar,-H.J.W.
AF: Alfred-Wegener-Inst. Polar- und Meeresforschung P.O. Box 120161, D-27515 Bremerhaven, FRG
SO: MAR.-CHEM. 1995 vol. 51, no. 3, pp. 177-192
LA: English
ER: M (Marine)
AB: Mid-winter total inorganic carbon (TCO sub(2)) and oxygen measurements are presented for the central fully ice-covered Weddell Sea. Lateral variations of these properties in the surface layer of the central Weddell Sea were small but significant. These variations were caused by vertical transport of Warm Deep Water into the surface layer and air-sea exchange before the ice cover. Oxygen saturation in the surface layer of the central Weddell Sea was near 82%, whereas in the eastern shelf area this was 89%. Surprisingly, pCO sub(2), as calculated under the assumption of (reported) conservativeness of alkalinity, was also found to be below saturation (86-93%). This was not expected since ongoing Warm Deep Water entrainment into the surface layer tends to increase the pCO sub(2). Rapid cooling and subsequent ice formation during the previous autumn, however, might have brought about a sufficiently low undersaturation of CO sub(2), that as to the point of sampling had not yet been replenished through Warm Deep Water entrainment. In the ensuing early summer the measurements were repeated. In the shelf area and the central Weddell Sea, where the ice-cover had almost disappeared, photosynthesis had caused a decrease of pCO sub(2) and an increase of oxygen compared to the previous winter. In between these two regions there was an area with significant ice-cover where essentially winter conditions prevailed. Based on the summer-winter difference a (late-winter) entrainment rate of Warm Deep Water into the surface layer of 4-5 m/month was calculated. A complete surface water balance, including entrainment, biological activity and air-sea exchange, showed that between the winter and summer cruises CO sub(2) and oxygen had both been absorbed from the atmosphere. The TCO sub(2) increase due to entrainment of Warm Deep Water was partly countered by (autumn) cooling, and partly through biological drawdown. Part of the CO sub(2) removed through biological activity sinks down the water column as organic material and is remineralised at depth. It is well-known that bottom water formation constitutes a sink for atmospheric CO sub(2). However, whether the Weddell Sea as a whole is a sink for CO sub(2) depends on the ratio of two counteracting processes, i.e. entrainment, which increases CO sub(2) in the surface and the biological pump, which decreases it. As deep water is not only entrained into the surface, but also conveyed out of the Weddell Sea, the relative importances of these (CO sub(2)-enriched) deep water transports are important as well.
AN: 3855921

                                                                    110 of 1521  
TI: Formation of recalcitrant organic matter: Humification dynamics of algal derived dissolved organic carbon and its hydrophobic fractions
AU: Lara,-R.J.; Thomas,-D.N.
AF: Alfred-Wegener-Inst. Polar- und Meeresforschung, Am Handelshafen 12, D-27570 Bremerhaven, FRG
SO: MAR.-CHEM. 1995 vol. 51, no. 3, pp. 193-199
LA: English
ER: M (Marine)
AB: The incorporation of radiolabeled carbon into XAD2-fractions of dissolved organic matter was followed during the growth, stationary and degradation phases of a batch culture of the Antarctic diatom Thalassiosira tumida. Changes in the fractions over the 267 day experiment were correlated with the production and decomposition of particulate organic matter. The bulk of the acid and neutral hydrophobic XAD-fractions, traditionally considered to be humic, were produced mainly during the diatom growth phase: 70% of this carbon was present in a relatively stable form by the end of the first month, representing 5% of the maximum carbon biomass. There was a progressive accumulation of a hydrophobic DOC fraction tightly bound to the XAD resin. This fraction is normally not considered following XAD2 extraction of aquatic humic material. However, it is evidently an important component of a resistant DOC pool, increasing during the experiment to levels between 40 and 50% of total DOC after 7-8 months. This fraction is thought to be mainly a product of particulate material degradation. At the end of the experiment the sum of all hydrophobic DOC fractions was 14% of the maximum particulate carbon.
AN: 3855920

                                                                    111 of 1521  
TI: Mineralization of dissolved organic carbon in the Sargasso Sea
AU: Hansell,-D.A.; Bates,-N.R.; Gundersen,-K.
AF: Bermuda Biol. Stn. Res., Inc., 17 Biological Lane, St. Georges, GE-01, Bermuda
SO: MAR.-CHEM. 1995 vol. 51, no. 3, pp. 201-212
LA: English
ER: M (Marine)
AB: The lability of dissolved organic carbon was estimated in the Sargasso Sea. Rates of DOC mineralization were estimated by monitoring, with high precision, the accumulation of CO sub(2) in dark incubation bottles after the removal of particles >0.8  mu m in size. The minimum incubation time used in these experiments was 24 h. Rates from three 24 h incubations conducted on water from 20 m fell in the narrow range of 0.44-0.45  mu M C d super(-1). These rates ranged from approximate equivalence to more than 100% greater than the concurrent rates of primary productivity, suggesting in some cases that gross primary productivity was underestimated or that there existed labile DOC produced earlier in time, thus supporting periods of net heterotrophy in the Sargasso Sea.
AN: 3855919

                                                                    112 of 1521  
TI: Carbon-isotope composition of sediments from the Gulf of Papua
AU: Bird,-M.I.; Brunskill,-G.J.; Chivas,-A.R.
AF: Res. Sch. Earth Sci., Australian Natl. Univ., Canberra, ACT 0200, Australia
SO: GEO-MAR.-LETT. 1995 vol. 15, no. 3-4, pp. 153-159
NT: Special issue: Tropical coastal sedimentary environments.
LA: English
ER: M (Marine)
AB: Rivers draining into the Gulf of Papua (GOP) from the Papua New Guinea mainland deliver approximately 340 x 10 super(6) t yr super(-1) of sediment to the marine environment. The terrestrially derived sediment contains 1.1  plus or minus  0.2% particulate organic carbon with a carbon-isotope composition of -26.5  plus or minus  0.2ppt, and amounts to 3.7  plus or minus  0.7 x 10 super(6) t yr super(-1). The carbon-isotope composition of sediments in the Gulf of Papua indicates that 40% of the sediment cover contains 75% or more terrestrially derived carbon. Suspended sediments that are transported beyond the delta complex of the Fly River are transported north and northwest, augmented by sediments from other rivers along the coast of the GOP. The carbon-isotope results suggest that a significant quantity of terrestrially derived sediment escapes from the GOP, either along the coastlines to east and west or into the deep ocean via the Moresby and Pandora troughs. Little sediment travels south onto the Great Barrier Reef shelf. Extrapolating the results from this study to the region of Oceania suggests a total flux of particulate organic carbon to the world's oceans from the islands of Oceania of  similar to 90 x 10 super(6) t yr super(-1) or twice the flux of riverine POC from the major rivers of North America, South America, and Africa combined. While such a calculation must be considered illustrative only, the similar tectonic, geomorphologic, and climatic features of the islands of Oceania suggest that the calculation is unlikely to be grossly in error and that the rivers of Oceania therefore represent a major but poorly documented source of sediment and organic carbon to the global ocean.
AN: 3855878

                                                                    113 of 1521  
TI: Role of riverine mangrove forests in organic carbon export to the tropical coastal ocean: A preliminary mass balance for the Fly Delta (Papua New Guinea)
AU: Robertson,-A.I.; Alongi,-D.M.
AF: Australian Inst. Mar. Sci., PMB No. 3, Townsville M.C., Qld. 4810, Australia
SO: GEO-MAR.-LETT. 1995 vol. 15, no. 3-4, pp. 134-139
NT: Special issue: Tropical coastal sedimentary environments.
LA: English
ER: M (Marine); F (Freshwater)
AB: A preliminary mass balance for organic carbon in the Fly Delta was constructed to determine the quantity and source of organic matter exported to the adjacent Gulf of Papua and Coral Sea. Total organic carbon input from the river to the delta is 1.7 x 10 super(12) g C yr super(-1), composed almost equally of DOC and POC. Benthic and pelagic respiration in the delta accounts for 1.0 x 10 super(12) g C yr super(-1), being a major sink for riverine organic carbon. Benthic flux measurements indicate that one third of all DOC entering the delta is taken up by sediments there. Mangrove forests export >3.0 x 10 super(11) g C yr super(-1) POC to delta waters, and it appears that this mangrove carbon is exported to the adjacent shelf and deep sea. These results imply that little of the riverine supply of organic carbon reaches the Gulf of Papua, but that mangrove forests in the Fly and other rivers lining the gulf play a major role in river-shelf carbon exchange.
AN: 3855803

                                                                    114 of 1521  
TI: Third Annual Walker Branch Watershed Research Symposium. Program and abstracts
CA: Oak Ridge Natl. Lab., TN (USA)
SO: 1992 53 pp
NT: NTIS Order No: DE92010786/GAR.
RN: CONF-920389-ABST (CONF920389ABST)
LA: English
ER: F (Freshwater)
AB: The methods and concepts of watershed research, originally applied in an experimental or monitoring mode to relatively small catchments, are increasingly being used at larger scales and for specific applied problems. Research at Oak Ridge National Laboratory, the Tennessee Valley Authority, the US Forest Service, and other agencies and institutions participating in this symposium reflects research over a broad range of spatial scales that is being integrated through large-scale experiments along with computer modeling and graphical interfaces. These research projects address the basic atmospheric, geophysical, biogeochemical, and biological processes that regulate the responses of forested ecosystems to natural environmental variation and anthropogenic stresses. Regional and global issues addressed by presentations include emissions of carbon dioxide, methane, and other hydrocarbons; deposition of sulfate, nitrate, and mercury; land-use changes; biological diversity; droughts; and water quality. The reports presented in this symposium illustrate a wide range of methods and approaches and focus more on concepts and techniques than on a specific physical site. Sites and projects that have contributed research results to this symposium include Walker Branch Watershed (DOE), the Coweeta Hydrologic Laboratory and LTER site (USFS and NSF), Great Smoky Mountains National Park (research funded by NPS, TVA, and EPRI), Imnavait Creek, Alaska (DOE), the TVA-Norris Whole-tree Facility (TVA and EPRI), and DOE's Biomass Program. (DBO)
AN: 3855557

                                                                    115 of 1521  
TI: Regional scale dynamical modelling of biogeochemical processes
AU: Robinson,-A.R.; McKay,-G.
CA: Harvard Univ., Cambridge, MA (USA). Div. of Applied Sciences
SO: 1990 31 pp
NT: NTIS Order No: AD-A240 115/6/GAR.
LA: English
ER: M (Marine)
AB: This project involved the design and development of 3D regional biogeochemical models. The biogeochemical models were designed for attachment to the Harvard Hierarchy of models, including the surface boundary layer (SBL) component of the open ocean baroclinic eddy resolving quasigeostrophic (QG) model, or its coastal extensions, and the open boundary primitive equation (PE) model with hybrid vertical coordinates. Selection of these physical models is motivated by the interest to study the time evolution of biogeochemical components with realistic physical fields, as they all have data assimilation schemes associated. The approach taken in this model design was first to construct simplified models with a minimal number of biogeochemical components, and then step-by-step to introduce further components and detailed intercomponent interactions. These simplifications allow focused research on important biological mechanisms in the presence of realistic physical fields. Construction of regional biogeochemical models with data assimilation schemes will provide a unique tool to determine processes and sensitivities operative in the real ocean and to facilitate efficient experimental design and model validation. The simplest biogeochemical model of interest is of the nitrogen cycle. During this contract we constructed two models with two different compartmentalizations of the nitrogen components. (DBO)
AN: 3855552

                                                                    116 of 1521  
TI: Redfield ratios along isopycnal surfaces -- a complementary study
AU: Minster,-J.-F.; Boulahdid,-M.
AF: UM 39 - CNES/GRGS, 18, Ave. Edouard Belin, 31055 Toulouse Cedex, France
SO: DEEP-SEA-RES.-A-OCEANOGR.-RES.-PAP. 1987 vol. 34, no. 12, pp. 1981-2003
LA: English
ER: M (Marine)
AB: The recent suggestion by Takahashi et al. to change the Redfield ratios from P/N/-O sub(2) = 1/18/138 to 1/17/172 is critically examined. As a complementary analysis we process the GEOSECS and TTO data in the Atlantic and Indian oceans along four isopycnal horizons. This is done separately for each basin in order to diminish the possible effects of diapycnal mixing. The occurrence of two or three end-member mixing is assessed through "NO" vs salinity plots. End-members are selected among stations at the geographical border of the basins. The Redfield ratios are calculated in a two or three end-member mixing and consumption model via a direct non-linear least-squares technique. The N/-O sub(2) Redfield ratio appears constant and equal to 9.1  plus or minus  0.4. For P/-O sub(2), we confirm the Takahashi et al. value for  sigma  sub( theta ) = 27.0 and 27.2ppt. For  sigma  sub( theta ) = 27.4ppt, we find a ratio of 1/141 and for  sigma  sub( theta ) = 27.8ppt, a value of 1/115. This change is related to the nitrate to phosphate ratio. These results suggest that phosphorus is less easily remobilized, or more strongly recycled in shallow levels, than nitrogen. (DBO)
AN: 3855422

                                                                    117 of 1521  
TI: Hydrogen cycling in the waters near Bermuda: The role of the nitrogen fixer, Oscillatoria thiebautii
AU: Scranton,-M.I.
AF: Mar. Sci. Res. Cent., State Univ. New York, Stony Brook, NY 11794, USA
SO: DEEP-SEA-RES.-A-OCEANOGR.-RES.-PAP. 1984 vol. 31, no. 2, pp. 133-143
LA: English
ER: M (Marine)
AB: Oceanic surface waters are frequently supersaturated with hydrogen gas relative to atmospheric equilibrium. One possible source for the excess hydrogen is production by nitrogen-fixing organisms, many of which are known to reduce hydrogen ion, H super(+), to H sub(2). Results from short-term, shore-based incubations in Bermuda have demonstrated that Oscillatoria thiebautii, a marine cyanobacterium, produces hydrogen in significant quantities, confirming previous work from St. Croix. Measurement of an acetylene reduction: super(15)N sub(2) fixation ratio of 2.85  plus or minus  0.36:1 for Oscillatoria thiebautii near Bermuda was in agreement with our relatively low rates of hydrogen production (0.002 to 0.05 nmol per colony per hour) compared with nitrogen fixation rates (0.3 to 1.5 nmol per colony per hour). Although hydrogen production was slow, rates would be sufficient to produce surface supersaturations if no removal mechanisms were important. However, data on water column distributions indicated that surface waters near Bermuda at the time of our experiment were undersaturated with hydrogen. Diffusion of hydrogen into the thermocline and in situ biological consumption appear to be the most likely hydrogen sinks. (DBO)
AN: 3855380

                                                                    118 of 1521  
TI: Scavenging residence times of trace metals and surface chemistry of sinking particles in the deep ocean
AU: Balistrieri,-L.; Brewer,-P.G.; Murray,-J.W.
AF: Woods Hole Oceanogr. Inst., Woods Hole, MA 02543, USA
SO: DEEP-SEA-RES.-A-OCEANOGR.-RES.-PAP. 1981 vol. 28, no. 2, pp. 101-121
LA: English
ER: M (Marine)
AB: The adsorption properties of sinking particulate matter in the deep subtropical Atlantic Ocean are modeled by combining the field observations of trace metal scavenging with theoretical surface chemistry. The treatment yields equilibrium constants that define metal interactions with deep-ocean particles. These equilibrium constants can be compared with those that define metal interactions with typical metal oxides and organic compounds. The comparison indicates that metal-particulate matter interactions closely resemble the interactions between organic compounds and metals. Therefore, it is suggested that the adsorption properties of marine particulate matter are controlled by organic coatings. In addition, quantifying the surface properties of deep-ocean particles provides a mean for estimating the scavenging residence times for metals for which the determination has not yet been made. (DBO)
AN: 3855347

                                                                    119 of 1521  
TI: Some aspects of the oxygen-deficient conditions and denitrification in the Arabian Sea
AU: Naqvi,-S.W.A.
AF: Natl. Inst. Oceanogr., Dona Paula, GOA 403 004, India
SO: J.-MAR.-RES. 1987 vol. 45, no. 4, pp. 1049-1072
LA: English
ER: M (Marine)
AB: Utilizing a fairly large amount of recently collected data, some outstanding questions concerning the Arabian Sea denitrification problem are addressed. The true levels of dissolved oxygen, determined colorimetrically, are about an order of magnitude lower than those reported previously from the oxygen minimum zone. Lateral advection of waters from south into the oxygen-deficient layer is suggested by the presence of an intermediate oxygen maximum discernible even at very low oxygen levels. an unusual minimum in nitrate and a corresponding maximum in nitrite are observed occasionally within the depth range 700-1,200 m at several stations, generally located in the northeastern Arabian Sea. These features probably represent the development of a deeper denitrifying layer, in addition to the main denitrifying layer invariably found in the northern Arabian Sea at shallower depths. The deeper layer appears to be related to an increase in particulate organic carbon, probably resulting from seasonal changes in primary production, lateral advection of waters from the slope region off the Indian coast, or an in-situ production of organic matter. (DBO)
AN: 3855103

                                                                    120 of 1521  
TI: A model for the dynamics of nutrients and oxygen in the Baltic Proper
AU: Stigebrandt,-A.; Wulff,-F.
AF: Dep. Oceanogr., Univ. Gothenburg, Box 4038, S-400 40 Gothenburg, Sweden
SO: J.-MAR.-RES. 1987 vol. 45, no. 3, pp. 729-759
LA: English
ER: M (Marine)
AB: A horizontally integrated, time-dependent physical-biogeochemical model of high vertical resolution has been developed for the Baltic Sea proper. A seasonal pycnocline model computes the physical state of the mixed surface layer. Below this is an advective-diffusive model. The vertical advection is caused by a time-dependent, entraining bottom current which transports dense seawater into the system. The vertical distributions of volumes and sediment areas are accounted for by the use of the hypsographic function of the system. The chemical/biological processes controlling the distributions of nitrogen and oxygen are modelled as follows: Primary production is controlled by light, temperature, nutrients and density stratification (critical depth). Nutrient recycling, nitrification and sedimentation are accounted for using simple, rather general process descriptions. Organic matter is broken down both in the water column and at the bottom. Denitrification in the water and sediment is controlled by the concentrations of oxygen, nitrate and organic substrate and by temperature. Sulphate reduction to hydrogen sulphide occurs during anaerobic conditions once nitrate has been depleted. The daily meteorological forcing of the model is synthetic and randomly selected from monthly statistical distributions of observed weather components. The dense water inflow from the sea used in the model is synthetic as well. Loadings of biologically active nitrogen compounds from rivers and atmospheric fall-out, representative of contemporary conditions, are used. (DBO)
AN: 3855092

                                                                    121 of 1521  
TI: The role of bacteria in the turnover of organic carbon in deep-sea sediments
AU: Rowe,-G.T.; Deming,-J.W.
AF: Brookhaven Natl. Lab., Upton, NY 11973, USA
SO: J.-MAR.-RES. 1985 vol. 43, no. 4, pp. 925-950
LA: English
ER: M (Marine)
AB: The cycling of organic carbon in the deep sea was inferred from measurements of sediment trap and box core samples taken on the Biscay and Demerara abyssal plains of the North Atlantic. Of the input of organic carbon to the bottom, less than 10% was buried, i.e., not , consumed biologically. Based on laboratory measurements of bacterial activity in the sediment samples, incubated under in situ temperature and pressure, it was possible to attribute at least 13 to 30% of the total inferred biological consumption of organic carbon to microbial utilization. The complementarity of results from these biochemical and microbiological measurements implies that the decompression of cold abyssal samples during retrieval efforts does not prevent meaningful experiments on the microbial inhabitants, once returned to in situ pressure. (DBO)
AN: 3855073

                                                                    122 of 1521  
TI: Annual cycles of nutrients and chlorophyll in Narragansett Bay, Rhode Island
AU: Pilson,-M.E.Q.
AF: Grad. Sch. Oceanogr., Univ. Rhode Island, Narragansett, RI 02882, USA
SO: J.-MAR.-RES. 1985 vol. 43, no. 4, pp. 849-873
LA: English
ER: M (Marine); B (Brackish)
AB: Nutrient concentrations in Narragansett Bay change in a regular way through the seasons, so that characteristic and well defined cycles are observed, but are different for each nutrient. The cyclic changes are not explainable by processes in the water column alone, nor by advection, even through the replacement time of water in the bay is only 10-40 days. It appears possible to incorporate much of the cycling activity in 13-m super(3) microcosms, so these must include the dominating features of the complex biogeochemical processes involved. Observations in the microcosms suggest that the processes maintaining the annual cycles are sufficiently strong that, in the absence of deliberate experimental manipulation, the cycles might continue not significantly altered through at least one year. Therefore, the nutrient cycles in the bay can be driven largely by activities internal to the bay, especially sediment-water exchanges. (DBO)
AN: 3855069

                                                                    123 of 1521  
TI: Some physical factors affecting ecosystems
AU: Klein,-P.; Steele,-J.H.
AF: Woods Hole Oceanogr. Inst., Woods Hole, MA 02543, USA
SO: J.-MAR.-RES. 1985 vol. 43, no. 2, pp. 337-350
LA: English
ER: M (Marine)
AB: The response of a simple pelagic ecosystem is investigated in a domain with zero, one- and two-dimensional descriptions of the physical processes. Assuming complete mixing, internal recycling and external exchange of nutrients and their biological products are not additive in terms of the rate of primary production. In a one-dimensional system, advection without diffusion leads to low values of primary production. With two horizontal dimensions, cross diffusion at the boundary gives higher values of production. The consequences for higher trophic levels are described. (DBO)
AN: 3855048

                                                                    124 of 1521  
TI: Rates of recycling of biogenic components of settling particles in the ocean derived from sediment trap experiments
AU: Walsh,-I.; Dymond,-J.; Collier,-R.
AF: Dep. Oceanogr., Texas A&M Univ., Coll. Stn., TX 77843, USA
SO: DEEP-SEA-RES.-A-OCEANOGR.-RES.-PAP. 1988 vol. 35, no. 1, pp. 43-58
LA: English
ER: M (Marine)
AB: The rates of recycling of the major components of the biologically produced particulate flux (organic carbon, calcium carbonate, and opal) were measured at three sites in the North Equatorial Pacific. The measured biogenic fluxes in sediment traps were normalized to the particulate aluminum flux, and reaction rate constants were derived assuming first order processes occurring during particle settling between adjacent pairs of sediment traps. Mid-water flux maxima were found at each site. Assuming a particle settling rate of 100 m/day, organic carbon, calcium carbonate and opal rate constants below the mid-water flux maxima were 3.7-13/y, 2.3-4.5/y, and 1.0-7.9/y, respectively. Ranges for rate constants above the mid-water flux maxima were 15-32/y for organic carbon, 11-20 y super(-1) for calcium carbonate, and 6.4-27/y for opal. (DBO)
AN: 3854972

                                                                    125 of 1521  
TI: Variations in nitrogen isotopic composition between sinking and suspended particles: Implications for nitrogen cycling and particle transformation in the open ocean
AU: Altabet,-M.A.
AF: Woods Hole Oceanogr. Inst., Woods Hole, MA 02543, USA
SO: DEEP-SEA-RES.-A-OCEANOGR.-RES.-PAP. 1988 vol. 35, no. 4, pp. 535-554
LA: English
ER: M (Marine)
AB: Significant and consistent differences in nitrogen isotopic ratio (measured as  delta  super(15)N relative to atmospheric N sub(2)) are observed between suspended and sinking particles in the Sargasso Sea. Suspended particles in the euphotic zone have an annual average of -0.2ppt while particles sinking out of the euphotic zone average 3.7ppt. This latter value is equivalent to the average  delta  super(15)N value for the sources of new nitrogen to the euphotic zone. The  delta  super(15)N of NO sub(3) super(-) below the euphotic zone is similar, confirming that this is the major source. The downward particle flux acts to preferentially export  super(15)N out of the euphotic zone, with the result that suspended particles are depleted in  super(15)N relative to new nitrogen sources. The observed difference in  delta  super(15)N is evidence that the net transformation of suspended into sinking particles in this region is a result of active processes such as macrozooplankton feeding, as opposed to passive physical effects. Suspended particles below 200 m are 6ppt higher in  delta  super(15)N relative to those within the euphotic zone. This observation reflects, in part, the origin of suspended particles below the euphotic zone from the larger, faster sinking particles which are enriched in  delta  super(15)N. Since these suspended particles are also higher in  delta  super(15)N relative to sinking particles by 3ppt, isotopic fractionation must occur during the disaggregation of sinking particles and/or the subsequent degradation of suspended particles. (DBO)
AN: 3854960

                                                                    126 of 1521  
TI: Re-evaluation of the nutrient exchanges in the Strait of Gibraltar
AU: Coste,-B.; Le-Corre,-P.; Minas,-H.J.
AF: Cent. d'Oceaonologie de Marseille, Faculte des Sci. de Luminy, Case 901, 13288 Marseille Cedex 9, France
SO: DEEP-SEA-RES.-A-OCEANOGR.-RES.-PAP. 1988 vol. 35, no. 5, pp. 767-775
LA: English
ER: M (Marine)
AB: New data of inorganic, particulate and dissolved organic forms of nitrogen, phosphorus and silicon from the Mediterranean Sea near the Strait of Gibraltar allow an estimate of the exchanges of these elements between the Mediterranean Sea and the Atlantic Ocean. Input by Atlantic waters is lower than output by the Mediterranean waters. The difference accounts for about 10% of the total nitrogen and phosphorus outflow and for about 50% of the total silicon outflow. The deficit appears to be balanced by the nutrient supply from land drainage. The dissolved organic nitrogen and phosphorus are about 50% of the total nitrogen and phosphorus inflow and less than 30% of the outflow. The Mediterranean Sea appears to be an active basin of mineralization. (DBO)
AN: 3854938

                                                                    127 of 1521  
TI: Phosphatases revisited: Analysis of particle-associated enzyme activities in aquatic systems
AU: Berman,-T.; Wynne,-D.; Kaplan,-B.
AF: Kinneret Limnol. Lab., Israel Oceanogr. and Limnol. Res, P.O. Box 345, Tiberias 14102, Israel
CO: Conf. on Limnology and Oceanography, , 26-29 Jun 1989
SO: FLUXES-BETWEEN-TROPHIC-LEVELS-AND-THROUGH-THE-WATER-SEDIMENT-INTERFACE. Bonin,-D.J.;Golterman,-H.L.-eds. 1990 vol. 207 pp. 287-294
ST: HYDROBIOLOGIA vol. 207
LA: English
ER: F (Freshwater)
AB: A modified assay for alkaline or acid phosphatases associated with microorganisms in aquatic environments has been developed. This is based on collecting microplankton on filters and subsequently determining the enzyme activities spectrophotometrically or fluorometrically, using p-nitrophenyl-phosphate or 4-methylumbelliferyl phosphate, respectively as substrates. The assay is simple and rapid, and has the further advantage of permitting phosphatase activities to be assigned to specific size fractions of the natural microplankton. In samples taken from Lake Kinneret and a nearby reservoir, a consistently high proportion of the total alkaline or acid phosphatase activity was associated with the size fraction <0.8  mu m >0.2  mu m indicating the potentially high contribution of bacteria to these activities. This approach can also be used to examine the enzymatic potential of microplankton to release orthophosphate from other organo-phosphate substrates. (DBO)
AN: 3854916

                                                                    128 of 1521  
TI: Incidence of mussel culture on biogeochemical fluxes at the sediment-water interface
AU: Baudinet,-D.; Alliot,-E.; Berland,-B.; Grenz,-C.; Plante-Cuny,-M.-R.; Plante,-R.; Salen-Picard,-C.
AF: Cent. Oceanol. Marseille, Stn. Mar. Endoume, 13007 Marseille, France
CO: Conf. on Limnology and Oceanography, , 26-29 Jun 1989
SO: FLUXES-BETWEEN-TROPHIC-LEVELS-AND-THROUGH-THE-WATER-SEDIMENT-INTERFACE. Bonin,-D.J.;Golterman,-H.L.-eds. 1990 vol. 207 pp. 187-196
ST: HYDROBIOLOGIA vol. 207
LA: English
ER: M (Marine)
AB: Upward nutrient fluxes at the sediment-water interface were studied in a mussel farming zone (Carteau, Gulf of Fos, France) in order to estimate the impact of organic matter input from biodeposition. Nitrate, nitrite, ammonia, silicate, phosphate and oxygen were measured. Fluxes were estimated by means of polyacrylate benthic chambers placed at sites located under (UM) and outside (OM) the rope hanging structures. Transformation of biodeposited organic matter increases phosphate, silicate and ammonia fluxes. No variation in nitrite fluxes could be detected and only minor differences were observed in nitrate and the oxygen production/consumption equilibrium at the two stations. Phosphate and silicate fluxes, which were always higher at the UM than at the OM site, decreased from spring to winter. Ammonia fluxes were very high under mussel cultures in May and September and lower in November. The fact that ammonia flux was always higher at the UM than at the OM sites might be explained by degradation of mussel biodeposit, as well as by benthic macrafauna excretion. Discrepancies between fluxes of the nutrients studied at the UM and OM sites increased as organic particulate matter in the water column decreased. Variations of oxygen flux followed a different pattern, since they were correlated with presence and abundance of photosynthetic microphytes on the bottom and in the water. Bottom respiration exceeded production of oxygen only in May 1988 at the UM station. As it now stands, biodeposit input into the sediment under mussel ropes does not affect the ecosystem, although the flow of nutrients towards the water column is higher than in other areas (DBO).
AN: 3854905

                                                                    129 of 1521  
TI: In situ biochemical and bacterial variation of sediments enriched with mussel biodeposits
AU: Grenz,-C.; Hermin,-M.-N.; Baudinet,-D.; Daumas,-R.
AF: Cent. Oceanol. Marseille, Stn. Mar. Endoume, 13007 Marseille, France
CO: Conf. on Limnology and Oceanography, , 26-29 Jun 1989
SO: FLUXES-BETWEEN-TROPHIC-LEVELS-AND-THROUGH-THE-WATER-SEDIMENT-INTERFACE. Bonin,-D.J.;Golterman,-H.L.-eds. 1990 vol. 207 pp. 153-160
ST: HYDROBIOLOGIA vol. 207
LA: English
ER: M (Marine)
AB: In order to estimate the qualitative variation of sedimented mussel deposits, biochemical and microbial measurements were undertaken after a sediment enrichment with fresh faeces and pseudo-faeces collected in a mussel farming area (Carteau, Gulf of Fos). During two months, cores sampled were investigated at three stations: a first station enriched with mussel deposits, a second considered as a reference station without mussel deposits and occasionally a third corresponding to a continuously enriched sediment under a rope culture. Carbohydrate, organic carbon and nitrogen contents in the sediments gave evidence of a short term variation after sedimentation. Bacterial production increased rapidly at the enriched station and returned to its initial level 8 days later. At this station, exoglucosidasic activity of bacteria, low at the beginning, presented a maximum two weeks after enrichment whereas exoproteolytic activity, which was high in the biodeposits, decreased in the course of the first week. These exoenzymatic activities were significantly higher at the enriched station than at the reference stations. Carbohydrate measurements were in agreement with these results. Degradation rate of biodeposits is discussed on the basis of exoenzymatic activity, organic carbon, nitrogen and free amino acid content at the three stations (DBO).
AN: 3854901

                                                                    130 of 1521  
TI: Study of the Ria Formosa ecosystem: Benthic nutrient remineralization and tidal variability of nutrients in the water
AU: Falcao,-M.; Vale,-C.
AF: Inst. Nac. Invest. Pescas, Cent. Reg. Invest. Pesq., Av. 5 de Outubro, 8700 Olhao, Portugal
CO: Conf. on Limnology and Oceanography, , 26-29 Jun 1989
SO: FLUXES-BETWEEN-TROPHIC-LEVELS-AND-THROUGH-THE-WATER-SEDIMENT-INTERFACE. Bonin,-D.J.;Golterman,-H.L.-eds. 1990 vol. 207 pp. 137-146
ST: HYDROBIOLOGIA vol. 207
LA: English
ER: M (Marine)
AB: Exchange of nutrients across the sediment-water interfaces of Ria Formosa was studied in the laboratory. In the field, water samples were collected (i) fortnightly, at low and high tide over one year, and (ii) semi-diurnally, over three neap-spring tidal cycles in winter. Results from both laboratory experiments and field collection were quite variable. Higher liberation rates of silicates, phosphates and ammonium occurred in chambers whose bottom was formed by mixtures of mud and sand covered by vegetation with clams. The bottom took up nitrates from the overlying water. Nutrient variations in the lagoon water were controlled both seasonally and tidally. Higher concentrations of silicates were found at low tide independently of the season; phosphates in spring/summer at low tide; nitrates in winter/spring at high tide. Tidal flushing appears to be an important removal-mechanism in this lagoon. (DBO)
AN: 3854899

                                                                    131 of 1521  
TI: Decrease in allochthonous organic inputs in dark submarine caves, connection with lowering in benthic community richness
AU: Fichez,-R.
AF: Sch. Environ. Sci., Univ. East Anglia, NR4 7TJ Norwich, UK
CO: Conf. on Limnology and Oceanography, , 26-29 Jun 1989
SO: FLUXES-BETWEEN-TROPHIC-LEVELS-AND-THROUGH-THE-WATER-SEDIMENT-INTERFACE. Bonin,-D.J.;Golterman,-H.L.-eds. 1990 vol. 207 pp. 61-69
ST: HYDROBIOLOGIA vol. 207
LA: English
ER: M (Marine)
AB: Ten sediment trap arrays were deployed over two years for periods of 3 to 40 days in three different sampling points along a 50 m long Mediterranean submarine cave. Mean total particulate matter flux decreased strongly from the semi-dark area (3.3 g m super(-2)/d) to the dark area (0.8 and 0.6 g m super(-2)/d). Carbon represented 3.3% to 3.5% and nitrogen 0.34% to 0.38% of settling dry matter. The decrease in organic input from the entrance to the terminal part of the cave results in increasingly oligotrophic conditions with distance from the cave entrance. Horizontal resource limitation can be connected with a strong zonal decrease in fauna richness. Biomass declines both in hard substrate and soft bottom communities. Despite major differences, some similarities are noticed between oligotrophic conditions that may occur in the dark cave and those in around 1000 m depth ecosystems. Dark oligotrophic submarine caves can be considered to be good scale models for the study of some aspects of general trophic pathways. (DBO)
AN: 3854844

                                                                    132 of 1521  
TI: Contribution of the water-sediment interface to the transformation of biogenic substances: Application to nitrogen compounds
AU: Daumas,-R.
AF: CNRS, Microbiol. Mar., Fac. Sci. Luminy, Case 907, 13288 Marseille Cedex 9, France
CO: Conf. on Limnology and Oceanography, , 26-29 Jun 1989
SO: FLUXES-BETWEEN-TROPHIC-LEVELS-AND-THROUGH-THE-WATER-SEDIMENT-INTERFACE. Bonin,-D.J.;Golterman,-H.L.-eds. 1990 vol. 207 pp. 15-29
ST: HYDROBIOLOGIA vol. 207
LA: English
ER: M (Marine); F (Freshwater)
AB: Up to now the water-sediment interface (WSI) has not been considered by limnologists and oceanographers as a theoretical frontier between two phases, but as a variable layer comprising the overlying bottom water, the superficial sediment, and the bioturbed sediment. This heterogeneous benthic boundary layer forms a non-equilibrated assemblage of an aqueous phase, a mineral phase influencing the exchanges, and a dissolved gaseous phase regulating biological activity, detrital organic matter present as dissolved or adsorbed compounds and particles, and a living benthic community dominated by microorganisms. Biological activity and the equilibrium between these components are linked to depth, bottom currents, primary production and allochtonous inputs of organic matter. The settling rate of particulate matter in the water column, which depends on both the size and density of particles, is also an important factor. Settled organic matter is broken down mainly by heterotrophic microorganisms. In the first stage, dissolved or particulate matter is depolymerized by exoenzymes linked to the bacterial membrane. Other heterotrophic organisms, like flagellates and ciliates, contribute to the activity of bacterial populations or to a modification of the physical and chemical characteristics of organic matter like macrofauna. Bacterial activity in the WSI is one to two orders of magnitude higher than in overlying bottom water, depending on the density of the bacterial population, on the amount of available organic matter, and on the presence of predators grazing on bacteria and macrofauna and increasing oxygen and dissolved substrates. The WSI is now considered as a sink for particulate matter and biopolymers, and/or as a sink or source for organic monomers and NH sub(4) super(+) depending on their concentrations. As a result of its contribution to mineral and organic cycles, the WSI is a crossroad for exchanges between aqueous and sediment layer. During the last decade, intensive work has been performed in this field, but progress has been slow due to the heterogeneity of the layer and the adsorptive properties of the mineral fraction. (DBO)
AN: 3854839

                                                                    133 of 1521  
TI: Nutrient dynamics and pelagic food web interactions in oligotrophic and eutrophic environments: An overview
AU: Capblancq,-J.
AF: Lab. Hydrobiol., Univ. Toulouse III, 118 Route de Narbonne, 31062 Toulouse Cedex, France
CO: Conf. on Limnology and Oceanography, , 26-29 Jun 1989
SO: FLUXES-BETWEEN-TROPHIC-LEVELS-AND-THROUGH-THE-WATER-SEDIMENT-INTERFACE. Bonin,-D.J.;Golterman,-H.L.-eds. 1990 vol. 207 pp. 1-14
ST: HYDROBIOLOGIA vol. 207
LA: English
ER: F (Freshwater)
AB: The concept of limiting nutrients is a cornerstone of theories concerning the control of production, structure and dynamics of freshwater and marine plankton. The current dogma is that nitrogen is limiting in most marine environments while freshwater ecosystems are mostly phosphorus-limited, although evidence of phytoplankton limitation by either N or P has been found in both environments. However, the same considerations apply to the availability of phosphorus in freshwater as to nitrogen in oceans. In resource-limited environments the plankton dynamics depend mostly on the internal mechanisms which act to recycle the limiting nutrient many times over within the surface waters. As the overall productivity increases, this dependence on nutrient regeneration decreases. The relationship between the stock of limiting nutrient, rates of supply and plankton dynamics must therefore be seen in the light of the processes operating within the entire food chain over quite different time scales. There is strong evidence that process-rates are mostly size-dependent and that food web interactions at the microbial level (picophytoplankton, bacteria, microheterotrophs) strongly affect the production of carbon and the regeneration of nutrients in the pelagic zone. (DBO)
AN: 3854838

                                                                    134 of 1521  
TI: Seasonal cycling of putrescine and amino acids in relation to biological production in a stratified coastal salt pond
AU: Lee,-C.; Joergensen,-N.O.G.
AF: Mar. Sci. Res. Cent., SUNY Stony Brook, Stony Brook, NY 11794-5000, USA
SO: BIOGEOCHEMISTRY 1995 vol. 29, no. 2, pp. 131-157
LA: English
ER: B (Brackish)
AB: Seasonal cycles of concentrations and microbial uptake of dissolved free amino acids and the polyamine, putrescine, were followed during summer stratification of a coastal salt pond. Stratification began in May and was clearly seen in profiles of temperature, salinity, pH and alkalinity. Primary production exhibited a mid-August maximum and the O sub(2)-H sub(2)S interface shoaled at that time. POC and phytopigments roughly followed the pattern of primary production. Cycling of putresince, like the amino acids, was strongly influenced by primary production and microbial decomposition. Putrescine concentration profiles appeared to follow the pattern of primary production more closely, while amino acids appeared to follow the pattern of microbial production. The absence of production of putrescine during the decomposition of dissolved ornithine and the correlation of putrescine concentration with primary production suggest a direct source from algae in the water column. Microbial uptake of amino acids and putrescine together accounted for 60-90% of the bacterial C production measured in oxic waters and almost 300% of that measured in the anoxic bottom layer. Since other organic carbon and nitrogen compounds are also being taken up, these data suggest that tracer uptake methods as we used them may overestimate the true microbial uptake rates, or release of other organic compounds by microbes occurs at the same time. Further work on carbon and nitrogen budgets is needed to resolve the apparent imbalance between organic C and N incorporation and bacterial production.
AN: 3852984

                                                                    135 of 1521  
TI: Metabolism of volatile sulfur compounds in Lake Ciso
AU: Simo,-R.; De-Wit,-R.; Villanueva,-J.; Grimalt,-J.
CO: 25. Congress in Barcelona, Barcelona (Spain), 21-27 Aug 1992
SO: CONGRESS-IN-BARCELONA-1992.-PROCEEDINGS. Sladeckova,-A.-ed. STUTTGART-FRG SCHWEIZERBART'-SCHE-VERLAGSBUCHHANDLUNG 1994 vol. 25, no. 2 pp. 743-746
ST: VERH.-INT.-VER.-THEOR.-ANGEW.-LIMNOL.-PROC.-INT.-ASSOC.-THEOR.-APPL.-LIMNOL.-TRAV.-ASSOC.-INT.-LIMNOL.-THEOR.-APPL. vol. 25, no. 2
LA: English
ER: F (Freshwater)
AN: 3851307

                                                                    136 of 1521  
TI: Improved construction, parametrization and interpretation of steady-state ecosystem models
AU: Pauly,-D.; Soriano-Bartz,-M.L.; Palomares,-M.L.D.
AF: ICLARM, MC P.O.B. 2631, Makati City 0718, Philippines
CA: International Cent. for Living Aquatic Resources Management, Manila (Philippines)
CO: ICES Theme Session on Trophic Models of Aquatic Ecosystems, Copenhagen (Denmark), Oct 1990
SO: TROPHIC-MODELS-OF-AQUATIC-ECOSYSTEMS. Christensen,-V.;Pauly,-D.-eds. MANILA-PHILIPPINES ICLARM 1993 no. 26 pp. 1-13
ST: ICLARM-CONF.-PROC. no. 26
LA: English
ER: M (Marine); F (Freshwater)
AB: An improved version of J.J. Polovina's ECOPATH program for the construction of steady-state multispecies ecosystem models from fisheries data is presented. This new version called "ECOPATH II", differs from the original, aside from being more user-friendly, in a number of important features, among othes: (1) use of a "generalized inverse" matrix routine allowing the system of linear equations used to estimate model parameters to be over- or slightly underdetermined; (2) estimation of (almost) any set of unknowns and not only of biomasses; (3) explicit consideration of respiratory, egestive and excretory losses (with defaults provided for inputs) and of the detritus pathways; (4) estimation of numerous derived quantities on species group or whole-system basis, such as gross and net efficiencies, trophic levels, food electivity, pathways and cycles involving any group and "ascendency" sensu R.E. Ulanowizc. The preliminary version of an empirical multiple regression model for the estimation from easy to estimate parameters of relative food consumption by fish populations is presented; this model provides reasonable values of the input into ecosystem models that were to date most difficult to estimate. An application to the coral reef ecosystem of French Frigate Shoals (Hawaii) is presented, along with some suggestions as to how this methodology could be applied to Kuwait waters.
AN: 3851122

                                                                    137 of 1521  
TI: Processes controlling chemical distributions in the Firth of Clyde (Scotland)
AU: Muller,-F.L.L.; Balls,-P.W.; Tranter,-M.
AF: Dept. of Oceanography, The University of Southampton, Southampton Oceanography Centre, Southampton SO14 3ZH, UK
SO: OCEANOL.-ACTA 1995 vol. 18, no. 5, pp. 493-510
LA: English
ER: M (Marine)
AB: A total of 28 chemical variables were measured on water samples taken on an approximately longitudinal section of the Firth of Clyde in August 1989, November 1989, March 1990, July 1990 and March 1991. The data were integrated in a study of the overall processes acting on these variables. The sampling section crossed two mixing zoness i.e. the Clyde Estuary Plume (30 < S < 32) and the Clyde Sea (32 < S < 34), with mixing times of 4-25 days and 60-150 days respectively. The interpretation of the distributional data was complicated in July 1990 by the penetration of an "older" water mass originating from one of the five sealochs bordering the Firth of Clyde. Heterogeneous reactions within the Clyde Estuary Plume generally modified the export fluxes of dissolved trace metals to the Clyde Sea in the order: Fe, Pb > Mn, Co > Zn, Cd, Cu, Ni. In the deep layers of the sealochs, dissolved Pb was scavenged by newly formed hydrous Mn oxides following Mn(II) diffusion from the underlying sediments. Resuspension of bottom sediments was a permanent feature of the inner Firth, although it did not significantly affect the solid-solution partitioning of trace metals. Organic matter decomposition promoted a tight inverse relationship between O sub(2)-% and pCO sub(2) in the deep layers (especially in November 1989 and July 1990), as did photosynthetic activity in the surface layers in July 1990. The latter process also manifested itself in the surface depletion of dissolved PO sub(4), NO sub(3). Si, ECO sub(2), Fe, Zn and Cd. A ratio P:N:Si:C of 1:9:6:68 was obtained in relation to the uptake of these elements by phytoplankton. Gas exchange at the air-sea interface - coupled with turbulent vertical mixing - was the main process controlling O sub(2) and CO sub(2) concentrations in the surface layers in March 1990 and 1991. At wind speeds below 8 m s super(-1), i.e. in the absence of bubble-induced gas exchange. O sub(2) reached saturation in the outer Firth but pCO2 remained above its atmospheric equilibrium value of 350 ppm. At wind speeds above 12 m s super(-1) (March 1990) pCO sub(2) was close to 350 ppm while O sub(2) became supersaturated. Water composition should be examined not only in relation to that anticipated trom instantaneous mixing between end members but also in relation to the transit times of water masses. An application of this approach suggests that the inner Firth, situated at the triple junction Clyde Estuary-Sealoch System outer Firth, is the area where the rates of heterogeneous reactions are fastest.
AN: 3851058

                                                                    138 of 1521  
TI: Effects of increased solar ultraviolet radiation on biogeochemical cycles
AU: Zepp,-R.G.; Callaghan,-T.V.; Erickson,-D.J.
AF: U.S. EPA, Environ. Res. Lab., 960 College Stn. Rd., Athens, GA 30605-2720, USA
SO: AMBIO 1995 vol. 24, no. 3, pp. 181-187
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: Increases in solar UV radiation could affect terrestrial and aquatic biogeochemical cycles thus altering both sources and sinks of greenhouse and chemically-important trace gases (e.g., carbon dioxide (CO sub(2)), carbon monoxide (CO), carbonyl sulfide (COS)). In terrestrial ecosystems, increased UV-B could modify both the production and decomposition of plant matter with concomitant changes in the uptake and release of atmospherically-important trace gases. Decomposition processes can be accelerated when UV-B photodegrades surface litter, or retarded when the dominant effect involves changes in the chemical composition of living tissues that reduce the biodegradability of buried litter. These changes in decomposition can affect microbial production of carbon dioxide and other trace gases, and also may affect the availability of nutrients essential for plant growth. Primary production can be reduced by enhanced UV-B, but the effect is variable between species and even cultivars of some crops. Likewise, the effects of enhanced UV-B on photoproduction of CO from plant matter is species dependent and occurs more efficiently from dead than living matter. Aquatic ecosystem studies in several different locations have shown that reductions in current levels of solar UV-B result in enhanced primary production, and Antarctic experiments under the ozone hole demonstrated that primary production is inhibited by enhanced UV-B. In addition to its effects on primary production, solar UV radiation can reduce bacterioplankton growth in the upper ocean with potentially important effects on marine biogeochemical cycles. Decomposition processes can be retarded when bacterial activity is suppressed by enhanced UV-B radiation or stimulated when solar UV radiation photodegrades aquatic dissolved organic matter (DOM). Photodegradation of DOM results in loss of UV absorption and formation of dissolved inorganic carbon (DIC), CO, and organic substrates that are readily mineralized or taken up by aquatic microorganisms. The marine sulfur cycle may be affected by UV-B radiation resulting in possible changes in the sea-to-air emissions of COS and dimethylsulfide (DMS), two gases that are degraded to sulfate aerosols in the stratosphere and troposphere, respectively.
AN: 3848713

                                                                    139 of 1521  
TI: Regulation of atmospheric O sub(2): Feedback in the microbial feedbag
AU: Kump,-L.R.; Mackenzie,-F.T.
AF: Dep. Oceanogr., Univ. Hawaii, Honolulu, HI 96822, USA
SO: SCIENCE-WASH. 1996 vol. 271, no. 5248, pp. 459-460
LA: English
ER: M (Marine)
AB: What controls the oxygen content of the atmosphere? This fundamental question has been asked innumerable times in the last several decades without a fully satisfactory answer. From conceptual models (1), increasingly complex numerical models (2) have been created. Given the few-million-year residence time of O sub(2) in the atmosphere, slight imbalances in the biogeochemical cycle of oxygen could have led, over geological time intervals, to large fluctuations in concentration. Catastrophic phenomena sensitive to extremes in oxygen levels, such as global wildfire or the extinction of large animals, would have occurred if O sub(2) concentrations had exceeded 30% (4) or had fallen to less than 10% or so. However, there is no geological evidence of prolonged global wildfires. It appears that there are feedback mechanisms in the natural cycle of O sub(2) operating on land and in the ocean that prevent such large fluctuations from occurring. Van Cappellen and Ingall argue that the important feedback mechanism resides in the ocean and involves the dependence of nutrient recycling rates on the oxygen content of the deep sea. Nitrogen (N) and phosphorus (P) are considered most important. The growth of marine algae involves the incorporation of N and P into living tissue. Ingestion by animals leads to the packaging of this material into relatively dense fecal pellets. Both N and P are preferentially regenerated by microbial degradation processes in the water column and are transported by upwelling waters moving to the surface, where they become available for biological uptake once again.
AN: 3847952

                                                                    140 of 1521  
TI: Seasonal cycling of Fe in saltmarsh sediments
AU: Kostka,-J.E.; Luther,-G.W.,III
AF: Cent. Great Lakes Stud., Univ. Wisconsin-Milwaukee, 600 E. Greenfield Ave., Milwaukee, WI 53204, USA
SO: BIOGEOCHEMISTRY 1995 vol. 29, no. 2, pp. 159-181
LA: English
ER: M (Marine); B (Brackish)
AB: This study combines an analysis of porewater chemistry with new, solid phase wet chemical extractions to examine the seasonal cycling of Fe in vegetated and unvegetated (cyanobacterial mat) saltmarsh sediments. Saltmarsh sediments are shown to contain more solid phase reactive Fe than other marine sediments studied so far. From the partitioning and speciation of solid Fe, and solid/soluble reduced S analysis in 10 sediment cores, we have observed that a majority of solid Fe in these sediments is cycled rapidly and completely between oxidized reactive Fe and reduced Fe as pyrite. Vegetated porewaters showed a lower pH and much higher Fe(II) concentrations on average than unvegetated porewaters in the top 10 cm, whereas sulfate, alkalinity, and sulfide concentrations were similar in the two environments. The amorphous Fe(III) oxide fraction showed a high negative correlation to solid and soluble reduced S (r super(2) = -0.86 and -0.71, respectively) in surface vegetated sediments whereas the crystalline Fe(III) oxide fraction showed a high negative correlation (r super(2) = -0.96) to sulfide only at depth. Though reactive Fe was observed in unvegetated sediments, no seasonal trend was apparent and the speciation of solid Fe revealed that most of it was reduced. Solid phase and porewater chemistry support the dominant role of the biota (Spartina alterniflora and bacteria) in controlling the reactivity of Fe and suggest that the current definition of solid phase, reactive Fe should be expanded to include crystalline Fe(III) minerals which are available for pyrite formation in saltmarsh sediments. In support of previous saltmarsh studies, we present evidence that the redox cycle of solid Fe is controlled by sulfate reduction and sediment oxidation which respond to both annual cycles (light, temperature) and to short-term, episodic effects such as weather and tides.
AN: 3847504

                                                                    141 of 1521  
TI: Biogeochemical controls on aluminum chemistry in the 0 horizon of a red spruce (Picea rubens Sarg.) stand in Central Maine, USA
AU: Rustad,-L.E.; Cronan,-C.S.
AF: Dep. Appl. Ecol. Environ. Sci., Univ. Maine, Orono, ME 04469, USA
SO: BIOGEOCHEMISTRY 1995 vol. 29, no. 2, pp. 107-129
LA: English
ER: F (Freshwater)
AB: This study examined the biotic and abiotic processes controlling solution chemistry and cycling of aluminum (Al) in the organic horizons of a northern coniferous forest ecosystem. A mass balance budget indicated that aboveground inputs of Al to the O horizon averaged 0.9 kg ha super(-1) yr super(-1), with major inputs accounted for by littefall (69%), followed by precipitation (21%), and net canopy throughfall plus stemflow (10%). Estimated leaching losses of Al from the O horizon averaged 2.1 kg Al ha super(-1) yr super(-1). We hypothesize that the difference between measured Al inputs and outputs can be accounted for by Al release from weathering of soil minerals admixed into the O horizon. Variations in O horizon solution Al chemistry were influenced by a number of factors, including pH, Al equilibria with different solid-phase organic exchange sites, and Al complexation with humic ligands in soil solution.
AN: 3847495

                                                                    142 of 1521  
TI: Alkalinity changes in the Sargasso Sea: Geochemical evidence of calcification?
AU: Bates,-N.R.; Michaels,-A.F.; Knap,-A.H.
AF: Bermuda Biological Station For Research Inc., 17 Biological Station Lane, Ferry Reach, GE01, Bermuda
SO: MAR.-CHEM. 1996 vol. 51, no. 4, pp. 347-358
LA: English
AB: Strong seasonal patterns in upper ocean total carbon dioxide (TCO2), alkalinity (TA) and calculated pCO2 were observed in a time series of water column measurements collected at the US Joint Global Ocean Flux Study (JGOFS) BATS site (31 degree 50'N, 64 degree 10'W) in the Sargasso Sea. TA distribution was a conservative function of salinity. However, in February 1992, a non-conservative decrease in TA was observed, with maximumdepletion of 25-30  mu moles kg-1 occuring in the surface layer and at the depth of the chlorophyll maximum ( similar to 80-100 m). Mixed-layer TCO2 also decreased, while surface pCO2 increased by 25-30  mu atm. We suggest these changes in carbon dioxide species resulted from open-ocean calcification by carbonate-secreting organisms rather than physical processes. Coccolithophore calcification is the most likely cause of this event although calcification by foraminifera or pteropods cannot be ruledout. Due to the transient increase in surface pCO2, the net annual transfer of CO2 into the ocean at BATS was reduced. These observations demonstrate the potential importance of open-ocean calcification and biological community structure in the biogeochemical cycling of carbon.
AN: 3846854

                                                                    143 of 1521  
TI: Phosphine from harbor surface sediments
AU: Gassmann,-G.; Schorn,-F.
AF: Biol. Anstalt Helgoland, W-2000 Hamburg, FRG
SO: NATURWISSENSCHAFTEN 1993 vol. 80, no. 2, pp. 78-80
LA: English
ER: M (Marine)
AB: Biogenic phosphine, the volatile constituent of the global biogeochemical phosphorus cycle, was found over sewage plant sludges in 1988. In earlier reports phosphine was found in soil, Black Sea sediments and biological iron corrosion processes. These findings contradict the idea that phosphine could not, as a matter of principle, be formed biologically in nature. This report shows the presence of phosphine in surface sediments of the Hamburg Harbor (Germany).
AN: 3843228

                                                                    144 of 1521  
TI: The dynamics of mire formation in relation to carbon accumulation and climate change.
OT: Soistumisdynamiikka, soiden hiilitase ja ilmaston muutos
AU: Korphola,-A.
AF: Dep. Geogr., Lab. Phys. Geogr., P.O. Box 9 (Siltavuorenpenger 20 A), FIN-00014 Univ. Helsinki, Finland
SO: TERRA 1994 vol. 106, no. 3, pp. 209-215
LA: Finnish
ER: F (Freshwater)
AB: Peatlands in their natural state are net accumulators of organic carbon and thus an important component of the global carbon cycle. Knowledge of general ecosystem dynamics, climatic controls, and rate of long-term peat accumulation are necessary for understanding and modelling the carbon cycle in mire environments. Here the role of different environmental factors in the process of carbon accumulation in peatland ecosystems is discussed. Examination of the formation and dynamics of an entire mire ecosystem, and the role of carbon in it is shown to be essential, instead of just making single-core analyses. Along vertical mire growth, the lateral expansion of mires in different time periods, for example, should be considered when calculating the long-term rates of carbon accumulation.
AN: 3843190

                                                                    145 of 1521  
TI: Spatial and temporal variation of physicochemical parameters in a shallow reservoir seasonally covered by Pistia stratiotes L. in Uruguay
AU: Mazzeo,-N.; Gorga,-J.; Crosa,-D.; Ferrando,-J.; Pintos,-W.
AF: Univ. Concepcion, Dep. Botanica, Casilla 2407. Ap. 10, Concepcion-Chile
SO: J.-FRESHWAT.-ECOL. 1995 vol. 10, no. 2, pp. 141-149
LA: English
ER: F (Freshwater)
AB: Spatial and temporal variation of physicochemical parameters of Cisne Reservoir were studied. A clear spatial pattern was observed between the tributaries and the reservoir, with the highest values of conductivity, alkalinity, pH, silicate and phosphate (SRP) in the tributaries. The incorporation of bicarbonate, silicate, SRP and other nutrients by littoral vegetation and the decomposition process of macrophytes could explain the spatial pattern and the temporal variation of the nutrients. The freshwater marsh situated between the tributaries and reservoir acts as sink for silicate and SRP. The temporal and spatial pattern of total phosphorus was correlated with suspended matter values. The low nitrogen concentration and the ratio of the inorganic nitrogen to SRP suggest that nitrogen is a limiting factor for primary production.
AN: 3843106

                                                                    146 of 1521  
TI: Bioavailable amino acids in sediments: A biomimetic, kinetics-based approach
AU: Mayer,-L.M.; Schick,-L.L.; Sawyer,-T.; Plante,-C.J.
AF: Dep. Oceanogr., Darling Mar. Cent., Univ. Maine, Walpole 04573 ME, USA
SO: LIMNOL.-OCEANOGR. 1995 vol. 40, no. 3, pp. 511-520
LA: English
ER: M (Marine)
AB: We developed a biomimetic approach, based on direct incubation with proteolytic enzymes, to measure bioavailable amino acids in sediments. The kinetics of release of monomers and oligopeptides, which are amenable to absorption by cells, is measured as either individual or total amino acids. Microbial proteases incubated with fresh sediments yield amino acids at a similar rate as gut juices from a deposit-feeding holothuroid. Amino acid release from fresh sediment was dominated by a slow hydrolysis step from a refractory substrate, which can be described with a first-order rate law. Typical rate constants for release were in the range 0.15-0.52/h, consistent with gut residence times of deposit feeders. The bioavailable pool of peptides had a composition resembling that of average biological tissue, but comparisons with tissue composition suggested dietary deficiency of some essential amino acids. The early stages of release exhibited significant contributions from osmolytes (e.g. glutamic acid and taurine), while a larger, more slowly released pool was anomalously low in methionine, suggesting a contribution from microbial coat proteins. Freezing the sediment led to greater yields of amino acids, which reduced the simulation of a deposit feeder's gut but indicated a larger pool of potentially bioavailable substrate protected by some kind of matrix. This larger pool of peptide substrate was usually dominated by higher molecular weight polypeptides as measured by the Coomassie Blue method.
AN: 3843002

                                                                    147 of 1521  
TI: Carbon and nitrogen cycling in intertidal sediments near Doel, Scheldt Estuary
AU: Middelburg,-J.J.; Klaver,-G.; Nieuwenhuize,-J.; Vlug,-T.
AF: Netherlands Inst. Ecol., Cent. Estuar. Coast. Ecol., Vierst. 28, NL-4401 EA Yerseke, Netherlands
SO: HYDROBIOLOGIA 1995 vol. 311, no. 1-3, pp. 57-69
NT: Special Issue: Major Biological Processes in European Tidal Estuaries.
LA: English
ER: B (Brackish)
AB: Carbon and nitrogen cycling in intertidal mud flat sediments in the Scheldt Estuary was studied using measurements of carbon dioxide, methane and nitrous oxide emission rates and pore-water profiles of  capital sigma CO sub(2), ammonium and nitrate. A comparison between chamber measured carbon dioxide fluxes and those based on  capital sigma CO sub(2) pore-water gradients using Fick's First law indicates that apparent diffusion coefficients are 2 to 28 times higher than bulk sediment diffusion coefficients based on molecular diffusion. Seasonal changes in gaseous carbon fluxes or  capital sigma CO sub(2) pore water concentrations cannot be used directly, or in a simple way, to determine seasonal rates of mineralization, because of marked seasonal changes in pore-water storage and exchange parameters. The annual amount of carbon delivered to the sediment is 42 mol/m super(2), of which about 42% becomes buried, the remaining being emitted as methane (7%) or carbon dioxide (50%). Each year about 2.6 mol N/m super(2) of particulate nitrogen reaches the sediment; 1.1 mol/m super(2) is buried and 1.6 mol/m super(2) is mineralized to ammonium. Only 0.42 mol/m super(2)/yr of the ammonium produced escapes from the sediments, the remaining being first nitrified (1.2 mol/m super(2)/yr) and then denitrified (1.7 mol/m super(2)/yr). Simple calculations indicate that intertidal sediment may account for about 14% and 30% of the total estuarine retention of nitrogen and carbon, respectively.
AN: 3842997

                                                                    148 of 1521  
TI: Seasonal nitrogen dynamics in Chesapeake Bay: A network approach
AU: Baird,-D.; Ulanowicz,-R.E.; Boynton,-W.R.
AF: Chesapeake Biol. Lab., Univ. Maryland Syst., P.O. Box 38, Solomons, MD 20688, USA
SO: ESTUAR.-COAST.-SHELF-SCI. 1995 vol. 41, no. 2, pp. 137-162
LA: English
ER: M (Marine); B (Brackish)
AB: The input, exchange, recycling and export of nitrogen in the mesohaline region of Chesapeake Bay have been assessed in this study. The seasonal rate of exchanges between the 36 most important components and the roles of these in the recycling process of nitrogen in the ecosystem have been quantified. Results show that the demand for nitrogen by phytoplankton, bacteria and benthic algae is the highest in summer (418 mg N m super(-2) day super(-1)) and lowest in winter (90 mg N m super(-2) day super(-1)). The supply of dissolved nitrogen however, is highest in spring (289 mg N m super(-2) day super(-1)), with the lowest exogenous supply of 'new' nitrogen during summer (53 mg N m super(-2) day super(-1)). The seasonal variation in supply and demand suggest that spring nitrogen loadings continue to sustain the high nitrogen demand in summer when this nutrient appears to be in short supply. Results also show that the efflux of nitrogen from the sediments to the overlying water dominates the recycling process and is abetted by water column regeneration, mostly by the smaller biota (<200  mu m). Mesozooplankton, suspension-feeders and fish as a whole contribute relatively little on a seasonal or annual basis to the total amount of regenerated nitrogen. Network analysis of the seasonal dynamics of nitrogen indicates that the pathways over which nitrogen is recycled are considerably more complicated and numerous than those which retain carbon in the system. The Finn Cycling Index (FCI) reveals that the rate of nitrogen recycling during summer approximates 70% of the total system activity compared with the 34-46% range during other seasons. In contrast, the FCI for carbon was almost a constant 20% over all seasons. As regards the pelagic microbiota, which functionated more as a shunt to convey excess carbon out of the system, analysis indicates they comprise very significant pathways for the retention of nitrogen in the system.
AN: 3842411

                                                                    149 of 1521  
TI: Diel changes of nitrogen species in surface and overlying water of an estuarine lake in summer: Evidence for benthic-pelagic coupling
AU: Vanamuro,-M.; Koike,-I.
AF: Mar. Geol. Dep., Higashi 1-1-3, Isukuba, Ibakari, Japan
SO: LIMNOL.-OCEANOGR. 1994 vol. 39, no. 7, pp. 1726-1733
LA: English
ER: B (Brackish)
AB: Diel changes in the concentration of nitrogen species [ammonium, nitrite, nitrate, dissolved organic N, and particulate organic N (PON)] and some biological parameters were monitored in the water column of Lake Shinji, a shallow estuarine lake in Japan. The sediment of the lake was densely inhabited by the filter-feeding bivalve Corbicula japonica. An overlying water sampler showed that PON at the sediment-water interface (less than a few millimeters above the sediment) was not depleted; nevertheless, active uptake of PON by C. japonica (10.4 mg-atoms N/m super(2)/d) is reported. Dissolved and particulate N species showed vertically uniform profiles at night, which we attributed to nocturnal water mixing associated with cooling surface water. These observations suggest benthic-pelagic coupling between filter-feeding bivalves and phytoplankton which enables the removal of nitrogen from the eutrophic lake through fisheries yield of bivalves.
AN: 3842246

                                                                    150 of 1521  
TI: Empirical models of phosphorus and nitrogen excretion rates by zooplankton
AU: Wen,-Yuan-Hua; Peters,-R.H.
AF: Dep. Biol., McGill Univ., 1205 Ave. Dr. Penfiled, Montreal, PQ H3A 1B1, Canada
SO: LIMNOL.-OCEANOGR. 1994 vol. 39, no. 7, pp. 1669-1679
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: Although rates of P and N excretion by zooplankton have important implications for nutrient cycling in aquatic ecosystems, the literature offers few quantitative general models of these processes. We used data collected from published studies to construct potentially predictive models of P and N excretion rates by zooplankton from freshwater and marine habitats. Excretion rates of P and N are strongly correlated (r super(2) = 0.88) and consequently each predicts the other best. Respiration rate is also highly significantly correlated with P and N excretion rates and is the second best predictor. Although body size explained relatively less overall variability, the inclusion of temperature, container volume, and experimental duration as independent variables in multiple regressions substantially improved the predictive power of models based on body size. The models can be corrected for taxonomic biases in zooplankton, but these biases were usually small. These models could provide both a basis for further empirical analysis of the determinants of zooplankton nutrient excretion and a means of predicting the fate of nutrients in aquatic ecosystems.
AN: 3842242

                                                                    151 of 1521  
TI: Oxygen regulation of nitrification and denitrification in sediments
AU: Rysgaard,-S.; Risgaard-Petersen,-N.; Sloth,-N.P.; Jensen,-K.; Nielsen,-L.P.
AF: Natl. Environ. Res. Inst., Vejlsovej 25, DK-8600 Silkeborg, Denmark
SO: LIMNOL.-OCEANOGR. 1994 vol. 39, no. 7, pp. 1643-1652
LA: English
ER: F (Freshwater)
AB: Oxygen regulation of nitrification and denitrification in sediments was investigated with  super(15)N-isotope techniques. Sediment cores from Vilhelmsborg Lake, Denmark were incubated in a continuous flowthrough system in which the O sub(2) concentration was varied in the overlying water while the NO sub(3) super(-) concentration was kept constant. Nitrification was stimulated with increasing O sub(2) concentrations in the overlying water from 0 to 100% of atmospheric saturation, whereas only a slight stimulation was observed above 100%. At O sub(2) concentrations below 100% of atmospheric saturation, NO sub(3) super(-) from the overlying water was the most important source of N for denitrification, whereas above 100% of atmospheric saturation, NO sub(3) super(-) produced by nitrification was the main source of N for denitrification. The converse effects of the O sub(2) levels on the source of NO sub(3) super(-) can be explained by applying a simple one-dimensional model: O sub(2) in the overlying water controls the diffusional distance of NO sub(3) super(-) to the anoxic zone of denitrification and consequently the location of NO sub(3) super(-) vertically in the sediment as well as the magnitude of the nitrification activity. Our results suggest that in aquatic environments containing low NO sub(3) super(-) concentrations in the overlying water (such as coastal waters), higher O sub(2) conditions will stimulate denitrification, while the opposite will occur in systems containing high NO sub(3) super(-) concentrations (such as eutrophic lakes and streams).
AN: 3842230

                                                                    152 of 1521  
TI: Antarctic bottom water formation and the global cadmium to phosphorus relationship
AU: Frew,-R.D.
AF: Sch. Environ. Sci., Univ. East Anglia, Norwich, UK
SO: GEOPHYS.-RES.-LETT. 1995 vol. 22, no. 17, pp. 2349-2352
LA: English
ER: M (Marine)
AN: 3841078

                                                                    153 of 1521  
TI: Modelling of the end products of the chemical decomposition of DMS in the marine boundary layer
AU: Hertel,-O.; Christensen,-J.; Hov,-O.
AF: Natl. Environ. Res. Inst., Dep. Emissions and Air Pollution, Frederiksborgvej 399, DK-4000 Roskilde, Denmark
SO: ATMOS.-ENVIRON. 1994 vol. 28, no. 15, pp. 2431-2449
LA: English
ER: M (Marine)
AB: A one-dimensional Lagrangian trajectory model (1DIM) with chemistry which includes a detailed description of the marine biogenic sulphur compounds is used to investigate the branching of the end products of the decomposition of DMS (methane sulphonic acid (MSA) and sulphate aerosols). Model runs for Brittany, France are compared with measurements form the OCEANO-NO sub(x) campaign in June 1989. The parameterization of the biogenic sulphur emissions is uncertain, but the modelled concentrations are in the right range and fit the observed concentrations fairly well. DMS is, however, often out of phase in time with the observed concentrations. This is probably due to a coastal effect linked to the shifting tide, which influences the DMS emissions. The observed ratio of MSA to SO sub(4) super(2-) is reproduced well. However, methane sulphinic acid (MSEA) concentrations comparable to and some times even higher than MSA are computed.
AN: 3838396

                                                                    154 of 1521  
TI: Growth characteristics of marine phytoplankton determined by cell cycle proteins: The cell cycle of Ethmodiscus rex (Bacillariophyceae) in the southwestern North Atlantic Ocean and Caribbean Sea
AU: Lin,-Senjie; Carpenter,-E.J.
AF: Mar. Sci. Res. Cent., SUNY, Stony Brook, NY 11794-5000, USA
SO: J.-PHYCOL. 1995 vol. 31, no. 5, pp. 778-785
LA: English
ER: M (Marine)
AB: Ethmodiscus spp. is an important contributor to oceanic tropical-ooze sediments and thus might be an important transport vehicle of carbon from the ocean surface to sediments. The knowledge of its cell cycle and growth rate, which is still lacking, is necessary to evaluate the importance of Ethmodiscus in nutrient cycling and to solve the discrepancy between its high sedimentary abundance and rarity in the plankton. We used immunofluorescence of a cell cycle protein, proliferating cell nuclear antigen (PCNA), and DNA-specific staining to study the progression of the cell cycle and roughly estimate the growth rate for E. rex (Rattray) Wiseman and Hendey in the southwestern North Atlantic Ocean and Caribbean Sea in June 1994 and January 1995. During the cell division cycle, the chloroplasts appeared to synthesize DNA before the nucleus (S phase). Following the S phase, the nucleus moved from one end of the cell toward the center underneath the midline of the girdle band (G2 phase) where it divided (M phase). During a very brief period, the parent cell split and moved apart from the girdle midline, and two new valves were produced (late M phase). The two daughter nuclei apparently remained attached at the joint of the two newly produced valves, where they appeared to be responsible for coordinating the symmetrical formation of the new valves. The morphologically complete daughter cells remained joined for a short period of time before separating into solitary cells whose nucleus was located at one end of the cell. Derived from the phase fraction curves, the duration of the cell cycle phases decreased in the order from G1, S, G2, to M. A conservative estimate of the growth rate in the study area obtained by using PCNA immunostaining was 0.39-0.46/d in June and 0.15/d in January. The validity and implication of the growth rate estimates are discussed.
AN: 3838286

                                                                    155 of 1521  
TI: Diagenetic evolution of the DOP facies from the Atlantis 2 Deep (Red Sea): Evidence of early hydrothermal activity
AU: Anschutz,-P.; Blanc,-G.
AF: Cent. Geochem. de la surface, UPR CNRS 6251, Inst. Geol., Univ. Louis Pasteur, 1 rue Blessig, 67084 Strasbourg Cedex, France
SO: OCEANOL.-ACTA 1995 vol. 18, no. 1, pp. 105-112
LA: French
ER: M (Marine)
AB: The 23,000 year old sediments of the Atlantis II Deep rest on a basaltic substratum and are overlaid by a dense and hot brine pool. The facies of the lower sequence of the West basin consists essentially of bioclastic and detrital particles (DOP facies). The primary calcite and aragonite of planktonic tests of the DOP facies have been transformed into Ca-, Mg-, Mn-, and Fe-carbonate solid solutions. Pyrite amounts to about 1-2% (wt) at the bottom of the sedimentary series, and as much as 20% (wt) in the upper part of the sequence. These high iron - and manganese - bearing minerals are the product of early diagenetic processes in an environment favourable to bacterial activity, to which biogenic and detrital particles, organic matter, and iron and manganese oxides were supplied. The high proportion of pyrite and secondary carbonates indicates that the environment of the W basin was different from the Red Sea pelagic environment during the deposition of the DOP facies, which take place between 23,000 and 11,000 years B.P. The  super(87)Sr/ super(86)Sr ratios, approaching 0.708, and the conservation of siliceous tests indicate the occurrence of an initial brine pool in the Atlantis II Deep. The Deep was therefore hydrothermally active prior to 11,000 years B.P., i.e. before the deposition of the purely metalliferous facies that overlie the DOP facies.
AN: 3838116

                                                                    156 of 1521  
TI: Phosphatogenesis in Polynesian atolls: Cyanobacterial mats-phosphorite filiation.
OT: Phosphatogenese en atolls polynesiens: La filiation mattes cyanobacteriennes-phosphorites
AU: Jehl,-C.; Rougerie,-F.
AF: ORSTOM, Lab. Halieutique-Ecosystemes Aquatiques, 911 Ave. Agropolis, BP 5045, 34032 Montpellier Cedex 1, France
SO: OCEANOL.-ACTA 1995 vol. 18, no. 1, pp. 79-93
LA: French
ER: M (Marine)
AB: Brackish ponds and lagoons located on Polynesian atolls are frequently colonized by thick cyanobacterial mats. The accumulated organic material (OM) is preserved due to prevailing anoxia. The high productivity of these microbial mats is controlled by high nutrient contents in the interstitial waters of the underlying limestone, in accordance with the geothermal endo-upwelling process (Rougerie and Wauthy, 1986, 1993). Observations and micro-analysis carried out on insular phosphate samples, and a comparative study of hydrocarbons extracted from kopara and phosphate, indicate a genetic link between the diagenetic evolution of the trapped OM and the apatite precipitation as follows: growth of thick microbial mats in brackish ponds and closed lagoons, and anoxic preservation of OM; oxydative degradation of these OM, liberation of PO sub(4) super(3-) ions to apatite saturation; primary apatite precipitation and phosphatization of the detrital carbonates through substitution of CO sub(3) by PO sub(4); polyphasic enrichment of the phosphate deposit induced by eustatic changes, through primary apatite dissolution and secondary apatite precipitation. This model of phosphogenesis provides explanations that are both qualitative (trapped organic matter and apatite substitution by elements in ratios corresponding to those of deep marine waters) and quantitative (10 super(6) to 10 super(8) tons of apatite accumulated on small atolls), lacking in previous models (degradation of guano or volcanic material).
AN: 3838114

                                                                    157 of 1521  
TI: Taxonomic diversity and metabolic activity of microbial communities in the water column of the Central Baltic Sea
AU: Hoefle,-M.G.; Brettar,-I.
AF: Gesellsch. Biotechnol. Forsch. mbH, Bereich Mikrobiol., Mascheroder Weg 1, D-38124 Braunschweig, FRG
SO: LIMNOL.-OCEANOGR. 1995 vol. 40, no. 5, pp. 868-874
LA: English
ER: M (Marine); B (Brackish)
AB: The water column of the Gotland Deep, an anoxic basin in the central Baltic Sea, was investigated as a representative and well-characterized part of a coastal marine ecosystem. We analyzed the overall structure of the bacterioplankton community by high resolution electrophoresis of the low-molecular-weight RNA (LMW RNA = 5S rRNA and tRNA). The results gave us a direct overview of the taxonomic diversity of the bacterial community (i.e. the number of taxa and their relative amounts in a sample). For further information about the identity of single taxa, we used partial sequencing of the 5S rRNA. Throughout the water column, we observed a rather limited number of abundant bacterial taxa (i.e. 3-7) with an increase of bacterial diversity in layers of increased turnover of organic matter. Comparison of samples taken from the euphotic zone during two consecutive summers indicated high similarity of taxonomic structure. One of the 5S rRNA bands occurring at the oxic-anoxic interface showed a partial sequence identical to Thiobacillus denitrificans, a species whose presence was hypothesized earlier from biogeochemical investigations. By using this novel approach, we could combine a direct overview of bacterial diversity with the ability to further analyze single species and thus provide means to elucidate major bacterial catalysts of biogeochemical cycling.
AN: 3838068

                                                                    158 of 1521  
TI: Copepod grazing and the biogeochemical fate of diatom iron
AU: Hutchins,-D.A.; Wang,-Wen-Xiong; Fisher,-N.S.
AF: Mar. Sci. Res. Cent., SUNY, Stony Brook, NY 11794-5000, USA
SO: LIMNOL.-OCEANOGR. 1995 vol. 40, no. 5, pp. 989-994
LA: English
ER: M (Marine)
AB: We investigated the effects of copepod grazing on fractionation of diatom cellular Fe into assimilated, dissolved, and fecal pellet pools. Grazer assimilation was only weakly dependent on prey N : Fe ratios, with assimilation efficiencies approximately tripling over a 100-fold increase in diatom N : Fe ratios. Assimilation efficiencies strongly correlated with prey subcellular partitioning, however, exhibiting a 1 : 1 relationship to cell cytoplasmic content and a 1 : 3 relationship with diatom intracellular content. Release of Fe from copepod fecal pellets conformed with a two-compartment loss model, with roughly 80% of associated Fe in a slowly released pool (tb sub( one half ) = 113 d). Partitioning into dissolved, assimilated, and fecal pellet pools indicated that all three are important fates for ingested cellular Fe.
AN: 3838061

                                                                    159 of 1521  
TI: In situ measurements of seawater pCO sub(2)
AU: DeGrandpre,-M.D.; Hammar,-T.R.; Smith,-S.P.; Sayles,-F.L.
AF: Dep. Mar. Chem. and Geochem., Woods Hole Oceanogr. Inst., Woods Hole, MA 02543, USA
SO: LIMNOL.-OCEANOGR. 1995 vol. 40, no. 5, pp. 969-975
LA: English
ER: M (Marine)
AB: A new instrument for studying seawater pCO sub(2) dynamics is described. The Submersible Autonomous Moored Instrument for CO sub(2) (SAMI-CO sub(2)) operates by equilibration of ambient seawater pCO sub(2) with a colorimetric pH indicator contained in a gas-permeable membrane. The indicator is periodically renewed to improve the stability and sensitivity typically reported for similar indicator-based pCO sub(2) sensors. The design combines off-the-shelf optical components, a miniature solenoid pump and valve, a low power data logger, and a fiber-optic flow cell to achieve low power consumption and easy assembly. SAMI-CO sub(2) is designed to operate down to 100 m and contains sufficient batteries and reagent for deployment up to 6 months while making 48 measurements per day. Extensive in situ field tests have been performed, including deployment in Woods Hole Harbor for > 30 d (May-June 1994). The field evaluation has confirmed that SAMI-CO sub(2) is capable of measuring seawater pCO sub(2) with exceptional long-term stability (no detectable drift in 1 month) and sensitivity comparable to ship-based equilibrator-infrared methods ( plus or minus 1  mu atm). The time-series data obtained from this study show that pCO sub(2) can be highly variable in nearshore environments with up to 100- mu atm changes detected over a 4-h period. The structurally rich data highlight the need for continuous mooring-based measurements of pCO sub(2) for understanding carbon cycling in natural waters.
AN: 3838058

                                                                    160 of 1521  
TI: Interspecific variability and environmental influence on particulate organic carbon  delta  super(13)C in cultured marine phytoplankton
AU: Leboulanger,-C.; Descolas-Gros,-C.*; Fontugne,-M.R.; Bentaleb,-I.; Jupin,-H.
AF: Lab. Hydrobiol., URA CNRS 1355, Univ. Montpellier II, F-34095 Montpellier Cedex 5, France
SO: J.-PLANKTON-RES. 1995 vol. 17, no. 11, pp. 2079-2091
LA: English
ER: M (Marine)
AB: The stable carbon isotope composition of particulate organic matter expressed as  delta  super(13)C was measured in cultures of 13 species of marine microalgae in different phylogenetic groups. The effects of salinity variations and changes in photoperiod were also assayed for three of them (i.e. Skeletonema costatum, Amphidinium operculatum and Isochrysis galbana); the effect of nature of nitrogen supply (nitrate, ammonium) was studied for one (S. costatum). These environmental parameters were chosen because of their variability in the ocean and their possible effects of  delta  super(13)C values of phytoplankton organic carbon. Batch culture conditions and sampling time after inoculum were strongly controlled in order to provide cells in good physiological state which were comparable from one culture to the other. In the same way, sampling was limited to the first 2 days of exponential growth, in order to avoid a possible dissolved inorganic carbon (DIC) limitation. Carboxylase activities [of the enzyme ribulose 1,5-bisphosphate carboxylase oxygenase (Rubisco), and the three  beta  carboxylases: phosphoenolpyruvate carboxylase (PEPC), phosphoenolpyruvate carboxykinase (PEPCK) and pyruvate carboxylase (PC)] and total chlorophyll a concentrations were assayed simultaneously. The  delta  super(13)C values observed were between -30.2ppt and -12.7ppt i.e. comparable to those observed in the world's oceans. The isotopic composition of phytoplankton organic carbon was shown to be under the influence of the paramaters tested but  delta  super(13)C variations are specific to the species considered. The nature of  beta  carboxylase found in each species, or systematic position, could not be linked to the isotopic composition of organic carbon. No linear or single correlation between  delta  super(13)C variations and environmental modifications were observed and there is no evidence for a simple and universal relation between  delta  super(13)C of phytoplankters and their environment. In monospecific cultures as in the field,  delta  super(13)C fractionation by Rubisco (and eventually by PEPCK) may be counterbalanced by other mechanisms.
AN: 3837979

                                                                    161 of 1521  
TI: Evidence for the seasonal accumulation of carbon-rich dissolved organic material, its scale in comparison with changes in particulate material and the consequential effect on net C/N assimilation ratios
AU: Williams,-P.J.leB.
AF: Sch. Ocean Sci., Univ. Wales, Bangor, Menai Bridge, Gwynedd, UK
SO: MAR.-CHEM. 1995 vol. 51, no. 1, pp. 17-29
LA: English
ER: M (Marine)
AB: An analysis is made of the seasonal cycles of particulate and dissolved organic carbon and nitrogen. The seasonal increase of the dissolved organic fraction (DOM) at all the sites studied is comparable to or exceeds that of the particulate fraction. The analysis revealed a mid-to late-summer accumulation of C-rich DOM, with C/N ratios twice or more the Redfield value of 6.6. It is illustrated that the formation of this C-rich material would give rise to net inorganic carbon and nitrogen assimilation ratios as high as 14:1, as such the could be the basis of high reported C/N assimilation ratios. Nitrogen limitation is speculated as a cause for the accumulation of the C-rich material. It is argued that systematic errors in the analytical methods would not give the patterns observed. The significance of accumulation of C-rich DOM in late summer is discussed in relation to reports which infer DOC to be a major form of carbon export from the euphotic zone. It is argued that the weak biochemical coupling of C and N in DOM as compared with the particulate fraction would loosen the link between the export of organic carbon and the import of inorganic nitrogen with important consequences on the biogeochemical control of carbon export from the upper ocean.
AN: 3835127

                                                                    162 of 1521  
TI: Accumulation of organic carbon in bottom sediments of the Benguela Upwelling zone.
OT: Nakoplenie organicheskogo ugleroda v donnykh osadkakh zony Bengel'skogo apvellinga
AU: Vetrov,-A.A.; Romankevich,-E.A.; Sipajlo,-L.E.
AF: Inst. Okeanol., Moscow, Russia
SO: OKEANOLOGIYA 1995 vol. 35, no. 4, pp. 550-555
LA: Russian
ER: M (Marine)
AB: The patterns of distribution and accumulation of organic matter in the recent epoch and the last glacial period are analized on the basis of sediment and pore water samples collected at sections along 17 degree S (62-4085 m depth), 23 degree S (42-3220 m) and 25 degree S (60-1010 m). The analysis revealed the following characteristics: not only high percentage concentrations of C sub(org) but accumulation of its considerable absolute masses caused by increased bioproductivity due to upwelling; decline of percentage C sub(org) concentrations in the shelf-slope-foot system and an even sharper decrease in its absolute masses; confinement of high absolute masses of C sub(org) and sediments to shallow water sediments of the inner shelf opposite Cunene R.; burial in the Cunene R. discharge zone during the glacial period of much higher absolute masses of sediments and C sub(org), which is characteristic of processes in the zones with a distinct type of avalanche sedimentation.
AN: 3834981

                                                                    163 of 1521  
TI: Aliphatic amines in Chesapeake Bay sediments
AU: Burdige,-D.J.; Huang,-C.M.; Krishna,-N.; Scully,-F.E.,Jr.
AF: Dep. Oceanogr., Old Dominion Univ., Norfolk, VA 23529, USA
SO: MAR.-CHEM. 1995 vol. 51, no. 1, pp. 45-54
LA: English
ER: M (Marine)
AB: Aliphatic amines were determined in sediments and sediment pore waters from several contrasting sites in Chesapeake Bay. The aliphatic amines diethylamine, sec-butylamine, n-propylamine, and i-propylamine were detected in a limited number of pore-water samples at concentrations generally less than  similar to  0.6  mu M. The occurrence of these amines showed no obvious correlation to other sediment geochemical parameters. Whole sediment (HF/HCl-extractable) aliphatic amines were less than  similar to  0.8 nmol/gdw. Isoamylamine and 2-methylbutylamine were the only amines that could be detected and quantified in sediment extracts, although diethylamine was below our detection limit in selected samples. When compared to other measured nitrogen pools in the sediments, these observations suggested that aliphatic amines may not represent a significant fraction of the nitrogen that is remineralized in these sediments, although more detailed concentration and rate studies are needed to verify their role in sediment nitrogen cycling. These aliphatic amines also did not appear to represent a major component of the uncharacterized nitrogen in these sediments.
AN: 3834816

                                                                    164 of 1521  
TI: The microbial food web in the European Regional Seas Ecosystem Model
AU: Baretta-Bekker,-J.G.; Baretta,-J.W.; Koch-Rasmussen,-E.
AF: Ecol. Modelling Cent., Joint Dep. DHI/VKI, Agern Alle 5, DK-2970 Horsholm, Denmark
SO: NETH.-J.-SEA-RES. 1995 vol. 33, no. 3-4, pp. 363-379
LA: English
ER: M (Marine)
AB: In the framework of the complex dynamical European Regional Seas Ecosystem Model (ERSEM) a module describing the microbial part of the pelagic ecosystem has been developed. The module contains the carbon and nutrient dynamics of pelagic bacteria, heterotrophic flagellates and microzooplankton and interacts with the other parts of the model via phytoplankton, particulate and dissolved organic matter and mesozooplankton. A short description of the module is given and the results are discussed. It is demonstrated that in an application of ERSEM to the North Sea there is a gradual shift in dominance from the continental coast boxes to the offshore deeper areas between the different food webs, from what in the literature is termed the classical food web to the microbial food web, concomitant with a gradual decrease in the efficiency of the microbial loop.
AN: 3834745

                                                                    165 of 1521  
TI: Modelling primary production in the North Sea using the European Regional Seas Ecosystem Model
AU: Varela,-R.A.; Cruzado,-A.; Gabaldon,-J.E.
AF: Cent. Estud. Av. Blanes, Cami Santa Barbara s/n, E-17300 Blanes (Girona), Spain
SO: NETH.-J.-SEA-RES. 1995 vol. 33, no. 3-4, pp. 337-361
LA: English
ER: M (Marine)
AB: The primary production module incorporated in the European Regional Seas Ecosystem Model (ERSEM) is described in detail. It considers two phytoplankton groups, diatoms and autotrophic flagellates, and four different nutrients: nitrate, ammonia, phosphate and silicate (only for diatoms). All the related state variables and fluxes are represented in terms of carbon, nitrogen, phosphorus and silicon. The potential carbon growth rate process is estimated by considering that nutrient availability acts as a limitation factor on the maximum growth rate which is itself a function of light and water temperature. Respiration, excretion of organic matter, lysis and sinking are the main carbon and nutrient loss processes. Results indicate that the model simulates well the annual phytoplankton dynamics in the central regions of the North Sea, underestimating primary production and chlorophyll in the southern North Sea. The model gave good correlations with the main dissolved nutrients, such as silicate, phosphate or nitrate. The primary production module proved to be especially sensitive to the flagellate/diatom interaction and competitive behaviour for inorganic nutrients as well as with regard to grazing losses. It is suggested that a major improvement could be made by including a third phytoplankton group (e.g., Phaeocytis) in the model structure, and that comparison with other phytoplankton growth schemes based on the Droop formulation is advisable.
AN: 3834744

                                                                    166 of 1521  
TI: Nutrient dynamics in the North Sea: Fluxes and budgets in the water column derived from ERSEM
AU: Radach,-G.; Lenhart,-H.J.
AF: Inst. Meeresk., Univ. Hamburg, Troplowitzst. 7, D-22529 Hamburg, FRG
SO: NETH.-J.-SEA-RES. 1995 vol. 33, no. 3-4, pp. 301-335
LA: English
ER: M (Marine)
AB: Nutrient dynamics for phosphate, nitrate, ammonium and silicate have been simulated with ERSEM, the European Regional Seas Ecosystem Model. From the model results budgets for the dissolved inorganic nutrients and the corresponding particulate fractions have been calculated. The annual cycles of the nutrients phosphate and silicate compare quite well with the observed ranges of variability. This does not hold for ammonium and nitrate. Biologically mediated transformations such as nutrient uptake and pelagic and benthic mineralization are the dominant processes in changing the nutrient concentrations with the horizontal advective contributions playing a minor role during the productive season. Vertical advection and vertical diffusion have a clear seasonal signal, with a maximum in February. The decay of the advective nutrient transport in summer is caused by the depletion of the upper layer of dissolved inorganic nutrients by algal uptake. The inflow of nutrients in the northwest is almost balanced by the outflow in the northeast, without causing large nutrient transports into the shallower areas from the north. However, from the coastal areas there is a nutrient flow towards the central North Sea, enhancing primary production in the central area.
AN: 3834743

                                                                    167 of 1521  
TI: Geochemical and isotopic comparisons between northern Lake Michigan and Conception Bay, Newfoundland
AU: Ostrom,-N.; Lee,-D.; Hall,-D.; Ostrom,-P.
AF: Dep. Geol. Sci., Michigan State Univ., East Lansing, MI 48824, USA
CO: 37. Conference of the International Association of Great Lakes Research and Estuarine Research Federation, Windsor, ON (Canada), 5-9 Jun 1994
SO: 37TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH-AND-ESTUARINE-RESEARCH-FEDERATION:-PROGRAM-AND-ABSTRACTS. International-Assoc.-for-Great-Lakes-Research,-Buffalo,-NY-USA BUFFALO,-NY-USA IAGLR 1994 166
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Northern Lake Michigan and Conception Bay, Newfoundland and although having contrasting salinities are similar in size, depth, climate, and alkalinity. Water column geochemical and isotopic data collected in these two systems are compared. Samples were collected off Frankfort, MI in July of 1992 and are compared to samples collected in July of 1990 in Conception Bay. Concentrations of oxygen, as determined by a Seabird CTD, in Lake Michigan, ranged between 2.4 and 8.5mL/L. A narrow (<10 m) wide oxygen minimum zone was evident at the base of the thermocline. Concentrations within the minimum zone decreased from 5.6 mL/L to 2.4 mL/L over a 24 hour period. Bottle collections were used in Conception Bay and may be the reason why an oxygen minimum zone was not observed. In both systems, the concentration of particulate organic matter (POM) decreased markedly across the thermocline. Marked increases in the  delta  super(15)N of POM were also evident in both systems. In Lake Michigan the  delta  super(15)N of POM increased with depth from values as low as 4.0 to a maximum of 17.7ppt. A minimum in carbon isotope values was also associated with the thermocline in both systems. These trends clearly indicate that the base of the thermocline is a region of intense microbial cycling. The  delta  super(15)N of nitrate in Lake Michigan varied between-1.3 and 1.5ppt and was similar to the average  delta  super(15)N of nitrate in Conception Bay of 0.2ppt. These values indicate that nitrate was derived similarly in both systems; from nitrification in sediments in which substantial isotopic fractionation was involved.
AN: 3832039

                                                                    168 of 1521  
TI: Benthic organic nitrogen mineralization dynamics: Comparison of results from sites in Lake Michigan and the Gulf of Mexico
AU: Gardner,-W.S.
AF: NOAA Great Lakes Environ. Res. Lab., 2205 Commonwealth Blvd., Ann Arbor, MI 48105, USA
CO: 37. Conference of the International Association of Great Lakes Research and Estuarine Research Federation, Windsor, ON (Canada), 5-9 Jun 1994
SO: 37TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH-AND-ESTUARINE-RESEARCH-FEDERATION:-PROGRAM-AND-ABSTRACTS. International-Assoc.-for-Great-Lakes-Research,-Buffalo,-NY-USA BUFFALO,-NY-USA IAGLR 1994 166
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Comparison of results from studies of benthic nitrogen mineralization and fate in Lake Michigan and in the Gulf of Mexico (near the Mississippi River plume) suggest interesting similarities and differences in benthic nitrogen dynamics between freshwater and marine coastal ecosystems. Excretion of ammonium by benthic macroinvertebrates was an important component (ca 10 to 40%) of total benthic organic nitrogen mineralization in both Lake Michigan and the Gulf of Mexico, an observation that supports the hypothesis of relatively direct transfer of nitrogen-rich particles from the euphotic zone to the benthos. However, the fate of the regenerated nitrogen was somewhat different in the two ecosystems. In the Gulf of Mexico experiments, a relatively large portion (24-65%) of the regenerated nitrogen was released into the water column as ammonium whereas in Lake Michigan, virtually all of the regenerated nitrogen was denitrified to nitrogen gas. This result is consistent with the hypothesis that sea salts enhance ammonium mobility across the sediment-water interface by forming ion pairs with ammonium and blocking cation exchange sites in the sediments.
AN: 3832035

                                                                    169 of 1521  
TI: The linkage of organic contaminant and natural organic matter cycling in the Great Lakes
AU: Eisenreich,-S.J.; Baker,-J.E.
AF: Gray Freshwat. Biol. Inst., P.O. Box 100, Navarre, MN 55392, USA
CO: 37. Conference of the International Association of Great Lakes Research and Estuarine Research Federation, Windsor, ON (Canada), 5-9 Jun 1994
SO: 37TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH-AND-ESTUARINE-RESEARCH-FEDERATION:-PROGRAM-AND-ABSTRACTS. International-Assoc.-for-Great-Lakes-Research,-Buffalo,-NY-USA BUFFALO,-NY-USA IAGLR 1994 166
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Our hypothesis is that the concentration, residence time, and fate of hydrophobic organic chemicals (HOCs) such as PCBs and many organochlorine pesticides in large aquatic systems such as the Great Lakes and Chesapeake Bay are controlled by the production, settling, mineralization, recycling, and burial of natural organic matter. HOCs partition into particulate organic matter (algae) in the surface waters and are delivered to the benthic region at rates of perhaps 5 to 100 m/day, thereby reaching the benthic region even in the deepest waters of Lake Superior in days to a few weeks. Several data sets from Lakes Superior and Michigan, Green Bay, and Chesapeake Bay exhibit specific linear relationships between PCB flux and OC flux. The PCB flux per unit of OC flux decreases from oligotrophic to eutrophic systems indicative of biomass dilution and changes in the quality of the available lipid pool. As the autochthonous matter is mineralized and re-packaged by benthic organisms, HOCs are released and are re-distributed into the available particle pool. In much of the Great Lakes, surface sediment is resuspended on a seasonal basis except for deep waters re-supplying the surface water with HOCs. The efficiency of recycling of PCBs in the benthic region is dependent on the hydrophobicity of the chemical; benthic recycling rates of PCBs in Lake Superior range from  similar to 10 for highly chlorinated congeners to  similar to 500-1,000 for dichloro-congeners. The factor most important in determining the sediment concentration of HOCs is likely the degree of organic matter preservation in the surface sediments. Specific examples from Lakes Superior and Michigan, Green Bay, and Chesapeake Bay will be presented.
AN: 3832034

                                                                    170 of 1521  
TI: The comparative geochemistry of trace metals in estuaries and lakes
AU: Church,-T.M.
AF: Coll. Mar. Stud., Univ. Delaware, Newark, DE 19716-3501, USA
CO: 37. Conference of the International Association of Great Lakes Research and Estuarine Research Federation, Windsor, ON (Canada), 5-9 Jun 1994
SO: 37TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH-AND-ESTUARINE-RESEARCH-FEDERATION:-PROGRAM-AND-ABSTRACTS. International-Assoc.-for-Great-Lakes-Research,-Buffalo,-NY-USA BUFFALO,-NY-USA IAGLR 1994 166
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Trace elements are introduced to lakes and coastal waters by both eolian and riverine/estuarine means from the weathering of rocks and waste disposal. The anthropogenic fraction introduced currently outweighs the natural fraction for most non-crustal elements for many estuaries and lakes in at least North America. Trace metals which enter seepage or Great Lakes is dominated by direct atmospheric deposition. Direct and indirect atmospheric deposition dominates trace metal input probably to estuarine and certainly to coastal waters of the mid-Atlantic region. In freshwater lakes the metals are processed largely by the natural Eh-pH biogeochemical cycles which eventually lead to their sediment deposition. In estuaries, trace elements are processed by both the chemical (Eh-pH) as well as salt (ionic strength) gradient inherent in their transmission from the land to the sea. Elements which readily hydrolyze (e.g., Fe, Mn, and Co) are geochemically processed and retained as sediments, while those that participate in biochemical cycles (e.g., Cu, Ni, and Zn) are reprocessed into robust organic complexes that are largely transmitted into the sea.
AN: 3832033

                                                                    171 of 1521  
TI: A simple model of biogeochemical element distribution in the oceanic water column
AU: Shopova,-D.; Dehairs,-F.; Baeyens,-W.
AF: Environ. Res. and Info. Cent., Sofia, Bulgaria
SO: J.-MAR.-SCI. 1995 vol. 6, no. 4, pp. 331-344
LA: English
ER: M (Marine)
AB: In the present paper a simple technique for data analysis of the distribution of biogeochemical elements in the oceanic water column is presented. It is based on a steady vertical model, which assumes that the turbulent diffusion and vertical advection are the main physical mechanisms influencing the conservative tracer concentration. The production/consumption rates of non-conservative tracers are computed on the basis of this model. Sensitivity analysis of this model has been performed, which permits assessing the eventual influence of horizontal advection on the results. It also permits the taking into account of its effects if some hypothesis for the horizontal gradients are made. The potential area of applicability of the presented simple technology for data analysis is broad. Examples of its application are presented as analysis of the oxygen data for some stations of the INDIGO3, 1987 expedition in the Southern Ocean. The calculated oxygen consumption rates for the Antarctic Circumpolar Current (Indian Ocean Sector) range between 1.8 and 2.22 mmol m super(-) super(2)/d  plus or minus  20%.
AN: 3831650

                                                                    172 of 1521  
TI: Benthic nutrient regeneration in the ERSEM ecosystem model of the North Sea
AU: Ruardij,-P.; Van-Raaphorst,-W.
AF: Netherlands Inst. Sea Res., P.O. Box 59, NL-1790 AB Den Burg, Texel, Netherlands
SO: NETH.-J.-SEA-RES. 1995 vol. 33, no. 3-4, pp. 453-483
LA: English
ER: M (Marine)
AB: In any ecosystem modelling approach to shallow seas an adequate description of the sediment-water interactions to all the essential nutrients is necessary. With this aim a fairly simple concept has been developed and applied for the modelling of the nutrient cycles of N, P and Si which includes the essential diagenetic processes such as vertical transport, oxic and anoxic mineralization, silicate dissolution, adsorption, nitrification and denitrification. All these processes are explicitly formulated for one or more distinct layers in the sediment. The model contains a low number of variables and is efficient with respect to computer time. The model is part of the European Regional Seas Ecosystem Model (ERSEM) of the North Sea, a joint effort of several institutes around the North Sea. The benthic-pelagic coupling of the ERSEM model is discussed with emphasis on the consequences for the benthic nutrient cycling and the interrelations between the different benthic nutrient submodels. The results show that the model is able to describe the seasonal variation of nutrient fluxes including the sediment-water exchanges and the vertical profiles in the pore water. From the model results is concluded that changes in organic matter deposition directly influence the benthic nitrification and denitrification through changes in the oxygen availability to the nitrifiers and, due to this, the supply of nitrate to the denitrifiers. Short fluctuations in organic deposition (e.g. after the spring bloom) are not reflected in the fluxes due to sorption buffering of phosphate in the oxidized surface layer of the sediment.
AN: 3831574

                                                                    173 of 1521  
TI: The benthic biological submodel in the European Regional Seas Ecosystem Model
AU: Ebenhoeh,-W.; Kohlmeier,-C.; Radford,-P.J.
AF: Carl von Ossietzky Univ., Postfach 2503, D-2611 Oldenburg, FRG
SO: NETH.-J.-SEA-RES. 1995 vol. 33, no. 3-4, pp. 423-452
LA: English
ER: M (Marine)
AB: The submodel describing benthic biology including a bioturbation module as incorporated in the European Regional Seas Ecosystem Model (ERSEM) is discussed. It is linked to a nutrient dynamic model. The structure of the benthic model food web is presented. There are four macrobenthic functional groups, meiobenthos and aerobic and anaerobic bacteria. The modelling uses 'standard organisms' as basic building blocks. The choice of parameter values is discussed. The results demonstrate the dependence of the benthic system on the pelagic system. The importance of features such as predation within functional groups for stability of the system is investigated. Detritus input from the pelagic system and detritus recycling is most important in the benthic food web. The web of carbon and nutrient fluxes through the system is analysed. On the basis of the food web analysis, the trophic positions of the functional groups are calculated. Besides the benthic biology, the mathematical formulation of the bioturbation and diffusion enhancement is discussed. Macrobenthic presence and activity enhance diffusion in the sediment and contribute essentially to vertical transport of particulate matter. This is of great importance for the vertical distribution of detritus, and as a consequence, for microbial activity in the sediment layers.
AN: 3831573

                                                                    174 of 1521  
TI: Modelling the predation, growth and population dynamics of fish within a spatially-resolved shelf-sea ecosystem model
AU: Bryant,-A.D.; Heath,-M.R.; Broekhuizen,-N.; Ollason,-J.G.; Gurney,-W.S.C.; Greenstreet,-S.P.R.
AF: Culterty Field Stn, Univ Aberdeen, Newburgh, Grampian AB41 OAA, UK
SO: NETH.-J.-SEA-RES. 1995 vol. 33, no. 3-4, pp. 407-421
LA: English
ER: M (Marine)
AB: The development and analysis of a fish population module within the European Regional Seas Ecosystem Model (ERSEM) is described. Fixed predation rates on ERSEM zooplankton and zoobenthos, which may be used in place of this dynamic module of fish, are described also. The dynamic module is age-structured, with state variables for the number of individuals and their weight, the latter partitioned into structural (skeletal, essentially) and remobilizable 'reserve' components. It is capable of prediction of observed patterns of both positive and negative changes in individual weight. The fish are modelled as one population for the whole North Sea, superimposed on the ERSEM box structure. Parameters have been derived from the literature where possible and, for herring (Clupea harengus), certain parameters have been adjusted to match independent estimates of growth in the field. Preliminary results show that herring growth rate depends inversely on biomass, when changes in the latter are caused by altered fishing mortality. The magnitude of these effects is in agreement with historical data for herring in the North Sea. The model is discussed in relation to previous attempts to model fish population dynamics, particularly in the North Sea.
AN: 3831572

                                                                    175 of 1521  
TI: Modelling the dynamics of the North Sea's mesozooplankton
AU: Broekhuizen,-N.; Heath,-M.R.; Hay,-S.J.; Gurney,-W.S.C.
AF: Natl. Inst. Water Atmos. Res., P.O. Box 11-115, 100 Aurora Terrace, Hillcrest, Hamilton, New Zealand
SO: NETH.-J.-SEA-RES. 1995 vol. 33, no. 3-4, pp. 381-406
LA: English
ER: M (Marine)
AB: A simple biomass-only zooplankton submodel is presented, describing the dynamics of copepods and carnivorous zooplankton in the North Sea. This submodel together with the other process-oriented submodels (viz. phytoplankton dynamics, the microbial food web, benthic processes, fish dynamics and large-scale advective transport) forms a spatially resolved simulation model of the North Sea ecosystem, the European Regional Seas Ecosystem Model (ERSEM). A large set of field measurements of zooplankton abundance has been assembled against which to compare the ERSEM's performance. These data are not only internally consistent, but have also been gathered at the large spatial scales appropriate to the ERSEM. In addition to the spatially resolved, monthly estimates of zooplankton abundance, several instantaneous, in situ estimates of the carbon fluxes between different components of the planktonic web in the northern North Sea are presented. Simulated dynamics are in good agreement with the data only during the mid-summer to mid-winter period. During the latter part of the winter and throughout the spring period zooplankton abundance is under-predicted and the simulated zooplankton growth rate is overpredicted during spring. The excessive decline of mesozooplankton biomass during winter may be caused by failing to capture many of the behavioural/physiological changes which zooplankton manifest during winter. It is suggested that the excessive spring growth is a consequence of a. a failure to properly distinguish between somatic and population growth, b. an inadequate representation of the small scale processes which influence feeding success, and c. an excessive spring phytoplankton bloom. The large phytoplankton bloom is, in part at least, a consequence of the excessively low simulated standing crop of omnivorous zooplankton in spring.
AN: 3831571

                                                                    176 of 1521  
TI: Molecular approaches to the study of aquatic and sedimentary organisms
AU: Nealson,-K.H.
AF: Cent. Great Lakes Stud., Univ. Wisconsin, 600 E. Greenfield Ave. Milwaukee, WI 53204, USA
CO: 37. Conference of the International Association of Great Lakes Research and Estuarine Research Federation, Windsor, ON (Canada), 5-9 Jun 1994
SO: 37TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH-AND-ESTUARINE-RESEARCH-FEDERATION:-PROGRAM-AND-ABSTRACTS. International-Assoc.-for-Great-Lakes-Research,-Buffalo,-NY-USA BUFFALO,-NY-USA IAGLR 1994 166
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Molecular genetics have supplied us with a variety of new approaches for the study of biogeochemistry and nutrient cycling. First, we have used molecular methods of hybridization, cloning, gene sequencing, and replacement mutagenesis to gain insight into factors that regulate metal reduction in the facultative anaerobe Shewanella putrefaciens. Such information allows one to predict the in situ activity of these bacteria in various environments. These approaches have revealed the presence of a regulatory gene that controls anaerobic respiration of several electron acceptors. Molecular methods are also in use to study the distribution and abundance of S. putrefaciens. Using hybridization probes directed at the 1 6S rRNA, it is now possible to directly identify the number of this species present in water samples. We are now cloning the gene for iron reduction [Fe(III) reductase], and when it is sequenced, it should allow us to develop function specific probes for the identification of iron reducers. Such approaches have been used successfully to identify species of luminous bacteria, using luxA gene probes. Finally, in collaboration with Dr. David Stahl, we are investigating the total sediment populations of Lake Michigan sediments by nucleic acid extraction and analysis. Preliminary results of these studies suggest that the organisms that are cultured using standard methods are markedly different from those seen in the nucleic acid profiles.
AN: 3831507

                                                                    177 of 1521  
TI: The benthic boundary layer of large lakes: Particle dynamics and biogeochemical cycling from the bottom looking up
AU: Klump,-J.V.
AF: Cent. Great Lakes Stud., Univ. Wisconsin-Milwaukee, 600 E. Greenfield Ave., Milwaukee, WI 53204, USA
CO: 37. Conference of the International Association of Great Lakes Research and Estuarine Research Federation, Windsor, ON (Canada), 5-9 Jun 1994
SO: 37TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH-AND-ESTUARINE-RESEARCH-FEDERATION:-PROGRAM-AND-ABSTRACTS. International-Assoc.-for-Great-Lakes-Research,-Buffalo,-NY-USA BUFFALO,-NY-USA IAGLR 1994 166
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: The importance of processes within the benthic boundary layer of large lakes is well recognized, but not yet fully understood. With water residence times that vary from a few years to a few centuries, nearly all lakes can be characterized as under the strong influence of benthic boundary layer dynamics. Nearly all cycles, whether of elements of biogeochemical interest or of exotic contaminants, are driven, in part, by the dynamics of the processes coupling pelagic and benthic systems. Long-term deposition patterns and the spatial distribution of sediment accumulation are now known for a number of the Great Lakes, and estimates of the permanent burial of sedimentary components in simple mass balances for these systems are possible. Our understanding of the short-term dynamics of particle movement, vertical resuspension, and horizontal redistribution is much less certain, and although much is made, for example, about the role of the so-called nepheloid layer in a variety of cycles, the dynamics of that system are poorly characterized. Major questions still exist with regard to the mechanisms controlling sediment-water chemical exchange; the scale, spin-up, and decay of boundary layer phenomena; and the place of benthic energy transfer in the ecology of lakes. An attempt will be made to look into the possible role of future technology in addressing some of these gaps in our knowledge.
AN: 3831505

                                                                    178 of 1521  
TI: Preferential flow and segregation of porewater solutes in wetland sediment
AU: Harvey,-J.W.; Chambers,-R.M.; Hoelscher,-J.R.
AF: United States Geol. Surv., Water Resour. Div., Mail Stop 496, 345 Middlefield Rd., Menlo Park, CA 94025, USA
CO: Pulsed Ecosystems: A New Paradigm?, Hilton Head, SC (USA), Nov 1993
SO: PULSED-ECOSYSTEMS:-A-NEW-PARADIGM?-PROCEEDINGS-OF-A-SYMPOSIUM-HELD-IN-HILTON-HEAD,-NOVEMBER-1993. Blum,-L.K.-ed. 1995 vol. 18, no. 4 pp. 568-578
ST: ESTUARIES vol. 18, no. 4
LA: English
ER: B (Brackish)
AB: Sediment macropores (with effective diameters larger than 100  mu m) comprise 11% of the bulk sediment volume in a tidal freshwater wetland vegetated with Peltandra virginica. In order to determine effects of macroporous sediment structure on solute transport, we conducted a solute tracer experiment in the sediment. The effective transport volume ( theta  sub(eff), the volume of sediment through which solute was transported normalized to sediment bulk volume) was 0.15 cm super(3) cm super(-3), which is considerably smaller than the total pore space that is potentially available for transport (porosity of sediment is 0.63 cm super(3) cm super(-3)). A mean transport time of 13 d was required to flush preferential flow paths in Peltandra hummocks; hydrologic turnover of the volumetrically dominant matrix pores (0.53 cm super(3) cm super(-3)) was apparently much slower. Based on porewater sampler design and hydrological principles, we suggest that N sub(2)-purged tension solution samplers and diffusion equilibrators preferentially sample porewater from macropore and matrix domains, respectively. Dissolved ammonium and orthophosphate concentrations were three-fold higher in matrix pores compared to macropores, which is consistent with our finding that more rapid hydrological flushing occurred in macropores compared to matrix pores. Further evaluation of porewater sampler designs in macroporous sediment is needed to improve studies of hydrologic transport and biogeochemical cycling in wetlands.
AN: 3831481

                                                                    179 of 1521  
TI: Carbon cycling in mesohaline Chesapeake Bay sediments 1: POC deposition rates and mineralization pathways
AU: Roden,-E.E.; Tuttle,-J.H.; Boynton,-W.R.; Kemp,-W.M.
AF: Dep. Biol. Sci., Univ. Alabama, Box 870344, Tuscaloosa, AL 35487-0344, USA
SO: J.-MAR.-RES. 1995 vol. 53, no. 5, pp. 799-819
LA: English
ER: M (Marine)
AB: Organic carbon cycling in sediments at two locations in the mesohaline Chesapeake Bay was analyzed using available data on sediment sulfate reduction, sediment oxygen consumption, and particulate organic carbon (POC) deposition and burial. Estimates of POC deposition based on the sum of integrated sediment metabolism and POC burial compared well with direct estimates derived from chlorophyll-a collection rates in mid-water column sediment traps. The range of POC deposition estimates (15-31 mol C m super(-2) yr super(-1)) accounted for a large fraction (36-74%) of average annual net primary production in the mesohaline Bay. The difference between rates of POC deposition and permanent burial indicated that 70-85% of deposited carbon is mineralized on the time scale of a year. Carbon mineralization through sulfate reduction accounted for 30-35% of average net primary production, and was likely responsible for 60-80% of total sediment carbon metabolism. Oxidation of reduced sulfur accounted for a large but quantitatively uncertain portion of SOC in mid-Bay sediments. Our results highlight the quantitative significance of organic carbon sedimentation and attendant anaerobic sediment metabolism in the carbon cycle of a shallow, highly productive estuary.
AN: 3828162

                                                                    180 of 1521  
TI: Overestimation of heterotrophic bacteria in the Sargasso Sea: Direct evidence by flow and imaging cytometry
AU: Sieracki,-M.E.; Haugen,-E.M.; Cucci,-T.L.
AF: Bigelow Lab. Ocean Sci., P.O. Box 475, McKown Point, W. Boothbay Harbor, ME 04575, USA
SO: DEEP-SEA-RES.-I-OCEANOGR.-RES.-PAP. 1995 vol. 42, no. 8, pp. 1399-1409
LA: English
ER: M (Marine)
AB: Accurate measurements of bacterial biomass in the ocean are needed for modeling marine microbial food webs and global biogeochemical cycling. We present direct evidence that previous estimates of heterotrophic bacteria biomass in the oligotrophic ocean are confounded by the presence of the abundant photosynthetic procaryote, Prochlorococcus. The chlorophyll autofluorescence of these photosynthetic bacterial cells is very faint and fades rapidly under epifluorescence microscopy. Detection and enumeration of these cells thus far has almost exclusively been by flow cytometry. Using a cooled, charge-coupled device (CCD) camera we were able to image these cells for direct biovolume measurements. A double-exposed image of DAPI-stained Prochlorococcus cells shows that they are indistinguishable from heterotrophic bacteria in standard slide preparations. At two Sargasso Sea stations Prochlorococcus could cause an overestimation of surface (top 150 m) integrated heterotrophic bacterial biovolume (biomass) of 18 and 22% determined by standard microscope methods. At the subsurface chlorophyll maximum Prochlorococcus was 33 and 43% of the heterotrophic bacterial biovolume (biomass) at these stations. Prochlorococcus cell size increased from 0.05  mu m super(3) in the surface mixed layer to about 0.2  mu m super(3) below 100 m, confirming previous interpretations of flow cytometric light scatter measurements. Shifting biomass from the heterotrophic bacteria pool to the primary producer compartment has significant implications for ecosystem structure and trophic transfer in marine food webs.
AN: 3828059

                                                                    181 of 1521  
TI: Economics, volcanoes, and Phanerozoic revolutions
AU: Vermeij,-G.J.
AF: Dep. Geol., Univ. California Davis, Davis, CA 95616-8605, USA
SO: PALEOBIOLOGY 1995 vol. 21, no. 2, pp. 125-152
LA: English
ER: M (Marine)
AB: Two intervals of the Phanerozoic stand out as times of biosphere-scale revolution in the sense that biogeochemical cycles came under increased control by organisms. These are the early Paleozoic (extending from just before the Cambrian to the Middle Ordovician, a duration of about 100 m.y.), characterized by the appearance of predators, burrowers, and mineralized skeletons, and by the subsequent diversification of planktonic animals and suspension-feeders: and the later Mesozoic (latest Triassic to mid-Cretaceous, a duration of somewhat more than 100 m.y.), marked by a great diversification of predators and burrowers and by the rise of mineralized planktonic protists. This paper explores the economic conditions that make such revolutions possible. I argue that opportunities for innovation and diversification are enhanced when raw materials and energy are supplied at increasing rates, or when organisms gain greater access to these commodities through rising temperatures and higher metabolic rates. Greater per capita availability of resources enables populations to grow; lessens or alters ecological constraints on functional improvement; makes possible the evolution of high metabolic rates (large incomes), which in turn permit improvement in each of several otherwise incompatible functions; and favors the establishment and spread of daughter species arising through founder speciation. Reductions in productivity reinforce adaptational constraints and may bring about extinctions. Massive submarine volcanism, together with its associated phenomena of warming, sea-level rise, and widening of warm-weather zones, is proposed to be the chief extrinsic trigger for the Phanerozoic revolutions. The later Mesozoic was characterized by continental rifting, which accompanied massive submarine volcanic eruptions that produced large quantities of nutrients and carbon dioxide. This activity began in the Late Triassic and peaked in the mid- to Late Cretaceous. The Early Cambrian was also a time of rifting and may likewise have been marked by large-scale submarine volcanism. Continental and explosive volcanism, weathering, and upwelling are other potential means for increasing evolutionary opportunity, but their effects are either local or linked directly or indirectly with cooling. Intense chemical weathering in the Early Cambrian, however, may have contributed to the early Paleozoic revolution. The extrinsic stimulus was greatly amplified through positive feedback by the evolution of higher metabolic rates and other means for acquiring, trading, retaining, and recycling resources more rapidly and from a wider range of environments. Because these novelties usually require a high and predictable supply of resources, their evolution is more likely when extrinsically controlled supplies increase rather than when per capita availability is low. In the view adopted here, the microevolutionary and microeconomic market forces of competition and natural selection operate against a backdrop of macroeconomic supply and demand. Resources are under both extrinsic and intrinsic control. Positive and negative feedbacks link processes at the micro- and macroeconomic levels. This view complements the genealogical and hierarchical conception of evolution by emphasizing that the pattern of descent is influenced by resources and by market forces operating at all scales of space and time.
AN: 3828046

                                                                    182 of 1521  
TI: Phosphate transfer between microbial size-fractions in Villefranche Bay (N. W. Mediterranean Sea), France in autumn 1992
AU: Dolan,-J.R.; Thingstad,-T.F.; Rassoulzadegan,-F.
AF: Observ. Sci. l'Univers., Univ. Paris IV/INSU/CNRS URA 716, Stn. Zool., B.P. 28, F-06230 Villefranche-Sur-Mer, France
CO: International Symposium on Nutrient Dynamics in Coastal and Estuarine Environments, Helsingoer (Denmark), 13-16 Oct 1993
SO: OPHELIA 1995 vol. 41, pp. 71-85
LA: English
ER: M (Marine); B (Brackish)
AB: Turnover time of orthophosphate, uptake of phosphate into particulate size-fractions (0.2-1, 1-5, 5-10, > 10  mu m), and subsequent release from size-fractions were examined using  super(32)P, in samples from surface waters of Villefranche Bay during the autumnal erosion of the thermocline. Turnover time of orthophosphate increased from 1.6 h in early October to 58 h in December. Throughout the study period, total uptake was dominated (50-68%) by the smallest size-fraction (0.2-1  mu m) presumably corresponding to auto- and heterotrophic bacteria as it contained little chlorophyll a. Among the size-fractions > 1  mu m, representing eucaryotic phytoplankton uptake, the erosion of the thermocline was accompanied by a shift from the total dominance of uptake by the 1-5  mu m fraction (98%) toward an increasing contribution from the > 10  mu m fraction ( similar to 0 to 50%). In cold chase experiments, release of  super(32)P from the size-fractions which dominated uptake (0.2-1  mu m & 1-5  mu m), was relatively slow ( less than or equal to  1% h super(-1)) indicating long turnover times in particulate fractions; transfer to larger size-fractions was undetectable. When the concentration of oligotrich ciliates (predators of organisms 1-6  mu m in size) was artifically increased, labeled  super(32)P declined in particulate fractions and increased in the pool of inorganic suggesting a low P retention efficiency.
AN: 3827981

                                                                    183 of 1521  
TI: Bio-volatilization of polonium: Results from laboratory analyses
AU: Hussain,-N.; Ferdelman,-T.G.; Church,-T.M.; Luther,-G.W.,III
AF: Coll. Marine Stud., Univ. Delaware, Newark, DE 19716, USA
SO: AQUAT.-GEOCHEM. 1995 vol. 1, no. 2, pp. 175-188
LA: English
ER: F (Freshwater)
AB: Polonium, like other elements in the Group VI oxygen series (S, Se, Te), has the potential to form volatile alkyl derivatives. This may be evident in its pervasive radioactive excesses in the atmosphere and coastal waters, and its deficiency in surface open ocean waters. We present evidence for the formation of volatile polonium species. The first evidence comes from duplicating experiments that proved the existence of volatile tellurium, its Group VI congener. Cultures of bread mold at room temperature spiked with polonium tracers showed a significant and reproducible loss of about 0.5% per day of volatile polonium species. In another set of experiments, between 30-50% loss of  super(210)Po was observed from Floridan groundwater when nitrogen was bubbled through it over durations of 5-30 minutes. Polonium volatility is highly relevant for biogeochemical studies because it may provide a natural radiochemical tracer for recycling of similar volatile sulfur and other Group VI metal species between the geosphere, atmosphere, and hydrosphere.
AN: 3827919

                                                                    184 of 1521  
TI: On photosynthesis, biotic balance and the trophic structure of marine benthic biota.
OT: O fotosinteze, bioticheskom balanse i troficheskoj strukture morskoj donnoj bioty
SO: FEEDING-OF-MARINE-INVERTEBRATES-IN-DIFFERENT-VERTICAL-AND-LATITUDINAL-ZONES.#PITANIE-MORSKIKH-BESPOZVONOCHNYKH-V-RAZNYKH-VERTIKAL'-NYKH-I-SHIROTNYKH-ZONAKH. Kuznetsov,-A.P.;Sokolova,-M.N.-eds. MOSKVA-RUSSIA IORAN 1993 pp. 7-22
NT: Incl. bibliogr.: 40 ref.
LA: Russian
ER: M (Marine)
AB: The author considers the evolution and role of photosynthesis as a perfect mechanism of solar radiation energy utilization and of producing initial living matter of the biosphere and as a planetary biogeochemical factor responsible for the origination and existence of the present-day state of the earth's surface geosystem including its biosystem.
AN: 3827910

                                                                    185 of 1521  
TI: Sources and cycling of organic matter in Lake Superior: A stable isotopic assessment
AU: Ostrom,-N.E.; Bell,-E.M.; Long,-D.T.
AF: Environ. Geosci. Program, Dep. Geol. Sci., 206 Nat. Sci., Michigan State Univ., East Lansing, MI 48824-1115, USA
CO: 38. Conference of the International Association for Great Lakes Research, East Lansing, MI (USA), 28 May-1 Jun 1995
SO: PROCEEDINGS-OF-THE-38TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-OF-GREAT-LAKES-RESEARCH. 2200-BONISTEEL-BOULEVARD,-ANN-ARBOR,-MI-48109-2099-USA INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH 1995 pp. 73-74
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: In June of 1994 a series of water column and sediment samples were collected at three stations within the Chefswet Basin of Lake Superior to evaluate the sources and cycling of organic matter within this system. This study presents data on the  delta  super(15)N and  delta  super(13)C of sedimentary and suspended particulate organic matter and dissolved inorganic matter. Water column temperatures were close to 4 degree C at all stations and the presence of a thermocline was observed at only the shallow station. Low concentrations of particulate material and fluorometer readings suggested that primary production was reduced at this time. Carbon isotope values for seston varied only slightly with station and depth and values ranged between -27.3 and 26.2ppt Average sediment  delta  super(13)C and  delta  super(15)N values of -26.8 and 5.2ppt, respectively, were similar to water column material and consistent with a phytoplankton origin. Seston  delta  super(15)N values were more variable than  delta  super(13)C and ranged between 0.4 and 6.9ppt. The  delta  super(15)N of nitrate ranged between -5.0 and 0.9ppt and was markedly depleted in  super(15)N relative to seston. These are some of the lowest  delta  super(15)N values reported for nitrate in aquatic systems. We content that phytoplankton release  super(15)N depleted dissolved organic matter and that upon mineralization and nitrification, DOM is the primary source of nitrate in Lake Superior.
AN: 3825518

                                                                    186 of 1521  
TI: Seasonal trends in the natural abundances of carbon and nitrogen stable isotopes in the east basin of Lake Ontario
AU: Leggett,-M.F.; Servos,-M.R.; Hesslein,-R.; Johannsson,-O.; Dixon,-D.G.
AF: Great Lakes Lab. Fish. Aquat. Sci., 867 Lakeshore Rd., Burlington, ON, Canada
CO: 38. Conference of the International Association for Great Lakes Research, East Lansing, MI (USA), 28 May-1 Jun 1995
SO: PROCEEDINGS-OF-THE-38TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-OF-GREAT-LAKES-RESEARCH. 2200-BONISTEEL-BOULEVARD,-ANN-ARBOR,-MI-48109-2099-USA INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH 1995 p. 73
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Selective discrimination in biota between naturally occurring stable isotopes of carbon  super(13)C and  super(12)C, and nitrogen  super(14)N and  super(15)N, in biochemical reaction kinetic has been exploited in studies of food web dynamics in different ecosystems. Conclusions of these studies often assume that observed relative ratios of these stable isotope pairs are solely a function of the total reaction kinetics involved in the transfer of energy through a food chain. It is also assumed that the ratio of stable isotope pairs at the bottom of the food chain remains constant. Environmental conditions have been shown to affect the ratio of stable isotopes found in primary producers, and seasonal cycling has been observed in source carbon (dissolved inorganic carbon, DIC) in aquatic ecosystems. A seasonal fluctuation of the  super(13)C/ super(12)C ratio is shown in DIC, particulate organic carbon (POC), Diacyclops thomasi, and Bosmina longirostris at a site in the east basin and a mid-lake site. When possible  super(15)N/ super(14)N was also determined for each sample and the results of this analysis are plotted.
AN: 3825517

                                                                    187 of 1521  
TI: Records of ecosystem changes in the isotope signatures of organic matter in Great Lakes cores
AU: Eadie,-B.J.; Lansing,-M.B.; Robbins,-J.A.
AF: NOAA/Great Lakes Environ. Res. Lab., 2205 Commonwealth Blvd., Ann Arbor, MI 48109, USA
CO: 38. Conference of the International Association for Great Lakes Research, East Lansing, MI (USA), 28 May-1 Jun 1995
SO: PROCEEDINGS-OF-THE-38TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-OF-GREAT-LAKES-RESEARCH. 2200-BONISTEEL-BOULEVARD,-ANN-ARBOR,-MI-48109-2099-USA INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH 1995 p. 73
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Over the past 25 years, nutrient abatement practices have reduced the loading of phosphorus dramatically although nitrogen inputs and concentrations continue to increase. Monitoring data from the lakes cover this time period in some detail, but the records from before the late 1960s must come from signals in the sediments. In the lower lakes (Erie and Ontario), the  delta  super(13)C of organic matter reaches its heaviest value in the early 1970s and then decreases as nutrient reduction went into effect and primary production decreased. This effect is much less pronounced in the upper lakes.  delta  super(15)N of the organic matter in the lower lakes increases dramatically from a background value of 2-3ppt to a recent value of 10ppt. Again this change is significantly less in the upper lakes. Although there has been a major increase in N loads and sources of N (fertilizer and atmospheric), it appears that most of the isotopic shift recorded in sediments is due to denitrification in Lake Erie, with subsequent transport of this signal downstream to Lake Ontario. The  delta  super(15)N shift in the sediments of the lower lakes began soon after 1850, which corresponds to the period of clearcutting and beginning of agriculture in the basin.
AN: 3825516

                                                                    188 of 1521  
TI: Cycling of radionuclides in Lake Erie surface waters: The key role of microzooplankton grazing
AU: Twiss,-M.R.; Campbell,-P.G.C.; Auclair,-J.-C.
AF: INRS-Eau Univ. Quebec, C.P. 7500, Ste-Foy, QC G1V 4C7, Canada
CO: 38. Conference of the International Association for Great Lakes Research, East Lansing, MI (USA), 28 May-1 Jun 1995
SO: PROCEEDINGS-OF-THE-38TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-OF-GREAT-LAKES-RESEARCH. 2200-BONISTEEL-BOULEVARD,-ANN-ARBOR,-MI-48109-2099-USA INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH 1995 pp. 68-69
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Recent measurements in the Great Lakes reveal very low levels of dissolved trace metals. Current approaches to estimating trace metal concentrations and residence times in the water column are based on surface complexation modelling (SCM). The majority of particles in pelagic systems are biotic - among the most productive are the picoplankton (bacteria and algae, 0.2-2  mu m) which have a high potential to scavenge dissolved trace metals. The ecological fate of this plankton involves consumption by microzooplankton (2-200  mu m; e.g., flagellates, ciliates, rotifers). This grazing might reasonably be expected to convert some trace metals from the particulate to dissolved phase, and to increase the availability of metal-complexing organic ligands in the dissolved phase. In turn, this would serve to increase trace metal residence times and concentrations in surface waters in a manner unaccountably for by current predictive models based on SCM. Evidence of this activity is presented from a field study on the fate of radiolabelled picoplankton added to the natural plankton community of pelagic Lake Erie. Trace metal fates were followed using gamma-emitting radionuclides (Cs-137, Cd-109, Zn-65 and Gd-153) representing a range of chemical behaviours.
AN: 3825509

                                                                    189 of 1521  
TI: Cycles in Lake Malawi
AU: Patterson,-G.; Allison,-E.H.
AF: Nat. Resour. Inst., NRL, Chatham Maritime Kent, ME4 4TB, UK
CO: 38. Conference of the International Association for Great Lakes Research, East Lansing, MI (USA), 28 May-1 Jun 1995
SO: PROCEEDINGS-OF-THE-38TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-OF-GREAT-LAKES-RESEARCH. 2200-BONISTEEL-BOULEVARD,-ANN-ARBOR,-MI-48109-2099-USA INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH 1995 p. 56
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: The seasonal wind-induced cycle of mixing has a strong influence on biological production in Lake Malawi. Periods of increased mixing result in increases in nutrient availability to photosynthesising phytoplankton in the epilimnion, leading to higher primary production and increases in available food to, and production of, herbivorous zooplankton. Engraulicycpris sardella and Chaoborus larvae, which are important predators on the zooplankton, also show marked seasonality of production which coincides with the seasonal pattern of the lower trophic levels. This is an example of the dependence of biological production on nutrient availability and shows many of the characteristics of "bottom-up" control. There is no evidence to suggest that the seasonal production cycles are significantly dampened up the food chain, at least to tertiary producers and we suggest that production is controlled primarily by food supply.
AN: 3825250

                                                                    190 of 1521  
TI: Comparison of phosphorus concentration and turnover rates in lakes Erie, Huron, and Michigan with those of the East African Great Lake Victoria
AU: Lehman,-J.T.
AF: Dep. Biol. and Cent. Great Lakes Aquat. Sci., Nat. Sci. Bldg., Univ. Michigan, Ann Arbor, MI 48109, USA
CO: 38. Conference of the International Association for Great Lakes Research, East Lansing, MI (USA), 28 May-1 Jun 1995
SO: PROCEEDINGS-OF-THE-38TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-OF-GREAT-LAKES-RESEARCH. 2200-BONISTEEL-BOULEVARD,-ANN-ARBOR,-MI-48109-2099-USA INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH 1995 p. 54
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: North American Great Lakes Erie, Huron, and Michigan exhibit almost unmeasurably low concentrations of SRP with turnover times in epilimnion and metalimnion of only a few minutes. This well known situation in the North American lakes compares with turnover times of 5 days in the pelagic region of Lake Victoria, where SRP concentrations can be 1 micromolar. Nonetheless, at its outflow as the Nile, SRP concentrations are reduced and turnover times fall to minutes, similar to North American Great Lake levels. The changes in P economy of Lake Victoria are associated with algal biomass increases in shallower water. Model formulations of the turnover dynamics and their relationship to biomass levels are investigated for these tropical and temperate Great Lakes.
AN: 3825244

                                                                    191 of 1521  
TI: A model-assisted technique for computing "effective" phosphorus loading from bottom sediments
AU: Martin,-S.C.
AF: Dep. Civ. Environ. Eng., Youngstown State Univ., Youngstown, OH 44555, USA
CO: 38. Conference of the International Association for Great Lakes Research, East Lansing, MI (USA), 28 May-1 Jun 1995
SO: PROCEEDINGS-OF-THE-38TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-OF-GREAT-LAKES-RESEARCH. 2200-BONISTEEL-BOULEVARD,-ANN-ARBOR,-MI-48109-2099-USA INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH 1995 p. 39
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: When phosphorus loading reduction measures are implemented in a lake, the water quality response is often delayed by recycling of phosphorus stored in the bottom sediments. Sediment phosphorus recycling may continue to retard recovery of the water column even when sediments are acting as a net sink of phosphorus. The importance of sediment loading may be difficult to quantify in such cases. In this study, a new quantity called "effective" sediment phosphorus loading was developed for this purpose. The "effective" sediment loading is defined as the difference between the net rate of phosphorus exchange at the sediment-water interface at any given time during the recovery and the exchange rate when the system has reached steady-state. If an adequate data base is available to calibrate a mass-balance model for total phosphorus in the lake, then the model can be applied to estimate both quantities. This technique was applied to forecast the role of sediment phosphorus recycle in delaying water quality improvements in St. Albans Bay, Lake Champlain (VT), following a 90% reduction in point source loading. It was predicted that the "effective" sediment phosphorus loading will decline from 42 kg/d (50% of total load) in 1993 to 8.4 kg/d (22% of total load) by the year 2015.
AN: 3825206

                                                                    192 of 1521  
TI: Plankton productivity and biomass in the western Equatorial Pacific: Biological and physical controls
AU: Mackey,-D.J.; Parslow,-J.; Higgins,-H.W.; Griffiths,-F.B.; O'-Sullivan,-J.E.
AF: NRO Div. Oceanogr., GPO Box 1538, Hobart, Tas., Australia
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1995 vol. 42, no. 2-3, pp. 499-533
LA: English
ER: M (Marine)
AB: During October 1990 in the western Equatorial Pacific, from 5 degree S to 5 degree N along 155 degree E, the isothermal and isopycnal lines (near 150 m) domed upwards, surface temperatures were high (29.5-30 degree C), surface salinites were low (33.8-34.2), SST anomalies were <0.5 degree C between 120 degree E and 160 degree E, and the westward flowing SEC was well developed. These conditions are typical of non-ENSO conditions. An eastward flowing surface current was observed that was probably the result of a westerly wind burst. Between 5 degree S and 5 degree N, the barrier layer was much thicker south of the equator and the thickness of the barrier layer varied from 88 m at 2 degree S to 6 m at 1 degree N. Nitrate and nitrite were not detected in surface waters, but phosphate and silicate were present at concentrations of about 0.15  mu M and 1.5  mu M, respectively. Nitrate was always present at the deep chlorophyll maximum (DCM), which varied in depth from about 74 to 96 m. The distribution of chlorophyll a (plus divinyl-chlorophyll a) about the equator was distinctly bimodal, with the highest values (0.4 mu g l super(-1)) occurring 2 degrees either side of the equator. Depth integrated values ranged from 23 to 32 mg m super(-2), and despite the very different oceanographic conditions these values are similar to those found in the nutrient-rich waters of the central and eastern equatorial Pacific. However, primary production estimates ranged from 96 to 241 mg C m super(-2) day super(-1) (8.0 to 20.1 mmol C m super(-2) day super(-1)), and these are much lower than previous rates reported for the central and eastern equatorial Pacific. The vertical distribution of cyanobacteria varied markedly from 5 degree S to 5 degree N. North of the equator, the concentrations were fairly high and uniform in the upper water column whereas, south of the equator, surface concentrations were low with a subsurface maximum. This distribution of cyanobacteria suggests that there was transient enrichment north of the equator but not to the south. The low salinity surface layer was highly oligotrophic and appeared to be effectively isolated the subsurface fluxes of nitrate or dissolved inorganic carbon (DIC). Productivity in the surface layer seemed to be limited by the supply of nutrients, although there were indications that transient nutrient enrichment of surface waters may have occurred north of the equator. In the DCM it appeared to be limited by light. Integrated primary production and cyanobacterial cell counts were elevated north of the equator where the barrier layer was thin. The isolation of the surface waters from the deeper waters that were enriched in nutrients and DIC caused the pCO sub(2) values in surface waters to be in near equilibrium with the atmosphere. Despite a strong N-S gradient in the thickness of the barrier layer, the nitracline and upper boundary of the deep chlorophyll maximum were independent of latitude and occurred at  approximately 60-70 m, close to the depth of 10% light penetration.
AN: 3823962

                                                                    193 of 1521  
TI: Sulfate reduction rates and low molecular weight fatty acid concentrations in the water column and surficial sediments of the Black Sea
AU: Albert,-D.B.; Taylor,-C.; Martens,-C.S.
AF: Curriculum Mar. Sci., Univ. North Carolina, Chapell Hill, NC 27599, USA
SO: DEEP-SEA-RES.-I-OCEANOGR.-RES.-PAP. 1995 vol. 42, no. 7, pp. 1239-1260
LA: English
ER: M (Marine)
AB: Sulfate reduction rates and concentrations of low molecular weight organic acids were measured in the water column and surficial sediments at two sites in the central Black Sea. Water column sulfate reduction rates were much lower than previously reported. The highest rate measured was 3.5 nM/day and on a depth integrated basis values of 1.2 and 0.22 mmol/m super(2)/day were obtained for the two sites. Sediment sulfate reduction rates were within the ranges previously reported but were higher than some for comparable abyssal sites. Rates were about 21  mu M/day in the flocculent layer at the sediment-water interface, decreasing to 2-3  mu M/day at 20 cm depth. On an areal, depth integrated basis, rates at the two sites were 1.45 and 1.29 mmol/m super(2)/day. Thus, the water column and sediments have comparable areal rates, but on a volume basis the sediment rates are several thousand times higher than the water column rates. Organic acid concentrations in the anoxic Black Sea water column were surprisingly high, reaching several  mu M in some cases. One deep sample contained 60  mu M acetate. Lactate, acetate and formate were the only acids detected in the water column. Some propionate was seen in sediment porewaters. Apparent turnover times of the organic acids in the water column, calculated for utilization solely by sulfate reducing bacteria, are tens to hundred of years. This suggests that sulfate reduction rates in the water column were not limited by organic substrate supply. In the sediments, apparent acid turnover times calculated in this way are generally less than one day, suggesting that sulfate reduction may be limited to by the supply of these substrates through fermentation reactions.
AN: 3823926

                                                                    194 of 1521  
TI: Spatial distribution and trophic transfer of lead in Lake Superior
AU: Beals,-T.M.; Long,-D.T.; Ostrom,-N.E.
AF: Dep. Geol. Sci., Michigan State Univ., East Lansing, MI 48824, USA
CO: 38. Conference of the International Association for Great Lakes Research, East Lansing, MI (USA), 28 May-1 Jun 1995
SO: PROCEEDINGS-OF-THE-38TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-OF-GREAT-LAKES-RESEARCH. 2200-BONISTEEL-BOULEVARD,-ANN-ARBOR,-MI-48109-2099-USA INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH 1995 p. 102
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Large lakes are composed of a number of physically distinct compartments, including: (1) dissolved components in the water column, (2) suspended solids, (3) sediments, and (4) pore waters. Chemical gradients within and between these compartments will affect the trophic transfer of contaminants in the biological community. Within a depositional basin spatial gradients in a contaminant's settling flux through the water column, rate of accumulation in the sediment, and diagenetic flux have implications on its uptake by benthic organisms and, subsequently, its fate in the environment. Water column, suspended sediment, sediment column, pore water, and biological samples were collected from Lake Superior using the R/S Clelia and R/V Edwin Link. Water column and pore water samples were analyzed by Graphite Fumace Atomic Absorption Spectrophotometry (GF/AAS). Solid phase samples were subjected to a HNO sub(3) microwave digestion and the leachate analyzed by GF/AAS. Preliminary results indicate that dissolved Pb concentrations in both the water column and pore waters are less than 1.0 g/L. Concentrations of Pb in both the benthic nepheloid and fluff layers are higher than that in the sediment column with the fluff being greater than the nepheloid. Concentration profiles of Pb in the sediment column exhibit anthropogenic loadings similar to ones determined by previous studies. However, the total anthropogenic Pb inventories are greater than previous studies and the peak concentration occurs at a greater depth due to continued sediment accumulation between the time of sampling. Sediment accumulation of Pb continues to decrease to the present day.
AN: 3823779

                                                                    195 of 1521  
TI: Biogeochemical origin of  delta  super(34)S isotopic signatures in a prairie marsh
AU: Cornwell,-J.C.; Neill,-C.; Stevenson,-J.C.
AF: Horn Point Environ. Lab., Univ. Maryland Cent. Environ. Estuar. Stud., Cambridge, MD 21613-0775, USA
SO: CAN.-J.-FISH.-AQUAT.-SCI.-J.-CAN.-SCI.-HALIEUT.-AQUAT. 1995 vol. 52, no. 8, pp. 1816-1820
LA: English
ER: F (Freshwater)
AB: Sulfur isotope ratios were determined in a prairie marsh at Delta, Manitoba, Canada, to determine whether organic matter produced in the marsh had distinctive isotopic signatures. High sulfate levels in sediments from the Delta Marsh arise from high salt concentrations in soils. Sulfate reduction is the major anaerobic metabolic pathway in this sediment system and sulfate diffused into sediment both from deeper soil horizons and from overlying water. Surface water  delta  super(34)S-SO sub(4) super(2-) values of 15  plus or minus  1ppt increased to a maximum of almost 40ppt in deeper sediment horizons, in marked contrast to sediment pore water  delta  super(34)S-H sub(2)S values of 2  plus or minus  4ppt. The high degree of discrimination between  delta  super(34)S in sulfate and in hydrogen sulfide is similar to that found in brackish and marine ecosystems.
AN: 3823740

                                                                    196 of 1521  
TI: Seasonal and lateral variations in carbon chemistry of surface water in the eastern Equatorial Pacific during 1992
AU: Wanninkhof,-R.; Feely,-R.A.; Atwood,-D.K.; Berberian,-G.; Wilson,-D.; Murphy,-P.P.; Lamb,-M.F.
AF: Atl. Oceanogr. and Meteorol. Lab., Miami, FL 33149, USA
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1995 vol. 42, no. 2-3, pp. 387-409
LA: English
ER: M (Marine)
AB: During the (boreal) spring and fall of 1992 the NOAA Ocean-Atmosphere Carbon Exchange Study did an intensive survey of upper water column (<1000 m) chemistry in the eastern equatorial Pacific from 110 degree W to 170 degree W. The spring-time conditions were influenced by an El Nino that had disappeared before the fall cruises. This contributed to a large seasonal contrast in surface temperature, carbon and nutrient concentrations, and thermocline depth. Nitrate, total inorganic carbon, and fugacity of CO sub(2) values were significantly lower in the spring, while sea surface temperatures south of the equator were higher. The seasonal change in surface water chemistry at the equator is due to changes in upwelling of nutrient and carbon enriched water. Oxygen and CO sub(2) anomalies at the surface point to approximately a three-fold increase in upwelling of thermocline water in the fall compared to the spring. The large-scale spatial variations in the surface chemistry patterns remained unchanged between spring and fall. There was a westward decrease in surface-water carbon and nitrate concentrations and a strong north to south asymmetry with higher carbon and nitrate values south of the equator. This pattern is attributed to input of carbon and nutrients with the South Equatorial Current from the east. Using velocities obtained from surface drifters tracks, along with reasonable gas exchange estimates, and a "Redfield analysis" to account for export biological production, this westward decrease in carbon and nutrients can be quantitatively accounted for in the region from 0 to 3 degree S and 110 degree W to 140 degree W in the spring. In the fall the calculated concentration decrease is greater than observed, which is attributed to input from local equatorial upwelling along the pathway of water transit.
AN: 3822077

                                                                    197 of 1521  
TI: The role of pH measurements in modern oceanic CO sub(2)-system characterizations: Precision and thermodynamic consistency
AU: Clayton,-T.D.; Byrne,-R.H.; Breland,-J.A.; Feely,-R.A.; Millero,-F.J.; Campbell,-D.M.; Murphy,-P.P.; Lamb,-M.F.
AF: Dep. Mar. Sci. Univ. South Florida, St. Petersburg, FL 33701, USA
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1995 vol. 42, no. 2-3, pp. 411-429
LA: English
ER: M (Marine)
AB: In May 1992, surface seawater samples were collected along an equatorial transit (130 to 100 degree W) and analyzes for total hydrogen ion concentration (expressed as spectrophotometric pH sub(T)) total dissolved inorganic carbon (coulometric C sub(T)), and total alkilinity (potentiometric A sub(T) and spectrophotometric A sub(T)). This data set, which presents a striking view of the chemical signature of tropical instability waves, is also unusual in that its "overdetermination" of the CO sub(2)-system in seawater includes both potentiometric A sub(T) data and the first spectrophotometric A sub(T) data collected at sea using a double-wavelength, one-step acid addition method. Our data set indicates that spectrophotometric A sub(T) measurements (A sub(Tspec)) are both precise ( plus or minus 1.8  mu mol/kg) and accurate; the mean observed difference between A sub(Tspec) and A sub(T) obtained potentiometrically in this study (A sub(Tpot)) is 1  mu mol/kg. As only two of the three measured parameters are required to characterize the CO sub(2)-system in seawater, this analytical redundancy of our analyses (C sub(T), A sub(T), pH) afforded an opportunity to evaluate, in terms of thermodynamic consistency, a recent calibration of m-cresol purple, a pH indicator. Using various carbonic acid dissociation constants, measured parameters were combined in pairs (C sub(T)-A sub(T), pH-C sub(T), and pH-A sub(T)) to calculate a third parameter for comparison with the shipboard measurements. Depending on the selected set of carbonic acid dissociation constants, the average offset between directly measured and predicted values of A sub(T) and C sub(T) was as small as  plus or minus 1  mu mol/kg. The results of this study indicate that the present 25 degree C mCP calibration, paired with the 25 degree C combined dissociation constants of Hansson and Mehrbach, produces accurate predictions of A sub(T) and C sub(T). Extensive replication of the shipboard spectrophotometric measurements made it possible to examine directly the sensitivity of derived parameters to variations or errors in input A sub(T) and pH. In accord with earlier theoretical treatments of this question, the results presented demonstrate that pH is imprecisely predicted from A sub(T) and C sub(T), whereas imprecision in measured pH-at the level typical of spectrophotometric measurements ( plus or minus 0.0004)-contributes negligibly ( plus or minus 0.3  mu mol/kg) to imprecision in derived A sub(T) and C sub(T). In view of the high precision of pH sub(Tspec) measurements and both the precision and reliability of C sub(T) measurements (supported by the use of certified SIO reference materials) pH sub(Tspec) and C sub(Tcoul) constitute a particularly useful pair of parameters for shipboard study of the oceanic carbon dioxide system. The results indicate, as well, that the A sub(T)-pH sub(Tspec) pairing is of particular interest in ocean regions where simple A sub(T) vs salinity relationships are observed. In light of recent advances, the role of pH measurements in CO sub(2)-system characterizations should be re-evaluated. Spectrophotometric measurements of pH have much to contribute in documenting the oceans' evolving response to anthropogenic CO sub(2).
AN: 3822075

                                                                    198 of 1521  
TI: Mesozooplankton grazing and metabolism at the equator in the Central Pacific: Implications for carbon and nitrogen fluxes
AU: Dam,-H.G.; Zhang,-Xinsheng; Butler,-M.; Roman,-M.R.
AF: Dep. Mar. Sci., Univ. Connecticut, Groton, CT 06340-6097, USA
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1995 vol. 42, no. 2-3, pp. 735-756
LA: English
ER: M (Marine)
AB: Primary productivity and chlorophyll in the Equatorial Pacific are lower than expected based on ambient nutrient concentrations. We tested the hypothesis that these conditions are due to a balance between phytoplankton growth and mesozooplankton grazing. Grazing rates and biomasses of three size classes of zooplankton in the size range of 200-200  mu m were measured during March-April and October of 1992 at the equator (140 degree W). El Nino conditions prevailed in March-April, whereas in October a tropical instability wave (TIW) passed through the study area. Weight-specific pigment ingestion rates of mesozooplankton tended to be higher in March-April than in October while the opposite was the case for biomass. There were no discernible temporal trends in mesozooplankton community grazing rates in March-April, but there were changes in October associated with the passage of the TIW. Mesozooplankton grazing removed 1-9% day super(-1) of the total chlorophyll and 1-12% of the primary production within the euphotic zone. Therefore, the grazing hypothesis as stated above is rejected, although a simple chlorophyll budget suggests that grazing (mostly by microzooplankton) and phytoplankton growth are roughly in balance. Most of the phytoplankton was <2  mu m and presumably unavailable as food for mesozooplankton. If we assume that mesozooplankton only fed on >2- mu m phytoplankton, we estimate removal rates of the >2- mu m chlorophyll standing stock of up to 27% day super(-1). Another question of biogeochemical importance is the rate of the production of large diatoms. Mesozooplankton grazing could have balanced growth of the large (>20- mu m) diatoms in March-April, but not in October. From estimates of respiration and excretion based on water temperature and body size, we infer that: (1) >80% of the carbon ingested by mesozooplankton is not phytoplankton; (2) mesozooplankton excretion supports <7% of the nitrogen demands of phytoplankton; (3) the flux of carbon passing through the mesozooplankton would be equivalent to 23% of the primary production; (4) mesozooplankton fecal carbon could account for 100% of the sinking POC flux in this region. Finally, a simple food chain analysis suggests that a significant fraction of the microzooplankton production probably passes through mesozooplankton.
AN: 3821988

                                                                    199 of 1521  
TI: Surface pH and pCO sub(2) distributions in the Bellingshausen Sea, Southern Ocean, during the early Austral summer
AU: Bellerby,-R.G.J.; Turner,-D.R.; Robertson,-J.E.
AF: Dep. Mar. Chem. and Geochem., Woods Hole Oceanogr. Inst., Woods Hole, MA 02543, USA
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1995 vol. 42, no. 4-5, pp. 1093-1107
LA: English
ER: M (Marine)
AB: Measurements of the carbon dioxide system (pH, pCO sub(2)) from the Bellingshausen Sea, Southern Ocean are discussed in relation to varying biological activity and hydrography. pH was determined using on-line indicator spectrophotometry and varied between 7.65 and 7.85 (at 25 degree C) and between 8.04 and 8.25 at in situ temperatures. Except for the Bransfield Strait, pCO sub(2) was below atmospheric pCO sub(2) for the duration of the cruise, with the average level being 295  plus or minus  32  mu atm (1 SE). Large mesoscale variability with no single control on the surface seawater carbon dioxide system was observed, although the majority of the study area was predominantly influenced by the hydrography of the circumpolar waters. The most significant exception being a region with high chlorophyll concentration south of the Southern Polar Front.
AN: 3820137

                                                                    200 of 1521  
TI: Spatial variability of inorganic nutrients in the marginal ice zone of the Bellingshausen Sea during the Austral spring
AU: Whitehouse,-M.J.; Priddle,-J.; Woodward,-E.M.S.
AF: Br. Antarct. Surv., NERC, High Cross, Madingley Rd., Cambridge CB3 0ET, UK
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1995 vol. 42, no. 4-5, pp. 1047-1058
LA: English
ER: M (Marine)
AB: Data on nutrients (nitrate, nitrite, ammonium, phosphate, silicate), biogenic-silica and chlorophyll a concentrations were collected along a south-to-north transect through the marginal ice zone of the Bellingshausen Sea during the Austral spring of 1992. There was a marked gradient in near-surface ( less than or equal to 100 m) concentrations from the most southerly occupied station (70 degree 15'S, 85 degree 07'W) to the northernmost (67 degree 30'S, 85 degree 00'W). Chlorophyll a concentrations increased from  similar to 0.1 at the most southerly station to >4.0 mg m super(-3) in the north. A simple ice-melt model suggests that only a proportion of the previous winter's sea-ice had melted in the study area. The impact of this ice-melt on nutrient concentrations was trivial. Predicted time-scales of nutrient removal by phytoplankton growth varied for the three nutrients. Nitrogen uptake appeared to be underestimated with respect to phosphorous, consistent with measurements of nitrogen preference from the same cruise. Silicate use appeared to have started later than nitrogen or phosphorus uptake, indicative of species succession in the phytoplankton.
AN: 3820134

                                                                    201 of 1521  
TI: A biogeochemical study in the Bellingshausen Sea: Overview of the STERNA 1992 expedition
AU: Turner,-D.R.; Owens,-N.J.P.
AF: Dep. Anal. and Mar. Chem., Goeteborg Univ. and Chalmers Univ. Technol., S-412 96 Goeteborg, Sweden
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1995 vol. 42, no. 4-5, pp. 907-932
LA: English
ER: M (Marine)
AB: A general overview and background of a two-ship study to examine biogeochemical fluxes in the marginal ice-zone of the Bellingshausen Sea (65-70 degree S; 80-87 degree W), SE Pacific sector of the Southern Ocean is presented. The major feature studied was an intense band of chlorophyll that was found geographically close to a receding ice-edge. However, the bloom appeared not to be a result of a shallow mixed layer caused by ice-melt stabilisation, but rather associated with an oceanic front that coincided with the ice-edge. Details of the hydrographic conditions existing along the 85 degree W meridian from the ice-edge to open water to the north, and detailed surveys of surface hydrographic conditions are presented.
AN: 3820128

                                                                    202 of 1521  
TI: The impact of marginal ice zone processes on the distribution of  super(210)Pb,  super(210)Po and  super(234)Th and implications for new production in the Bellingshausen Sea, Antarctica
AU: Shimmield,-G.B.; Ritchie,-G.D.; Fileman,-T.W.
AF: Mar. Geosci. Unit, Dep. Geol. and Geophys., Univ. Edinburgh, West Mains Rd., Edinburgh EH9 3JW, UK
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1995 vol. 42, no. 4-5, pp. 1313-1335
LA: English
ER: M (Marine)
AB: The vertical distributions of  super(210)Pb,  super(210)Po and  super(234)Th in both dissolved and particulate phases of seawater were measured at five stations along the 85 degree W meridian in the Bellingshausen Sea, Antarctica. Sea-ice conditions during the expedition ranged from fully ice-covered (fast ice) to open water away from the marginal ice zone. Concurrent primary productivity and algal chlorophyll measurements revealed a band of high productivity at approximately 67 degree 30'S, which remained in a rather static location during ice melt-back. Along the transect a progressive increase in removal ("scavenging") and sinking of  super(210)Pb,  super(210)Po and  super(234)Th occurred towards the north (open water conditions). Application of a simple, irreversible scavenging model, and particulate organic carbon and organic nitrogen to radionuclide ratios measured on suspended particulate matter, allows the calculation of export production for this region. Radionuclide estimates of new production are significantly greater than those obtained by traditional sediment trap methods. This may be due to the dynamic nature (short duration and spatial variability) of algal growth in the Southern Ocean.
AN: 3820121

                                                                    203 of 1521  
TI: Nitrogen dynamics in the Bellingshausen Sea during the Austral spring of 1992
AU: Waldron,-H.N.; Attwood,-C.G.; Probyn,-A.; Lucas,-M.I.
AF: Dep. Oceanogr., Univ. Cape Town, Priv. Bag, Rondesbosch, Cape Town 7700, South Africa
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1995 vol. 42, no. 4-5, pp. 1253-1276
LA: English
ER: M (Marine)
AB: A series of  super(15)N experiments were conducted in the early summer of 1992 during the course of cruise 198 of R.R.S. Discovery, with a focus on the seasonal ice zone (SIZ) of the Bellingshausen Sea. Nitrogen (NO sub(3), NH sub(4) and urea) uptake was measured over the nominal euphotic zone, and size fractionation experiments of a similar nature were conducted on surface waters. The most productive zone during this study was not associated with stable ice-melt water but with a west-east oriented, haline dominated density front centred around 67.3 degree S. The pelagic bloom coincident with the area south of the front had a banded structure with chlorophyll a concentrations up to 5 mg m super(-3). The bloom was dominated by Porosira glacialis, Coscinodiscus bouvet, Thalassiosira antarctica and Phaeocystis spp. The rates of new production presented here are the first to have been made in the Bellingshausen Sea and as such can be incorporated in regional and global models relating to the sink of carbon.
AN: 3820120

                                                                    204 of 1521  
TI: super(13)C and  super(15)N uptake by phytoplankton in the marginal ice zone of the Bellingshausen Sea
AU: Bury,-S.J.; Owens,-N.J.P.; Preston,-T.
AF: Scottish Univ. Res. and Reactor Cent., East Kilbride, Glasgow G75 0QF, UK
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1995 vol. 42, no. 4-5, pp. 1225-1252
LA: English
ER: M (Marine)
AB: A two-ship cruise to the Bellingshausen Sea marginal ice zone (MIZ) in the Austral spring-summer 1992 enabled a detailed study of the phytoplankton dynamics during the retreat of the ice sheet. Stations were set up along a transect from within the ice sheet 70 degree S, 85 degree W to the open ocean 67 degree S, 85 degree W, and the rates of primary production and nitrogen uptake were determined in the ice and water column using in situ  super(13)C and  super(15)N incubation techniques. Nitrogen uptake was subdivided into components of nitrate, ammonium and urea uptake, and fractionated into <20  mu m and >20  mu m size classes. A detailed discussion of methods available for f-ratio calculations using several different data sets from this cruise are given. Varied estimates resulting from this exercise have important implications in terms of global carbon budget calculations. Productivity estimates from  super(13)C and  super(15)N uptake data are compared with  super(14)C data, and nitrate, phosphate, chlorophyll and pCO sub(2) mass balance estimates. These data are discussed in the context of past studies in other areas of the Southern Ocean.
AN: 3820119

                                                                    205 of 1521  
TI: Water column and sea-ice primary production during Austral spring in the Bellingshausen Sea
AU: Boyd,-P.W.; Robinson,-C.; Savidge,-G.; William,-P.J.leB.
AF: Dep. Oceanogr., Univ. British Columbia, Vancouver, BC V6T 1Z4, Canada
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1995 vol. 42, no. 4-5, pp. 1177-1200
LA: English
ER: M (Marine)
AB: The findings of a cruise to study the phytoplankton bloom dynamics associated with the marginal ice zone (MIZ) in the Bellingshausen Sea during Austral spring (November-December) 1992 are reported. Biomass and rate process measurements were carried out at stations located in the ice, ice edge and open water along the 85 degree W meridian in order to establish the productivity of the microalgae associated with sea-ice and in the water column. In addition, a series of transects along 85 degree W from sea-ice to open water conditions enabled an assessment of the development of phytoplankton populations. Low phytoplankton biomass and production were noted at ice-covered and ice-edge stations and in the open water close to the ice edge. Observations from the transects indicated no development of a classical ice edge bloom despite evidence that sea-ice had retreated more than 100 km during the study period. A modelling approach using  super(14)C observations suggested that phytoplankton growth was less than the sum of the algal loss terms within this feature. An advective supply of cells therefore would be required to sustain the observed high and constant algal biomass. In addition, although this high chlorophyll feature was initially observed during brash-ice conditions, the available data suggest that it was initiated under open water conditions.
AN: 3820118

                                                                    206 of 1521  
TI: A biological acoustic survey in the marginal ice-edge zone of the Bellingshausen Sea
AU: Murray,-A.W.A.; Watkins,-J.L.; Bone,-D.G.
AF: Br. Antarct. Surv., High Cross, Madingley Rd., Cambridge CB3 0ET, UK
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1995 vol. 42, no. 4-5, pp. 1159-1175
LA: English
ER: M (Marine)
AB: An acoustic survey at 38 kHz was carried out from R.R.S. Discovery in the Bellingshausen Sea from 23 November to 7 December 1992 as part of the U.K. Joint Global Ocean Flux Study (JGOFS) Southern Ocean investigations [Turner D. and N.J.P. Owens (1995) Deep-Sea Research II, 42, 907-932]. A total of 285 targets were identified and described from the chart record of the echo sounder. Mean volume backscattering strength data were collected using an echo integration system. These data are used to describe the spatial and temporal variability of krill (Euphausia superba) distribution and biomass in the marginal ice-edge zone. Krill biomass density varied from a mean of 42 g m super(-2) during the first survey phase to 20 g m super(-2) on the second survey phase. The number of small swarms detected during the second phase was greater than during the first phase. On this first survey a large swarm (2.8 km in extent) had a potential biomass of 3.7 x 10 super(4) tonnes. Some calculations are presented to show the potential impact of krill on the flux of carbon in the area of the survey.
AN: 3820117

                                                                    207 of 1521  
TI: Role of suspension-feeders in the exchanges at the water-sediment interface in a coastal area subject to strong tidal currents: Experimental approach
OT: Role des organismes suspensivores dans les transferts pelago-benthiques d'une zone de fort hydrodynamisme: Approche experimentale
AU: Migne,-A.; Davoult,-D.
AF: Stn. Marine URA-CNRS 1363, BP 80, 62930 Wimereux, France
SO: J.-RECH.-OCEANOGR. 1995 vol. 20, no. 1-2, pp. 9-14
LA: French
ER: M (Marine)
AB: A rich benthic community (mean biomass: 270 g m super(-2) in ash-free dry weight), exposed to strong tidal currents, is dominated by suspension-feeders. Experimental measurements of transfers of matter through nutrition, excretion and respiration of the 3 dominant species (Biothrix fragilis, Urticina felina and Alcyonium digitatum) were used to estimate carbon and nitrogen fluxes between the water and the benthic community.
AN: 3817474

                                                                    208 of 1521  
TI: Influence of the tube-building spionid polychaete Polydora ciliata on benthic parameters, associated fauna and transport processes
AU: Noji,-C.I.M.
AF: Inst. Fish. Mar. Biol. Univ. Bergen, Thormohlensgt 55, 5008 Bergen, Norway
CO: 4. Conference Internationale des Polychetes, Angers (France), 27 Jul-1 Aug 1992
SO: PROCEEDINGS-OF-THE-4TH-INTERNATIONAL-POLYCHAETE-CONFERENCE,-27-JULY-1-AUGUST-1992,-ANGERS,-FRANCE.-ACTES-DE-LA-4E-CONFERENCE-INTERNATIONALE-DES-POLYCHETES,-27-JUILLET-1-AOUT-1992,-ANGERS,-FRANCE. Dauvin,-J.-C.;Laubier,-L.;Reish,-D.J.-eds. PARIS-FRANCE EDITIONS-DU-MUSEUM-NATIONAL-D'-HISTOIRE-NATURELLE 1994 vol. 162 pp. 493-501
ST: MEM.-MUS.-NATL.-HIST.-NAT.-ZOOL. vol. 162
LA: English
ER: M (Marine)
AB: The influence of thc tube-building spionid Polydora ciliata Johnston on benthic community, sediment properties and exchange processes through the sediment surface was investigated. Findings showed that spionid tube lawns (eight or more tubes. cm- super(2)) lowered sediment stability and enhanced accumulation of suspended particles. Organic matter was selectively transported into the sediment via feeding, which enriched sediments by up to 100 %. Only a slight increase in fluid transport in the upper sediment layers was attributed to P. ciliata. Polydora tube lawns significantly increased abundance and diversity of meio- and macrofauna. Further they increased food input to the sediments and substrate area for colonization by micro- and meiofauna. Their fecal pellets may serve as a food source for meiofauna and chemotrophs in deeper sediment layers. Hence, Polydora ciliata, a well-known pioneer species, reconditions disturbed sediments, where it may represent a food item for benthic grazers.
AN: 3817307

                                                                    209 of 1521  
TI: Ecology and biogeochemistry of Paralvinella sulfincola at northeast Pacific hydrothermal vents: Review and comparison with Alvinella spp. of the East Pacific Rise
AU: Juniper,-S.K.
AF: Geotop & Dep. Sci. Biol., Univ. Quebec a Montreal, C.P. 8888, Succ.A., Montreal, PQ H3C 398, Canada
CO: 4. Conference Internationale des Polychetes, Angers (France), 27 Jul-1 Aug 1992
SO: PROCEEDINGS-OF-THE-4TH-INTERNATIONAL-POLYCHAETE-CONFERENCE,-27-JULY-1-AUGUST-1992,-ANGERS,-FRANCE.-ACTES-DE-LA-4E-CONFERENCE-INTERNATIONALE-DES-POLYCHETES,-27-JUILLET-1-AOUT-1992,-ANGERS,-FRANCE. Dauvin,-J.-C.;Laubier,-L.;Reish,-D.J.-eds. PARIS-FRANCE EDITIONS-DU-MUSEUM-NATIONAL-D'-HISTOIRE-NATURELLE 1994 vol. 162 pp. 453-462
ST: MEM.-MUS.-NATL.-HIST.-NAT.-ZOOL. vol. 162
LA: English
ER: M (Marine)
AB: The "sulfide worm" Paralvinella sulfincola Desbruyeres & Laubier 1993. of Northeast Pacific hydrothermal vents, builds mucous tubes on the surface of high temperature chimneys. as does Alvinella spp. on the East Pacific Rise. P. sulfincola is a deposit feeder and likely grazes on thermophilic chimney bacteria. It is argued that deposit feeding is also the primary source of nutrition for Alvinella spp. The influence of both worms on the sulfur cycle and on chimney mineralization processes is discussed. While Alvinella appears to be more elaborate in its adaptations to the high temperature chimney environment, the functional significance of some of these apparent adaptations remains unclear. Observed effects of P. sulfincola on chimney mineralization suggest that the question of how Alvinella spp. influences chimney growth patterns needs to be re-addressed. Two previously proposed roles for the epibiotic bacteria in Alvinella spp., nutrition and detoxification, can be accomplished by P. sulfincola without the aid of episymbionts. This is a strong argument for a re-evaluation of the nature of the Alvinella bacteria symbiosis.
AN: 3817302

                                                                    210 of 1521  
TI: Biogeochemical cycling of nutrients and trace metals in anoxic freshwater sediments of the Neckar River, Germany
AU: Song,-Y.; Muller,-G.
AF: Heidelberg Univ. Inst. of Sedimentol., D-69020 Heidelberg, FRG
CO: 6. International Symposium. International Association for Sediment Water Sciences Santa Barbara, CA (USA)
SO: MAR.-FRESHWAT.-RES. 1995 vol. 46, no. 1, pp. 237-243
NT: 33 ref.
LA: English
ER: F (Freshwater)
AB: Pore-water components including nutrients alkalinity and pH were determined at three sites in the Neckar River. Sequential extraction procedures and trace metals in both pore waters and sediments are reported in order to evaluate the mobility of trace metals in contaminated sediments. The results show that the mineralisation of organic matter plays an important role in the cycling. Pore-water profiles suggest that the element maxima at the sediment-water interface are caused by the decomposition of biomass. Low concentrations of dissolved trace metals in the anoxic sediments can be explained by a sharp decrease in sulphate in pore water concomitant with hydrogensulfide ion production. This leads to the formation of highly insoluble metal sulfides. Solubility calculations show that the sediments act as a sink for trace metals with respect to sulfides. No significant fluxes of ammonium or phosphate into overlying water were found, due to the existence of an oxic surface layer.
AN: 3815244

                                                                    211 of 1521  
TI: Comparison of the sedimentation of a diatom spring bloom and of a subsurface chlorophyll maximum
AU: Olesen,-M.
AF: Mar. Biol. Lab., Univ. Copenhagen, DK-3000 Helsingoer, Denmark
SO: MAR.-BIOL. 1995 vol. 121, no. 3, pp. 541-547
NT: Bibliogr.: 27 ref.
LA: English
ER: M (Marine)
AB: The seasonal pattern of sedimentation was determined over a 8-mo investigation period covering the productive season at a permanent station in the Southern Kattegat (Denmark) in 1990. The phytoplankton succession was characterised by a 4-mo long subsurface maximum associated with the pycnocline which was entirely dominated by the dinoflagellate Gyrodinium aureolum. The bulk sedimentation of organic matter took place during this period and accounted for >60% of the annual particulate organic carbon (POC) and particulate organic nitrogen (PON) sedimentation. The spring bloom period contributed 60% of the sedimentation of intact phytoplankton cells, but only 20% of the POC and PON sedimentation. A minor fraction of the sedimenting matter from the subsurface phytoplankton maximum consisted of intact phytoplankton (< 20%), suggesting that the phytoplankton was processed by heterotrophs and that it was mainly products from this activity which contributed to the vertical flux of organic matter. The variation in oxygen concentration below the pycnocline coincided with the pattern of sedimentation with a delay of 3 to 6 wk.
AN: 3812468

                                                                    212 of 1521  
TI: Evidence of the potential influence of planktonic community structure on the interannual variability of particulate organic carbon flux
AU: Boyd,-P.; Newton,-P.
AF: Dep. Oceanogr., Univ. British Columbia, 6270 University Blvd., Vancouver, BC V6T 1W5, Canada
SO: DEEP-SEA-RES.-I-OCEANOGR.-RES.-PAP. 1995 vol. 42, no. 5, pp. 619-639
LA: English
ER: M (Marine)
AB: The functioning of the biological pump during spring blooms was assessed with biogeochemical data from JGOFS (Joint Global Ocean Flux Study) process studies in the NE Atlantic during 1989 and 1990. A comparison of the integrated primary productivity signal (estimated by the  super(14)C technique and from changes in ambient surface-water [tCO sub(2)] and [NO sub(3) super(-)] during the spring blooms of the two years revealed close similarities. These observations suggest that the magnitude of the biological drawdown of CO sub(2) via photosynthetic activity during these periods was comparable. However, despite similarities in the magnitudes of these and other surface rate processes, sediment trap particulate organic carbon (POC) fluxes at 3100 m representing the spring bloom settlement events were 1.8 times greater in 1989 than in 1990. Taking into account the spatial and temporal resolutions of pelagic and deep trap datasets, these observations suggest that the coupling between organic carbon production in surface waters and its transfer to the deep ocean was stronger in the period studied in 1989 than in 1990. That is, the biological pump was more efficient in 1989. The size of the dominant phytoplankton species was observed to the principal difference between the two spring bloom data sets. The potential influence of the observed algal size differences on the vertical POC flux was quantified from size-fractionated productivity data in conjunction with a food web-vertical flux model. The derived POC fluxes from the surface layer were two times greater in spring 1989 than in the bloom period in 1990, and a comparison of these flux estimates with those from other methods is favourable. Extrapolation of these derived shallow POC fluxes to 3100 m with existing empirical algorithms yields deep POC fluxes that are consistent with those collected by sediment traps at this depth. Differences in algal size between the two spring blooms can thus account for the observed interannual differences in deep-water POC fluxes without the need to invoke interannual differences in unmeasured mid-water processes. This work provides a clear demonstration that although observations of oceanic productivity may yield the input to the biological pump, they cannot, on annual timescales, reliably provide information on the efficiency of the pump in transferring carbon to the deep ocean.
AN: 3810599

                                                                    213 of 1521  
TI: The role of a silicate pump in driving new production
AU: Dugdale,-R.C.; Wilkerson,-F.P.; Minas,-H.J.
AF: Dep. Biol. Sci., Univ. Southern California, Los Angeles, CA 90089, USA
SO: DEEP-SEA-RES.-I-OCEANOGR.-RES.-PAP. 1995 vol. 42, no. 5, pp. 697-719
LA: English
ER: M (Marine)
AB: In the past, the importance of silicate as a limiting nutrient for new production in the ocean, and in determining global productivity and carbon budgets, has been relegated to the lower ranks compared to the role of nitrogen and, more recently, iron. This paper describes a "silicate pump" that acts in diatom-dominated communities to enhance the loss of silicate from the euphotic zone to deep water compared to nitrogen, which is more readily recycled in the grazing loop, thus leading the system to silicate limitation. The impact of this silicate pump is described for the HNLC (High Nutrient-Low Chlorophyll) waters offshore from 15 degree S, Peru and reproduced in a simulation model of a diatom-dominated ecosystem. Silicate pumping to deep water results in low silicate, high nitrate conditions in the mixed layer, shown here to be a characteristic of many HNLC areas. These areas should more accurately be termed HNLSLC (High Nitrate-Low Silicate-Low Chlorophyll) areas. Silicate dynamics may control and dominate new production processes in these areas and consequently control the rate at which newly upwelled CO sub(2) in the surface regions is reduced by the phytoplankton. In such silicate-controlled systems, export production (i.e. production that is lost to deep water) of silicon and nitrogen are not equivalent, since export production of silicon is controlled by input of silicate, whereas export production of nitrogen is controlled by grazing rate and regeneration.
AN: 3810597

                                                                    214 of 1521  
TI: Analytical intercomparison results from the 1990 Intergovernmental Oceanographic Commission open-ocean baseline survey for trace metals: Atlantic Ocean
AU: Landing,-W.M.; Cutter,-G.A.; Dalziel,-J.A.; Flegal,-A.R.; Powell,-R.T.; Schmidt,-D.; Shiller,-A.; Statham,-P.; Westerlund,-S.; Resing,-J.
AF: Dep. Oceanogr., Florida State Univ., Tallahassee, FL 32306-3048, USA
SO: MAR.-CHEM. 1995 vol. 49, no. 4, pp. 253-265
NT: Special Issue: IOC Contaminants Baseline Study.
LA: English
ER: M (Marine)
AB: "Dissolved" (<0.4  mu m filtered) and "total dissolvable" (unfiltered) trace element samples were collected using "clean" sampling techniques from four vertical profiles in the eastern Atlantic Ocean on the first IOC Trace Metals Baseline expedition. The analytical results obtained by 9 participating laboratories for Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, and Se on samples from station 4 in the northeast Atlantic have been evaluated with respect to accuracy and precision (intercomparability). The data variability among the reporting laboratories was expressed as 2 x SD for a given element and depth, and was comparable to the 95% confidence interval reported for the NASS seawater reference standards (representing analytical variability only). The discrepancies between reporting laboratories appear to be due to inaccuracies in standardization (analytical calibration), blank correction, and/or extraction efficiency corrections. Several of the sampling bottles used at this station were not adequately pre-cleaned (anomalous Pb results). The sample filtration process did not appear to have been a source of contamination for either dissolved or particulate trace elements. The trace metal profiles agree in general with previously reported profiles from the Atlantic Ocean. We conclude that the sampling and analytical methods we have employed for this effort, while still in need of improvement, are sufficient for obtaining accurate concentration data on most trace metals in the major water masses of the oceans, and to enable some evaluation of the biogeochemical cycling of the metals.
AN: 3810329

                                                                    215 of 1521  
TI: Behavior of dissolved antimony, arsenic, and selenium in the Atlantic Ocean
AU: Cutter,-G.A.; Cutter,-L.S.
AF: Dep. Oceanogr., Old Dominion Univ., Norfolk, VA 23529-0276, USA
SO: MAR.-CHEM. 1995 vol. 49, no. 4, pp. 295-306
NT: Special Issue: IOC Contaminants Baseline Study.
LA: English
ER: M (Marine)
AB: Vertical profiles for dissolved antimony, arsenic, and selenium were obtained at four stations in the eastern basins of the North and South Atlantic Ocean, and on a surface-water transect from 24 degree S to 31 degree N. Total dissolved selenium displays surface-water depletion and deep-water enrichment, with organic selenide (selenium in soluble peptides) being the predominant species in surface waters and selenate predominating in deep waters. Although the concentrations of total selenium in surface waters of the Northern and Southern Hemispheres are similar, the ratio of inorganic to organic selenium is strongly influenced by the intensity of upwelling. Total inorganic arsenic is depleted in the surface waters of all stations, and increases to relatively constant deep-water concentrations (c. 20 nmol/l). In contrast, total inorganic antimony shows surface-water maxima at two stations. Although the average surface-water arsenic and antimony concentrations in the Northern and Southern Hemispheres are identical, there is some evidence for the atmospheric deposition of antimony. Overall, the cycling of the metalloids in the Atlantic is dominated by in situ biotic reactions, and modified by inputs from upwelling and atmospheric deposition.
AN: 3810326

                                                                    216 of 1521  
TI: Reactive mercury in the eastern North Atlantic and southeast Atlantic
AU: Dalziel,-J.A.
AF: Phys. and Chem. Sci. Branch, Dep. Fish. and Oceans, Bedford Inst. Oceanogr., P.O. Box 1006, Dartmouth, NS B2Y 4A2, Canada
SO: MAR.-CHEM. 1995 vol. 49, no. 4, pp. 307-314
NT: Special Issue: IOC Contaminants Baseline Study.
LA: English
ER: M (Marine)
AB: The vertical distribution of reactive mercury has been measured at two stations in the eastern North Atlantic and one station in the southeast Atlantic in conjunction with the IOC Open Ocean Baseline Survey. The average concentrations of reactive Hg in vertical profiles ranged from 0.70 to 1.07 pM with the highest values found at the northeast Atlantic stations and the lowest at the southeast station. No significant concentration gradients were found below the surface mixed layer at the two stations in the eastern North Atlantic. At station 7, in the southeast Atlantic, an increase in reactive Hg was noted in the water adjacent to the mixed layer (35-200 m) which was coincident with an oxygen depletion, down to 20% saturation at 200 m. The concentration of reactive Hg in the North Atlantic Deep Water (0.48-1.34 pM), the Antarctic Intermediate Water (0.47 pM), the Antarctic Bottom Water (0.67-1.25 pM), and the Mediterranean Outflow Water (0.83-1.06 pM) were noted. The trends in Hg concentration in the water masses between stations showed the concentration decreasing with distance from the water mass source except for Hg in the Antarctic Bottom Water. The increase noted in this water mass was attributed to mixing with North Atlantic Deep Water and or release from bottom sediments.
AN: 3810325

                                                                    217 of 1521  
TI: Mineralization of inositol hexaphosphate in aerobic and anaerobic marine sediments: Implications for the phosphorus cycle
AU: Suzumura,-M.; Kamatani,-A.
AF: Lab. Mar. Biochem., Ocean Res. Inst., Univ. Tokyo, Minamidai, Nakano-ku, Tokyo 164, Japan
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 5, pp. 1021-1026
LA: English
ER: M (Marine)
AB: Inositol hexaphosphate (IP sub(6)) is a significant carrier of organic P in riverine sediments and suspended matter. Its mineralization in coastal sediments was investigated by laboratory experiments under simulated marine environments. Despite being chemically refractory, IP sub(6) was effectively mineralized to inorganic P by aerobic and anaerobic degradation processes. The extent and rate of IP sub(6) mineralization were found to be strongly regulated by the redox conditions: under anaerobic conditions, IP sub(6) decomposed almost completely within 40 days, whereas about 50% of IP sub(6) remained under aerobic conditions during a 60 days experiment. Most of the IP sub(6) added to sediment/seawater mixtures was bound to the sediment particles in both aerobic and anaerobic samples. The soluble fraction of IP sub(6) in the aqueous phase was, however, depressed under aerobic conditions, which could account for the reduced efficiency of aerobic IP sub(6) mineralization. These results suggest that terrigenous IP sub(6) decomposes rapidly under marine environmental conditions and thus may be an important P source in marine ecosystems.
AN: 3810312

                                                                    218 of 1521  
TI: First data on trace metal level and behaviour in two major Arctic river-estuarine systems (Ob and Yenisey) and in the adjacent Kara Sea, Russia
AU: Dai,-M.-H.; Martin,-J.-M.
AF: Inst. Biogeoch. Mar., UA CNRS No. 386, Unit. Rech. Mar. IFREMER No. 6, Ecole Norm. Super., 1 Rue Maurice Arnoux, 92120 Montrouge, France
SO: EARTH-PLANET.-SCI.-LETT. 1995 vol. 131, no. 3-4, pp. 127-141
LA: English
ER: B (Brackish)
AB: Dissolved and colloidal trace element concentrations (Cd, Cu, Fe, Ni, and Pb) were determined in the Ob and Yenisey river-estuary systems and in the adjacent Kara Sea in September 1993. The data show a natural low concentration level of 'dissolved' (<0.4  mu m) trace metals (Cd, Cu, Fe, Ni, and Pb) in the two rivers and in the Kara Sea as compared to world unpolluted rivers and the central Arctic Ocean, suggesting that the region studied is pristine with respect to trace metals. The pathway of trace metals transported from rivers to the ocean seems to be complicated, and largely influenced by biogeochemical processes taking place in the estuarine mixing zone. Colloidal material (10 super(4) Daltons-0.4  mu m), in addition to its significant contribution to the so-called 'dissolved' fraction, has been shown to play a fundamental role in determining the behaviour of both conservative and non-conservative trace metals during estuarine mixing. Hence, colloids may control to a large extent the fate of 'dissolved' trace metals as well as their net input from the rivers to the Kara Sea.
AN: 3810310

                                                                    219 of 1521  
TI: In-situ measurement of dissolved nitrogen and oxygen in the ocean
AU: McNeil,-C.L.; Johnson,-B.D.; Farmer,-D.M.
AF: Inst. Ocean Sci., 9860 W. Saanich Rd., P.O. Box 6000, Sidney, BC, Canada
SO: DEEP-SEA-RES.-I-OCEANOGR.-RES.-PAP. 1995 vol. 42, no. 5, pp. 819-826
LA: English
ER: M (Marine)
AB: Motivated by the need to separate changes in dissolved gas concentrations due to air-sea fluxes from biological production, a novel method of inferring dissolved nitrogen in the ocean is described. The method requires a local measurement of gas tension, dissolved oxygen, water temperature and salinity. Such instrumentation has been developed and tested at sea. Preliminary open ocean data are presented. The measurements during periods of low wind speed show a clear diurnal dissolved oxygen signal, incorporating biological photosynthetic response, solar heating and nocturnal convective mixing. The diurnal variability of the inferred nitrogen signal is approximately 10% that of the measured oxygen diurnal variability. The nitrogen diurnal variability is attributed to a 10 m separation between the primary measurements of gas tension and dissolved oxygen rather than any intrinsic change in dissolved nitrogen. These results are, however, consistent with the relative insensitivity of dissolved gaseous nitrogen to biological activity compared to that of dissolved oxygen. The open ocean results give good evidence for the integrity of the measurement scheme and indicate the potential for simultaneous measurement of dissolved nitrogen and oxygen in the study of biological cycling as well as gas transfer in the upper ocean.
AN: 3810251

                                                                    220 of 1521  
TI: Experimental transplantation of eelgrass (Zostera marina) in Kiel Bight, Baltic Sea: Effects of sediment nutrient enrichment and initial shoot density
AU: Worm,-B.; Reusch,-T.B.H.
AF: Inst. Meeresk., 24105 Kiel, FRG
CO: 23. Benthic Ecology Meeting, New Brunswick, NJ (USA), 17-19 Mar 1995
SO: TWENTY-THIRD-BENTHIC-ECOLOGY-MEETING. Grassle,-J.P.;Kelsey,-A.;Oates,-E.;Snelgrove,-P.V.-eds. Rutgers-the-State-Univ.,-New-Brunswick,-NJ-USA.-Inst.-Marine-Coastal-Sciences 1995 vp
NT: Abstract only.
LA: English
ER: M (Marine)
AB: Although considerable loss of eelgrass habitats has occurred in the Baltic Sea during the past decades mitigation measures by transplantation have not yet been attempted. The goal of this experiment was to investigate effects of fertilization (with additional transplantation of Mytilus edulis or with a commercial slow-release NPK-fertilizer) and planting density (20 or 40 cm distance between shoots) on plant performance, shoot density and areal extension of transplants. In contrast to previous techniques involving shootbundles, we planted only single shoots which were equidistantly placed in circular plots. In situ leaf growth rates in July were significantly higher when Zostera was associated with Mytilus whereas application of the commercial fertilizer had no effect on any of the response variables. Surprisingly, the increase in shoot density over a 6.5 month period in the high-density plots was double the increase found in the low-density plots. Also, with higher transplant density, we found relatively higher rates for shoot growth, shoot addition and transplant coverage, suggesting the presence of mutualistic processes among eelgrass shoots.
AN: 3809917

                                                                    221 of 1521  
TI: Amount of water, energy and heating brought by Estonian rivers to the Baltic Sea
AU: Vedom,-R.
AF: Estonian Meteorol. Hydrol. Inst., Liivalaia 9, EEO1O6 Tallinn, Estonia
CO: First Study Conference on BALTEX, Visby (Sweden), 28 Aug-1 Sep 1993
SO: FIRST-STUDY-CONF.-ON-BALTEX. A.-Omstedt-ed. GEESTHACHT-GERMANY INT.-BALTEX-SECRETARIAT 1995 vol. 3 pp. 176-177
ST: vol. 3,
NT: Summary only.
LA: English
ER: M (Marine)
AB: The purpose of this paper is to create the approximate carrying-out model for water, energy and heating as a basis for future estimates of suspended matter, hydrochemical and/or biological components of input to the Baltic Sea from Estonia.
AN: 3809213

                                                                    222 of 1521  
TI: Oxygen and carbon isotope study of the Holocene oyster reefs and paleoenvironmental reconstruction on the northwest coast of Bohai Bay, China
AU: Hong,-Wang; Keppens,-E.; Nielsen,-P.; Van-Riet,-A.
AF: Dep. Quaternary Geol., Tianjin Inst. Geol. and Mineral Resour., MGMR, Tianjin 300170, People's Rep. China
SO: MAR.-GEOL. 1995 vol. 124, no. 1-4, pp. 289-302
NT: Special Issue: Coastal Evolution in the quaternary: IGCP Project 274.
LA: English
ER: M (Marine)
AB: The northwest coast of Bohai Bay supports large areas of Holocene Crassostrea gigas (oyster) reefs. Their huge size and the fact that the shells are composed of consecutive microgrowth layers, consisting of primary calcite, make them an ideal object for a stable isotope study. The  delta  super(18)O and  delta  super(13)C compositions of the oysters reveal a number of interesting features. The most important are annual cycles related to seasonal variations, the regional  delta  super(18)O (water) versus salinity ratio, and a stop in shell secretion below a water temperature of 11.5  plus or minus  1.5 degree C. Between ca. 6500 yrs cal B.P. and 2300 yrs cal B.P. the salinity in Bohai Bay increased from less than 20ppt to 30ppt. Based on geological data combined with ecological data from C. gigas, we suggest that precipitation decreased during this period, while the input of fluvial sediments increased. The sediment load of rivers increased markedly after ca. 4000 yrs cal B.P., possibly due to a change in climate. In our study area this resulted in the development of the Oyster Plain.
AN: 3809165

                                                                    223 of 1521  
TI: A U.S. JGOFS process study in the equatorial Pacific (EqPac): Introduction
AU: Murray,-J.W.; Johnson,-E.; Garside,-C.
AF: Sch. Oceanogr., Univ. Washington, P.O. Box 35794, Seattle, WA 98195-7940, USA
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1995 vol. 42, no. 2-3, pp. 275-293
LA: English
ER: M (Marine)
AB: This special issue contains data and scientific results from the JGOFS Process Study in the equatorial Pacific. Most of the contributions are from the U.S. JGOFS Process Study (EqPac) but the French and Australian results are represented as well. The equatorial Pacific plays a major role in the oceanic and atmospheric carbon cycles, and these studies are the first step for synthesizing the cycle of carbon and related elements in this region.
AN: 3808484

                                                                    224 of 1521  
TI: The effects of vegetation on watershed biogeochemistry at Loch Vale Watershed, Rocky Mountain National Park, Colorado
AU: Arthur,-M.A.
CA: Cornell University
SO: DISS.-ABST.-INT.-PT.-B-SCI.-and-ENG. 1990 vol. 51, no. 4, 196 pp
NT: Diss. Ph.D.: Order No.: DA9027102.
LA: English
ER: F (Freshwater)
AB: I examined the biogeochemistry of Loch Vale Watershed (LVWS) in Rocky Mountain National Park because scientists and policy-makers are concerned about the lack of information regarding the possible susceptibility of Rocky Mountain watersheds to damage from acid deposition. The objective of the research was to quantify the role of the forest vegetation, which comprised about 6% of the watershed area, in controlling watershed biogeochemistry. Specifically, I estimated the magnitude of acid generation within the ecosystem and compared this with acid deposition to better understand ecosystem biogeochemistry. Knowledge about the intensity of internally-generated acidity will improve our ability to predict future impacts of acidic atmospheric deposition on the watershed and its biota. To calculate the generation of acidity within the forest it was necessary to quantify the major fluxes of basic cations and acid anions, including canopy and soil leaching, tree root uptake and return in litter fall, and mineralization of detritus. A series of process studies was performed in intensive research plots within LVWS to quantify these fluxes. The process studies revealed that the old-growth forest in LVWS was maintained by active recycling of nutrients. For example, large amounts of K, Ca, and dissolved organic carbon were leached from the forest canopy by summer rains, whereas NH sub(4) and NO sub(3) were retained by the canopy. Net primary production (NPP) in the LVWS was relatively low (441 g/m super(2)/yr), but root uptake of basic cations, which replaced nutrients in senesced tissues, was high (210 mEq/m super(2)/yr). A large proportion of NPP and root uptake was associated with fine root production and turnover (34 percent). Organic anions and SO sub(4) were the principal mobile anions in soil solutions, due to coarse soils and very low sulfate adsorption capacity. Flux of free acidity from the soil was very low (4.5 mEq/m super(2)/yr); thus, H-ions released to the soil during root uptake were completely consumed within the soil by ion exchange reactions and primary mineral weathering. Weathering rates in the forest were about four times higher than in non-forested areas of the watershed. Both the release of acidity during root uptake and the dissociation of large quantities of weak acid organic anions in the soil contributed substantially to the higher rate of weathering. On a forest area basis, the accumulation of cations in biomass accounted for 10 times as much H-ion generation as did precipitation inputs. On a whole watershed basis, forest growth generated about 2/3 as much acidity as was added by atmospheric deposition. Forests play an important role in the acid-base balance of subalpine ecosystems; thus, any disturbance to the forested area could have a disproportionate impact on watershed biogeochemistry. (DBO)
AN: 3808376

                                                                    225 of 1521  
TI: Ecosystem analysis of the Bering/Chukchi seas using a coupled time-dependent physical/biological simulation model
AU: Shuert,-P.G.
CA: University of South Florida
SO: DISS.-ABST.-INT.-PT.-B-SCI.-and-ENG. 1990 vol. 51, no. 4, 205 pp
NT: Diss. Ph.D.: Order No.: DA9024916.
LA: English
AB: A coupled, time-dependant, 3-dimensional, physical/biological mathematical model was constructed to simulate some of the important biological and physical processes of the northern Bering and southern Chukchi Sea ecosystem. This model simulates the time-dependant changes in nutrient and chlorophyll fields on a broad ecosystem scale to examine the importance of physical forcing and chemical conditions on biological rates, particularly primary production. Some of the important results from the model follow. The distribution of chlorophyll and productivity in the northern Bering Sea is determined primarily by the strength of the advection and secondarily by the nutrient and chlorophyll distributions at the southern boundaries of the model domain. Ammonium concentrations are spatially determined by both benthic regeneration and by the advective field. Approximately 60% of the nitrate entering the model remains unutilized, to be exported at the model's downstream boundary within  similar to 200 Km of the Siberian coast. This unutilized nitrate presumably is available to enrich the nutrient concentrations of the East Siberian Sea waters at least as far west as Wrangel Island. Declining light availability from mid-summer on, manifested in shorter daylengths and lower sun angles, leads to a decline in productivity in spite of ample nutrients. Zooplankton are an unimportant influence on chlorophyll, productivity and nutrient distributions, consuming only  similar to 1% of the daily productivity. Benthic respiration of carbon, and concomitant regeneration of nitrogen, constitute important sources of dissolved carbon and nitrogen to the model domain, without which, productivity is significantly curtailed. Approximately 3.6 g C/m super(2)/yr (calculated over 150 days), is buried in the Bering/Chukchi Sea sediments, or  similar to 1% of the annual productivity. (DBO)
AN: 3808370

                                                                    226 of 1521  
TI: Studies of trace metals in shelf waters of the British Isles
AU: Tappin,-A.D.
CA: University of Southampton (United Kingdom)
SO: DISS.-ABST.-INT.-PT.-B-SCI.-and-ENG. 1990 vol. 51, no. 4, 332 pp
NT: Diss. Ph.D.: Order No.: BRDX89593.
LA: English
AB: Results are presented for the distributions of a number of dissolved trace metals (Cd, Co, Cu, Mn, Ni, Pb, Sn; ancillary data were also available for reactive aluminium) during several detailed surveys of the central and western areas of the English Channel. The sampling plan was designed to give information on the importance of potential sources of metals in influencing distributions, and sampling was undertaken under contrasting seasonal conditions (Nov. 1985, May & Aug. 1986) in order to obtain information on the effects of phytoplankton activity and water column stability on the biogeochemical cycling of metals. The mixing of Atlantic Ocean surface water and freshwaters with higher concentrations of dissolved trace metals was a significant basic factor affecting the distributions of the trace metals, as shown by significant inverse correlations of each metal investigated, with salinity. The scatter shown in these relationships indicates, however, that other factors influenced the distributions, and the possible roles of atmospheric and benthic inputs, and of interactions between dissolved and particulate (including biogenic) material are considered. Concentrations of dissolved manganese increased progressively from winter to summer (2.0  plus or minus  0.7 (mean  plus or minus  .0) to 5.0  plus or minus  3.0 nmol/l). A surface enrichment in the upper mixed layer of the western Channel, relative to deeper water, was also observed. Concentrations of dissolved cobalt also increased from winter to spring (from  less than or equal to 0.02-0.50 to 0.08-0.71 nmol/l), paralleling those of dissolved manganese, and then decreased into summer (to  less than or equal to 0.08-0.56 nmol/l). The regional distribution of dissolved lead had changed by May, possibly reflecting removal by diatoms and decreased riverine inputs, although overall mean concentrations remained similar throughout the year (0.22 nmol/l). Concentrations of reactive aluminium decreased in response to biological activity, being related to those of dissolved silicon during spring, and to those of phosphate and nitrate during the summer, with depletion in the upper mixed layer of the stratified waters of the western Channel. Concentrations of dissolved cadmium (0.20 nmol/l), copper (3.2 nmol/l), nickel (3.8 nmol/l) and zinc (7.6 nmol/l), and their regional distributions, remained relatively uniform over the period of the cruises. This behaviour, which contrasts with the open oceanic observations (surface depletion and regeneration at depth), may be attributable to high background levels of dissolved metals, rapid recycling of metals from sedimented phytoplankton, increased riverine inputs, and rapid mixing of the water column, which prevents the integrated effects of repeated cycles of removal from the euphotic zone from developing. (DBO)
AN: 3808181

                                                                    227 of 1521  
TI: Biogeochemical phosphorus cycling in the Delaware, an urbanized coastal plain estuary
AU: Lebo,-M.E.
SO: DISS.-ABST.-INT.-PT.-B-SCI.-and-ENG. 1991 vol. 51, no. 11, 272 pp
NT: Diss. Ph.D.: Order No.: DA9109948.
LA: English
ER: B (Brackish)
AB: Man's activities over the past several centuries have greatly affected the transport and cycling of phosphorus in estuaries. In the Delaware Estuary, industrial and municipal inputs into the tidal river near Philadelphia strongly influence both nutrient cycles and water chemistry. In the tidal river, the flux of phosphorus increases by 280% due to large inputs. The observed increase is, however, much lower than expected from known inputs to the system. Within the tidal river, geochemical processes remove 50-65% of phosphorus inputs; large increases occur in particulate phosphorus associated with iron, aluminum, and organic matter. This geochemical repackaging within the river partially mitigates the impact of anthropogenic phosphorus inputs, and it leads to a nearly constant flux of phosphorus into the salinity gradient. In addition to increasing phosphorus transport, anthropogenic inputs also change the ecology of phosphorus cycling. In the region of maximum anthropogenic inputs, bacteria rather than phytoplankton dominated (up to 70%) the uptake of phosphate. Throughout the remainder of the estuary, phytoplankton contributed 75-85% of biological phosphate uptake. In contrast to the urban river, phosphorus cycling in Delaware Bay (salinity gradient) is dominated by biological production. Although phosphorus is released from both suspended and bottom sediments, phosphate uptake and regeneration within the water column control phosphate concentrations. The link between phosphorus cycling in the bay and biological production imparts strong seasonal variations in phosphorus distributions. During the intense spring phytoplankton bloom, phosphate is completely removed, and 50% of total phosphorus entering from the river is retained within the bay. This trapping of phosphorus is only temporary, however, as phosphorus is regenerated after the bloom dissipates in the late spring. On an annual basis, 87% of the phosphorus entering the bay from the river is exported to coastal waters. (DBO)
AN: 3808115

                                                                    228 of 1521  
TI: Geochemical and physical processes influencing the composition of particles in diverse environments, eastern North Atlantic Ocean
AU: Isley,-A.E.
CA: University of Rhode Island
SO: DISS.-ABST.-INT.-PT.-B-SCI.-and-ENG. 1991 vol. 51, no. 11, 173 pp
NT: Diss. Ph.D.: Order No.: DA9109466.
LA: English
ER: M (Marine)
AB: To understand global biogeochemical cycling in the oceans it is imperative to develop comprehensive models of the processes influencing elements in the suspended particulate phase. This thesis examines the character of particles from a wide variety of environments in the Eastern North Atlantic Ocean in order: (1) to enhance our knowledge of the physical and geochemical processes influencing resuspended matter; (2) to determine over what distances distinct water masses can transport characteristic particle suites; (3) to develop models for the formation and transformation of distinct mineral phases associated with hydrothermal plumes. Particles were collected by filtering water from 30 liter Niskin bottles and by using in situ high-volume filtration equipment during the FLUX-ATLANTE (R/V Suroit, 1985) and RRS Discovery 159 (1986) cruises. Particles were characterized using some or all of the following techniques: instrumental neutron activation (for Al, Ca, Fe, Mn, Cu, V, and/or I), scanning electron microscopy and energy dispersive x-ray analyses. Differences between resuspended nepheloid materials and underlying surface sediments are attributed to preferential resuspension of fine-grained materials with a distinctive geochemical signature. Classical signs of early alteration processes such as dissolution of biogenic tests and remineralization of organic matter in the sediment column are observed. Long-distance transport (to 800 km) of aluminosilicates occurs with advection of Mediterranean Outflow Water (MEDW). Mixing with Eastern North Atlantic Intermediate Water (ENAIW) accounts for an enhanced particulate Ca/Al and Mn/Al in intermediate waters with distance from Gibraltar and there is no evidence for adsorption of dissolved Mn introduced with the MEDW plume over distance scales  approximately 1000 km. Between 15 to 75% of the materials transported in the Trans-Atlantic Geotraverse hydrothermal plume (26 degree N, Mid-Atlantic Ridge) are of resuspended origin. Hydrothermal particles are dominated by amorphous iron oxides along the length of the equilibrated plume. Copper oxides are present in the region of 2.5 km from the venting site. Manganese-rich particles are introduced to the plume via resuspension. Sulfides may be transported into the far-field hydrothermal plume only if their grain sizes are <3  mu . (DBO)
AN: 3808114

                                                                    229 of 1521  
TI: Secondary suspended particulate matters and the bioelement loop in sea water column
AU: Wu,-Yuduan; Chen,-Cimei; Luo,-Xiaohong
AF: Dep. Oceanogr., Xiamen Univ., Xiamen 361005, People's Rep. China
SO: TROP.-OCEANOL.-REDAI-HAIYANG 1994 vol. 13, no. 3, pp. 84-89
LA: Chinese
ER: M (Marine)
AB: We studied the process of marine environment resources development (mainly the resources of productivity and purification ability) in the coastal area, in which the formation of the secondary suspended particulate matters is induced, especially the aquatic culture rises and domestic sewage discharges in the nearshore zone. The following topics were emphasized: The mechanisms of the secondary S.P.M. formed; The buffering and controlling role in geochemical behaviour, process, fate and cycle of bioelement in water column; The effect on the kinetics of transformation among the various speciations of bioelement and the content levels of nutrient in water. Therefore, it may turn into a potential source for the eutrophication in near shore water.
AN: 3802993

                                                                    230 of 1521  
TI: Dissolved organic carbon in the equatorial Atlantic Ocean
AU: Thomas,-C.; Cauwet,-G.; Minster,-J.-F.
AF: UMR39/GRGS, 18 Ave. E. Belin, 31055 Toulouse, France
SO: MAR.-CHEM. 1995 vol. 49, no. 2-3, pp. 155-169
LA: English
ER: M (Marine)
AB: We measured the concentration of dissolved organic carbon (DOC) in the equatorial Atlantic Ocean, using a high-temperature carbon oxidation technique and platinized-quartz catalysts. Below 400 m, values are nearly homogeneous near 46  plus or minus  7  mu M C. Concentrations are higher, up to 97  mu M C at the surface, outside of the equatorial upwelling during the warm season. They are somewhat lower, near 66  mu M C on average, in upwelling waters during the cold season. These values are close to previously published data from the subtropical Atlantic Ocean, and to recent values for the Pacific Ocean. A box model of the equatorial upwelling suggests that only 20  plus or minus  15% of the exported flux of total biogenic carbon is in dissolved form.
AN: 3802697

                                                                    231 of 1521  
TI: Sedimentary organic matter preservation: An assessment and speculative synthesis
AU: Hedges,-J.I.; Keil,-R.G.
AF: Sch. Oceanogr., Box 357940, Univ. Washington, Seattle, WA 98195-7940, USA
SO: MAR.-CHEM. 1995 vol. 49, no. 2-3, pp. 81-115
LA: English
ER: M (Marine)
AB: Throughout Earth history, almost all preserved organic matter has been incorporated in marine sediments deposited under oxygenated waters along continental margins. Given modern oceanic productivity and sediment burial rates of 50 x 10 super(15) and 0.16 x 10 super(15) gC yr super(-1), respectively, organic preservation in the marine environment is <0.5% efficient. Although correlative information is often used to suggest that productivity, sediment accumulation rate, bottom water oxicity, and organic matter source are key variables, the mechanisms governing sedimentary organic matter preservation have remained unclear. The factors which directly determine preservation vary with depositional regime, but have in common a critical interaction between organic and inorganic materials over locally variable time scales. More than 90% of total sedimentary organic matter from a wide variety of marine depositional environments cannot be physically separated from its mineral matrix. This strongly associated organic component varies directly in concentration with sediment surface area and thus appears to be sorbed to mineral grains. Sediments accumulating outside deltas along continental shelves and upper slopes characteristically exhibit mineral surface area loadings approximately equivalent to a single molecular covering. These monolayer-equivalent coatings include a fraction of reversibly bound organic molecules that are intrinsically labile, but resist appreciable mineralization as they pass rapidly through oxygenated surface sediments and are preserved within underlying anoxic deposits. The delivery of mineral surface area is the primary control on organic matter preservation within these expansive coastal margin regions where roughly 45% of all organic carbon accumulates. Deltaic sediments account for roughly another 45% of global carbon burial, but often exhibit much less than monolayer-equivalent organic coatings. This pattern is seen in periodically oxygenated sediments off the mouth of the Amazon River, even though the component clastic minerals are discharged by the river with monolayer coatings. Comparably extensive losses of organic matter, including distinct particles such as pollen grains, occur in the surfaces of deep-sea turbidities in which long term reaction with O sub(2) is clearly the causative factor. Sub-monolayer organic coatings also are observed in continental rise and abyssal plain sediments where slower accumulation rates and deeper O sub(2) penetration depths result in increased oxygen exposure times and little ( similar to 5% of the global total) organic matter preservation. A transition zone between monolayer and sub-monolayer organic coatings apparently occurs on lower continental slopes, and is marked along the Washington coast by parallel offshore decreases in total organic matter and pollen between 2000-3000 m water depth.
AN: 3802689

                                                                    232 of 1521  
TI: Sedimentary organic matter preservation: An assessment and speculative synthesis -- a comment
AU: Pedersen,-T.F.
AF: Dep. Oceanogr., Univ. British Columbia, Vancouver, BC V6T 1Z4, Canada
SO: MAR.-CHEM. 1995 vol. 49, no. 2-3, pp. 117-119
LA: English
ER: M (Marine)
AN: 3802688

                                                                    233 of 1521  
TI: Sedimentary organic matter preservation: An assessment and speculative synthesis -- a comment
AU: Berner,-R.A.
AF: Dep. Geol. and Geophys., Yale Univ., New Haven, CT 06520-8109, USA
SO: MAR.-CHEM. 1995 vol. 49, no. 2-3, pp. 121-122
LA: English
ER: M (Marine)
AN: 3802687

                                                                    234 of 1521  
TI: Sedimentary organic matter preservation: An assessment and speculative synthesis -- a comment
AU: Mayer,-L.M.
AF: Dep. Oceanogr., Darling Mar. Cent., Univ. Maine, Walpole, ME 04573, USA
SO: MAR.-CHEM. 1995 vol. 49, no. 2-3, pp. 123-126
LA: English
ER: M (Marine)
AN: 3802686

                                                                    235 of 1521  
TI: Sedimentary organic matter preservation: An assessment and speculative synthesis -- a comment
AU: Henrichs,-S.M.
AF: Inst. Mar. Sci., P.O. Box 757220, Univ. Alaska, Fairbanks, AK 99775-7220, USA
SO: MAR.-CHEM. 1995 vol. 49, no. 2-3, pp. 127-136
LA: English
ER: M (Marine)
AN: 3802685

                                                                    236 of 1521  
TI: Sedimentary organic matter preservation: An assessment and speculative synthesis
AU: Hedges,-J.I.; Keil,-R.G.
SO: MAR.-CHEM. 1995 vol. 49, no. 2-3, pp. 137-139
LA: English
ER: M (Marine)
AN: 3802684

                                                                    237 of 1521  
TI: Oceanic transport and storage of carbon emissions
AU: Keller,-A.A.; Goldstein,-R.A.
AF: Electric Power Res. Inst., P.O. Box 10412, Palo Alto, CA 94303, USA
SO: CLIM.-CHANGE 1995 vol. 30, no. 4, pp. 367-395
LA: English
ER: M (Marine)
AB: Using a global carbon cycle model (GLOCO) that considers seven terrestrial biomes, surface and deep ocean layers based on the HILDA model and a single mixed atmosphere, we analyzed the response of atmospheric CO sub(2) concentration and oceanic DIC and DOC depth profiles to additions of carbon to the atmosphere and ocean. The rate of transport of carbon to the deepest oceanic layers is rather insensitive to the atmosphereic-ocean surface gas exchange coefficient over a wide range, hence discrepancies between researchers on the precise global average value of this coefficient do not significantly affect predictions of atmospheric response to anthropogenic inputs. Upwelling velocity, on the other hand, amplifies oceanic response by increasing primary production in the upper ocean layers, resulting in a larger flux into DOC and sediments and increased carbon storage; experiments to reduce the uncertainty in this parameter would be valuable. The location of the carbon addition, whether it is released in the atmosphere or in the middle of the oceanic thermocline, has a significant impact on the maximum atmospheric CO sub(2) concentration (pCO sub(2)) subsequently reached, suggesting that oceanic burial of a significant fraction of carbon emissions (e.g. via clathrate hydrides) may be an important management option for limiting pCO sub(2) buildup. Our analysis indicates that the effectiveness of ocean burial decreases asymptotically below about 1000 m depth. With a constant emissions scenario (at 1990 levels), pCO sub(2) at year 2100 is reduced from 501 ppmv considering all emissions go to the atmosphere, to 422 ppmv with ocean burial at a depth of 1000 m of 50% of the fossil fuel emissions. An alternative scenario looks at stabilizing pCO sub(2) at 450 ppmv; with no ocean burial of fossil fuel emissions, the rate of emissions has to be cut drastically after the year 2010, whereas oceanic burial of 2 GtC/yr allows for a smoother transition to alternative energy sources.
AN: 3802655

                                                                    238 of 1521  
TI: A comparison of electron transport system (ETS) activity in stream and beaver pond sediments
AU: Songster-Alpin,-M.S.; Klots,-R.L.*
AF: Dep. Biol. Sci., SUNY, Cortland, NY 13045, USA
SO: CAN.-J.-FISH.-AQUAT.-SCI.-J.-CAN.-SCI.-HALIEUT.-AQUAT. 1995 vol. 52, no. 6, pp. 1318-1326
LA: English
ER: F (Freshwater)
AB: Electron transport system (ETS) activity of sediments as an indication of microbial metabolic activity was measured at four beaver pond sites in central New York State. ETS activity, an indication of microbial biomass and respiration, was measured as the reduction of 2-(p-iodophenyl) -3- (p-nitrophenyl) -5- phenyl tetrazolium chloride (INT) to INT-formazan. Since INT can be reduced by both aerobes and anaerobes, the total microbial respiratory activity in the sediments was measured. The ETS activity increased from means of 11.1-65.0  mu g O sub(2) g super(-1) dry weight h super(-1) at the free-flowing upstream reaches to means of 221.2-262.6  mu g O sub(2) g super(-1) dry weight h super(-1) within the beaver ponds. ETS activity decreased with increased depth of sediment probably because of the loss of aerobic activity.
AN: 3802561

                                                                    239 of 1521  
TI: The chemistry of the anoxic waters in the Framvaren Fjord, Norway
AU: Yao,-Wensheng; Millero,-F.J.
AF: Univ. Miami, Rosenstiel Sch. Mar. Atmos. Sci., 4600 Rickenbacker Causeway, Miami, FL 33149, USA
SO: AQUAT.-GEOCHEM. 1995 vol. 1, no. 1, pp. 53-88
LA: English
ER: B (Brackish)
AB: In the summer of 1993, a number of chemical parameters (H sub(2)S, O sub(2), pH, TA, TCO sub(2), NH sub(4) super(+), PO sub(4) super(3-), Mn super(2+) and Fe super(2+)) were measured in the Framvaren Fjord, a permanently super-anoxic fjord in southern Norway. The extremely steep gradient of sulfide near the interface suggests that other than downward flux of oxygen, three other possible oxidants, particulate manganese and iron oxides, phototrophic sulfur oxidation bacteria and horizontally transported oxygen account for the oxidation of the upward flux of H sub(2)S. Water intrusion through the sill accounts for the temperature inflection above the interface, which, together with internal waves (Stigerbrandt and Molvaer, 1988), may cause fluctuations of the depth of interface. Significant gradients of hydrographic properties and chemical species between 80-100 m suggest that there is a "second interface" at about 90 m that separates the deep and older bottom waters. A stoichiometric model is applied to examine the biogeochemical cycles of S, C, N and P in the Framvaren. High C:S, C:N and C:P ratios are found while the nutrients (N, P) have Redfield ratio. Based on the C:N:P ratio of 155:16:1 in organic matter, about 30% of sulfide produced by sulfate reduction is estimated to be removed by processes such as oxidation, formation of FeS sub(2), degassing and incorporation into organic matter. The rates of oxidation of H sub(2)S by Mn and Fe oxides in the water near the interface were slightly faster than the observed values in the laboratory, probably due to the presence of bacteria.
AN: 3800555

                                                                    240 of 1521  
TI: Prospects for modeling the behavior and fate of mercury, globally and in aquatic systems
AU: Mackay,-D.; Wania,-F.; Schroeder,-W.H.
AF: Inst. Environ. Stud., Univ. Toronto, Toronto, ON M5S 1A4, Canada
CO: 3. International Conference on Mercury as a Global Pollutant, Whistler, BC (Canada), 10-14 Jul 1994
SO: THIRD-INTERNATIONAL-CONFERENCE-ON-MERCURY-AS-A-GLOBAL-POLLUTANT. Porcella,-D.;Huckabee,-J.;Wheatley,-B.-eds. 1995 vol. 80, no. 1-4 pp. 941-950
ST: WATER,-AIR,-SOIL-POLLUT. vol. 80, no. 1-4
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: The phenomena of cold condensation and fractionation of chemical contaminants on a global scale are discussed. The net result of these phenomena is that concentrations of certain atmospherically transported contaminants are higher than expected in the condensed, i.e. non gaseous media of water, soils, sediments and biota as a result of the temperature dependence of partitioning and transport phenomena. It is argued that the phenomena are best investigated by a combination of monitoring and modeling. This approach is illustrated in the form of a nine meridional segment model for hexachlorocyclohexane. It is suggested that this approach should be applied to Hg, but this is not presently possible because of the lack of data on Hg species properties and conversion rates. Available data have been used to test the hypothesis that lower temperatures cause enhanced partitioning from the atmosphere to a lake ecosystem at low temperatures by compiling a three species model of an atmosphere-water-sediment-fish system at 25 degree C and 0 degree C. Preliminary results show that the effect of this drop in temperature is to cause increases in concentrations throughout the aquatic ecosystem of factors of three to four, other factors being equal. Thus it is likely that a comprehensive global model will show that Hg is subject to the global fractionation phenomenon. It is recommended that attempts be made to develop such a model.
AN: 3799838

                                                                    241 of 1521  
TI: The role of microorganisms in elemental mercury formation in natural waters
AU: Mason,-R.P.; Morel,-F.M.M.; Hemond,-H.F.
AF: Chesapeake Biol. Lab., Solomons, MD 20688, USA
CO: 3. International Conference on Mercury as a Global Pollutant, Whistler, BC (Canada), 10-14 Jul 1994
SO: THIRD-INTERNATIONAL-CONFERENCE-ON-MERCURY-AS-A-GLOBAL-POLLUTANT. Porcella,-D.;Huckabee,-J.;Wheatley,-B.-eds. 1995 vol. 80, no. 1-4 pp. 775-787
ST: WATER,-AIR,-SOIL-POLLUT. vol. 80, no. 1-4
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: Gas evasion of elemental Hg (Hg degree ) from the open ocean plays a prominent role in the global mercury cycle. Elemental Hg is formed primarily by reduction of ionic Hg in the mixed layer of aquatic systems. By culturing phytoplankton in defined media, and by incubating natural seawater and freshwater samples, we have demonstrated that Hg degree  is produced by microorganisms, with formation rates (0.5 to 10%) similar to those estimated from mass balance studies. Our results also suggest that <3  mu m microorganisms are the primary Hg reducers in natural waters. Eucaryotic phytoplankton are capable of reducing ionic Hg to Hg degree  but the rate of reduction is insufficient to account for the observed reduction rates found in incubated field samples. Bacteria are thus the more likely Hg reducers. In seawater, cyanobacteria such as Synecococcus may account for much of the mercury reduction, while in the eutrophic, polluted Upper Mystic Lake north of Boston other procaryotic microorganisms are contributing to the overall Hg reductive capacity of the medium. By reducing ionic Hg, microorganisms play a pivotal role in the aquatic biogeochemistry of Hg, not only by enabling evasion to the atmosphere, but by directly decreasing the amount of ionic Hg available for methylation.
AN: 3796202

                                                                    242 of 1521  
TI: Dimethylmercury and dimethylmercury-sulfide of microbial origin in the biogeochemical cycle of Hg
AU: Baldi,-F.; Parati,-F.; Filippelli,-M.
AF: Dip. Biol. Ambient., Univ. Siena Via P.A. Mattioli 4, I-53100 Siena, Italy
CO: 3. International Conference on Mercury as a Global Pollutant, Whistler, BC (Canada), 10-14 Jul 1994
SO: THIRD-INTERNATIONAL-CONFERENCE-ON-MERCURY-AS-A-GLOBAL-POLLUTANT. Porcella,-D.;Huckabee,-J.;Wheatley,-B.-eds. 1995 vol. 80, no. 1-4 pp. 805-815
ST: WATER,-AIR,-SOIL-POLLUT. vol. 80, no. 1-4
LA: English
ER: M (Marine)
AB: The transformation of MeHg under anaerobic conditions in axenic cultures of Desulfovibrio desulfuricans strain LS is compared to that in anoxic marine sediments contaminated by Hg of industrial origin. MeHg was added to cultures of D. desulfuricans strain LS and incubated at 28 degree C for two weeks. Significant amounts of dimethylmercury and metacinnabar were produced. These two Hg compounds were formed from the slow decomposition of the intermediate dimethylmercury-sulfide. Other collateral compounds, such as methane and ionic Hg, were also detected during the MeHg degradation process. On the other hand a sample of fresh sediment (1.5 g d.w.) was spiked with 10  mu g of MeHg and 2 mmoles.ml super(-1) of pyruvate, as carbon source for sulfate-reducing bacteria. After 9 days of incubation at 28 degree C, significant amounts of dimethylmercury were produced. A lower content of this volatile species was found in a subsample of sediment supplemented with sodium molybdate, which is a strong inhibitor of sulfate-reducing activity. A kinetic study showed the disappearance of monomethylmercury from the sediment and the formation of dimethylmercury over the incubation period. The environmental significance of dimethylmercury and dimethylmercury-sulfide in the natural biogeochemical cycle of Hg is discussed.
AN: 3796198

                                                                    243 of 1521  
TI: Mercury cycling in the Allequash Creek watershed, northern Wisconsin
AU: Krabbenhoft,-D.P.; Benoit,-J.M.; Babiarz,-C.L.; Hurley,-J.P.; Andren,-A.W.
AF: U.S. Geol. Survey, Water Resour. Div., Madison, WI 53719, USA
CO: 3. International Conference on Mercury as a Global Pollutant, Whistler, BC (Canada), 10-14 Jul 1994
SO: THIRD-INTERNATIONAL-CONFERENCE-ON-MERCURY-AS-A-GLOBAL-POLLUTANT. Porcella,-D.;Huckabee,-J.;Wheatley,-B.-eds. 1995 vol. 80, no. 1-4 pp. 425-433
ST: WATER,-AIR,-SOIL-POLLUT. vol. 80, no. 1-4
LA: English
ER: F (Freshwater)
AB: Although there have been recent significant gains in our understanding of mercury (Hg) cycling in aquatic environments, few studies have addressed Hg cycling on a watershed scale. In particular, attention to Hg species transfer between watershed components (upland soils, groundwater, wetlands, streams, and lakes) has been lacking. This study describes spatial and temporal distributions of total Hg and MeHg among watershed components of the Allequash Creek watershed (northern Wisconsin, USA). Substantial increases in total Hg and MeHg were observed as groundwater discharged through peat to form springs that flow into the stream, or rivulets that drain across the surface of the wetland. This increase was concomitant with increases in DOC. During fall, when the Allequash Creek wetland released a substantial amount of DOC to the stream, a 2-3 fold increase in total Hg concentrations was observed along the entire length of the stream. Methylmercury, however, did not show a similar response. Substantial variability was observed in total Hg (0.9 to 6.3) and MeHg (<0.02 to 0.33) concentrations during synoptic surveys of the entire creek. For the Allequash Creek watershed, the contributing groundwater basin is about 50% larger than the topographic drainage basin. Total Hg concentrations in groundwater, the area of the groundwater basin, and annual stream flow data give a watershed-yield rate of 1.2 mg/km super(2)/d, which equates to a retention rate of 96%. The calculated MeHg yield rate for the wetland area is 0.6 to 1.5 mg/km super(2)/d, a value that is 3-6 fold greater than the atmospheric deposition rate.
AN: 3796179

                                                                    244 of 1521  
TI: Methylated and elemental mercury cycling in surface and deep ocean waters of the North Atlantic
AU: Mason,-R.P.; Rolfhus,-K.R.; Fitzgerald,-W.F.
AF: Chesapeake Biol. Lab., Univ. Maryland, Solomons, MD 20688, USA
CO: 3. International Conference on Mercury as a Global Pollutant, Whistler, BC (Canada), 10-14 Jul 1994
SO: THIRD-INTERNATIONAL-CONFERENCE-ON-MERCURY-AS-A-GLOBAL-POLLUTANT. Porcella,-D.;Huckabee,-J.;Wheatley,-B.-eds. 1995 vol. 80, no. 1-4 pp. 665-677
ST: WATER,-AIR,-SOIL-POLLUT. vol. 80, no. 1-4
LA: English
ER: M (Marine)
AB: Biogeochemical cycling of mercury (Hg) in the ocean and air-sea exchange are integral parts of the global Hg cycle. Ionic Hg (i.e. reactive Hg-Hg super(o)) is converted in ocean surface waters to elemental Hg (Hg super(o)) with the subsequent loss, via gas evasion, of the Hg super(o) to the atmosphere. During a recent cruise in the North Atlantic Ocean, Hg super(o) in surface waters was a substantial fraction of the reactive Hg (85%, on average) and there was a relationship between photosynthetic pigment concentration and Hg super(o). In addition, there was evidence of Hg bound to "collodial" material (of greater than 1,000 molecular weight). Ionic Hg concentrations were around 0.15 pM, similar to the average colloidal Hg concentration of 0.2 pM. Methylated Hg compounds, both dimethylHg (DMHg) and monomethylHg (MMHg), were found in the deeper waters with DMHg being the predominant methylated species. This contrasts with freshwater lakes where MMHg is the principal species and no DMHg has been found. Preliminary modelling, using estimated rate constants for the formation and decomposition of DMHg and MMHg, predicts an enhanced stability of DMHg in ocean waters relative to fresh water. Deep ocean waters, formed by sinking of surface waters, can preserve DMHg that was produced in the more productive surface regime.
AN: 3796172

                                                                    245 of 1521  
TI: Mercury cycling in the water column of a seasonally anoxic urban lake (Onondaga Lake, NY)
AU: Jacobs,-L.A.; Klein,-S.M.; Henry,-E.A.
AF: PTI Environ. Serv., 15375 SE 30th Place, Suite 250, Bellevue, WA 98007, USA
CO: 3. International Conference on Mercury as a Global Pollutant, Whistler, BC (Canada), 10-14 Jul 1994
SO: THIRD-INTERNATIONAL-CONFERENCE-ON-MERCURY-AS-A-GLOBAL-POLLUTANT. Porcella,-D.;Huckabee,-J.;Wheatley,-B.-eds. 1995 vol. 80, no. 1-4 pp. 553-562
ST: WATER,-AIR,-SOIL-POLLUT. vol. 80, no. 1-4
LA: English
ER: F (Freshwater)
AB: Onondaga Lake, New York, is a hypereutrophic, urban lake that was subjected to industrial discharges of mercury (Hg) between 1947 and 1988. Water samples were collected from April through November 1992 and analyzed for filtered and unfiltered total Hg, methylmercury (CH sub(3)Hg), dimethylmercury, ionic Hg, and elemental Hg to characterize the biogeochemical cycling of Hg during water column stratification and hypolimnetic anoxia. In the spring and late fall when the water column was isothermal, total Hg and CH sub(3)Hg concentrations were relatively constant throughout the water column, at approximately 3-7 ng/L and 0.3-1 ng/L, respectively. Through the summer and early fall, CH sub(3)Hg concentrations systematically increased in the deeper waters, reaching peak concentration in August and September. In September 1992, CH sub(3)Hg concentrations increased from 0.3 ng/L in the epilimnion to 10.6 ng/L in the hypolimnion, an increase of nearly 2 orders of magnitude. At the same time, total Hg increased from 6.6 ng/L in surface water to 21.7 ng/L at depth, a 3-fold increase. The spatial and temporal patterns observed for CH sub(3)Hg agree well with manganese, suggesting that CH sub(3)Hg and manganese are controlled by processes of the same or parallel cycles.
AN: 3796159

                                                                    246 of 1521  
TI: Microbial activity and phosphorus dynamics in eutrophic lake sediments enriched with Microcystis colonies
AU: Brunberg,-A.-K.
AF: Inst. Limnol., Uppsala Univ., Norbyvaegen 20, S-752 36 Uppsala, Sweden
SO: FRESHWAT.-BIOL. 1995 vol. 33, no. 3, pp. 541-555
LA: English
ER: F (Freshwater)
AB: Sediments from hypereutrophic Lake Vallentunasjoen were enriched with Microcystis colonies from the lake water, thereby simulating the conditions after the autumn sedimentation. Release of phosphorus to the overlying lake water was followed during 2-3 weeks in the laboratory. X-ray microanalysis of individual Microcystis and bacterial cells, and chemical phosphorus fractionation, were used to assess the phosphorus pool size in different fractions of the sediment. Release of molybdate-reactive phosphorus to the overlying lake water was larger from sediment cores enriched with Microcystis colonies than from control cores. X-ray microanalysis showed that the phosphorus bound in Microcystis cells decreased by -0.300 mg g super(-1) DW in the October experiment, due both to a decrease in biomass (i.e. mineralization) and to a decrease in phosphorus content in the remaining cells.
AN: 3794300

                                                                    247 of 1521  
TI: A first-order nutrient budget for the tropical Moresby Estuary and catchment, north Queensland, Australia
AU: Eyre,-B.
AF: Cent. Coast. Manage., P.O. Box 5125, East Lismore, N.S.W. 2480, Australia
SO: J.-COAST.-RES. 1995 vol. 11, no. 3, pp. 717-732
LA: English
ER: B (Brackish)
AB: Dry and wet season phosphorus and nitrogen budgets for the Moresby Estuary and catchment are constructed to interpret cause-effect relationships between catchment landuse and nutrient loads in the coastal waterways of the Great Barrier Reef region. Samples were collected during seasonal extremes to reflect as wide a range of conditions as possible. Smaller scale processes cannot be resolved at this level of nutrient balance due to large budget uncertainties. However, the nutrient budget does give an insight into catchment scale processes. Fertilizer application on cane land in the catchment is the dominant source of phosphorus (about 3,566  plus or minus  735 x 10 super(3) moles) and nitrogen (about 79,330  plus or minus  11,338 x 10 super(3) moles), contributing 88 times more phosphorus and nitrogen to the catchment than is supplied by other sources (e.g., septic tanks, atmospheric fallout, natural runoff and natural springs). However, only about 4  plus or minus  2% of the phosphorus and about 11  plus or minus  7% of the nitrogen added to the catchment is transferred to the estuary. About 82% of the phosphorus and about 90% of the nitrogen flux from the catchment occurs during the wet season. Once in the estuary, only small amounts of phosphorus and nitrogen are retained with most of the phosphorus being transferred to the ocean and it is suggested that most of the nitrogen may be used biologically. The fact that the Moresby Estuary is not a strong sink for nutrients (i.e., it is not becoming eutrophic with time) suggests that current levels of agricultural activity in the catchment can be maintained without adverse effects on ecological components of the estuary and catchment.
AN: 3794066

                                                                    248 of 1521  
TI: Nitrogen uptake and regeneration in a frontal region of the Algerian current (western Mediterranean Sea): New evaluation of new production
OT: Absorption et regeneration de l'azote dans la zone frontale du courant Algerien (Mediterranee Occidentale): Reevaluation de la production nouvelle
AU: Gentilhomme,-V.; Raimbault,-P.
AF: Cent. Oceanol. Marseille, Observatoire Sci. Univers, Fac. Sci. Luminy, Case 901, 13288 Marseille Cedex 9, France
SO: OCEANOL.-ACTA 1995 vol. 17, no. 5, pp. 555-562
LA: English
ER: M (Marine)
AB: The uptake and regeneration of 4 forms of nitrogen have been studied in the euphotic layer of a frontal area in relation with hydrological, chemical and biological parameters. In this area vertical stratification is pronounced; a deep chlorophyll maximum at the bottom of the euphotic layer is present. Results show the importance of measuring urea uptake and regeneration in the study of nitrogen cycling, because the component can be regenerated as rapidly as ammonia, and is source of nitrogen for phytoplankton. Other results show the oxidation of ammonia to nitrate in the euphotic layer. This nitrification is a source of in situ regeneration nitrate and could lead to a wrong estimation of the new production estimation. In the deep chlorophyll maximum, there is a maximum of nitrogen primary production but not a maximum of new production. Regenerated production is the most important process over the whole euphotic layer of the Algerian basin.
AN: 3788993

                                                                    249 of 1521  
TI: Biodegradability of organic matter in the water column and fluid mud of the Loire estuary
OT: Biodegradabilite de la matiere organique dans le bouchon vaseux et la creme de vase de l'estuaire de la Loire
AU: Maurice,-L.
AF: IFREMER Cent. Toulon, DEL, BP 330, 83507 La Seyne/Mer, France
SO: OCEANOL.-ACTA 1995 vol. 17, no. 5, pp. 501-516
LA: English
ER: M (Marine); B (Brackish)
AB: The organic matter trapped in the turbidity maximum zone of the Loire estuary, as a support of bacterial activity, constitutes a basic element in the biogeochemical cycle which permits us to understand the causes of the anoxia observed in September. The anaerobic fluid mud is presumed to be the centre of fermentation and/or hydrolysis processes; the formation rate of dissolved organic carbon (DOC) in this layer reaches 3 g C.m super(-3). D super(-1). When particles in the water column, the organic products formed in the fluid mud are integrated into the aerobic metabolic cycle and contribute to the decrease of dissolved oxygen concentrations. The fluid mud participates in ammonia regeneration in the turbidity maximum zone. Causes of the anoxia cannot be studied without a thorough knowledge of the transformation processes of organic and mineral components in the fluid mud.
AN: 3788989

                                                                    250 of 1521  
TI: Fe, Zn, Mn and N transfer between size classes in a coastal phytoplankton community: Trace metal and major nutrient recycling compared
AU: Hutchins,-D.A.; Bruland,-K.W.
AF: Mar. Sci. Res. Cent., SUNY Stony Brook, Stony Brook, New York, NY 11794-5000, USA
SO: J.-MAR.-RES. 1995 vol. 53, no. 2, pp. 297-313
LA: English
ER: M (Marine)
AB: Experiments were performed to investigate transfer of  super(59)Fe,  super(65)Zn,  super(54)Mn, and  super(15)N from labeled cyanobacteria to the large (> 8  mu m or > 5  mu m) phytoplankton size class from Monterey Bay, California. Transfer of metal isotope activity was measured from and into total (for all isotopes) and intracellular ( super(59)Fe only) pools. Results demonstrated rapid and efficient transfer of nitrogen to the large phytoplankton size class; intracellular  super(59)Fe was transferred into the intracellular and total pools of the > 8  mu m phytoplankton size class 70% and 130% as efficiently as nitrogen, respectively.  super(65)Zn and  super(54)Mn were transferred between size classes 48% and 23% as efficiently as N. Extracellular  super(59)Fe and  super(65)Zn from the added cyanobacteria also appeared quickly in the large size fraction, although most of the Fe transfer appeared to be the result of surface adsorption rather than biological uptake. These data are discussed in relation to the biological recycling efficiencies of the four elements and the resulting implications for biogeochemical cycling of trace and major nutrient elements.
AN: 3788841

                                                                    251 of 1521  
TI: On the organic carbon maximum on the continental slope of the eastern Arabian Sea
AU: Calvert,-S.E.; Pedersen,-T.F.; Naidu,-P.D.; Von-Stackelberg,-U.
AF: Dep. Oceanogr., Univ. British Columbia, Vancouver, BC V6T 1Z4, Canada
SO: J.-MAR.-RES. 1995 vol. 53, no. 2, pp. 269-296
LA: English
ER: M (Marine)
AB: We critically examine the hypothesis that the oxygen minimum in the eastern Arabian Sea is the site of enhanced organic matter accumulation and preservation using analyses of suites of samples with wide geographical coverage along this margin. The distribution of organic matter on the western Indian continental margin is controlled by (1) variations in supply (decreasing westward away from the centers of coastal upwelling and also decreasing with increasing water depth), (2) dilution by other sedimentary components, and (3) the texture of the sediments (coarser-grained sediments having lower carbon contents), which is controlled in turn by sediment supply and reworking. The evidence available suggests that the organic carbon maximum on this slope is not related to the position of the oxygen minimum.
AN: 3788840

                                                                    252 of 1521  
TI: Computer modelling of phosphatic surfaces
AU: Suharan,-S.; Taylor,-M.G.; Simkiss,-K.
AF: Sch. Anim. and Microb. Sci., Dep. Zool., Univ. Reading, Reading RG6 2AJ, UK
CO: 7. Int. Symp. on Biomineralization, Monaco (Monaco), 17 Nov 1993
SO: BIOMINERALIZATION-'-93.-1.-FUNDAMENTALS-OF-BIOMINERALIZATION. Allemand,-D.;Cuif,-J.P.-eds. MONACO-MONACO INSTITUT-OCEANOGRAPHIQUE 1994 vol. NS 14, no. 1 pp. 81-84
ST: MEM.-INST.-OCEANOGR.-MONACO vol. NS 14, no. 1
LA: English
ER: M (Marine); F (Freshwater)
AB: Calcium phosphates in the form of inorganic granules are released into the marine environment by many marine invertebrates in faecal pellets which become part of the marine phosphate cycle. This cycle can result in the long term increase or decrease of phosphates in the environment. The key to any quantitative evaluation of the fate of these particles and their effect on the phosphate cycle is to predict reactions at the surface of these pellets. The approach used here is to develop a potential model for atomistic type simulations of the bulk and surface structures of crystalline calcium phosphates which will be transferable to the granules.
AN: 3787738

                                                                    253 of 1521  
TI: Evaluation of the physicochemical state of heavy metals in Danube water in various stretches
AU: Linnik,-P.N.; Osadchaya,-N.N.; Nabivanets,-Y.B.; Evtushenko,-N.Y.
AF: Inst. Hydrobiol., Ukrainian Acad. Sci., Ukraine
SO: WATER-RESOUR.;VODNYE-RESURSY 1994;1993 vol. 20, no. 4, pp. 48-55;vol. 20, no. 4, pp. 449-454
NT: Special issue: Investigation of the Danube River ecosystem.
LA: English
ER: F (Freshwater)
AB: Among pollutants contained in wastewaters, heavy metals (HMs) occupy one of the first places in toxicity. As is known, they are not subject to biodegradation and, gradually accumulating in various components of the ecosystem, participate in biological cycles. The chemical reactivity and biological activity of HMs are determined not so much by their gross concentrations as by the physicochemical state in the aquatic environment. Works on estimating the content of HMs in the Ukrainian stretch of the Danube began in the late 1970s. Profound studies of coexisting forms of HMs have been being carried out since 1980. Two international expeditions were conducted in March 1988 and September-October 1990, which made it possible to characterize the state of HMs in various stretches of the river.
AN: 3787430

                                                                    254 of 1521  
TI: Benthic microbial production of oxygen supersaturates the bottom water of a stratified hypersaline lake
AU: Burke,-C.M.
AF: Dep. Aquacult., Univ. Tasmania at Launceston, P.O. Box 1214, Tasmania 7250, Australia
SO: MICROB.-ECOL. 1995 vol. 29, no. 2, pp. 163-171
LA: English
AB: Lake Hayward is a hypersaline lake that stratifies seasonally and maintains oxygen supersaturation in its bottom water for about 6 months each year. This phenomenon was found to be the result of photosynthesis by the benthic microbial communities, composed primarily of the cyanobacteria Cyanothece spp., Spirulina sp., and Oscillatoria sp. When these communities were present and the lake was stratified, the bottom water was supersaturated with oxygen. During illumination, the benthic microbial communities rapidly developed very high concentrations of oxygen, which then diffused into the overlying water. However, while the overlying water became supersaturated, the concentration in the water was lower than in the benthic microbial communities because (1) transport across the sediment-water interface was limited by diffusion, and (2) turbulence rapidly mixed the oxygen throughout the much larger volume of the bottom water.
AN: 3787391

                                                                    255 of 1521  
TI: Spatial and seasonal patterns in sediment nitrogen remineralization and ammonium concentrations in San Francisco Bay, California
AU: Caffrey,-J.M.
AF: U.S. Geol. Surv., 345 Middlefield Rd, MS 496, Menlo Park, CA 94025, USA
SO: ESTUARIES 1995 vol. 18, no. 1B, pp. 219-233
LA: English
ER: B (Brackish)
AB: Nitrogen remineralization and extractable ammonium concentrations were measured in sediments from several locations in North and South San Francisco bays. In South Bay, remineralization rates decreased with depth in sediment and were highest in the spring following the seasonal phytoplankton bloom. At the channel stations, peak remineralization lagged peak water-column phytoplankton biomass (as measured by chlorophyll a) by a month. Remineralization rates were generally higher in South Bay than North Bay. The lower remineralization rates in North Bay may be a result of anomalously low phytoplankton production and thus reduced deposition to the sediments, as well as low riverine organic inputs to the upper estuary in recent years. Remineralization rates were positively correlated to carbon and nitrogen content of the sediments. In general, ammonium profiles in South Bay sediments showed no increase in deeper (4-8 cm) sediments. In North Bay, ammonium concentrations were greatest at stations with highest remineralization rates, and, in contrast to South Bay, extractable ammonium increased in deeper sediment. Differences in ammonium pools between North Bay and South Bay may be a result of increased irrigation by deep-dwelling macrofauna, which are more abundant in South Bay.
AN: 3787028

                                                                    256 of 1521  
TI: Organic matter fluxes and marsh stability in a rapidly submerging estuarine marsh
AU: Nyman,-J.A.; DeLaune,-R.D.; Pezeshki,-S.R.; Patrick,-W.H.,Jr.
AF: Dep. Biol., P.O. Box 42451, Univ. Southwestern Louisiana, Lafayette, LA 70504-2451, USA
SO: ESTUARIES 1995 vol. 18, no. 1B, pp. 207-218
LA: English
ER: B (Brackish)
AB: We studied organic matter cycling in two Gulf Coast tidal, nonsaline marsh sites where subsidence causes marine intrusion and rapid submergence, which mimics increased sea-level rise. The sites experienced equally rapid submergence but different degrees of marine intrusion. Vegetation was hummocked and much of the marsh lacked rooted vegetation. Aboveground standing crop and production, as measured by sequential harvesting, were low relative to other Gulf Coast Spartina patens marshes. Soil bulk density was lower than reported for healthy S. alterniflora growth but that may be unimportant at the current, moderate sulfate levels. Belowground production, as measured by sequential harvesting, was extremely fast within hummocks, but much of the marsh received little or no belowground inputs. Aboveground production was slower at the more saline site (681 g m super(2)/yr) than at the less saline site (1,252 g m super(2)/yr). Belowground production over the entire marsh surface averaged 1,401 g m super(2)/yr at the less saline site and 585 g m super(2)/yr at the more saline site. Respiration, as measured by CO sub(2) emissions in the field and corrected for CH sub(4) emissions, was slower at the less saline site (956 g m super(2)/yr) than at the more saline site (1,438 g m super(2)/yr), reflecting greater contributions by S. alterniflora at the more saline site which is known to decompose more rapidly than S. patens. Burial of organic matter was faster at the less saline site (796 g m super(2)/yr) than at the more saline site (434 g m super(2)/yr), likely in response to faster production and slower decomposition at the less saline site. Thus vertical accretion was faster at the less saline site (1.3 cm/yr) than at the more saline site (0.85 cm/yr); slower vertical accretion increased flooding at the more saline site. More organic matter was available for export at the less saline site (1,377 g m super(2)/yr) than at the more saline site (98 g m super(2)/yr). These data indicated that organic matter production decreased and burial increased in response to greenhouse-like conditions brought on by subsidence.
AN: 3787027

                                                                    257 of 1521  
TI: Inputs, transformations, and transport of nitrogen and phosphorus in Chesapeake Bay and selected tributaries
AU: Boynton,-W.R.; Garber,-J.H.; Summers,-R.; Kemp,-W.M.
AF: Univ. Maryland Syst., Cent. Environ. Estuar. Stud., Chesapeake Biol. Lab., Box 38, Solomons, MD 20688, USA
SO: ESTUARIES 1995 vol. 18, no. 1B, pp. 285-314
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: In this paper we assemble and analyze quantitative annual input-export budgets for total nitrogen (TN) and total phosphorus (TP) for Chesapeake Bay and three of its tributary estuaries (Potomac, Patuxent, and Choptank rivers). The budgets include estimates of TN and TP sources (point, diffuse, and atmospheric), internal losses (burial in sediments, fisheries yields, and denitrification), storages in the water column and sediments, internal cycling rates (zooplankton excretion and net sediment-water flux), and net downstream exchange. Our budgets indicate that the annual mass balance of TN and TP is maintained by a net landward exchange of TP and, with one exception (Choptank River), a net seaward transport of TN. The budgets for all systems revealed that inorganic nutrients entering these estuaries from terrestrial and atmospheric sources are rapidly converted to particulate and organic forms. Discrepancies between our budgets and others in the literature were resolved by the inclusion of sediments derived from shoreline erosion. The greatest potential for errors in our budgets can be attributed to the absence of or uncertainties in estimates of atmospheric dry-fall, contributions of nutrients via groundwater, and the sedimentation rates used to calculate nutrient burial rates.
AN: 3786954

                                                                    258 of 1521  
TI: Elemental ratios and the uptake and release of nutrients by phytoplankton and bacteria in three lakes of the Canadian Shield
AU: Elser,-J.J.; Chrzanowski,-T.H.; Sterner,-R.W.; Schampel,-J.H.; Foster,-D.K.
AF: Dep. Zool., Arizona State Univ., Tempe, AZ 85287, USA
SO: MICROB.-ECOL. 1995 vol. 29, no. 2, pp. 145-162
LA: English
ER: F (Freshwater)
AB: The dynamics of carbon (C), nitrogen (N), and phosphorus (P), elemental ratios, and dark uptake/release of N and P in bacterial and phytoplankton size fractions were studied during summer 1992 in three lakes of contrasting food web structure and trophic status. The authors wished to determine if phytoplankton and bacteria differed in their elemental characteristics and to evaluate whether the functional role of bacteria in nutrient cycling (i.e., as sink or source) depended on bacterial elemental characteristics. Bacterial contributions to total suspended particulate material and to fluxes of nutrients in the dark were substantial and varied for different elements. This indicated that some techniques for assaying phytoplankton physiological condition are compromised by bacterial contributions. C/N ratios were generally less variable than C/P and N/P ratios.
AN: 3786575

                                                                    259 of 1521  
TI: The role of bacteria in the nutrient exchange between sediment and water in a flow-through system
AU: Kairesalo,-T.; Tuominen,-L.*; Hartikainen,-H.; Rankinen,-K.
AF: Dep. Limnol. and Environ. Prot., P.O. Box 27, FIN-00014 Univ. Helsinki, Finland
SO: MICROB.-ECOL. 1995 vol. 29, no. 2, pp. 129-144
LA: English
ER: F (Freshwater)
AB: The contribution of bacteria to phosphorus and nitrogen release from, or retention in, sediment was studied in a flow-through system. "Live" and formaldehyde-"killed" sediment communities were incubated in 25-liter bottles with a continuous flow of P- or P + N-enriched water. Sediment bacteria in the killed communities were inhibited by adding formaldehyde to the sediment before the start of the experiment. Bacterial activity in the live sediments measured with [ super(3)H]thymidine and [ super(14)C]leucine incorporation techniques did not change essentially during the experiment period (7-8 days). Chemical mechanisms were found to be of principal importance in PO sub(4)-P retention in the sediment. In the live samples, the net retention of PO sub(4)-P was lower than in the killed samples, which was likely due to the reduced O sub(2) conditions in the sediment as a consequence of bacterial mineralization. In total P exchange, however, bacteria increased the retention rate by recycling dissolved organic P in the sediment.
AN: 3786574

                                                                    260 of 1521  
TI: Seasonal patterns of nitrification and denitrification in a natural and a restored salt marsh
AU: Thompson,-S.P.; Paerl,-H.W.; Go,-M.C.
AF: Univ. North Carolina, Inst. Mar. Sci., 3431 Arendell St., Morehead City, NC 28557, USA
SO: ESTUARIES 1995 vol. 18, no. 2, pp. 399-408
LA: English
ER: M (Marine); B (Brackish)
AB: Seasonal patterns of microbially-mediated nitrogen cycling via the nitrification-denitrification pathway were compared between a natural and a restored salt marsh. Sedimentary denitrification rates, measured with a modification of the acetylene block technique, were approximately 44 times greater in the natural marsh relative to an adjacent transplanted marsh. Nitrification rates were similar at both sites. The difference in denitrification rates was attributed to oxygen inhibition at low tide and tidal flushing of porewater nutrients at high tide in the coarse sediments of the restored marsh. Denitrification was positively correlated with nitrification throughout the year in the natural marsh with a seasonal fall peak in denitrification corresponding to a maximum in porewater ammonia concentration. A weak correlation existed between the two processes in the restored marsh, where nitrification rates exceeded denitrification rates by a factor of 20. Transplanted marsh denitrification rates exhibited a spring peak, corresponding to elevated porewater ammonia concentrations. Our findings demonstrate functional differences in microbial nitrogen dynamics of a young (0-3 yr) restored marsh relative to a mature (>50 yr) salt-marsh system.
AN: 3785336

                                                                    261 of 1521  
TI: Cyclic and secular variation in microfossil biomineralization: Clues to the biogeochemical evolution of Phanerozoic oceans
AU: Martin,-R.E.
AF: Dep. Geol., Univ. Del., Newark, DE 19716, USA
SO: GLOBAL-PLANET.-CHANGE 1995 vol. 11, no. 1-2, pp. 1-23
LA: English
ER: M (Marine)
AB: The stratigraphic occurrence and mineralogy of major protistan microfossil taxa tend to reflect evolutionary innovation in response to ocean chemistry and fertility. In foraminifera, the characteristic test composition-and, in some cases, ultrastructure-of each suborder is indicative of the degree of surface ocean CaCO sub(3) saturation, which varied in a cyclic manner through the Phanerozoic, at the time of origin of the suborder. High dissolve phosphate and low CaCO sub(3) saturation in late Precambrian-Early Cambrian surface waters may have prevented calcification in primitive non-calcareous (organic, agglutinated) foraminiferal stocks. Scattered reports of coccolithophorid-like microfossils from the Paleozoic are indicative of a secular trend in rising nutrient levels and marine productivity that controlled the initiation of calcareous oozes. Based on acritarch, carbon isotope, and phosphorite records, extremely low nutrient levels ("superoligotrophic" conditions) in Cambrian-to-Devonian seas typically limited population densities of calcareous nannoplankton and prevented the formation of calcareous oozes. The overall "superoligotrophic" surface conditions of the Paleozoic were punctuated, though, by episodes of "catastrophic" eutrophication in the Late Ordovician, Late Devonian, and Late Carboniferous (Worsley et al., 1986). Following each episode, CaCO sub(3) rain rates were presumably enhanced because Marine C:P (MCP) burial ratios increased permanently above previous levels (Worsley et al., 1986). Nevertheless, it was not until the Carboniferous that the CCD had deepened sufficiently (via erosion of cratonic limestones) to allow pelagic calcareous oozes to begin to accumulate. Prior to this time, surface waters appear to have been sufficiently corrosive (high atmospheric pCO sub(2) and low CaCO sub(3) saturation), and the CCD sufficiently shallow, to dissolve virtually all incipient calcareous nannofossils. Following Late Permian extinctions, plankton re-expanded in response to both eustatic sea level rise (increased habitat availability) and increased nutrient levels ("mesotrophic" conditions). As organic matter (C sub(org)) and CaCO sub(3) rain rates increased, bioturbation rates also increased, thereby recycling nutrients back to the surface and accentuating productivity and calcareous ooze formation. MCP episodes further accelerated nutrient cycling and productivity in the Neogene, as indicated by the expansion of diatoms, which prefer nutrient-rich ("eutrophic") conditions. Ironically, while permanently increasing C:P burial ratios and productivity through the Phanerozoic, catastrophic fluctuations in nutrient levels may have also exacerbated mass extinctions via shortening of pelagic food chains. Nevertheless, re-expansion of the marine biosphere following each extinction episode resulted in a secular trend of increasing biomass and biotic diversity that may have contributed to the decline in background extinction rates through the Phanerozoic.
AN: 3785193

                                                                    262 of 1521  
TI: Sediment-water fluxes of inorganic nitrogen compounds along the transport route of organic matter in the North Sea
AU: Lohse,-L.; Malschaert,-J.F.P.; Slomp,-C.P.; Helder,-W.; Van-Raaphorst,-W.
AF: Netherlands Inst. Sea Res., P.O. Box 59, 1790 AB Den Burg, Netherlands
CO: International Symposium on Nutrient Dynamics in Coastal and Estuarine Environments, Helsingoer (Denmark), 13-16 Oct 1993
SO: OPHELIA 1995 vol. 41, pp. 173-197
LA: English
ER: M (Marine)
AB: Sediment-water fluxes of ammonium and nitrate, as well as nitrification and denitrification were measured in different types of sediments in the North Sea in August 1991 and February 1992. Stations were located along the main transport route of organic matter and included depositional areas located on the southern shelf (German Bight) and on the north-eastern shelf-slope transition in the Skagerrak. Based on sedimentary organic carbon content and grain size distribution, the stations were divided into three clusters. I: depositional areas with median grain size <50  mu m; II: transition zones with grain sizes between 80 and 180  mu m, and III: coarse sediments with median grain size >280  mu m. Porewater profiles of nitrate and ammonium corresponded well to this clustering. The very high mineralisation in the German Bight in August demonstrates the importance of deposition of locally produced organic matter in this area. Total ammonium production in the Skagerrak in August and February indicates that here N-cycling is dominated by the input of refractory organic matter from the southern shelf. Consequently, the shelf-slope transition in the Skagerrak does not represent an area of intensified nitrogen mineralisation.
AN: 3785184

                                                                    263 of 1521  
TI: A review of the U.S. Global Change Research Program and NASA's Mission to Planet Earth/Earth Observing System
CA: National Research Counc., Washington, DC (USA)
SO: WASHINGTON,-DC-USA NATIONAL-ACADEMY-PRESS 1995 107 pp
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: This report reflects the results of a July 1995 workshop convened as the first phase of a two-part review of the U.S. Global Change Research Program. The workshop's objective was to conduct an initial assessment of scientific progress to date, and to review the role of NASA's Mission to Plant Earth/Earth Observing System program in the light of budgetary pressures. The report identifies priority issues in four areas of Earth science: seasonal to interannual climate prediction (El Nino, land-atmosphere interactions); atmospheric chemistry (tropospheric and stratospheric ozone, global distribution of aerosols, biogenic gases); ecosystems (global carbon cycle, vegetation-climate-land use interrelationships, oceanic food chain, exchange of water, carbon dioxide and biogenic gases); and decadal to centennial climate (forcing factors influencing climate, ocean-land-atmosphere-ice processes, long-term monitoring).
AN: 3779381

                                                                    264 of 1521  
TI: A global model for the early diagenesis of organic carbon and organic phosphorus in marine sediments
AU: Tromp,-T.K.; Van-Cappellen,-P.; Key,-R.M.
AF: Atmos. and Environ. Res., Inc., 840 Memorial Dr., Cambridge, MA 02139, USA
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 7, pp. 1259-1284
LA: English
ER: M (Marine)
AB: Sediments are the main repository in the oceanic cycles of carbon (C) and phosphorus (P). In order to relate the deposition of organic C and organic P from the water column, and ultimate burial in sediments, we present a model for the early diagenesis of organic matter in marine sediments. This general diagenetic model was developed for inclusion in global circulation models and is based on a single master variable, the sedimentation rate. The processes included are sediment advection, particle mixing by bioturbation, porewater diffusion, organic matter degradation by aerobic respiration, sulfate reduction, and methanogenesis. Despite the model's simplicity, the model quantitatively reproduces the rates of organic matter oxidation and the burial fluxes of organic C and P. The predicted trends of oxygen penetration depth and the relative importance of oxygen and sulfate reduction are in good agreement with field observations.
AN: 3777848

                                                                    265 of 1521  
TI: Reservoir timescales for anthropogenic CO sub(2) in the atmosphere
AU: O'-Neill,-B.C.; Gaffin,-S.R.; Tubiello,-F.N.; Oppenheimer,-M.
AF: Dep. Earth Syst. Sci., NYU, New York, NY 10003, USA
SO: TELLUS-B-CHEM.-PHYS.-METEOROL. 1994 vol. 46B, no. 5, pp. 378-389
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: Non-steady state timescales are complicated and their application to specific geophysical systems requires a common theoretical foundation. We first extend reservoir theory by quantifying the difference between turnover time and transit time (or residence time) for time-dependent systems under any mixing conditions. We explicitly demonstrate the errors which result from assuming these timescales are equal, which is only true at steady state. We also derive a new response function which allows the calculation of age distributions and timescales for well-mixed reservoirs away from steady state, and differentiate between timescales based on gross and net fluxes. These theoretical results are particularly important to tracer-calibrated "box models" currently used to study the carbon cycle, which usually approximate reservoirs as well-mixed. We then apply the results to the important case of anthropogenic CO sub(2) in the atmosphere, since timescales describing its behavior are commonly used but ambiguously defined. All relevant timescales, including lifetime, transit time, and adjustment time, are precisely defined and calculated from data and models. Apparent discrepancies between the current, empirically determined turnover time of 30-60 years and longer model-derived estimates of expected lifetime and adjustment time are explained within this theoretical framework. We also discuss the results in light of policy issues related to global warming, in particular since any comparisons of the "lifetimes" of different greenhouse gases (CO sub(2), CH sub(4), N sub(2)O, CFC's etc.) must use a consistent definition to be meaningful.
AN: 3777834

                                                                    266 of 1521  
TI: Influence of changes in CO sub(2) concentration and temperature on marine phytoplankton  super(13)C/ super(12)C ratios: An analysis of possible mechanisms
AU: Raven,-J.A.; Johnston,-A.M.; Turpin,-D.H.
AF: Dep. Biol. Sci., Univ. Dundee, Dundee DD1 4HN, UK
SO: GLOBAL-PLANET.-CHANGE 1993 vol. 8, no. 1-2, pp. 1-12
NT: Special issue: Ocean carbon cycle and climate change.
LA: English
ER: M (Marine)
AB: The  super(13)C/ super(12)C fractionation associated with net transport fluxes and chemical conversions, and with equilibria, associated with inorganic C assimilation processes in marine phytoplankton are quite well understood, though some gaps remain. These values are used in models of overall  super(13)C/ super(12)C fractionation in inorganic C assimilation involving the two major mechanisms involved in inorganic C entry, i.e. diffusion of CO sub(2) and active transport of CO sub(2) and/or HCO sub(3) super(-). The CO sub(2) diffusion model predicts the observed decrease in the  super(13)C/ super(12)C of plankton organic C relative to source CO sub(2) when CO sub(2) concentration increases and/or temperature decreases. The inorganic C active transport model is complicated by repression of the active transport mechanism at high inorganic C levels, but this model also predicts the observed effect on cell  super(13)C/ super(12)C of changes in CO sub(2) partial pressure or temperature for cell growth. More refined modelling and more input data are needed for both transport processes. Operation of either of the alternative mechanisms for inorganic C entry can be consistent with growth rate not being limited by inorganic C supply even when the photosynthetic rate is inorganic C-limited.
AN: 3775648

                                                                    267 of 1521  
TI: Chemical tracers of biological processes in shallow waters of North Pacific: Preformed nitrate distributions
AU: Emerson,-S.; Hayward,-T.L.
AF: Sch. Oceanogr., WB-10, Univ. Washington, Seattle, WA 98195, USA
SO: J.-MAR.-RES. 1995 vol. 53, no. 3, pp. 499-513
LA: English
ER: M (Marine)
AB: Distributions of nitrate and Apparent Oxygen Utilization in the upper subtropical North Pacific Ocean reveal a layer with negative values of preformed nitrate. This layer occurs at depths just below the 1% light level and above the density of sigma theta 25.6. We show that large-scale spatial patterns in the distribution of this feature are determined by an interaction between light penetration and the depth of isopycnal surfaces which are ventilated in nutrient rich surface waters. The geographic and depth distributions of the negative preformed nitrate feature are most readily explained by respiration of nitrogen-poor dissolved organic matter (DOM) from the surface ocean with the possible accompaniment of nitrate uptake. Dissolved organic carbon gradients and transport calculations suggest that a significant fraction of the carbon flux out of the euphotic zone may be via DOM, indicating that the processes responsible for creating the negative preformed nitrate feature could alter the metabolite stoichiometry in upper subtropical Pacific Ocean.
AN: 3773841

                                                                    268 of 1521  
TI: Seasonal variability of light availability and utilization in the Sargasso Sea
AU: Siegel,-D.A.; Michaels,-A.F.; Sorensen,-J.C.; O'-Brien,-M.C.; Hammer,-M.A.
AF: Inst. Comput. Earth Syst., Univ. California, Santa Barbara, CA 93106, USA
SO: J.-GEOPHYS.-RES.-C-OCEANS 1995 vol. 100, no. C5, pp. 8695-8713
LA: English
ER: M (Marine)
AB: A 2 year time series of optical, biogeochemical, and physical parameters, taken near the island of Bermuda, is used to evaluate the sources of temporal variability in light availability and utilization in the Sargasso Sea. Integrated assessments of light availability are made by examining the depth of constant percent incident photosynthetically available radiation (%PAR) volumes. Determinations of in situ primary production rates and daily mean PAR fluxes are used to diagnose the relative role of light limitation in determining vertically integrated rates of primary production  integral of PP. The mean depth of the light-saturated zone (the vertical region where the daily mean PAR flux was greater than or equal to the saturation irradiance I sub(k)) is only  similar to 40 m, although more than one half of  integral of PP occurred within this zone. Production model results illustrate the accurate predictions of  integral of PP are dependent upon rates of light-saturated production rather than upon indices of light limitation. It seems unlikely that significant improvements in simple primary production models will come from the partitioning of the Earth's seas into biogeochemical provinces.
AN: 3773801

                                                                    269 of 1521  
TI: Forms and distribution of inorganic phosphorus in sediments of two shallow eutrophic lakes in Florida
AU: Olila,-O.G.; Reddy,-K.R.; Harris,-W.G.
AF: Univ. Florida, Inst. Food Agric. Sci., Soil Water Sci. Dep., Gainesville, FL 32611, USA
SO: HYDROBIOLOGIA 1995 vol. 302, no. 2, pp. 147-161
LA: English
ER: F (Freshwater)
AB: Phosphorus (P) reactivity and bioavailability in lake sediments may be determined by different forms of P and their distribution. Reactive and nonreactive P pools in two shallow subtropical lake sediments (Lake Apopka and Lake Okeechobee) were determined by sequential chemical extraction using 1 M NH sub(4)Cl (pH 7.0), 0.1 M NaOH, and 0.5 M HCl, reportedly representing loosely-bound P, Fe-and Al-bound P, and Ca- and Mg-bound P respectively. The sequential P fractionation was tested using pure P compounds and selected P minerals. The scheme effectively separated Fe- and Al-P from Ca-P fractions in an FePO sub(4)-AlPO sub(4)-Ca sub(3)(PO sub(4)) sub(2) mixture. Readily available P, defined as the sum of water-soluble P and NH sub(4)Cl-extractable P, in the unconsolidated gyttja (UCG) layer (surface 0-30 cm) of Lake Apopka sediments accounted for 10.1 to 23.7% of total P (TP). This sediment P fraction constitutes a large reservoir which may act as a source of P to the overlying water. In subsurface marl layers (134-148 cm depth) of Lake Apopka, NH sub(4)Cl-P constituted <1% of TP whereas Ca-Mg-bound P and highly resistant P (residual P) accounted for 35 and 64% of TP respectively. Results suggest that 1 M NH sub(4)Cl (pH 7.0) and 0.5 M HCl, reported to dissolve carbonate-bound P and Ca-Mg-bound P, respectively, may not be extracting distinct pools of P. Lake Okeechobee mud sediments had low concentrations of readily available P (2% of TP) and were dominated by Ca-Mg-bound P (HCl-P greater than or equal to 58% of TP). Sediments in the littoral and peat areas of Lake Okeechobee, however, had high concentrations of readily available P (9.7 and 17.4% of TP respectively); hence, these sediments may play an important role in internal P cycling. The NaOH-P (Fe-Al-P) concentrations for Lake Okeechobee sediments were strongly correlated with amorphous and poorly-crystalline Fe (p<0.01), suggesting that some P reactions in these sediments may be sensitive to changes in physico-chemical conditions such as redox potential and sediment resuspension.
AN: 3773206

                                                                    270 of 1521  
TI: Terrestrial and marine biomarkers in a seasonally ice-covered Arctic estuary -- integration of multivariate and biomarker approaches
AU: Yunker,-M.B.; Macdonald,-R.W.; Veltkamp,-D.J.; Cretney,-W.J.
AF: 7137 Wallace Dr., Brentwood Bay, BC V8M 1G9, Canada
SO: MAR.-CHEM. 1995 vol. 49, no. 1, pp. 1-50
LA: English
ER: M (Marine)
AB: Hydrocarbons, including alkanes, alkenes, hopane triterpenes and polycyclic aromatic hydrocarbons, plus sterols, n-alcohols and a number of higher plant triterpenoids have been determined for suspended particulate, sediment trap and sediment samples taken from the Mackenzie River and the adjacent Mackenzie shelf in the Beaufort Sea. These biomarkers are valuable tracers of terrigenous and petrogenic inputs from the river to the shelf water column and are also useful for assessing marine production in the Mackenzie River estuary. We use Principal Component Analysis to provide a robust classification of biomarkers according to their primary source (e.g. terrigenous, marine) and to identify which biomarkers covary. To quantify dispersal of riverine material on the adjacent shelf in the context of dilution by marine production, we develop a multivariate Partial Least Squares (PLS) path model. We find that the PLS results strengthen geochemical interpretations based on individual biomarkers by providing a quantitative representation of the differences among samples.
AN: 3773204

                                                                    271 of 1521  
TI: Hydrochemistry of the Bay of Bengal: Possible reasons for a different water-column cycling of carbon and nitrogen from the Arabian Sea
AU: Rao,-C.K.; Naqvi,-S.W.A.*; Kumar,-M.D.; Varaprasad,-S.J.D.; Jayakumar,-D.A.; George,-M.D.; Singbal,-S.Y.S.
AF: Natl. Inst. Oceanogr., Dona Paula, Goa 403 004, India
SO: MAR.-CHEM. 1994 vol. 47, no. 3-4, pp. 279-290
NT: Special issue: Chemistry of the Northern Indian Ocean.
LA: English
ER: M (Marine)
AB: A study on biogeochemical cycling in the western Bay of Bengal was undertaken during two seasons (pre-southwest monsoon and northeast monsoon of 1991). Relationships of the conservative tracers NO and PO with potential temperature ( Theta ) are used to identify three end-member water masses in the Bay: the low-salinity surface water, the high-salinity intermediate water advecting from the Arabian Sea, and the deep water of circumpolar origin. A hydrochemical discontinuity at  similar to  12 degree C appears to define the boundary of zones of linear mixing among these waters. The shallower occurrence of the discontinuity in the Bay as compared to the Arabian Sea appears to restrict the thickness of the oxygen minimum layer in the former region. Marked seasonal changes appear to occur in intermediate waters, presumably reflecting changes in the coastal circulation off India. It is proposed that lower respiration rates in the Bay might result from a rapid sinking of organic matter with relatively little decomposition within the water column caused by the large inputs of terrigenous material.
AN: 3773201

                                                                    272 of 1521  
TI: Deep penetration of sedimentary fluids in basement rocks from southern Norway: Evidence from hydrocarbon and brine inclusions in quartz veins
AU: Munz,-I.A.; Yardley,-B.W.D.; Banks,-D.A.; Wayne,-D.
AF: Mineral.-Geol. Mus., Univ. Oslo, N-0562 Oslo, Norway
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 2, pp. 239-254
LA: English
AB: This paper presents evidence for fluid flow and fluid-rock interaction at upper crustal levels within the crystalline basement of southern Norway. In the high-grade Modum Complex postmetamorphic veins of quartz occur in association with albitisation of metagabbros and metasediments. Pressure-temperature conditions for the formation of these veins are in the range 250-300 degree C and ca. 1-2 kbar. Primary and pseudosecondary fluid inclusions in the quartz veins show two fluids: (1) hydrocarbon  plus or minus  CO sub(2) inclusions and (2) aqueous inclusions with variable salinities. Dark carbonaceous solid inclusions are also present. The hydrocarbon inclusions are methane dominated (ca. 80-100 mol%), and the presence of higher, complex hydrocarbons is demonstrated. The types and chemistry of the hydrocarbons in these veins indicate a biogenic origin of the hydrocarbon fluids. The inclusion fluids are interpreted as derived from an overlying sedimentary basin in late Precambrian or Permian times. The veining is interpreted as the deep expression of the percolation of basinal fluids into the metamorphic basement during crustal extension.
AN: 3769475

                                                                    273 of 1521  
TI: The effects of water temperature, stratification, and biological activity on the stable isotopic composition and timing of carbonate precipitation in a hypersaline lake
AU: Rosen,-M.R.; Turner,-J.V.; Coshell,-L.; Gailitis,-V.
AF: Inst. Geol. and Nucl. Sci., Wairakei Res. Cent., Priv. Bag 2000, Taupo, New Zealand
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 5, pp. 979-990
LA: English
ER: B (Brackish); F (Freshwater)
AB: The  delta  super(18)O of carbonate minerals in a seasonally stratified hypersaline lake are > +2.3ppt PDB and are inconsistent with calculated  delta  super(18)O values for carbonate in equilibrium with the lake water during the spring and winter. The  delta  super(13)C values of the calcium carbonate minerals precipitated in the lake are heavier than the dissolved inorganic carbon values ( delta  super(13)C sub(DIC)) of the lake water and cannot be explained by kinetic fractionation, indicating a biologic control on primary carbonate precipitation. The  delta  super(13)C of dolomite found in the lake sediments are in equilibrium with porewater  delta  super(13)C sub(DIC), suggesting a high degree of porewater interaction in dolomitization. Both the  delta  super(18)O and  delta  super(13)C compositions of the dolomite suggest that it formed in equilibrium with current porewater but not in equilibrium with the coexisting calcium carbonate minerals.
AN: 3769473

                                                                    274 of 1521  
TI: Glacial enrichments of authigenic Cd and U in Subantarctic sediments: A climatic control on the elements oceanic budget?
AU: Rosenthal,-Y.; Boyle,-E.A.; Labeyrie,-L.; Oppo,-D.
AF: Biosphere 2, Oracle, AZ, USA
SO: PALEOCEANOGRAPHY 1995 vol. 10, no. 3, pp. 395-413
LA: English
ER: M (Marine)
AB: We examine the possibility that glacial increase in the areal extent of reducing sediments might have changed the oceanic Cd inventory, thereby decoupling Cd from PO sub(4). We suggest that the precipitation of Cd-sulfide in suboxic sediments is the single largest sink in the oceanic Cd budget and that the accumulation of authigenic Cd and U is tightly coupled to the organic carbon flux into the seafloor. Sediments from the Subantarctic Ocean and the Cape Basin (South Atlantic), where oxic conditions currently prevail, show high accumulation rates of authigenic Cd and U during glacial intervals associated with increased accumulation of organic carbon. These elemental enrichments attest to more reducing conditions in glacial sediments in response to an increased flux of organic carbon. A third core, overlain by Circumpolar Deep Water (CPDW) as are the other two cores but located south of the Antarctic Polar Front, shows an approximately inverse pattern to the Subantarctic record. The contrasting patterns to the north and south of the Antarctic Polar Front suggest that higher accumulation rates of Cd and U in Subantarctic sediments were driven primarily by increased productivity. This proposal is consistent with the hypothesis of glacial stage northward migration of the Antarctic Polar Front and its associated belt of high siliceous productivity.
AN: 3769355

                                                                    275 of 1521  
TI: Influence of variable rates of neritic carbonate deposition on atmospheric carbon dioxide and pelagic sediments
AU: Walker,-J.C.G.; Opdyke,-B.C.
AF: Space Phys. Res. Lab., Dep. Atmos., Ocean. Space Sci., Univ. Michigan, Ann Arbor, MI, USA
SO: PALEOCEANOGRAPHY 1995 vol. 10, no. 3, pp. 415-427
LA: English
ER: M (Marine)
AB: Short-term imbalances in the global cycle of shallow water calcium carbonate deposition and dissolution may be responsible for much of the observed Pleistocene change in atmospheric carbon dioxide content. However, any proposed changes in the alkalinity balance of the ocean must be reconciled with the sedimentary record of deep-sea carbonates. The possible magnitude of the effect of shallow water carbonate deposition on the dissolution of pelagic carbonate can be tested using numerical simulations of the global carbon cycle. Boundary conditions can be defined by using extant shallow water carbonate accumulation data and pelagic carbonate deposition/dissolution data. On timescales of thousands of years carbonate deposition versus dissolution is rarely out of equilibrium by more than 1.5 x 10 super(13) mole/yr. Results indicate that the carbonate chemistry of the ocean is rarely at equilibrium on timescales less than 10 ka. This disequilibrium is probably due to sea level-induced changes in shallow water calcium carbonate deposition/dissolution, an interpretation that does not conflict with pelagic sedimentary data from the central Pacific.
AN: 3769354

                                                                    276 of 1521  
TI: Chronology for climate change: Developing age models for the Biogeochemical Ocean Flux Study cores
AU: Manighetti,-B.; McCave,-I.N.; Maslin,-M.; Shackleton,-N.J.
AF: Dep. Earth Sci., Univ. Cambridge, Cambridge, UK
SO: PALEOCEANOGRAPHY 1995 vol. 10, no. 3, pp. 513-525
NT: Special Section: The Biogeochemical Ocean Flux Study.
LA: English
ER: M (Marine)
AB: We construct age models for a suite of cores from the northeast Atlantic Ocean by means of accelerator mass spectrometer dating of a key core, BOFS 5K, and correlation with the rest of the suite. The effects of bioturbation and foraminiferal species abundance gradients upon the age record are modeled using a simple equation. The degree of bioturbation is estimated by comparing modeled profiles with dispersal of the Vedde Ash layer in core 5K, and we find a mixing depth of roughly 8 cm for sand-sized material. Using this value, we estimate that age offsets between unbioturbated sediment and some foraminifera species after mixing may be up to 2500 years, with lesser effect on fine carbonate (<10  mu m) ages. The bioturbation model illustrates problems associated with the dating of "instantaneous" events such as ash layers and the "Heinrich" peaks of ice-rafted detritus. Correlations between core 5K and the other cores from the BOFS suite are made on the basis of similarities in the downcore profiles of oxygen and carbon isotopes, magnetic susceptibility, water and carbonate content, and via marker horizons in X radiographs and ash beds.
AN: 3769348

                                                                    277 of 1521  
TI: Bacterial oxidation of methane in the Enisei R. estuary and the Kara Sea.
OT: Bakterial'noe okislenie metana v ehstuarii reki Enisej i karskom more
AU: Namsaraev,-B.B.; Rusanov,-I.I.; Mitskevich,-I.N.; Veslopolova,-E.F.; Bol'-shakov,-A.M.; Egorov,-A.V.
AF: Inst. Mikrobiol. RAN, Moscow, Russia
SO: OKEANOLOGIYA 1991 vol. 35, no. 1, pp. 88-93
LA: Russian
ER: M (Marine); F (Freshwater)
AB: The paper presents tabulated data on the abundance of methane-oxidizing bacteria and the rate of CH sub(4) oxidation in the water and bottom sediments of the Estuary, Yenisey Bay and adjacent Kara Sea areas. The number of methane-oxidizing bacteria amounts to 7900 per ml water. The rate of CH sub(4) oxidation is 0.4-200 nl/l/day in the water column and 4-3300 nl/kg/day in the sediments. The rates are higher in the river and lower in the sea.
AN: 3769036

                                                                    278 of 1521  
TI: Transformation of particle-bound phosphorus at the land-sea interface
AU: Conley,-D.J.; Smith,-W.M.; Cornwell,-J.C.; Fisher,-T.R.
AF: Danmarks Miljoundersogelser, Natl. Environ. Res. Inst., P.O. Box 358, Frederiksborgvej 399, DK-4000 Roskilde, Denmark
SO: ESTUAR.,-COAST.-SHELF-SCI. 1995 vol. 40, no. 2, pp. 161-176
LA: English
ER: M (Marine)
AB: The distribution of phosphorus was examined along the salinity gradient of the Chesapeake Bay estuary during spring and summer in 1989 and 1990. Particulate phosphorus (PP) was the dominant form of phosphorus in the estuary accounting for 23-90% of total phosphorus (TP). Particulate phosphorus was highest in the upper estuary (0.42-1.84  mu M) and rapidly decreased in concentration in the upper bay with only slight decreases observed down-estuary. Dissolved organic phosphorus (DOP) often comprised a somewhat larger fraction of the TP (8-43%) than did dissolved inorganic phosphorus (DIP; 5-40%) with DOP and DIP concentrations highest in bottom waters during summer anoxia. Both DIP and DOP concentrations were maintained at relatively low levels in surface waters by plankton, especially during the spring phytoplankton bloom. The distribution of particle-bound phosphorus in the suspended matter of the Chesapeake Bay was partitioned by a sequential chemical leaching technique into three major fractions: (1) an organic and loosely-bound fraction (Org-P), (2) an iron-associated fraction extracted with citrate-dithionate-bicarbonate (CDB-P), and (3) a detrital (apatite rich) fraction extracted with hydrochloric acid (HCl-P). The particle-bound phosphorus was associated mainly with Org-P (43-61%), followed by CDB-P (32-46%), with HCl-P generally comprising only a small fraction of the total particle-bound phosphorus (5-13%). The majority of changes in the composition of the particle-bound phosphorus occurred early in the transition from fresh- to saltwater with declines in both iron-associated phosphorus (CDB-P) and apatite-associated phosphorus (HCl-P). The ratios of CDB-Fe to CDB-P in suspended matter were relatively low suggesting that the particulate matter of Chesapeake Bay has a low capacity to absorb additional phosphorus through interactions with iron. Biological processes in the bay were much more important to the biogeochemical cycle of phosphorus than in many other estuaries previously examined for phosphorus biogeochemistry. Although inorganic exchange reactions may occur, they do not have the capacity to 'buffer' DIP concentrations throughout the Chesapeake Bay estuary.
AN: 3766313

                                                                    279 of 1521  
TI: Contribution of mathematical modeling to lake ecosystem understanding: Lake Bourget (Savoy, France)
AU: Vincon-Leite,-B.; Tassin,-B.; Jaquet,-J.-M.
AF: CERGRENE, Ec. Natl. Ponts et Chaussees, Ec. Natl. Genie Rural, des Eaux et des Forets, F-93167 Noisy-le-Grand, France
CO: 2. Int. Congress of Limnology and Oceanography, Evian (France), 25-28 May 1993
SO: SPACE-PARTITION-WITHIN-AQUATIC-ECOSYSTEMS. Balvay,-G.-ed. 1995 vol. 300-301 pp. 433-442
ST: HYDROBIOLOGIA vol. 300-301
LA: English
ER: F (Freshwater)
AB: This paper demonstrates how mathematical modeling can contribute to improve understanding of lake behavior. Since the 60's Lake Bourget, one of the largest in France, had been suffering from eutrophication which was checked in 1980 by the diversion of the main sewers entering the lake. A research program was implemented between 1987 and 1990, including an on-site sampling campaign conducted concurrently with thermal and biogeochemical modeling of lake behavior. The model helped provide a better understanding of the ecosystem, displaying some processes hitherto misunderstood: (1) Winter overturn does not reach the bottom of the water column when the weather is mild. This leads to a incomplete reoxygenation of the hypolimnion and to redox conditions inducing the release of orthophosphate from the sediment, (2) Grazing by herbivorous zooplankton is getting more important in the control of spring algal growth as eutrophication of the lake regresses, (3) Settling of particulate phosphorus seems a complex and very important process in Lake Bourget, showing high sedimentation rates for particulate mineral phosphorus.
AN: 3765417

                                                                    280 of 1521  
TI: Examination through a principal component analysis of the phosphorus exchanges between sediments and water in trophically different reservoirs
AU: Mhamdi,-M.A.; Aleya,-L.*; Devaux,-J.
AF: Lab. Zool. Protistol., URA CNRS 138, 63177 Aubiere Cedex, France
CO: 2. Int. Congress of Limnology and Oceanography, Evian (France), 25-28 May 1993
SO: SPACE-PARTITION-WITHIN-AQUATIC-ECOSYSTEMS. Balvay,-G.-ed. 1995 vol. 300-301 pp. 383-389
ST: HYDROBIOLOGIA vol. 300-301
LA: English
ER: F (Freshwater)
AB: Phosphorus exchange at the sediment-water interface coupled with several parameters were assessed in several reservoirs with geologically different catchment basins and different trophic status in Morocco and France. The results showed that these exchanges were regulated by a combination of factors: physical chemical variability of the environment, the geological composition of catchment basins and the trophic status of the lake. In the hypereutrophic Villerest, iron-bound phosphorus is the major form of phosphorus trapped by the sediment whereas, in Moroccan reservoirs, calcium-bound phosphorus prevailed. We suggest that a drastic control of phosphorus inputs into the waters must be done through a large program of dephosphatization of tributaries to avoid Microcystis aeruginosa bloom formation in Villerest (Aleya et al., 1993) and calcium-bound phosphorus dissociation in Moroccan reservoirs with upward release of bioavailable phosphorus.
AN: 3765381

                                                                    281 of 1521  
TI: Is there a downward transport of organic matter associated with dial vertical migrations of animals in the ocean?
AU: Tsejtlin,-V.B.
AF: IORAN, Moscow, Russia
SO: RUSS.-J.-AQUAT.-ECOL.-ZH.-VODN.-EHKOL. 1992 vol. 1, no. 1, pp. 73-79
LA: English
ER: M (Marine)
AB: The paper considers two possible means of downward organic matter transport by planktonic animals performing vertical migrations: 1) transport of organic matter in the tissues of the migrants bodies; and 2) transport with the migrants faeces. The magnitude of transport in the first case is calculated as the difference between the consumption of the migrants by predators at a lower depth and the proportion of their own food intake at this depth. It is shown that even if a small portion of the diurnal food intake is consumed in deeper waters, the transport of organic matter by this means is negligible. The maximum C sub(org) flux produced by the migrants does not exceed 8% of that produced by sinking detritus. In the second case the transport is possible only with the faeces of macroplanktonic animals and constitutes only a very small fraction of the detritus flux from above.
AN: 3765112

                                                                    282 of 1521  
TI: Impact of pressure on bacterial activity in water columns situated at the European continental margin
AU: Poremba,-K.
AF: Inst. Meereskd., Univ. Kiel, D-24105 Kiel, FRG
SO: NETH.-J.-SEA-RES. 1994 vol. 33, no. 1, pp. 29-35
LA: English
ER: M (Marine)
AB: The vertical profiles of bacterial abundance and activity were measured in water columns situated at the European continental margin of the Celtic Sea in July 1993 and January 1994. The stations lay in the middle of a submarine canyon (depth: 3713 m) and at the base of the continental slope (depth: 4480 m). The bacterial numbers were counted using epifluorescence microscopy, the cell multiplication was determined as  super(3)H-thymidine uptake, the accumulation of proteinaceous biomass was measured as  super(3)H-leucine uptake, and the impact of pressure on bacterial activity was studied in experiments under pressure conditions between 1 and 450 atm. In upper water layers or in July, the ratio of leucine uptake compared to thymidine uptake was generally higher than in deep layers or in January. The populations of all water layers generally preferred their in situ pressure, especially in July, while in January the barotolerance of the upper communities in 10 to 150 m water depth increased. A comparison of per-cell activity under in situ pressure showed that cells close to the bottom occasionally possessed higher specific activities than in the euphotic water layer. These findings indicate that the performance of experiments under elevated pressure is highly recommended, if the detection of phenomena such as those shown here in the deep sea is wanted.
AN: 3764984

                                                                    283 of 1521  
TI: Paleoclimatic history of Devils Lake, North Dakota: Final report
AU: Lyons,-W.B.
CA: Mackay Sch. of Mines, Reno, NV (USA)
SO: REP.-U.S.-GEOL.-SURV.-WATER-RESOUR.-DIV. 1991 32 pp
NT: NTIS Order No.: PB91-168963/GAR.
RN: USGS/G-1655 (USGSG1655)
LA: English
ER: F (Freshwater)
AB: Analyses were made on a series of sediment, porewater and groundwater samples in and around the Devils Lake, N.D. region in order to: (1) establish a short term (i.e. approx. 500yr) climatic record, (2) determine the relationship between hydrologic forcing and the lake's biological response, (3) calculate a chemical budget for the lake waters and (4) understand the influence of the Spiritwood Aquifer on the overall lake system. Data indicate that the sediments of the lake provide a detailed paleohydrologic and paleobiological record of the lake. Biogenic silica correlates extremely well with changes in lake level and therefore represents an extremely sensitive indicator of the paleohydrology of the drainage basin. Time series analyses of the sediment data demonstrates a close correlation between in-situ lake biological activity and the approx. 11 yr sun spot cycle. Geochemical budget of the lake suggests that the lake sediments are an important source of solutes to the lake waters especially at high stand periods. The groundwater analyses show that the major recharge to the Spiritwood Aquifer is probably from winter precipitation. (DBO)
AN: 3757852

                                                                    284 of 1521  
TI: Coupling of strontium and calcium cycles in Lake Constance
AU: Stabel,-H.-H.
AF: Water Control Res. Lab., ZV Bodensee-Wasserversorgung, D-7770 Uberlingen, FRG
CO: 4. Symp. on Sediment/Water Interactions, Melbourne (Australia), 16-20 Feb 1987
SO: SEDIMENT-WATER-INTERACTIONS. Sly,-P.G.;Hart,-B.T.-eds. 1989 vol. 176-177 pp. 323-329
ST: HYDROBIOLOGIA vol. 176-177
LA: English
ER: F (Freshwater)
AB: The contents of Sr and Ca were measured weekly in Lake Constance in 1986. Epilimnetic concentrations of Ca changed between 1.30 x 10 super(-3) mol/l (during homothermy) and 0.9 x 10 super(-3) mol/l (during thermal stratification). The seasonal fluctuations of Ca were correlated with those of Sr (between 4.61 and 5.36  mu mol/l). The epilimnion was permanently oversaturated with respect to calcite but not with respect to SrCo sub(3). Analysis of the settling process by use of sedimentation traps revealed two short episodes of very high authigenic settling fluxes of CaCO sub(3), triggered by phytoplankton diatoms. Seasonal changes of the Ca contents (between 4.1 and 30.7 percent of the dry weight) and of the Sr concentrations (from 12 to 75 x 10 super(-3) percent) in the settling material were closely correlated. This suggests a coprecipitation mechanism with a nearly constant stoichiometry of (atoms Sr/atoms Ca) x 1000 of 0.84. Coprecipitation of Sr or Ca with organic matter was insignificant. In the hypolimnion some Sr and Ca were released from the settling material. These results strongly suggest that the cycle of Sr in Lake Constance is driven predominantly by coprecipitation with calcite. The principal chemical mechanisms leading to coprecipitation are discussed. (DBO)
AN: 3757721

                                                                    285 of 1521  
TI: Seasonal variations in the loosely sorbed phosphorus fraction of the sediment of a shallow and hypereutrophic lake
AU: Soendergaard,-M.
AF: Bot. Inst. Univ. Aarhus, Nordlandsuej 68, 8240 Risskov, Denmark
CO: 4. Symp. on Sediment/Water Interactions, Melbourne (Australia), 16-20 Feb 1987
SO: SEDIMENT-WATER-INTERACTIONS. Sly,-P.G.;Hart,-B.T.-eds. 1989 vol. 176-177 pp. 321-322
ST: HYDROBIOLOGIA vol. 176-177
LA: English
ER: F (Freshwater)
AB: On the basic of selective extractions loosely sorbed phosphorus (ADS-P) has been shown to constitute much of the total phosphorus in the P-rich near-surface sediments of Lake Sobygaard, Denmark. The concentrations of ADS-P are seasonally variable, ranging from 0.2 mg P/g DW in the winter to more than 2 mg P/g DW in the summer. The variations can be observed as deep as 10 cm into the sediment but are most pronounced in the upper few centimeters. During the summer lake and pore water pH levels are very high, and photosynthetic activity causes elevation to pH 10-11 in the lake Laboratory experiments demonstrated a strong association between ADS-P and high pore water pH. It is likely that Lake Sobygaard represents an extreme example of pH control on sediment/water phosphorus equilibria in which high concentrations of internal ADS-P contribute significantly to the total P load of the lake. (DBO)
AN: 3757720

                                                                    286 of 1521  
TI: Use of radionuclides in the study of contaminant cycling processes
AU: Santschi,-P.H.
AF: Dep. Mar. Sci., Texas A&M Univ., Galveston, TX 77553-1675, USA
CO: 4. Symp. on Sediment/Water Interactions, Melbourne (Australia), 16-20 Feb 1987
SO: SEDIMENT-WATER-INTERACTIONS. Sly,-P.G.;Hart,-B.T.-eds. 1989 vol. 176-177 pp. 307-320
ST: HYDROBIOLOGIA vol. 176-177
LA: English
AB: Of all the geochemical boundaries, the sediment-water interface can exert the greatest control on the cycling of many elements in shallow aquatic environments such as lakes, rivers, estuaries and coastal embayments and, to a lesser extent in the deep sea. Across this interface, the gradients in physical properties (i.e. density), in chemical conditions (i.e. pH, pE, ligand concentrations), biota abundance (i.e. fauna and flora living near the interface) are large, thus producing potentially large fluxes. Some of the physical, chemical, biological and sedimentary controls operating at or near these interfaces can be deciphered from the measurements of natural radioisotopes (e.g. U/Th series or cosmic-ray produced), bomb fallout isotopes or, most recently, fallout from the Chernobyl-reactor accident. Commercially available, reactor-produced isotopes are most often used in enclosures to elucidate the coupling of the various processes at the sediment-water interface, while the former are used both as geochronological tools in the sediments and as tracers to measure or calibrate the rates of exchange across this interface of nutrients or trace elements associated with water or particles. Applications of radioisotopes for studying biological, physical, chemical and sedimentary processes near the sediment-water interface are discussed. In particular, multitracer approaches to study the dynamic coupling of physical, chemical and biological transport processes in lakes are emphasized. Examples from two hard-water lakes in Switzerland, Lake Biel and Lake Zurich, give evidence for the resuspension of fine ('rebound') particles, radionuclides and trace metals from the horizontal boundaries focussing them to their final repositories in the interior of the lake. (DBO)
AN: 3757719

                                                                    287 of 1521  
TI: Heavy metals in eelgrass (Zostera marina L.) during growth and decomposition
AU: Lyngby,-J.E.; Brix,-H.
AF: Water Qual. Inst., 11, Agern Alle, DK-2970 Hoersholm, Denmark
CO: 4. Symp. on Sediment/Water Interactions, Melbourne (Australia), 16-20 Feb 1987
SO: SEDIMENT-WATER-INTERACTIONS. Sly,-P.G.;Hart,-B.T.-eds. 1989 vol. 176-177 pp. 189-196
ST: HYDROBIOLOGIA vol. 176-177
LA: English
ER: B (Brackish)
AB: The distributions of cadmium, chromium, lead, and zinc in eelgrass were studied in samples collected from the field, and the loss/accumulation of the metals during decomposition of eelgrass leaves was studied in laboratory experiments. Concentrations of heavy metals in the below grounds parts were greater in the roots than in the different age groups of the rhizomes. In the rhizomes, the highest concentrations of lead were recorded in the oldest parts, whereas highest chromium and zinc concentrations were found in the youngest parts. The concentration of cadmium did not vary. In the above ground parts, the concentrations of cadmium, lead, and zinc increased with age of the leaves, and concentrations in the leaves were greater than in the stem fraction. The concentrations of chromium decreased with age of the leaves. In the laboratory study of decomposition of leaf material, the concentrations of chromium, lead and zinc increased significantly and a net absorption from the surrounding water was recorded. Cadmium concentrations were relatively constant and a loss of cadmium was proportional to the release of soluble organic compounds indicating an association of cadmium with the soluble phase. The investigation demonstrated the utility of compositional analyses and decomposition experiments in assessing the significance of eelgrass in the heavy metal cycling in coastal areas. Furthermore, significant differences in the fate of heavy metals associated with eelgrass detritus are discussed. (DBO)
AN: 3757708

                                                                    288 of 1521  
TI: [General limnology]
OT: Limnologie generale
AU: Pourriot,-R.; Meybeck,-M.
SO: COLL.-ECOL. PARIS-FRANCE MASSON 1995 200 pp
LA: French
ER: F (Freshwater)
AB: The first part of this paper deals with physical and chemical limnology (study of lakes and basins, the water dynamic, the organic matter, the lacustrine sediments). The second part is devoted to biological limnology (growth and dynamics of algal populations, planktonic and benthic invertebrates, and fish; community structure and organization; trophic relationships (food webs) and predation effects). The third part deals with biogeochemical cycles: the carbon cycle, oxygen cycle and balance, nitrogen and phosphorus cycles, and ecosystem modeling.
AN: 3756627

                                                                    289 of 1521  
TI: Biochemistry of mercury in estuaries and in coastal waters
OT: Biogeochimie du mercure en milieu estuarien et cotier
AU: Coquery,-M.
CA: Paris 6 Univ. (France)
SO: PARIS-FRANCE UNIVERSITE-PARIS-6 1994 270 pp
NT: Thesis (Doct. Oceanologie Meteorologie Environnement).
LA: French
ER: M (Marine); B (Brackish)
AB: The distribution and speciation of mercury was determined in three stratified Arctic estuaries (Lena, Ob and Yenisei), three macrotidal European estuaries (Loire, Seine and Elbe) and in the North Sea. Concentrations in Arctic rivers were among the lowest ever measured. In macrotidal estuaries, contamination is higher in the Seine and in the Elbe than in the Loire. The distribution between dissolved and particulate mercury shows the predominance of the particulate phase. Concentrations of elemental mercury were related to primary production in coastal waters of the Loire and the Seine. Elemental mercury and dimethyl mercury were detected in the low oxygen zone of the Seine Estuary. Concentrations of particulate monomethyl mercury in the Loire were higher in fresh and marine waters than within the high turbidity zone of the estuary.
AN: 3756494

                                                                    290 of 1521  
TI: Simulation of O sub(2), PO sub(4) and organic carbon behavior during a benthic chamber experiment on the deep sea floor
AU: Rabouille,-C.; Gaillard,-J.-F.
AF: Lab. Geochim. Eaux, Univ. Paris 7, Inst. Phys. Globe, 2 Place Jussieu, 75251 Paris Cedex 05, France
SO: OCEANOL.-ACTA 1994 vol. 17, no. 4, pp. 405-416
LA: English
ER: M (Marine)
AB: Using a time-dependent model for organic matter mineralization by oxygen and the resulting phosphate production in deep-sea sediments, the progress of a benthic chamber experiment is simulated.The vertical distribution of chemical species in the sediments, pore water and solids, and the concentrations in the benthic chamber are calculated. The results of the calculations show that the concentration gradients of solutes at the sediment-water interface and the penetration depth of O sub(2) in the sediment undergo important changes during the deployment of a benthic chamber. The model is further used to perform numerical experiments and the different techniques used to calculate fluxes (linear regression, zero-order model) are compared.
AN: 3756490

                                                                    291 of 1521  
TI: C sub(32)-C sub(36) polymethyl alkenes in Black Sea sediments
AU: Damste,-J.S.S.; Erkes,-A.-M.W.E.P.; Rijpstra,-W.I.C.; De-Leeuw,-J.W.; Wakeham,-S.G.
AF: Netherlands Inst. Sea Res. (NIOZ), Div. Mar. Biogeochem., P.O. Box 59, 1790 AB Den Burg, Texel, Netherlands
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 2, pp. 347-353
LA: English
ER: M (Marine)
AB: A series of novel C sub(32)-C sub(36) polymethylhentriacontenes has been identified in near-surface sediments of the Black Sea. Hydrogenation of these components indicated that they possess the 5,8,14,24,27-pentamethyl-, 8,14,24,27-tetramethyl-, 8,14,24-trimethyl-, 8,14-dimethyl-, and 14- and 15-methylhentriacontane C skeletons, which was confirmed by synthesis of an authentic standard of the C sub(34) member. The dominant C sub(36) member of this series contains eight double bonds. The  super(13)C content of these polymethylhentricontenes indicated that they are probably biosynthesized by photoautotrophs and that blooming or bicarbonate pumping affected the  super(13)C content of the fixed C. Their structures suggest that they were biosynthesized by methylation of an unsaturated n-C sub(31) precursor at specific positions in a well-defined sequence. This biosynthetic pathway represents an alternative for the biosynthesis of isoprenoid-like components.
AN: 3756348

                                                                    292 of 1521  
TI: Carbon-sulfur plots to show diagenetic and epigenetic sulfidation in sediments
AU: Leventhal,-J.S.
AF: U.S. Geol. Surv., Fed. Cent., MS 973, Denver, CO 80225, USA
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 6, pp. 1207-1211
LA: English
ER: M (Marine)
AB: Organic carbon vs. sulfide sulfur plots are now being used regularly by many geochemists to help understand recent and ancient depositional environments and diagenetic processes. Usually, these plots are useful to recognize nonmarine vs. marine environments or oxic vs. anoxic vs. euxinic depositional environments. However, C vs. S plots can also indicate diagenetic and epigenetic events that produce "excess" sulfide. Four new examples are presented and discussed.
AN: 3756345

                                                                    293 of 1521  
TI: CO sub(2) cycling in the coastal ocean. 1. A numerical analysis of the southeastern Bering Sea with applications to the Chukchi Sea and the northern Gulf of Mexico
AU: Walsh,-J.J.; Dieterle,-D.A.
AF: Dep. Mar. Sci., Univ. South Florida, St. Petersburg, FL 33701, USA
SO: PROG.-OCEANOGR. 1994 vol. 34, no. 4, pp. 335-392
LA: English
ER: M (Marine)
AB: A quasi-two dimensional model of the carbon and nitrogen cycling above the 70m isobath of the southeastern Bering Sea at 57 degree N replicates the observed seasonal cycles of nitrate, ammonium,  capital sigma CO sub(2), pCO sub(2), light penetration, chlorophyll, phytoplankton growth rate, and primary production, as constrained by changes in wind, incident radiation, temperature, ice cover, vertical and lateral mixing, grazing stress, benthic processing of phytodetritus and zooplankton fecal pellets, and the pelagic microbial loop of DOC, bacteria, and their predators. About half of the seasonal resupply of nitrate stocks to their initial winter conditions is derived from in situ nitrification, with the rest obtained from deep-sea influxes. Under the present conditions of atmospheric forcing, shelf-break exchange, and food web structure, this shelf ecosystem serves as a sink for atmospheric CO sub(2), with storage in the forms of exported DOC, DIC, and unutilized POC (phytoplankton, bacteria, and fecal pellets). As a consequence of just the rising levels of atmospheric pCO sub(2) since the Industrial Revolution, however, the biophysical CO sub(2) status of the Southeastern Bering Sea shelf may have switched over the last 250 years, from a prior source to the present sink, since this relatively pristine ecosystem has undergone little eutrophication. Such fluctuations of CO sub(2) status may thus be reversed by the physical processes of: (1) reduction of atmospheric pCO sub(2), (2) increased onwelling of deep-sea  capital sigma CO sub(2), and (3) warming of shelf waters. Based on our application of this model to the Chukchi Sea and the Gulf of Mexico, about 1.0-1.2 gigatons C y super(-1) of atmospheric CO sub(2) may now be sequestered by temperate and polar shelf ecosystems. When tropical systems are included, however, a positive net sink of only 0.6-0.8 x 10 super(15)g C/y may prevail over all shelves.
AN: 3755736

                                                                    294 of 1521  
TI: Use of aspartic acid racemization and post-bomb  super(14)C to reconstruct growth rate and longevity of the deep-water slit shell Entemnotrochus adansonianus
AU: Goodfriend,-G.A.; Kashgarian,-M.; Harasewych,-M.G.
AF: Geophys. Lab., Carnegie Inst. Washington, 5251 Broad Branch Rd. NW, Washington, DC 20015-1305, USA
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 6, pp. 1125-1129
LA: English
ER: M (Marine)
AB: Slit shells are living fossils which inhabit the continental slope. Aspartic acid racemization in the nacreous layer of the slit shell Entemnotrochus adansonianus is shown to occur at a remarkably high rate, sufficient to provide annual resolution of the ages of samples taken along the growth spiral of the shells, thus providing information on growth rates and longevity. Calibration of the racemization rate was obtained by  super(14)C analysis of a post-bomb specimen. The form of the racemization curve was determined by a heating experiment at 60 degree C; a cubic transformation of the D/L values was found to be linear with respect to time. In three specimens in which a detailed series of samples was analyzed, juvenile growth was found to be very rapid and adult growth 1-2 orders of magnitude slower; adulthood is reached in 2-4 years. Analysis of lip and apical samples of additional shells (total n = 9) shows that individuals reaching adulthood have life spans averaging six years (maximum: 14 yr). The life histories of these deep-water gastropods are thus similar to littoral taxa. Analysis of the prismatic layer shows that this racemizes at a much slower rate than the nacreous layer.
AN: 3754322

                                                                    295 of 1521  
TI: Comment on "Aspartic acid racemization and protein diagenesis in corals over the last 350 years" by G.A. Goodfriend, P.E. Hare, and E.R.M. Druffel
AU: Brinton,-K.L.F.; Bada,-J.L.
AF: Scripps Inst. Oceanogr., Univ. California at San Diego, La Jolla, CA 92093-0212, USA
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 2, pp. 415-416
LA: English
ER: M (Marine)
AB: Goodfriend (1992) and Goodfriend et al. (1992) have reported that aspartic acid (Asp) racemizes markedly faster in land snail and coral samples <350 years BP in comparison to older samples. They suggest that the differing racemization rates of protein-bound vs. free Asp residues explain the observed nonlinear racemization kinetics and propose that the initial rapid racemization could provide an important tool for dating of young samples. The samples of Goodfriend (1992) and Goodfriend et al. (1992) were hydrolyzed in 6 N HCl at 100 degree C to yield free amino acids. Under these hydrolysis conditions, asparagine (Asn) undergoes quantitative deamidation to Asp. Therefore, the land snail and coral results represent the combined racemization of Asp and Asn (Asx). Goodfriend himself noted in an earlier paper (Goodfriend, 1991) that the sum of the racemization rates of Asp and Asn under hydrolysis conditions is nonlinear, and he suggested that Asn may racemize faster than Asp. The amount of Asn relative to Asp in the proteins contained in the carbonate matrix of land snails and corals is not known. We therefore suggest that the nonlinear racemization observed for Asx by Goodfriend et al. (1992a,b) could have been caused by the rapid racemization of Asn in comparison to that of Asp.
AN: 3754319

                                                                    296 of 1521  
TI: Reply to the Comment by K.L.F. Brinton and J.L. Bada on "Aspartic acid racemization and protein diagenesis in corals over the last 350 years"
AU: Goodfriend,-G.A.; Hare,-P.E.
AF: Geophys. Lab., Carnegie Inst. Washington, 5251 Broad Branch Rd., NW, Washington, DC 20015-1305, USA
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 2, pp. 417-418
LA: English
ER: M (Marine)
AN: 3754318

                                                                    297 of 1521  
TI: Application of LP-ICP-MS to benthic foraminifers
AU: Wu,-Guoping; Hillaire-Marcel,-C.
AF: Cent. Rech. Geochim. Isot. et Geochronol. (GEOTOP), Univ. Quebec Montreal, Montreal, PQ H3C 3P8, Canada
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 2, pp. 409-414
LA: English
ER: M (Marine)
AB: A laser microprobe coupled with an inductively coupled plasma mass spectrometer (LP-ICP-MS) was used to determine Mg, Mn, Sr, and Ba contents of benthic foraminifers in the solid state. Calcite shells of Cibicides wuellerstorfi, Oridorsalis umbonatus, Pyrgo spp., and aragonite tests of Hoeglundina elegans, which were taken from the surface sediments of the northwestern North Atlantic Ocean, were ablated by a laser beam. Multiple measurements were achieved on single tests since the diameters of ablation pits (20-50  mu m) are significantly smaller than those of the shells ( similar to 250  mu m). Mg/Ca, Mn/Ca, and Ba/Ca of the ablated materials are significantly affected by Fe-Mn oxide coatings and extraneous Ba-bearing phases, and Sr/Ca is not noticeably influenced by those contaminants. There is no substantial variation of Sr/Ca within and between shells of a foraminiferal species. On the contrary, Sr/Ca is species-dependent: Sr/Ca of Pyrgo spp. is three times as high as that of H. elegans, and nearly twice as high as those of C. wuellerstorfi and O. umbonatus.
AN: 3754317

                                                                    298 of 1521  
TI: Significance of colloids in the biogeochemical cycling of organic carbon and trace metals in the Venice Lagoon (Italy)
AU: Martin,-J.-M.; Dai,-Min-Han; Cauwet,-G.
AF: Inst. Biogeochim. Mar., Unite Assoc. CNRS No. 386, 1, Rue Maurice Arnoux, 92120 Montrouge, France
SO: LIMNOL.-OCEANOGR. 1995 vol. 40, no. 1, pp. 119-131
LA: English
ER: M (Marine)
AB: Colloidal organic C and trace metals from the waters of a highly productive coastal environment (the Venice Lagoon, Italy) have been separated by a cross-flow ultrafiltration device. On average, 18% of organic C, 34% of Cd, 46% of Cu, 87% of Fe, 18% of Ni, 58% of Pb, and 54% of Mn which previously would have been considered in the dissolved phase are actually associated with colloidal material. Thus, past studies overestimate the dissolved trace-metal concentration in the nearshore environment. Compared to total concentration, the proportion of the colloidal fraction represents on average 15% of organic C, 18% of Cd, 28% of Cu, 11% of Fe, 11% of Ni, 29% of Pb, and 12% of Mn. This fraction acts differently from the truly dissolved and macroparticulate phases. The behavior of organic C and trace elements during mixing between freshwater and seawater is more complicated than expected when a colloidal fraction is involved. The flocculation of colloids, encountered normally during estuarine mixing, is not very significant on the time scale of mixing in the lagoon. Conversely, the interaction between colloidal and truly dissolved phases seems important. The partitioning of trace metals between different fractions of organic C appears variable, Fe and Mn are preferentially tied to macroparticulate organic matter, and Cu and Cd are preferentially tied to colloidal organic matter in seawater. Truly dissolved organic C appears to be important for Ni. Pb is mainly associated with macroparticulate organic matter at most stations except in the highly productive region where Pb prefers colloidal organic C.
AN: 3754310

                                                                    299 of 1521  
TI: Nitrate reductase activity quantitatively predicts the rate of nitrate incorporation under steady state light limitation: A revised assay and characterization of the enzyme in three species of marine phytoplankton
AU: Berges,-J.A.; Harrison,-P.J.
AF: Build. 318, Brookhaven Natl. Lab., Upton, NY 11973, USA
SO: LIMNOL.-OCEANOGR. 1995 vol. 40, no. 1, pp. 82-93
LA: English
ER: M (Marine)
AB: The enzyme nitrate reductase (NR) has been proposed as an index of nitrate incorporation rates in marine phytoplankton, but it has proven difficult to interpret NR measurements in field settings because many previous NR assays have been poorly optimized and NR activity in phytoplankton has been poorly characterized under steady state conditions. An NR assay was developed for the diatom Thalassiosira pseudonana using an extraction in phosphate buffer with Triton X-100, EDTA, dithiothreitol, polyvinyl pyrrolidone, and bovine serum albumin. NR activity in homogenates was stable for up to 1 h, but filtered samples could be stored for 96 h in liquid nitrogen without significant loss of activity. Addition of FAD to crude extracts of T. pseudonana had no effect, whereas the effect on desalted extracts or crude extracts from other species, varied from decreases in NR activity to over 250% increases. Half-saturation constants (K sub(m)) varied between species; high levels of NADH or nitrate were found to be inhibitory in some cases. These results indicate a wide diversity of forms of NR in marine phytoplankton. Under continuous, light-limited growth, NR activity was quantitatively related to calculated rates of nitrate incorporation ( mu  sub(N)) in T. pseudonana, Skeletonema costatum, and three other diatom species examined. The relationship differed for 10 other species; NR activity was equal to  mu  sub(N) in some cases, but higher or lower in others. In dinoflagellates, in particular, NR activity was highly correlated with  mu  sub(N), but accounted for <20% of  mu  sub(N) in Amphidinium carterae.
AN: 3754307

                                                                    300 of 1521  
TI: A re-assessment of Redfield correlations between dissolved iodine and nutrients in oceanic waters and a strategy for further investigations of iodine
AU: Truesdale,-V.W.
AF: 36, Ladycroft Park, Blewbury, Oxon OX11 9QW, UK
SO: MAR.-CHEM. 1994 vol. 48, no. 1, pp. 43-56
LA: English
ER: M (Marine)
AB: The use of the Redfield nutrient model to explain the behaviour of iodine in the oceanic water column is re-assessed using a rigorous theoretical approach together with existing hydrographic information. It is shown that tests of the model's applicability need to be based upon stations which display a marked turning point in their nutrient profile. Stations that do not, e.g. North and South Atlantic, should be avoided. The earlier use of mixtures of the two types is shown to have biased the conclusion in favour of a fit with Redfield. Reasons are given for believing that, in comparison with the plant nutrients, a greater proportion of iodine is re-cycled in the shallow domain of the profile. The possible correlations between inorganic iodine and the Redfield variables are considered from both theoretical and empirical standpoints.
AN: 3754270

                                                                    301 of 1521  
TI: Phosphate sorption in superficial intertidal sediments
AU: Van-Raaphorst,-W.; Kloosterhuis,-H.T.
AF: Netherlands Inst. Sea Res. (NIOZ), P.O. Box 59, 1790 AB Den Burg, Texel, Netherlands
SO: MAR.-CHEM. 1994 vol. 48, no. 1, pp. 1-16
LA: English
ER: M (Marine)
AB: The influence of sorption on phosphorus cycling in intertidal sediments was examined by measuring sorption characteristics (isotherms, kinetics) and sediment content of exchangeable PO sub(4) (extracted with 0.1 M NaOH). The latter contents were highly correlated with Fe-oxides and showed a seasonal pattern with highest values in autumn and winter, and lowest in spring and early summer. Part of the PO sub(4) produced through mineralization in late summer and autumn is stored through sorption in the oxic sediment layers and becomes available to e.g. primary producers in the next season. Sorption experiments showed linear isotherms with adsorption coefficients between 6.9 and 22.7 ml/g. Slow PO sub(4) release due to mineralization of organic matter was visible after c. 50 h of incubation. We applied a dynamic model to correct the sorption data for mineralization and to estimate the sorption kinetics. The first order sorption rates obtained were between 0.7 and 5 ml/g/h. When applying the film model for the upper 5 mm of the sediments, measured fluxes and PO sub(4) gradients could only be reproduced with unrealistically high diffusion coefficients. Diffusion coefficients close to molecular diffusion were obtained by using a simple reaction-diffusion model including the data on sorption kinetics. This model indicates that the transfer of PO sub(4) at the sediment-water interface is enhanced by the sorption reaction and that high fluxes can be maintained at low pore water concentrations in the upper millimeters of the sediment. We conclude that the sorption kinetics together with diffusion control the PO sub(4) concentration in the superficial intertidal sediments.
AN: 3754253

                                                                    302 of 1521  
TI: Photosynthetic fractionation of  super(13)C and concentrations of dissolved CO sub(2) in the Central Equatorial Pacific during the last 255,000 years
AU: Jasper,-J.P.; Hayes,-J.M.; Mix,-A.C.; Prahl,-F.G.
AF: Dep. Mar. Sci., Univ. Connecticut, New Haven, CT 06050, USA
SO: PALEOCEANOGRAPHY 1994 vol. 9, no. 6, pp. 781-798
LA: English
ER: M (Marine)
AB: Carbon isotopically based estimates of CO sub(2) levels have been generated from a record of the photosynthetic fractionation of  super(13)C ( identical with   epsilon  sub(p)) in a central equatorial Pacific sediment core that spans the last  similar to 255 ka. Contents of  super(13)C in phytoplankton biomass were determined by analysis of C sub(37) alkadienones. These compounds are exclusive products of Prymnesiophyte algae which at present grow most abundantly at depths of 70-90 m in the central equatorial Pacific. A record of the isotopic composition of dissolved CO sub(2) was constructed from isotopic analyses of the planktonic foraminifera Neogloboquadrina dutertrei, which calcifies at 70-90 m in the same region. Values of  epsilon  sub(p), derived by comparison of the organic and inorganic  delta  values, were transformed to yield concentrations of dissolved CO sub(2) ( identical with  c sub(e)) based on a new, site-specific calibration of the relationship between  epsilon  sub(p) and C sub(e). It is concluded that the observed record of  epsilon  sub(p) most probably reflects significant variations in  Delta pCO sub(2), the ocean-atmosphere disequilibrium, which appears to have ranged from  similar to 110  mu atm during glacial intervals (ocean > atmosphere) to  similar to 60  mu atm during interglacials.
AN: 3753723

                                                                    303 of 1521  
TI: Selective preservation of chitin during the decay of shrimp
AU: Baas,-M.; Briggs,-D.E.G.; van-Heemst,-J.D.H.; Kear,-A.J.; de-Leeuw,-J.W.
AF: Div. Mar. Biogeochem., Netherlands Inst. Sea Res., P.O. Box 5G, 1790 AB Den Burg, Netherlands
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 5, pp. 945-951
LA: English
ER: M (Marine)
AB: The preservation potential of chitin in the marine environment is a matter of debate. To determine the relative survival of chitin and other organic components, the shrimp Crangon was decayed under different laboratory conditions. Solid state  super(13)C NMR and Curie point pyrolysis-gas chromatography-high resolution mass spectrometry demonstrated that slightly transformed chitin represents the major component of the remaining biomass after only eight weeks. This selective preservation confirms that the resistance of chitin to decay may be a major factor in accounting for the extensive fossil record of arthropods lacking a biomineralized skeleton. It also suggests that chitin is likely to be an important contributor to the organic content of recent marine sediments. The pyrolysate of the preserved cuticle of fossil shrimps reveals a homologous series of alkanes and alkenes indicating a substitution of chitin by more resistant organic matter derived from other sources.
AN: 3753650

                                                                    304 of 1521  
TI: Glacial-interglacial paleoenvironments of the eastern Atlantic Ocean: The Biogeochemical Ocean Flux Study (BOFS) paleoceanography program
AU: Elderfield,-H.; Thomas,-E.
AF: Dep. Earth Sci., Univ. Cambridge, Cambridge, UK
SO: PALEOCEANOGRAPHY 1995 vol. 10, no. 3, pp. 509-511
NT: Special Section: The Biodegradation Ocean Flux Study.
LA: English
ER: M (Marine)
AB: The papers in this special section discuss many aspects of paleoenvironmental analysis performed using various proxies on cores collected in the northeastern and tropical eastern Atlantic during two cruises in the framework of the NERC Biogeochemical Ocean Flux Study Program (BOFS). Coring of the northern BOFS leg was carried out on Leg 3 of the 1989 BOFS program (RRS Discovery cruise 184). Forty-one cores were taken on a North-South transect at about 20 degree W, from the flanks of the Mid-Atlantic Ridge (47 degree N) to Gardar Drift (59 degree N), at water depths between 1150 and 4050 m. Of these, 15 cores were taken using a 3 m - long, large-diameter kastenlot corer. The southern leg coring was carried out on Leg C of the 1990 BOFS program (RRS Charles Darwin cruise 53 [Shimmield, 1990]). Forty-six cores, including 14 using the kastenlot corer, were taken along a transect at about 20 degree W, between 18 and 42 degree N, at depths between 3000 and 4900 m and focusing on an area off northwest Africa. Most papers in this section are concerned with different aspects of the differences in oceanic environments between glacial and interglacial periods, and especially between the last glacial and the Holocene, with much attention paid to changes in productivity and circulation patterns. All studies were conducted at high resolution (a few centimeter depth, corresponding to several hundred to a thousand or so years). The studies are unique in that many different proxies were collected on the sample sets of samples and at high time resolution.
AN: 3753546

                                                                    305 of 1521  
TI: The Key West campaign
AU: Tooma,-S.G.; Richardson,-M.D.
AF: Coast. Benthic, Bound. Layer Program, Nav. Res. Lab., Stennis Space Cent., MS, USA
SO: SEA-TECHNOL. 1995 vol. 36, no. 6, pp. 17-26
LA: English
ER: M (Marine)
AB: During February 1995, four research vessels (WFS Planet, R/Vs Seward Johnson, Pelican, and Seaward Explorer) and 115 scientists and technicians from five nations mounted a major scientific campaign in waters off the western Florida Keys. Experiments focused on the shallow-water, carbonate, sedimentary environments in the vicinity of the Marquesas Keys and the Dry Tortugas in recognition that naval operations have shifted focus to nearshore coastal operations that emphasize mine counter-measures (MCM).
AN: 3753533

                                                                    306 of 1521  
TI: Terminal Proterozoic reorganization of biogeochemical cycles
AU: Logan,-G.A.; Hayes,-J.M.; Hieshima,-G.B.; Summons,-R.E.
AF: Biogeochem. Lab., Dep. Geol. Sci., Indiana Univ., Bloomington, IN 47405-1403, USA
SO: NATURE 1995 vol. 376, no. 6535, pp. 53-56
LA: English
ER: M (Marine)
AB: The Proterozoic aeon (2,500-540 million years ago) saw episodic increases in atmospheric oxygen content, the evolution of multicellular life and, at its close, an enormous radiation of animal diversity. These profound biological and environmental changes must have been linked, but the underlying mechanisms have been obscure. Here we show that hydrocarbons extracted from Proterozoic sediments in several locations worldwide are derived mainly from bacteria or other heterotrophs rather than from photosynthetic organisms. Biodegradation of algal products in sedimenting matter was therefore unusually complete, indicating that organic material was extensively reworked as it sank slowly through the water column. We propose that a significant proportion of this reworking will have been mediated by sulphate-reducing bacteria, forming sulphide. The production of sulphide and consumption of oxygen near the ocean surface will have inhibited transport of O sub(2) to the deep ocean. We find that preservation of algal-lipid skeletons improves at the beginning of the Cambrian, reflecting the increase in transport by rapidly sinking faecal pellets. We suggest that this rapid removal of organic matter will have increased oxygenation of surface waters, leading to a descent of the O sub(2)-sulphide interface to the sea floor and to marked changes in the marine environment, ultimately contributing to the Cambrian radiation.
AN: 3753409

                                                                    307 of 1521  
TI: Pb super(2+) interactions with the marine phytoplankton Dunaliella tertiolecta
AU: Santana-Casiano,-J.M.; Gonzalez-Davila,-M.; Perez-Pena,-J.; Millero,-F.J.
AF: Dep. Quim., Fac. Cienc. Mar, Univ. Las Palmas de Gran Canaria, Las Palmas G.C., 35071, Spain
SO: MAR.-CHEM. 1995 vol. 48, no. 2, pp. 115-129
LA: English
ER: M (Marine)
AB: Metal ions become adsorbed to algal surface groups and complexed to organic material released by algae at all growth stages influencing their distribution in the seawater. In this study, the differential pulse anodic stripping voltammetry (DPASV) technique was used to evaluate the adsorption and the interaction between the exudates excreted by the marine algae Dunaliella tertiolecta and Pb super(2+). The adsorption process has been studied in seawater as a function of pH (2 to 8), temperature (5 to 45 degree C), salinity (5 to 36), biomass and the presence of a second metal, copper. The rate of adsorption was found to occur in two steps: first a relatively fast adsorption step (10 min) and second, a slow, diffusion-controlled uptake into the cells. A two-site model which considers the presence of two major functional groups, namely: high-affinity binding and low-affinity binding was used to fit the experimental data. The values for the stability constants of Pb super(2+) on these two groups were log *K super(S) sub(H,1) = 8.40  plus or minus  0.18 and log *K super(S) sub(H,2) = 7.25  plus or minus  0.31. The high-affinity constant is similar to the complexing capacity of the exudates (log *K super(2) sub(M) super(+) sub(e) = 8.40  plus or minus  0.05) produced by the alga showing that extracellular ligands play an important role in buffering the concentration of the free metal concentration. A decrease in the temperature and salinity result in lower adsorption of Pb super(2+) to the algae and a higher complexation of lead with the exudate. The presence of copper decreases the lead complexation to the algal surface by 70%.
AN: 3750403

                                                                    308 of 1521  
TI: Comparison of the linear Van den Berg/Ruzic transformation and a non-linear fit of the Langmuir isotherm applied to Cu speciation data in the estuarine environment
AU: Gerringa,-L.J.A.; Herman,-P.M.J.; Poortvliet,-T.C.W.
AF: Netherlands Inst. Ecol., Cent. Estuar. Coast. Ecol., Vierstr. 28, 4401 EA Yerseke, Netherlands
SO: MAR.-CHEM. 1995 vol. 48, no. 2, pp. 131-142
LA: English
ER: M (Marine); B (Brackish)
AB: Copper complexation measurements in estuarine organic-rich samples with differential pulse anodic stripping voltammetry (DPASV) and differential pulse cathodic stripping voltammetry (DPCSV) show a relatively large scatter in the data, due to a high organic matter content. Two methods for the estimation of the complexation parameters according to the Langmuir isotherm are compared: the linear transformation of Van den Berg/Ruzic and the non-linear method according to Wilkinson. For DPASV measurements in estuarine samples the values of the conditional stability constant (K super(1)), estimated with the linearization method are systematically lower than those estimated with the Wilkinson method. The Van den Berg/Ruzic linearization is more susceptible to outliers or data points that do not follow the model of the Langmuir isotherm. For DPCSV measurements, where the data followed the Langmuir isotherm more closely, this difference could not be demonstrated. The non-linear method is to be preferred because this method is more suited to the error structure of the data, which is of constant absolute magnitude. Moreover it offers the advantage that the standard error of the estimated parameters can be calculated consistently.
AN: 3750373

                                                                    309 of 1521  
TI: Simulation and prediction of anthropogenic lead perturbation in the Mediterranean Sea
AU: Tian,-Ru-Cheng; Ruiz-Pino,-D.
AF: Inst. Maurice Lamontagne, B378, C.P.1000, Mont-Joli, PQ G5H 3Z4, Canada
SO: SCI.-TOTAL-ENVIRON. 1995 vol. 164, no. 2, pp. 135-150
LA: English
ER: M (Marine)
AB: Simulations of Pb biogeochemical cycles were carried out based on a box model previously developed and tested by in-situ measurements. It has been demonstrated that the different evolutions of the fluxes determining the Pb budget lead to disequilibrium in Pb biogeochemical cycles in the Mediterranean Sea, particularly the anthropogenic perturbation governed by economical development and political regulations. Such a disequilibrium resulted in an increase in the concentration of lead between 1950 and 1976. Pb concentrations have decreased since 1976 in the Western Basin thanks to the application of limited Pb consumption regulations in the western countries. However Pb concentrations will increase again and the critical concentration for marine organisms will be reached by the middle of the next century if Pb consumption is not limited in the eastern countries. In relation to the exchange with the North Atlantic, the Mediterranean Sea acted as a sink for Pb before 1980, but since 1981, has become a source. Concerning the accumulation in the sediments, about half of the total external input was estimated to have been deposited between 1950 and 1992.
AN: 3750354

                                                                    310 of 1521  
TI: An improved head-space analysis method for methane in seawater
AU: Lammers,-S.; Suess,-E.
AF: GEOMAR - Forschungszent. Mar. Geowissenschaften, Wischhofstr. 1-3, D-24148 Kiel, FRG
SO: MAR.-CHEM. 1994 vol. 47, no. 2, pp. 115-125
LA: English
ER: M (Marine)
AB: A widely used degassing method for methane in seawater employing vacuum was tested and subsequently improved. It yielded 62  plus or minus  3.8% of the total dissolved methane, hence a reproducible correction factor was established. The method was then applied to measure CH sub(4) in the sea-air boundary layer and simultaneously in the overlying air along two transects in the eastern Equatorial Pacific off Peru in March of 1992. The results showed surprising small-scale reversals of the methane exchange between ocean and atmosphere in this region. Generally the ocean acted as a source of methane but also methane uptake by the ocean was found. This was mainly a consequence of high CH sub(4) concentrations in the air which deviated considerably from the long-term and large-scale average. If applied to the flux rate calculations, the observed variabilities indicate that both rate and direction of the methane flux through the air-sea interface vary considerably depending on the atmospheric CH sub(4) content. The implications are that even ocean areas with high concentrations of dissolved CH sub(4) can be considerably weaker sources than would be expected on the basis of 1.7 ppmv mean atmospheric methane content. Based on improved simultaneous analyses of both air and water samples, the ocean-atmosphere flux of methane would therefore be more dynamic than previously thought.
AN: 3750336

                                                                    311 of 1521  
TI: Isolation and characterization of methanesulfonic acid-degrading bacteria from the marine environment
AU: Thompson,-A.S.; Owens,-N.J.P.; Murrell,-J.C.*
AF: Dep. Biol. Sci., Univ. Warwick, Coventry CV4 7AL, UK
SO: APPL.-ENVIRON.-MICROBIOL. 1995 vol. 61, no. 6, pp. 2388-2393
LA: English
ER: M (Marine)
AB: Two methylotrophic bacterial strains, TR3 and PSCH4, capable of growth on methanesulfonic acid as the sole carbon source were isolated from the marine environment. Methanesulfonic acid metabolism in these strains was initiated by an inducible NADH-dependent monooxygenase, which cleaved methanesulfonic acid into formaldehyde and sulfite. The presence of hydroxypyruvate reductase and the absence of ribulose monophosphate-dependent hexulose monophosphate synthase indicated the presence of the serine pathway for formaldehyde assimilation. Cell suspensions of bacteria grown on methanesulfonic acid completely oxidized methanesulfonic acid to carbon dioxide and sulfite with a methanesulfonic acid/oxygen stoichiometry of 1.0:2.0. Oxygen electrode-substrate studies indicated the dissimilation of formaldehyde to formate and carbon dioxide for energy generation. Carbon dioxide was not fixed by ribulose bisphosphate carboxylase. It was shown that methanol is not an intermediate in methanesulfonic acid metabolism, although these strains grew on methanol and other one-carbon compounds, as well as a variety of heterotrophic carbon sources. These two novel marine facultative methylotrophs have the ability to mineralize methanesulfonic acid and may play a role in the cycling of global organic sulfur.
AN: 3749300

                                                                    312 of 1521  
TI: Role of SO sub(4) adsorption and desorption in the long-term S budget of a coniferous catchment on the Canadian Shield
AU: Houle,-D.; Carignan,-R.*
AF: Univ. Montreal, Dep. Sci. Biol., 90 Ave. Vincent-d'Indy, C.P. 6128, Succ. A Montreal, PQ H3C 3J7, Canada
SO: BIOGEOCHEMISTRY 1995 vol. 28, no. 3, pp. 161-182
LA: English
ER: F (Freshwater)
AB: The hypothesis that SO sub(4) desorption can explain apparent long term net SO sub(4)-S losses (5 kg/ha/yr on average) at the Lake Laflamme catchment from 1982 to 1991 is examined. Field observations show that SO sub(4) concentrations in the soil solution are strongly buffered during percolation through the Bf horizon. In the Bf horizon, SO sub(4) exchange reactions between the adsorbed and aqueous compartments are rapid (hours). Most ( approximately  60%) of the adsorbed SO sub(4) may be readily desorbed with deionized water. These observations and the presence of an important adsorbed SO sub(4)-S reservoir in the Bf horizon as compared with annual wet SO sub(4)-S deposition (7 kg/ha), suggest that on the short-term, adsorption and desorption reactions can control dissolved SO sub(4) concentration in the Bf horizon. To examine were SO sub(4) adsorption/desorption could explain long-term SO sub(4)-S losses by the catchment, an aggregated Langmuir isotherm for the Bf horizon was used to calculate the catchment's resilience to changing SO sub(4)-S loads. The results indicate that the soil should adjust rapidly (within 4 years) to changing SO sub(4)-S loads and that SO sub(4) desorption alone cannot explain long-term net SO sub(4)-S losses. Other possibilities, such as an underestimation of dry deposition or the weathering of S-bearing minerals also appear unlikely. Our results suggest a net release of SO sub(4)-S from the soil organic S reservoirs (1230 kg/ha) present in the catchment.
AN: 3749208

                                                                    313 of 1521  
TI: Geochemical consequences of the Chernobyl accident
AU: Kopeykin,-V.A.
AF: All-Russian Nonmetallic Min. Resour. Geol. Res. Inst., Kazan, Russia
SO: GEOCHEM.-INT.;GEOKHIMIYA 1994;1993 vol. 31, no. 5, pp. 134-137;no. 10
LA: English
ER: F (Freshwater)
AB: The Chernobyl disaster discharged a vast amount of radioactive material into the atmosphere, which was deposited near the station and far away. The power station is located on the bank of the Pripyat R., and the floodplain of the river is very marshy, with a high groundwater level near the station. A large area of pine forest died as a result of the irradiation. The first forecasts on fallout dissolution were meant to be reassuring, and no dissolution phenomena were expected in the immediate future. The result of this forecast had a bearing on the storage of radioactive wastes: the dead pines with the radioactive dust on them were felled in 1987 and buried in trenches cut in the sandy soil, without clay screening. This storage is without visible signs now, i.e., the stores are very difficult to locate. One of the areas for this storage to the west of Chernobyl lies on the first terrace of the Pripyat above the floodplain at levels of 111.7 to 113.4 m. The region is composed in the main of Quaternary fine-grained sands, often clayey. The groundwater table in this region is at depths from 0.5 to 1.6 m. The average annual water-table level fluctuation is 0.4 m.
AN: 3748506

                                                                    314 of 1521  
TI: Data management for JGOFS: Theory and design
AU: Flierl,-G.R.; Bishop,-J.K.B.; Glover,-D.M.; Paranjpe,-S.
CO: Ocean Climate Data Workshop, Greenbelt, MD (USA), 18-21 Feb 1992
SO: PROCEEDINGS-OF-THE-OCEAN-CLIMATE-DATA-WORKSHOP,-FEBRUARY-18-21,-1992. J.-Churgin-comp. Commission-of-the-European-Communities,-Brussels-Belgium GREENBELT,-MD-USA GODDARD-SPACE-FLIGHT-CENT. 1992 pp. 229-250
LA: English
ER: M (Marine)
AB: We have constructed prototypes of the servers, methods, and constructed objects. We have much of the North Atlantic Bloom data entered into the system, along with various historical data sets and (separately) data from the SYNOP program. The process of documenting and training users will begin this year; assessment of the merits of the approach are still to come. However, we believe that, for on-going projects, on-line access to current data sets has many advantages. Likewise, the idea of building "extensible" data systems, analysis packages, and graphics packages should offer significant improvements in our abilities to share software.
AN: 3747017

                                                                    315 of 1521  
TI: Data management for community research projects: A JGOFS case study
AU: Lowry,-R.K.
CO: Ocean Climate Data Workshop, Greenbelt, MD (USA), 18-21 Feb 1992
SO: PROCEEDINGS-OF-THE-OCEAN-CLIMATE-DATA-WORKSHOP,-FEBRUARY-18-21,-1992. J.-Churgin-comp. Commission-of-the-European-Communities,-Brussels-Belgium GREENBELT,-MD-USA GODDARD-SPACE-FLIGHT-CENT. 1992 pp. 251-274
LA: English
ER: M (Marine)
AB: Since the mid 1980s, much of the marine science research effort in the United Kingdom has been focused into large scale collaborative projects involving public sector laboratories and university departments, termed Community Research Projects. Two of these, the Biogeochemical Ocean Flux Study (BOFS) and the North Sea Project incorporated large scale data collection to underpin multidisciplinary modeling efforts. The challenge of providing project data sets to support the science was met by a small team within the British Oceanographic Data Centre (BODC) operating as a topical data centre. The role of the data centre was to both work up the data from the ship's sensors and to combine these data with sample measurements into online databases. The working up of the data was achieved by a unique symbiosis between data centre staff and project scientists. The project management, programming and data processing skills of the data centre were combined with the oceanographic experience of the project communities to develop a system which has produced quality controlled, calibrated data sets from 49 research cruises in 3.5 years of operation. The data centre resources required to achieve this were modest and far outweighed by the time liberated in the scientific community by the removal of the data processing burden.
AN: 3747016

                                                                    316 of 1521  
TI: Regulation of copper concentration in the oceanic nutricline by phytoplankton uptake and regeneration cycles
AU: Sunda,-W.G.; Huntsman,-S.A.
AF: Beaufort Lab., NMFS/NOAA, 101 Pivers Island Rd., Beaufort, NC 28516, USA
SO: LIMNOL.-OCEANOGR. 1995 vol. 40, no. 1, pp. 132-137
LA: English
ER: M (Marine)
AB: Similar sigmoidal relationships were observed between cellular Cu:C ratios and free cupric ion concentration for the neritic alga Thalassiosira pseudonana and two oceanic species (Thalassiosira oceanica and Emiliania huxleyi) grown in trace metal ion buffered media. Only 5-9-fold variations in cell Cu:C were observed for these species over the [Cu super(2+)] range 3 x 10 super(-15) to 3 x 10 super(-12) M, with increasing cell copper vs. [Cu super(2+)] slopes above and below this range. At the mean [Cu super(2+)] for the euphotic zone of the North Pacific (10 super(-13.2) M), cell Cu:C ratios for the three species were 4.4, 4.4, and 3.8  mu mol/mol, similar to values for plankton taken from North Pacific waters. These values also match the mean Cu:C ratio of 4.1  mu mol/mol determined from slopes of linear relationships between Cu and PO sub(4) in the nutricline of the central North Pacific and the "Redfield" C:PO sub(4) ratio in plankton of 106:1. This agreement provides strong evidence that copper concentrations in remote oceanic nutriclines are regulated by phytoplankton uptake and regeneration processes.
AN: 3745817

                                                                    317 of 1521  
TI: What determines sedimentary C/S ratios?
AU: Morse,-J.W.; Berner,-R.A.
AF: Dep. Oceanogr., Texas A&M Univ., College Station, TX 77843, USA
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 6, pp. 1073-1077
LA: English
ER: M (Marine)
AB: The weight ratio of organic carbon to pyrite sulfur (C/S) has been observed to fall within a relatively narrow range (2.8  plus or minus  0.8) in most fine-grained normal marine siliciclastic sediments. Although an increasing number of exceptions to this typical C/S ratio have been observed, it is nonetheless remarkable that so many modern and ancient marine sediments fall within a range of about a factor of two in C/S ratios. Here we demonstrate that this demands that the three major factors that control this ratio must be quite closely coupled to each other. These factors are (1) the fraction of organic carbon that is metabolized, (2) the fraction of metabolized organic carbon that is metabolized via sulfate reduction, and (3) the fraction of reduced sulfide that is not oxidized and is buried in pyrite. A simple model is presented that has utility in demonstrating the relationships among these parameters that are necessary to produce typical normal marine sediments C/S ratios.
AN: 3745506

                                                                    318 of 1521  
TI: Long-term hydrologic and biogeochemical responses of a soft water seepage lake in north central Wisconsin
AU: Wentz,-D.A.; Rose,-W.J.; Webster,-K.E.
AF: U.S. Geol. Surv., Portland, OR, USA
SO: WATER-RESOUR.-RES. 1995 vol. 31, no. 1, pp. 199-212
LA: English
ER: F (Freshwater)
AN: 3744700

                                                                    319 of 1521  
TI: Carbon flux and recycling associated with zooplanktonic fecal pellets on the shelf of the Middle Atlantic Bight
AU: Lane,-P.V.Z.; Smith,-S.L.; Urban,-J.L.; Biscaye,-P.E.
AF: Mar. Biol. and Fish. Div., Rosenstiel Sch. Mar. and Atmos. Sci., 4600 Rickenbacker Causeway, Miami, FL 33149, USA
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1994 vol. 41, no. 213, pp. 437-457
LA: English
ER: M (Marine)
AB: Sediment traps were deployed for 5 days during March 1988, at 20 and 33 m in 42 m of water over the continental shelf off Norfolk, Virginia (SEEP-II study area). During the sediment trap deployment, a time-series study determined the community and age-structure of copepods as well as the standing stocks, production rates and settling velocities of fecal pellets. Fecal pellets comprised less than 1% of the total particulate carbon collected in the sediment traps and ca 0.3% of particulate carbon found in the water column. Mean fecal pellet production by adult copepods feeding in natural seawater ranged from 1 to 2 pellets animal super(-1) day super(-1), equalling approximately 0.1-0.3  mu g C day super(-1). Average fecal pellet volume ranged from 4 x 10 super(5)  mu m super(3) for pellets produced by Centropages typicus females to 14 x 10 super(5)  mu m super(3), for pellets produced by Calanus finmarchicus females. The pellets produced by C. finmarchicus were important in the downward vertical transport of phytoplankton carbon, while pellets produced by smaller copepods were primarily recycled in the water column. Lateral advective processes altered the species composition of zooplankton at our study site. The onshore and offshore movement of different zooplankton communities with varying size-structure could have a substantial impact on the magnitude of vertical carbon transport on continental shelves.
AN: 3743519

                                                                    320 of 1521  
TI: super(210)Pb balance and implications for particle transport on the continental shelf, U.S. Middle Atlantic Bight
AU: Bacon,-M.P.; Belastock,-R.A.; Bothner,-M.H.
AF: Woods Hole Oceanogr. Insti., Woods Hole, MA 02503, USA
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1994 vol. 41, no. 2/3, pp. 511-535
LA: English
ER: M (Marine)
AB: Supply of  super(210)Pb to the continental shelf off the northeastern United States is dominated by the deposition from the atmosphere, the rate of which is reliably known from previously published work. Excess  super(210)Pb inventories in the shelf sediments show accumulations that are nearly in balance with the supply, even in areas of relict sands where it is believed that no net accumulation of sediment presently occurs. The  super(210)Pb distributions in shelf and slope water indicate that the two-way fluid exchange at the shelf-slope front and the net transport in the alongshore flow make comparatively small contributions to the shelf  super(210)Pb budget. The near balance between supply and decay of  super(210)Pb on the shelf implies a limit to the particle export flux. It is concluded that the export of particulate organic carbon does not exceed 60 g m super(-2) y super(-1) ( similar to 25% of primary production) and is probably lower. The hypothesis is advanced that fine particulate matter introduced to the continental shelf is detained in its transit of the shelf because of bioturbational trapping in the sediment due to benthic animals. Distributions of  super(210)Pb in suspended particulate matter and in the fine fraction of shelf sediments suggest that the average fine particle must undergo several cycles of deposition-bioturbation-resuspension-redeposition and requires a number of decades for its transit and ultimate export from the shelf. Thus, only the most refractory organic matter is likely to be exported.
AN: 3742857

                                                                    321 of 1521  
TI: Microbial carbon utilization on the continental shelf and slope during the SEEP-II experiment
AU: Kemp,-P.F.
AF: Brookhaven Natl. Lab., Oceanogr. and Atmos. Sci. Div., Upton, NY 11973, USA
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1994 vol. 41, no. 2/3, pp. 563-581
LA: English
ER: M (Marine)
AB: Microbial processes were measured as part of the Shelf Edge Exchange Processes II (SEEP-II) experiment, which was designed to re-examine the hypothesis that a substantial fraction of primary production on the continental shelf is exported to the slope and deeper ocean. Bacterial-mediated carbon remineralization was defined as the sum of measured bacterial production plus estimated bacterial respiration. Carbon remineralization, summed over the water column plus surficial sediment, was 90-180 mg C m super(-2)/day on the shelf and 270-540 mg C m super(-2)/day on the slope. These are equivalent to 12-24% and 33-66% of daily primary production on the shelf and slope, respectively. The majority of bacterial activity occurs in sediments on the shelf, but on the slope it is attributable to bacteria in the deep water column. Concurrent sediment trap data indicate that material sinking from surface waters overlying the slope can supply only a small fraction of carbon remineralized by bacteria in the intermediate water column. Bacterial production in slope water and sediments may be subsidized by export from the shelf. Because of the greater width of the shelf than slope, this additional demand on shelf carbon would represent only 7.5-15% of shelf primary production. Mean specific growth rates of sediment bacteria were very uniform at depths between 40 and 2000 m. This suggests bacterial growth may be limited by some common factor, although environmental factors known to affect growth rates generally vary with depth. DNA synthesis rates (measured by thymidine incorporation) were comparable to rates observed for marine bacteria in nutrient-replete culture. The implication is that sediment bacteria were not limited by nutrient availability. If true, water column and sediment bacterial production are likely to be controlled by very different processes: water-column bacteria by both nutrient limitation and grazing, and sediment bacteria by grazing alone.
AN: 3742855

                                                                    322 of 1521  
TI: Particle export at Cape Hatteras
AU: Walsh,-J.J.
AF: Dep. Mar. Sci., Univ. South Florida, St. Petersburg, FL 33701, USA
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1994 vol. 41, no. 2/3, pp. 603-628
LA: English
ER: M (Marine)
AB: A simple model of shelf, slope and basin waters near Cape Hatteras, North Carolina is used to estimate the sources and sinks of organic carbon within the Gulf Stream System. The analysis employs water transport estimates, nutrient data, satellite imagery, surficial sediment records and particle distributions caught by bottle, camera and sediment trap to compute vertical and lateral fluxes of particulate carbon. Particle export from the SAB and MAB shelf ecosystems may constitute 62-82% of the source of the carbon flux within the Gulf Stream near 75 degree W, after settling at 100 m/day, with an oxidation loss of 4%/day, to a nominal mid-depth of 1000 m on the slope. As a result of light limitation, denitrification and DON solubilization, partial utilization of onwelled nitrate from the Gulf Stream System by coastal phytoplankton suggests that the time-averaged f ratio may be as small as 0.12 for the ratio of the "new" portion of primary production to the total. After burial loss, the export of particulate matter from the shelves then represents at most 11% of the total carbon fixation of coastal waters. If the shelf export of DON and unutilized NO sub(3) is consumed within adjacent slope waters, however, the f ratio and the percentage of particle export from the carbon fixation of shelf-affected waters might increase to 0.25 and 24%.
AN: 3742854

                                                                    323 of 1521  
TI: The lateral flux of biogenic particles from the eastern North American continental margin to the North Atlantic Ocean
AU: Falkowski,-P.G.; Biscaye,-P.E.; Sancetta,-C.
AF: Oceanogr. and Atmos. Sci. Div., Brookhaven Natl. Lab., Upton, NY 11973, USA
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1994 vol. 41, no. 2/3, pp. 583-601
LA: English
ER: M (Marine)
AB: Sediment trap samples from two field programs on the continental margin of the northeast coast of the United States, which constituted the Shelf Edge Exchange Program (SEEP), were analyzed for phytoplankton taxonomic composition and the fluxes of organic carbon, nitrogen and opaline silica. The traps, with a rotating carousel collection system, were located on taut-wire moorings between 150 and 2700 m below the surface and extended from the 500 m isobath on the upper continental shelf to the 2750 m isobath at the edge of the abyssal plain of the western North Atlantic Ocean. The temporal and spatial distributions of phytoplankton in the azide-poisoned trap samples revealed a general increase of intact cells with depth, which is consistent with lateral transport from the margins to the ocean interior. Taxonomic analysis of the phytoplankton indicated that >90% of the intact cells (containing identifiable intracellular structures) consisted of diatoms. The distribution of the species further supports the lateral transport origin of the particles, and indicates that the particulate materials are delivered to the ocean interior primarily in pulses of rapidly sinking aggregates. However, quantitative analysis suggests that intact phytoplankton contribute only 0.8  plus or minus  0.7% (mean and S.D.) and 0.9  plus or minus  0.7% of the total particulate carbon and nitrogen fluxes, respectively. Using silica-to-carbon ratios to budget the remaining trap organic carbon fluxes, it would appear that between 17 and 100% of the sedimenting particles were originally diatomaceous, but that the organic carbon became solubilized and/or oxidized in the water column during descent. A simple two-dimensional model was developed to quantify the contribution of the flux of particulate organic carbon to the interior of the North Atlantic Ocean. The results suggest that north of Cape Hatteras, the mean lateral flux of particulate organic carbon sinking through the upper 500 m of the water column into the western edge of the basin is 4.8 x 10 super(12) g C/y, which is about 6% of the primary production on the shelf. This flux represents the lateral export of carbon from the continental margin to the interior of the North Atlantic Ocean. Based on estimates of vertical export production for the basin of about 4.2 x 10 super(14) g C/y, we estimate that the export of carbon from the western margin, north of Cape Hatteras, represents about 1% of the new production of the entire basin. This export is a significant source of energy which fuels the high benthic respiration on the continental slope.
AN: 3742853

                                                                    324 of 1521  
TI: Deep-sea floor respiration as an indication of lateral input of biogenic detritus from continental margins
AU: Rowe,-G.T.; Boland,-G.S.; Phoel,-W.C.; Anderson,-R.F.; Biscaye,-P.E.
AF: Dep. Oceanogr., Texas A&M Univ., College Station, TX 77843, USA
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1994 vol. 41, no. 2/3, pp. 657-668
LA: English
ER: M (Marine)
AB: Sediment oxygen demand, estimated using in situ chambers on a benthic lander, incubations of recovered cores and values previously published by others, has been used as a measurement of the flux of organic matter to the sea floor from the continental shelf and slope out to the abyssal plain in the northwest Atlantic. Rates were highest on the continental margin, and declined precipitously offshore. On the middle continental slope, rates were almost as high as those on the continental shelf, supporting the idea that mid-slope depths at ca 1000 m depth are a "depocenter" for particulate organic debris. The sediment oxygen demand, in terms of carbon equivalents (mg C m super(-2)/day), was generally lower than near-bottom POC fluxes measured in sediment traps. This imbalance is attributed to a combination of burial, anaerobic metabolism not reflected in oxygen demand, and continued lateral export along or offshore near the bottom. The exception to this pattern was the mid-slope depocenter, where the measured POC input was slightly less than the total organic carbon demand estimated with the lander. A comparison with other work suggests that at most depths on the continental margin the sediment oxygen demand is higher off the west coast of the U.S.A. than off the east coast. The upper to middle continental slope (500-1500 m depth) is the only zone over which sediment oxygen demand is higher on the east coast, but this can be attributed to the physiological limitations of low ambient oxygen concentration on heterotrophic metabolism in the pronounced oxygen minimum on the west coast.
AN: 3742851

                                                                    325 of 1521  
TI: The shelf edge exchange processes experiment, SEEP-II: An introduction to hypotheses, results and conclusions
AU: Biscaye,-P.E.; Flagg,-C.N.; Falkowski,-P.G.
AF: Lamont-Doherty Earth Obs. Columbia Univ., Palisades, NY 10964, USA
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1994 vol. 41, no. 2/3, pp. 231-252
LA: English
ER: M (Marine)
AB: The SEEP (Shelf Edge Exchange Processes)-II experiment was the second of two that took place in the Middle Atlantic Bight (MAB) of the eastern U.S. continental shelf and slope. The experiment included an array of 10 multi-instrumented moorings deployed for 15 months and 10 oceanographic cruises, all designed to address the problem of the fate of continental shelf particulate matter in general, and organic carbon in particular. This paper provides the setting and background for the SEEP Program, the SEEP-II experiment and an introduction to the 18 papers constituting the subject of this special volume. Because those papers lack one of a general nature on the physical oceanographic setting of the experiment, that aspect is treated in somewhat more detail here. The results of the experiment overwhelmingly show that the working hypothesis on which the SEEP Program was undertaken and sponsored by the Department of Energy is not valid. That is, there is not an export to the adjacent slope and open ocean of a large proportion of the particulate matter introduced to and biologically generated in the waters of the continental shelf; most of the biogenic particulate matter is recycled by consumption (bacterial and otherwise) and oxidation on the shelf, and only a small proportion (of order << 5%) is exported to the adjacent slope. The small amount that is exported appears to be deposited preferentially in the sediments of an area of the slope centered at about 1000 m, and the export and sedimentation to that depocenter appears to increase from the northern to the southern MAB.
AN: 3742849

                                                                    326 of 1521  
TI: Modelling physical-biological coupling in the ocean: The U.S. GLOBEC Program
AU: Eckman,-J.E.
AF: Skidaway Inst. Oceanogr., 10 Ocean Science Circle, Savannah, GA 31411, USA
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1994 vol. 41, no. 1, pp. 1-5
LA: English
ER: M (Marine)
AB: Evidence continues to accumulate that the Earth's environment is changing. The change is not localized, but extends from the tropics to the poles, and is apparent in the atmosphere, on land and in the ocean. Some of these shifts are thought to be anthropogenic (e.g. ozone depletion at high latitudes, increasing concentrations of "greenhouse" gases), but paleoclimatic records also suggest that the Earth has experienced significant climatic changes in the past. We do not known whether many of these changes occur cyclically, stochastically, episodically or represent long-term trends. We have little knowledge about time scales characterizing most of these changes. Some clearly are relatively short-lived (e.g. El Nino/Southern Oscillation events), while others may operate over long time scales (e.g. incorporation of carbon into the deep sea). Researchers who study these changes are engaged in attempts to verify the existence, magnitude and causes of these shifts. One of the great and important challenges facing scientists is using the discoveries of these researchers to predict the direction and magnitude of the responses of the Earth's biota to current climatic shifts. The U.S. GLOBEC (GLOBal Ocean ECosystems Dynamics) program is a research initiative organized by the oceanographic and fisheries communities, and supported principally by the National Science Foundation (NSF) and National Oceanic and Atmospheric Administration (NOAA), that aims to understand how changes in the global environment are expected to affect the abundances and production of animals in the sea.
AN: 3742544

                                                                    327 of 1521  
TI: Studies on regeneration rate of nitrogen in decomposition of plankton in lake
AU: Zhuang,-Yuanyi; Dai,-Shugui; Zhang,-Mingshun
AF: Dep. Environ. Sci., Nankai Univ., Tianjin 300071, People's Rep. China
SO: CHINA-ENVIRON.-SCI.-ZHONGGUO-HUANJING 1993 vol. 13, no. 2, pp. 81-84
LA: Chinese
ER: F (Freshwater)
AB: Informations about the nitrogen regeneration in decomposition of plankton sampled from Dianchi Lake and the factors influencing the decomposition are presented in this paper. The results of the simulation test show that the main regeneration products in decomposition of plankton are NH sub(4) super(+)-N and NO sub(3) super(-) + NO sub(2) super(-) - N in water, NH sub(4) super(+)-N and organic N in sediment. The decomposition rates constant in water in dark are 0.07/d and 0.12/d at 20 degree C and 30 degree C respectively. The decomposition in light can stimulate the growth of algae in water.
AN: 3742533

                                                                    328 of 1521  
TI: Trace metal distribution, partition and fluxes in the Seine Estuary (France) in low discharge regime
AU: Chiffoleau,-J.-F.; Cossa,-D.; Auger,-D.; Truquet,-I.
AF: IFREMER, Cent. Nantes, BP 1049, 44037 Nantes Cedex 01, France
SO: MAR.-CHEM. 1994 vol. 47, no. 2, pp. 145-158
LA: English
ER: M (Marine); B (Brackish)
AB: Samples collected in surface waters of the Seine estuary (France) during a low discharge period were analyzed for dissolved and particulate trace metals (Cd, Co, Cu, Mn, Ni, Pb and Zn). The studies showed that these trace elements are reactive in the estuary: an addition to the dissolved phase is observed for Cd, Co, Cu, Mn, Ni and Zn and a removal for Pb. Cd, Cu, Ni and Zn are released from seaward fluxing riverine particles or estuarine sediments directly in the water column, while the dissolved Co-salinity distribution, similar to Mn distribution suggests a preliminary release in the sediment pore water. Rapid adsorption onto the suspended load plays a major role in Pb removal from the dissolved phase. Partition coefficients for the dissolved and particulate phase (K sub(D)) decrease in the order: Pb > Co > Cu, Zn > Ni > Cd, i.e. a sequence similar to those reported from others European areas. Gross riverine inputs to the estuary and net efflux of dissolved trace metals to the English Channel are estimated. Values show that the Seine river and its estuary constitute a significant source of trace metals for the North Sea.
AN: 3742324

                                                                    329 of 1521  
TI: Development of a gold amalgam voltammetric microelectrode for the determination of dissolved Fe, Mn, O sub(2), and S(-II) in porewaters of marine and freshwater sediments
AU: Brendel,-P.J.; Luther,-G.W.,III
AF: Dep. Chem. Biochem. Coll., Mar. Stud., Univ. Delaware, Lewes, DE 19958, USA
SO: ENVIRON.-SCI.-TECHNOL. 1995 vol. 29, no. 3, pp. 751-761
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: A solid-state voltammetric gold amalgam microelectrode has been developed for the measurement of dissolved O sub(2), S(-II), Fe, and Mn in the porewaters of marine sediments. This electrode can provide more information at (sub)millimeter depth resolution on all of the major redox species found in the environment than membrane microelectrodes which usually can measure only one of these species per electrode. We describe the construction, standardization, analytical validation, and application of a microelectrode to marine sediments. The use of the microelectrode takes advantage of the fast scan voltammetric methods for simultaneous measurement of all redox species during one potential scan. Electrochemical conditioning of the solid-state microelectrode between voltage scans while deployed in waters and sediments allows for repeated use of the electrode. Finally, we demonstrate depth profiles at millimeter resolution for the redox species in a Delaware salt marsh. The profiles observed are consistent with the known biogeochemical cycling of the target redox species. In addition, we provide evidence for H sub(2)O sub(2), iron(II) sulfide complexes, and iron(III) colloids or organic complexes in porewaters.
AN: 3742172

                                                                    330 of 1521  
TI: The remineralization of organic carbon on the North Carolina continental slope
AU: Blair,-N.E.; Plaia,-G.R.; Boehme,-S.E.; DeMaster,-D.J.; Levin,-L.A.
AF: Dep. Mar., Earth and Atmos. Sci., North Carolina State Univ., Raleigh, NC 27695-8208, USA
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1994 vol. 41, no. 4-6, pp. 755-766
LA: English
ER: M (Marine)
AB: The sources and fates of metabolizable organic carbon were examined at three sites on the North Carolina slope positioned offshore of Cape Fear, Cape Lookout and Cape Hatteras. The  super(13)C/ super(12)C compositions ( delta  super(13)C) of the solid phase organic matter, and the dissolved inorganic carbon ( capital sigma CO sub(2)) produced during its oxidation, suggested that the labile fraction was predominantly marine in origin. The  capital sigma CO sub(2) concentration gradient across the sediment-water interface, and by inference the  capital sigma CO sub(2) flux and production rate, increased northward from Cape Fear to Cape Hatteras. Methane distributions and  capital sigma CO sub(2)  delta  super(13)C values suggest that the rate of anaerobic diagenesis increased northward as well. The differences in sedimentary biogeochemistry are most likely driven by an along-slope gradient of reactive organic carbon flux to the seabed. This trend in reactive organic carbon flux correlates well with macrofaunal densities previously observed at the three sites. Proximity to the shelf and the transport of particulate material by surface boundary currents may control the deposition of metabolizable material on the Carolina slope. Evidence for methanogenesis was found only on the Cape Hatteras slope. The methane, which was produced at a depth of approximately 1 m in the seabed, was consumed nearly quantitatively in the biologically mixed layer as it diffused upward. Irrigation of the sediments by infauna may have provided the necessary oxidant for the consumption of the methane.
AN: 3740443

                                                                    331 of 1521  
TI: Iron chemistry in seawater and its relationship to phytoplankton: A workshop report
AU: Wells,-M.L.; Price,-N.M.; Bruland,-K.W.
AF: Inst. Mar. Sci., Univ. California, Santa Cruz, CA 95064, USA
SO: MAR.-CHEM. 1995 vol. 48, no. 2, pp. 157-182
LA: English
ER: M (Marine)
AB: The perceptions of ocean chemists and algal physiologists have shifted enormously over the past two decades, from attempts to correlate metal uptake by phytoplankton with bulk measurements of total "dissolved" metals, to recognizing that metal speciation is the critical factor. This evolution in thinking began with well-defined, metal buffered laboratory culture experiments and the principles learned there have appeared to work well for predicting the biological effects of various metals (e.g. Cu, Zn, and Mn) in natural systems; until iron. It became apparent during the workshop discussions that two main factors contribute to the vexing difficulty in characterizing the relationship between iron chemistry and phytoplankton dynamics. First, the marine chemistry of iron is more complex and less explored than many other bioactive metals. The second complicating factor is the diversity of iron uptake strategies likely employed by phytoplankton. Though a central goal of the workshop was to better define iron availability to help develop analytical tools for quantifying this bioavailable fraction in seawater, this task is not possible given the foundation of our present knowledge. Quantification of iron "availability" in natural waters awaits better characterization of the marine chemistry of iron in conjunction with exploration of the uptake strategies used by different members of the algal community. What emerged then from this workshop was a shift in the paradigm of iron biogeochemistry in seawater, from one in which iron/phytoplankton interactions behave similarly as for other bioactive metals to one in which iron stands as truly unique.
AN: 3740329

                                                                    332 of 1521  
TI: Effects of man-made and natural sources on the heavy-metal patterns in bottom sediments in the Gulf of Peter the Great, Sea of Japan
AU: Anikiyev,-V.V.; Perepelitsa,-S.A.; Shumilin,-Y.N.
AF: Pac. Oceanol. Inst., Far East Div., Russian Acad. Sci., Vladivostok, Russia
SO: GEOCHEM.-INT.;GEOKHIMIYA 1994;1993 vol. 31, no. 4, pp. 73-85;no. 9
LA: English
ER: M (Marine)
AB: Flame atomic-absorption spectrophotometry has been used to study the distribution of Zn, Pb, Ag, Cd, Cu, Ni, Co, and Mn in bottom sediments in the Gulf of Peter the Great (Sea of Japan). Zones of impact on the sediment composition are identified due to the following sources: a) dumping in Gornostay Bay, b) the cities of Vladivostok and Bol'shoy Kamen', and c) the Razdol'naya River. The Zn, Pb, Cd, Cu, and Ag contents in bottom sediments in regions affected by human action are controlled by the positions and outputs of the pollution sources. The distribution of the lithophile elements (Mn, Ni, and Cu) in the bottom sediments of the gulf have been governed mainly by natural processes: chemical weathering of bedrock, denudation above the principal erosion base, and coastal abrasion.
AN: 3740128

                                                                    333 of 1521  
TI: Input, accumulation and cycling of materials on the continental slope off Cape Hatteras: An introduction
AU: Blake,-J.A.; Diaz,-R.J.
AF: Sci. Appl. Int. Corp., 89 Water St., Woods Hole, MA 02543, USA
SO: DEEP-SEA-RES.-II-TOP.-STUD.-OCEANOGR. 1994 vol. 41, no. 4-6, pp. 707-710
LA: English
ER: M (Marine)
AB: The studies reported in this special issue of Deep-Sea Research are largely derived from data collected as part of programs supported by the U.S. Department of the Interior, Minerals Management Service (MMS) in response to concerns about the effect of oil and gas exploration on the largely unknown continental slope environment. Results of the MMS U.S. South Atlantic continental slope and rise program conducted off the Carolinas from Cape Hatteras to off Charleston in depths ranging from 600-3500 m identified the importance of the slope off Cape Hatteras in cycling of materials from the shelf to the deep sea. Other more detailed investigations followed which filled numerous gaps in our knowledge of the role played by such special regions of the continental slope in the global cycling of carbon and other materials.
AN: 3739786

                                                                    334 of 1521  
TI: Solute fluxes and sulfur cycling in forested catchments in SW Germany as influenced by experimental (NH sub(4)) sub(2)SO sub(4) treatments
AU: Feger,-K.H.
AF: Inst. Soil Sci. and Forest Nutr., Albert-Ludwig-Univ., Bertoldstr. 17, D-79085 Freiburg i.Br., FRG
CO: BIOGEOMON, The Symposium on Ecosystem Behaviour: Evaluation of Integrated Monitoring in Small Catchments, Prague (Czech Rep.), 18-20 Sep 1993
SO: WATER,-AIR,-SOIL-POLLUT. 1995 vol. 79, no. 1-4, pp. 109-130
LA: English
ER: F (Freshwater)
AB: Results are presented from the research project ARINUS which investigates biogeochemical cycling in Norway spruce (Picea abies KARST.) ecosystems in the Black Forest (SW Germany) and effects of experimental (NH sub(4)) sub(2)SO sub(4) additions. The interaction of the terrestrial and aquatic system is assessed using an integrated approach which combines flux measurements in representative plots on the stand level with input-output budgets of small catchments. The approach, field installations and experimental manipulations are described. Results from element flux measurements in the untreated systems are presented and processes controlling N and S transformations are discussed for two catchments representing contrasting site conditions. Even though the S budget is negative for both systems there is a distinct difference in the relation between organic vs. inorganic S fractions in the soil. Sulfate mineralization and desorption, respectively are discussed as controlling processes. Sulfate retention is not only a function of soil properties, but also of water fluxes and pathways. The uptake of added SO sub(4) super(2-) was highly controlled by the counter-cation. Microbial N retention in the soil was highly influenced by the site management history. The extent of streamwater acidification was highly dependent on the transformations and mobility of N and S in the soils which in turn controlled cation leaching and alkalinity.
AN: 3736396

                                                                    335 of 1521  
TI: Ion mass budgets for small forested catchments in Finland
AU: Forsius,-M.; Kleemola,-S.; Starr,-M.; Ruoho-Airola,-T.
AF: Water and Environ. Res. Inst., P.O. Box 250, FIN-00101 Helsinki, Finland
CO: BIOGEOMON, The Symposium on Ecosystem Behaviour: Evaluation of Integrated Monitoring in Small Catchments, Prague (Czech Rep.), 18-20 Sep 1993
SO: WATER,-AIR,-SOIL-POLLUT. 1995 vol. 79, no. 1-4, pp. 19-38
LA: English
ER: F (Freshwater)
AB: Ion mass and H super(+) budgets were calculated for three pristine forested catchments using bulk deposition, throughfall and runoff data. The catchments have different soil and forest type characteristics. A forest canopy filtering factor for each catchment was estimated for base cations, H super(+), Cl super(-) and SO sub(4) super(2-) by taking into account the specific filtering abilities of different stands based on the throughfall quality and the distribution of forest types. Output fluxes from the catchments were calculated from the quality and quantity of the runoff water. Deposition, weathering, ion exchange, retention and biological accumulation processes were taken into account to calculate catchment H super(+) budgets, and the ratio between external (anthropogenic) and internal H super(+) sources. In general, output exceeded input for Na super(+), K super(+), Ca super(2+), Mg super(2+), HCO sub(3) super(-) (if present) and A super(-) (organic anions), whereas retention was observed in the case of H super(+), NH sub(4) super(-), NO sub(3) super(-) and SO sub(4) super(2-). The range in the annual input of H super(+) was 22.8-26.3 meq m super(-2) yr super(-1), and in the annual output, 0.3-3.9 meq m super(-2) yr super(-1). Compared with some forested sites located in high acid deposition areas in southern Scandinavia, Scotland and Canada, the catchments receive rather moderate loads of acidic deposition. The consumption of H super(+) was dominated by base cation exchange plus weathering reactions (41-79%), and by the retention of SO sub(4) super(2-) (17-49%). The maximum net retention of SO sub(4) super(2-) was 87% in the Hietajaervi 2 catchment, having the highest proportion of peatlands. Nitrogen transformations played a rather minor role in the H super(+) budgets. The ratio between external and internal H super(+) sources (excluding net base cation uptake by forests) varied between 0.74 and 2.62, depending on catchment characteristics and acidic deposition loads. The impact of the acidic deposition was most evident for the southern Valkeakotinen catchment, where the anthropogenic acidification has been documented also by palaeolimnological methods.
AN: 3736393

                                                                    336 of 1521  
TI: Sulfur isotope dynamics in a high-elevation catchment, West Glacier Lake, Wyoming
AU: Finley,-J.B.; Drever,-J.I.; Turk,-J.T.
AF: Dep. Geol., Miami Univ., Oxford, OH 45056, USA
CO: BIOGEOMON, The Symposium on Ecosystem Behaviour: Evaluation of Integrated Monitoring in Small Catchments, Prague (Czech Rep.), 18-20 Sep 1993
SO: WATER,-AIR,-SOIL-POLLUT. 1995 vol. 79, no. 1-4, pp. 227-241
LA: English
ER: F (Freshwater)
AB: Stable isotopes of S are used in conjunction with dissolved SO sub(4) super(2-) concentrations to evaluate the utility of  delta  super(34)S ratios in tracing contributions of bedrock-derived S to SO sub(4) super(2-) in runoff. Water samples were collected over the annual hydrograph from two tributaries in the West Glacier Lake, Wyoming, catchment. Concentrations of SO sub(4) super(2-) ranged from 12.6 to 43.0  mu eq L super(-1);  delta  super(34)S ratios ranged from -1.8 ppt to +4.9 ppt. The  delta  super(34)S value of atmospherically derived SO sub(4) super(2-) is about +5.6 ppt; four samples of pyrite from the bedrock had  delta  super(34)S ratios that ranged from +0.7 to +4.1 ppt. Concentrations of SO sub(4) super(2-) were inversely related to  delta  super(34) and discharge. The data for the tributary with the higher SO sub(4) super(2-) concentrations were reasonably consistent with mixing between atmospheric S and S from a bedrock source with a  delta  super(34)S ratio of about -4.5 ppt. The difference from the measured bedrock values presumably indicates that S isotopes in the bedrock pyrite are heterogeneously distributed. The data from the tributary with lower SO sub(4) super(2-) concentrations did not follow a two-component mixing line. Deviation from a two-component mixing line is most likely caused by preferential elution of SO sub(4) super(2-) from the snowpack during the early stages of snowmelt, although microbially mediated fractionation of S isotopes in the soil zone also may cause the deviation from the mixing line. Sulfur isotopes are useful in identifying whether or not there is a substantial contribution of bedrock S to runoff, but quantifying that contribution is problematic.
AN: 3736376

                                                                    337 of 1521  
TI: Modeling excess sulfur deposition on wetland soils using stable sulfur isotopes
AU: Morgan,-M.D.
AF: Dep. Biol., Div. Pinelands Res., Rutgers Univ., Camden, NJ 08102, USA
CO: BIOGEOMON, The Symposium on Ecosystem Behaviour: Evaluation of Integrated Monitoring in Small Catchments, Prague (Czech Rep.), 18-20 Sep 1993
SO: WATER,-AIR,-SOIL-POLLUT. 1995 vol. 79, no. 1-4, pp. 299-307
LA: English
ER: F (Freshwater)
AB: Freshwater wetlands exposed to excess S deposition can potentially store significant amounts of reduced S in soils by dissimilatory sulfate reduction. If this storage is permanent, the harmful environmental effects of S deposition and the accompanying acidity are reduced, particularly on surface waters into which wetlands drain. Total non-sulfate S in freshwater peat is divided into three fractions: reduced inorganic S, ester sulfate and carbon-bonded sulfur (CBS). Each fraction is further divided based on its origin: assimilatory via plant and microbial uptake, and dissimilatory via microbial reduction. The CBS fraction dominates in peat, so the amount of dissimilatory CBS in the soil is a direct measure of the beneficial effect of storage of reduced S. Unfortunately, there is no way to directly measure dissimilatory CBS. A model is developed which, with three assumptions, provides a method to calculate dissimilatory CBS using S pool size and stable isotope measurements. Application of the model to a wetland in the New Jersey Pinelands, U.S.A., shows that large amounts of reduced dissimilatory S are stored in the soil. As a consequence, the impact of S deposition and acidity on the surface water environment is significantly reduced.
AN: 3736375

                                                                    338 of 1521  
TI: Effects of the physicochemical properties of bioinorganic complexes on the content of elements in marine organisms
AU: Karyakin,-A.V.; Sayenko,-G.N.; Zorina,-L.G.
AF: Vernadskiy Inst. Geochem. and Anal. Chem., Russian Acad. Sci., Inst. Oceanol., Moscow, Russia
SO: GEOCHEM.-INT.;GEOKHIMIYA 1994;1993 vol. 31, no. 4, pp. 107-111;no. 9
LA: English
ER: M (Marine)
AN: 3735531

                                                                    339 of 1521  
TI: Evaluation of the role of submerged plant beds in the metal budget of a fluvial lake
AU: St-Cyr,-L.; Campbell,-P.G.C.; Guertin,-K.
AF: INRS-Eau, Univ. Quebec, C.P. 7500, Sainte-Foy, PQ G1V 4C7, Canada
SO: HYDROBIOLOGIA 1994 vol. 291, no. 3, pp. 141-156
LA: English
ER: F (Freshwater)
AB: In a study of a large fluvial lake (Lake St. Pierre, St. Lawrence River system, Quebec), we have determined the biomass of the submerged vegetation (dominated by Vallisneria americana and Potamogeton spp) during the peak seasonal biomass (August) and senescence (October), and have estimated the content of Cd, Cr, Cu, Ni, Pb and Zn in the above-ground portions of these plants. Multispectral remote sensing data (MEIS-II) were used to extrapolate from point measures of biomass (g m super(-2)) to the entire area of the lake. By combining field information (biomass values and metal concentrations) with the more extensive remote sensing data base of biomass values, and by using geostatistical estimation techniques (kriging), we have estimated the seasonal storage of metals in Lake St. Pierre plants to be: 30 kg Cd, 89 kg Cr, 450 kg Cu, 280 kg Ni, 71 kg Pb and 2200 kg Zn. During the seasonal biomass peak, the quantities of Cd, Pb and Zn stored in the plants were higher than those dissolved in the water column, but much lower than those present in the surficial, recent sediments. Mass balance calculations for the summer months indicated that the 'macrophyte' compartment represented only a small proportion of the metals entering the lake: Cu and Ni, <1%; Cd and Zn, 2%; Pb, 4%. Senescence and the downstream drifting of plant material noted in October suggested that most of the metals associated with the above-ground parts of the submerged vegetation were not recycled within the lake, but instead were exported at the end of the summer.
AN: 3734919

                                                                    340 of 1521  
TI: The biogeochemical cycling of elemental mercury: Anthropogenic influences
AU: Mason,-R.P.; Fitzgerald,-W.F.; Morel,-F.M.M.
AF: Ralph Parsons Lab., MIT, Cambridge, MA 02139, USA
SO: GEOCHIM.-COSMOCHIM.-ACTA 1994 vol. 58, no. 15, pp. 3191-3198
NT: The Clair C. Patterson Special Issue.
LA: English
ER: M (Marine)
AB: A review of the available information on global Hg cycling shows that the atmosphere and surface ocean are in rapid equilibrium; the evasion of Hg super(0) from the oceans is balanced by the total oceanic deposition of Hg(II) from the atmosphere. The rapid equilibrium of the surface oceans and the atmosphere, coupled with the small Hg sedimentation in the oceans makes deposition on land the dominant sink for atmospheric Hg. About half of the anthropogenic emissions appear to enter the global atmospheric cycle while the other half is deposited locally, presumably due to the presence of reactive Hg in flue gases. We estimate that over the last century anthropogenic emissions have tripled the concentrations of Hg in the atmosphere and in the surface ocean. Thus, two-thirds of the present Hg fluxes (such are deposition on land and on the ocean) are directly or indirectly of anthropogenic origin. Elimination of the anthropogenic load in the ocean and atmosphere would take fifteen to twenty years after termination of all anthropogenic emissions.
AN: 3734912

                                                                    341 of 1521  
TI: Reactive trace metals in the stratified Central North Pacific
AU: Bruland,-K.W.; Orians,-K.J.; Cowen,-J.P.
AF: Inst. Mar. Sci., Univ. California Santa Cruz, Santa Cruz, CA 95064, USA
SO: GEOCHIM.-COSMOCHIM.-ACTA 1994 vol. 58, no. 15, pp. 3171-3182
NT: The Clair C. Patterson Special Issue.
LA: English
ER: M (Marine)
AB: Vertical concentration profiles of the dissolved and suspended particulate phases were determined for a suite of reactive trace metals, Al, Fe, Mn, Zn, and Cd, during summertime at a station in the center of the North Pacific gyre. Reactive trace metals exhibit a range of biogeochemical behaviors that can be characterized by two endmembers, nutrient-type and scavenged-type. Nutrient-type metals, best exemplified by Zn and Cd, are primarily removed from surface waters by biogenic particles and then remineralized at depth. Internal biogeochemical cycles together with physical mixing and circulation patterns control the distributions of nutrient-type metals. Scavenged-type metals, best exemplified by Al, continue to be removed onto particles in intermediate and deep waters as well as at the surface. External inputs, such as the deposition of aeolian dust, control the concentrations and distributions of scavenged-type metals. Other metals, such as Fe, exhibit a mixture of the characteristic behaviors of these two endmembers.
AN: 3734849

                                                                    342 of 1521  
TI: Impact of UV-B radiation on pelagic freshwater ecosystems: Report of working group on bacteria and phytoplankton
AU: Karentz,-D.; Bothwell,-M.L.; Coffin,-R.B.; Hanson,-A.; Herndl,-G.J.; Kilham,-S.S.; Lesser,-M.P.; Lindell,-M.; Moeller,-R.E.; et-al.
AF: Dep. Biol., Univ. San Francisco, San Francisco, CA 94117-1080, USA
SO: IMPACT-OF-UV-B-RADIATION-ON-PELAGIC-FRESHWATER-ECOSYSTEMS STUTTGART-FRG SCHWEIZERBART'-SCHE-VERLAGSBUCHHANDL. 1994 no. 43 no. 43, pp. 31-69
ST: ERGEB.-LIMNOL.-ADV.-LIMNOL. no. 43
NT: Bibliogr.: 5 ref. pages
LA: English
ER: F (Freshwater)
AB: Ultraviolet B (UV-B) radiation has always been an important environmental factor. Recent global trends in stratospheric ozone depletion could increase the amount of UV-B within aquatic environments and this has generated a growing interest in how UV-B can affect aquatic ecosystems. While much has been learned about the UV photobiology and photochemistry of natural waters, evaluating ecosystem responses is a very complex task. This report summarizes biological and hydrological data related to UV-B exposure. Gaps in our knowledge are indicated and the potential effects of increased UV-B on pelagic freshwater ecosystems are discussed. Appendices include an extensive bibliography relating to the UV-photobiology of aquatic microorganisms and macroalgae.
AN: 3732894

                                                                    343 of 1521  
TI: Use of nutrient diffusing substrata to assess nutrient limitation in a stream impacted by agriculture and silviculture
AU: Nord,-B.; Toetz,-D.*
AF: Dep. Zool., Oklahoma State Univ., Stillwater, OK 74078, USA
SO: J.-FRESHWAT.-ECOL. 1994 vol. 9, no. 4, pp. 289-298
LA: English
ER: F (Freshwater)
AB: The nutrient status of streams impacted by agriculture and silviculture is little known, especially in Oklahoma and Arkansas, USA. In this research the authors assessed the impact of nutrients on biofilms in the Glover River, Oklahoma, which drains a watershed impacted by poultry manure, clear-cutting, and forest fertilization. They used nutrient diffusing substrata with two independent measures of biomass and N:P ratios to assess N and P limitation in this stream during 1988-1990. The substrata data revealed limitation by N. However, N:P supply ratios indicated P limitation during 1990. The nutrient regime, turbidity and discharge changed radically during the study. Caution is advised in use of nutrient diffusing substrata in streams impacted by high turbidity and high discharge.
AN: 3732514

                                                                    344 of 1521  
TI: Mercury and arsenic distribution in Lake Champlain sediments
AU: Fuller,-R.D.; McIlroy,-L.M.; Demarte,-B.L.; Lassell,-C.M.; King,-J.W.; Appleby,-P.; McIntosh,-A.W.
AF: Cent. Earth Environ. Sci., SUNY, Plattsburgh, NY 12901, USA
CO: 36. Conf. of the Int. Association for Great Lakes Research, De Pere, WI (USA), 4-10 Jun 1993
SO: OME-36TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH,-JUNE-4-10,-1993.-PROGRAM-AND-ABSTRACTS. 1993 p. 136
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Distributions of mercury and arsenic in sediments of Lake Champlain were studied as part of an overall research effort sponsored by the Lake Champlain Management Conference examining fate and effects of pollutants in Lake Champlain. Mercury concentrations are of concern due to elevated levels in fish tissue. Arsenic distribution is noteworthy because its deposition via the atmosphere is among the highest in the northeastern U.S. An initial screening survey of the top two cm of sediments was performed at 30 sites throughout the lake. Based on the distribution of toxic pollutants in this survey, nine sites were selected for extraction of sediment cores to ascertain pollution history. Surface sediment concentrations ranged from 0.05 to 0.89 mg/kg for mercury and 3.6 to 39.7 mg/kg for arsenic. Sediment mercury values are representative of average ranges found in the Great Lakes, whereas arsenic concentrations are higher. Concentrations of mercury were highest in the embayments of Burlington, Vt. and Plattsburgh N.Y. Arsenic concentrations were highest in Mallett's Bay, Vt. Core profile mercury concentrations increased with depth near the sediment-water interface and then decreased to relatively low background concentrations. In contrast to mercury profiles, arsenic concentrations were generally highest at the interface and decreased with depth.
AN: 3731246

                                                                    345 of 1521  
TI: Virtual elimination of toxic and persistent chemicals from Lake Superior, a mass balance study
AU: Mackay,-D.; Sang,-S.; Diamond,-M.L.; Vlahos,-P.; Dolan,-D.; Voldner,-E.
AF: Inst. Environ. Stud., Univ. Toronto, Toronto, ON M5S 1A4, Canada
CO: 36. Conf. of the Int. Association for Great Lakes Research, De Pere, WI (USA), 4-10 Jun 1993
SO: OME-36TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH,-JUNE-4-10,-1993.-PROGRAM-AND-ABSTRACTS. 1993 p. 133
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: In recent years several mass balancing projects have been undertaken to establish the linkage between the loadings of specific chemicals and concentration of these chemicals in the water, sediment, and biota of the Great Lakes. A simple "rate constant" model have been developed by Mackay et al (1993) which is the basis of the present paper. The rate constant model has been modified for Lake the Superior and is applied to PCBs and lead. The structure of the model is described and its results are discussed. The model can be used to establish a range of reasonable virtual elimination scenarios for the two chemicals. It is concluded that any efforts to virtually eliminate chemicals from the Great Lakes must be based on understanding the sources and fate of the chemicals in question. The use of mass balance model helps to quantify these sources and eliminate the insignificant processes and sources. An ongoing effort is needed to expand the model to include primary sources, atmospheric transport from primary sources and Watershed retention.
AN: 3731242

                                                                    346 of 1521  
TI: A mass balance analysis of mercury in lakes Ontario and Superior
AU: Diamond,-M.L.; Mackay,-D.; Sang,-S.
AF: Dep. Geogr., 100 St. George St., Univ. Toronto, Toronto, ON M5S 1A1, Canada
CO: 36. Conf. of the Int. Association for Great Lakes Research, De Pere, WI (USA), 4-10 Jun 1993
SO: OME-36TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH,-JUNE-4-10,-1993.-PROGRAM-AND-ABSTRACTS. 1993 p. 133
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: A multi-species balance model based on the fugacity/aquivalence approach has been developed and applied to mercury in Lakes Ontario and Superior. The model links land-based and atmospheric loadings of elemental, inorganic and methyl mercury to concentrations and movement in water, surface sediment and air. Given the steady-state proportions of each species in each phase, the model provides estimates of net species interconversion in water and sediment. Most mercury entering and within the lakes is inorganic with roughly equal amounts being buried in and exported from Lake Ontario, and most being buried in Lake Superior. About 10% of total inputs is reduced to elemental mercury in the water column which then volatilizes. The estimated persistence of total mercury in the water and sediments of 5 and 20 years for Lakes Ontario and Superior is relatively short considering water renewal times of 6.5 and 191 years, respectively. To reduce mercury concentrations in Lake Ontario land-based sources must be controlled whereas atmospheric sources must be reduced for Lake Superior. Unlike other inorganics but similarly to persistent volatile organics, the response of the lakes to loading reductions will be prolonged as mercury cycles and recycles between the atmospheric pool and lakes and terrestrial systems.
AN: 3731241

                                                                    347 of 1521  
TI: MICHTOX, a mass balance and bioaccumulation model for toxic chemicals in Lake Michigan
AU: Endicott,-D.D.; Richardson,-W.L.; Kandt,-D.J.
AF: USEPA, Large Lakes Res. Stn., Grosse Ile, MI, USA
CO: 36. Conf. of the Int. Association for Great Lakes Research, De Pere, WI (USA), 4-10 Jun 1993
SO: OME-36TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH,-JUNE-4-10,-1993.-PROGRAM-AND-ABSTRACTS. 1993 p. 143
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: A mass balance and bioaccumulation model for priority toxic chemicals was developed for Lake Michigan. The objectives of modeling were (1) to demonstrate the utility of the mass balance approach for the Lake Michigan Lakewide Management Plan (LaMP), and (2) present mass balance study design alternatives to provide various levels of accuracy and resolution. The model was validated using data for plutonium, lead and polychlorinated biphenyls (PCBs) - toxics for which loadings could be reliably estimated. The utility of the model was demonstrated by predicting the effectiveness of several alternative PCB load reduction scenarios. Uncertainty analysis (Bayesian Monte Carlo) was used to estimate the reliability of predictions, both before and after model calibration to field data. The effects of system lag time and independent atmospheric concentration upon the relationship between chemical loads and concentrations are illustrated.
AN: 3731219

                                                                    348 of 1521  
TI: Gas cycling at the sediment-water interface of Lake Taupo, New Zealand
AU: Adams,-D.D.
AF: Cent. Earth Environ. Sci., State Univ. New York, Plattsburgh, NY 12901, USA
CO: 36. Conf. of the Int. Association for Great Lakes Research, De Pere, WI (USA), 4-10 Jun 1993
SO: OME-36TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH,-JUNE-4-10,-1993.-PROGRAM-AND-ABSTRACTS. 1993 p. 91
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Dissolved gases (O sub(2), CH sub(4), N sub(2) and N sub(2)O) and other redox species (NO sub(2), NO sub(3) and SO sub(4)) were measured at 3-mm intervals near the sediment-water interface (SWI) to asses oxidation/reduction as related to the microbial cycling of C and N. The penetration of oxygen into the surface sediments averaged 5-6 mm, with a calculated flux to the SWI of 3 to 5 mM m super(-2) d super(-1) depending on the site and variability between cores. The calculated upward diffusive flux of CH sub(4) (1-2 mM m super(-2) d super(-1)) to the interface accounted for 60-70% of the oxygen consumption. Concentration profiles in the sediments of N sub(2)O (range of 0.03-0.14 uM) and N sub(2) (0.8-2.7 mM) suggest active zones of nitrification and denitrification. N sub(2) gas was always highly supersaturated in these surface sediments compared to overlying waters within 0-5 cm of the SWI. During the 1990-1991 period, an additional 16 gravity cores at four sampling sites were collected to obtain further information about porewater gases and other chemical variables; microelectrode oxygen profiles were also measured in 68 cores.
AN: 3731182

                                                                    349 of 1521  
TI: Application of the QWASI fugacity/aquivalence model to assessing the fate of contaminants in the water and sediment of Hamilton Harbour
AU: Ling,-H.; Diamond,-M.; Mackay,-D.
AF: Inst. Environ. Stud., Univ. Toronto, Toronto, ON M5S 1A4, Canada
CO: 36. Conf. of the Int. Association for Great Lakes Research, De Pere, WI (USA), 4-10 Jun 1993
SO: OME-36TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH,-JUNE-4-10,-1993.-PROGRAM-AND-ABSTRACTS. 1993 p. 70
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Three simple steady-state mass balance models based on the QWASI (Quantitative Water Air Sediment Interaction) fugacity/aquivalence model have been developed for Hamilton Harbour. These models correspond to three types of compartmentalization, i.e. (1) epilimnion, hypolimnion, and surficial sediment during summer months, (2) a single water column and surficial sediment during other seasons, and (3) a single water column and two surficial sediment compartments to account for sediment focusing. Processes treated are chemical emissions, advective inflows, atmospheric deposition, diffusion between air and water, and between sediment and water, sediment deposition, resuspension, and burial, transformation reactions in water and sediment, mass exchange between epilimnion and hypolimnion, and advective outflows. The models describe the fate of four chemicals, PCBs, B(a)P, Pb, and Zn. A complete picture of the behavior of these chemicals in the Harbour is deduced and the time responses of the system inferred. The results illustrate the relative importance of the various partitioning, transport, transformation processes, and of the various sources of contaminants including sediment-water transfer. It is suggested that most of the chemicals do not persist in the Harbour water and surface sediment longer than 3 years, that the major contamination sources are industrial emissions, or STPs, and that the sediment is of secondary importance as a source. The application of mass balance models for remedial action planning is discussed.
AN: 3731151

                                                                    350 of 1521  
TI: Closing off the southern ocean surface
AU: Heinze,-C.; Broecker,-W.S.
AF: Max-Planck-Inst. Meteorol., Hamburg, Germany
SO: PALEOCEANOGRAPHY 1995 vol. 10, no. 1, pp. 49-58
LA: English
ER: M (Marine)
AB: Equilibrium integrations with the three-dimensional Hamburg ocean carbon cycle circulation model show the effect of a Southern Ocean surface outcrop that is closed off for gas exchange with the atmosphere and export production of particulate organic carbon and CaCO sub(3) south of 32.5  degree S. For such a close-off, the northern Atlantic outcrop assumes a greater degree of control of atmospheric CO sub(2) partial pressure. Contrary to expectations, the atmospheric pCO sub(2) increases compared to a control run without close-off. Maximizing the nutrient utilization in the North Atlantic can compensate for this increase. However, it does not draw down the pCO sub(2) to glacial levels.
AN: 3731035

                                                                    351 of 1521  
TI: Sensitivity of the phosphate-cadmium-carbon isotope relation in the ocean to cadmium removal by suboxic sediments
AU: Van-Geen,-A.; McCorkle,-D.C.; Klinkhammer,-G.P.
AF: Lamont-Doherty Earth Obs. Columbia Univ., Palisades, NY, USA
SO: PALEOCEANOGRAPHY 1995 vol. 10, no. 2, pp. 159-170
LA: English
ER: M (Marine)
AB: Reconstructions of past deep ocean nutrient concentrations rely largely on the carbon isotopic composition and cadmium content of shells of benthic foraminifera. When comparing records of these two paleonutrient tracers, a relation similar to the phosphate-cadmium-carbon isotope relation in the water column today is generally assumed. We present new water column, sediment, and pore water data from the California continental margin which demonstrate that Cd accumulation is enhanced in suboxic sediments. These results suggest that the oceanic Cd inventory is sensitive to changes in the areal extent and redox intensity of suboxic sediments and thus that the phosphate-cadmium relation in the ocean could have been different in the past. The magnitude of this effect and its evolution through time is presently hard to quantify because the oceanic Cd budget is poorly constrained.
AN: 3731019

                                                                    352 of 1521  
TI: Sulphate reduction in the hypolimnion and sediments of Lake Kinneret, Israel
AU: Hadas,-O.; Pinkas,-R.
AF: Israel Oceanogr. and Limnol. Res., Yigal Allon Kinneret Limnol. Lab., P.O. Box 345, Tiberias 14102, Israel
SO: FRESHWAT.-BIOL. 1995 vol. 33, no. 1, pp. 63-72
LA: English
ER: F (Freshwater)
AB: Lake Kinneret is a warm monomictic lake. Between January and June a heavy annual bloom of the dinoflagellate Peridinium gatunense dominates phytoplankton biomass. At the beginning of the summer, degradation and decomposition of the Peridinium biomass occurs, serving as a trigger for intense sulphate reduction in the hypolimnion and sediments. The rates of sulphate reduction in the sediments varied seasonally from 12 to 1700 nmol SO sub(4) super(-2) reduced cm super(-3)/day in December and July, respectively. The availability of organic matter and sulphate is high in June after the crash of the Peridinium bloom and the beginning of stratification and is lowest in December before overturn. The lake is not depleted of sulphate at any time, so the sulphate reduction process in Lake Kinneret is not limited by sulphate concentrations except in the sediments just before overturn.
AN: 3729603

                                                                    353 of 1521  
TI: Biolimitation of iodine distribution in Antarctic Ocean
AU: Cheng,-Xianhao; Pan,-Jianming; Zhang,-Haisheng; Zhang,-Ping
AF: 2nd Inst. Oceanogr., SOA, Hangzhou 310012, People's Rep. China
SO: OCEANOL.-LIMNOL.-SIN.-HAIYANG-YU-HUZHAO 1994 vol. 25, no. 1, pp. 38-47
LA: Chinese
ER: M (Marine)
AB: Based on the analysis of samples collected during Sixth Chinese Antarctic Exploration, this paper discusses the geochemical distribution of iodine species and chemical forms. Special interest is directed to the relations among the iodine species, and parameters related organism activity. The concentrations of total inorganic iodine are from 0.267 to 0.443  mu mol/dm super(3) (mostly iodate) in the surface seawater. There are closely relations between nutrients and the concentrations of iodine and iodate. The results shows dissolved organic iodine concentration distributes stably horizontally and vertically is about 10% of the total inorganic iodine. The absorption and assimilation rate of phytoplankton for iodine is about 0.17  mu mol/(m super(2)/d); the associated iodine as suspended organic particulates is about 4.3  mu mol/m super(3), in which the iodine instanding crop averages 16%. The deposit rate of the particulate iodine is more than 7.2 d/m, within the euphotic zone. A biogeochemical cycle model is proposed.
AN: 3729425

                                                                    354 of 1521  
TI: Mineralogical and geochemical compositions of modern bivalve shells from the Mediterranean coast of Egypt
AU: Holail,-H.; Tony,-R.
AF: Univ. Qatar, Fac. Sci., Geol. Dep., P.O. 2713, Doha-Qatar
SO: GEOJOURNAL 1995 vol. 35, no. 4, pp. 481-486
LA: English
ER: M (Marine)
AB: The stable isotopic composition ( delta  super(13)C and  delta  super(18)O) and elemental (Sr and Mg) of marine molluscs are presented for Carditacea and Solenacea shells collected off the Mediterranean coast of Egypt. Based on shell microstructures and mineralogy, the bivalve shells are preserved in their original mineralogy and chemistry. The Sr and Mg concentrations of the bivalve shells have mean values of 1960 ppm and 226 ppm respectively. The stable isotopic composition generally show high values of  delta  super(18)O and  delta  super(13)C. The  delta  super(18)O values range from +0.1 to -1.8ppt PDB and most shells are highly enriched in  super(13)C; averaging +2.5ppt PDB. These elemental and isotopic signatures are analogous to modern marine bivalves from other localities. The oxygen and carbon isotopes, together with the calculated temperatures, suggest that the aragonitic bivalve shells were precipitated in isotopic equilibrium from warm marine waters.
AN: 3729389

                                                                    355 of 1521  
TI: Effects of marine sediment resuspension on organic matter processing in coastal environments: A simulation model
AU: Wainright,-S.C.; Hopkinson,-C.S.,Jr.
AF: Inst. Mar. and Coast. Sci., Rutgers Univ., New Brunswick, NJ 08903-0231, USA
CO: 23. Benthic Ecology Meeting, New Brunswick, NJ (USA), 17-19 Mar 1995
SO: TWENTY-THIRD-BENTHIC-ECOLOGY-MEETING. Grassle,-J.P.;Kelsey,-A.;Oates,-E.;Snelgrove,-P.V.-eds. Rutgers-the-State-Univ.,-New-Brunswick,-NJ-USA.-Inst.-Marine-Coastal-Sciences 1995 vp
NT: Abstract only.
LA: English
ER: M (Marine)
AB: A model, constructed using STELLA super(TM), was used to simulate changes in standing stocks and flows of organic matter resulting from sediment resuspension in shallow coastal environments. Previous studies suggested that resuspension may determine the sites and rates of organic matter mineralization in shallow environments. Those studies predicted that resuspended organic material could exert an enhanced demand on dissolved oxygen and could contribute towards shifting the system metabolic balance towards heterotrophy. Our model results confirm these hypotheses. Total system metabolism (benthic + pelagic) received an increasing contribution from the water column as settling rate decreased, and as the frequency and intensity of resuspension events increased. Furthermore, total system metabolism increased in response to resuspension.
AN: 3729343

                                                                    356 of 1521  
TI: The use of natural strontium isotopes as tracers in environmental studies
AU: Aaberg,-G.
AF: Inst. Energy Technol., Box 40, N-2007 Kjeller, Norway
CO: BIOGEOMON, The Symposium on Ecosystem Behaviour: Evaluation of Integrated Monitoring in Small Catchments, Prague (Czech Rep.), 18-20 Sep 1993
SO: WATER,-AIR,-SOIL-POLLUT. 1995 vol. 79, no. 1-4, pp. 309-322
LA: English
ER: F (Freshwater)
AB: Naturally occurring isotopes of elements like strontium have proved to be good tools for tracing the past and for monitoring of processes in the present. The spread and variation in  super(87)Sr/ super(86)Sr ratios make Sr isotopes a powerful tool when it comes to detecting trends in the soil-vegetation system. There is also a great potential in combining different parameters like soil, water, biological material and isotopes for detecting environmental changes over short as well as long time periods. Sampling of the past is a difficult task but biological material, in combination with inorganic material, proves advantageous as environmental archives. There is also the possibility of using museum collections as environmental historic archives. This paper discusses the potential of using the natural  super(87)Sr/ super(86)Sr ratio as a tracer for environmental studies. The results presented point to an ongoing impoverishment of the environment and show that the temporal trend in Sr isotope composition for different media is similar despite material and location of test area.
AN: 3729340

                                                                    357 of 1521  
TI: Biogeochemistry of dissolved hydrogen sulfide species and carbonyl sulfide in the western North Atlantic Ocean
AU: Radford-Kncery,-J.; Cutter,-G.A.
AF: IFREMER, Dep. DRO/GM, B.P. 70, F-29280 Plouzane, France
SO: GEOCHIM.-COSMOCHIM.-ACTA 1994 vol. 58, no. 24, pp. 5421-5431
LA: English
ER: M (Marine)
AB: The biogeochemistry of total sulfide dissolved in the open ocean is a poorly understood component of the global sulfur cycle. Here, the cycling of total sulfide was examined in the western North Atlantic Ocean using specially developed sampling and analytical methods. Sources of total sulfide were examined. In particular, the rate of carbonyl sulfide (OCS) hydrolysis was redetermined under oceanographic conditions, and the depth distribution of OCS was examined. The patterns of near-surface enrichment (up to 150 pmol/L) and depletion at depth observed in OCS depth profiles suggest in situ production of OCS. To quantify the sources and sinks of total sulfide in the mixed layer of the Sargasso Sea, a budget was constructed. The significant difference between the known sources and sinks indicates that other processes are important for the cycling of sulfide.
AN: 3729223

                                                                    358 of 1521  
TI: Effect of UV-B radiation on the fatty acid composition of the marine phytoplankter Tetraselmis sp.: Relationship to cellular pigments
AU: Goes,-J.I.; Handa,-N.; Taguchi,-S.; Hama,-T.
AF: Inst. Hydros.-Atmos. Sci., Nagoya Univ., Chikusa-ku 464, Japan
SO: MAR.-ECOL.-PROG.-SER. 1994 vol. 114, no. 3, pp. 259-274
NT: Bibliogr.: 71 ref.
LA: English
ER: M (Marine)
AB: The effect of UV-B (280 to 320 nm) radiation on the fatty acid and pigment composition of Tetraselmis was examined as part of a larger effort to understand the possible consequences of an enhancement in natural levels of UV-B radiation on photosynthetic processes in marine phytoplankton. At levels that still permitted the assimilation of carbon within the cell, UV-B radiation induced a rapid increase in intracellular carotenoids and a marked decline in chlorophyll a. Absolute concentrations of fatty acids within the cells were lower in presence of UV-B, attributable largely to suppression of polyunsaturated fatty acid (PUFA) synthesis. The suppression of PUFAs by UV-B radiation and the inability of the cells to produce these compounds in the dark suggests that over a diel cycle, if natural phytoplankton are exposed to UV-B radiation during the day, the cells may be incapable of restoring the cellular balance of fatty acids during the night. Amongst the PUFAs, the production of 16:4 was highly susceptible to UV-B radiation. In contrast, the production of the saturated fatty acid 16:0 continued unabated in the presence of UV-B radiation. The carbon weight ratio of 16:0 to 16:4 related well with the dose of UV-B radiation and appears to be a promising indicator of UV-B induced stress in green algae. A hypothesis explaining the selective suppression of cellular PUFA synthesis, in particular that of 16:4 by UV-B, is presented and discussed in relation to concurrent changes in intracellular pigments. The implications of enhanced UV-B radiation on the marine food chain and on biogeochemical cycling in the sea are discussed in the light of these findings.
AN: 3729084

                                                                    359 of 1521  
TI: Microbial-mineral floc associated with nascent hydrothermal activity on CoAxial segment, Juan de Fuca Ridge
AU: Juniper,-S.K.; Martineu,-P.; Sarrazin,-J.; Gelinas,-Y.
AF: GEOTOP, Univ. Quebec, Montreal, PQ, Canada
SO: GEOPHYS.-RES.-LETT. 1995 vol. 22, no. 2, pp. 179-182
LA: English
ER: M (Marine)
AN: 3726987

                                                                    360 of 1521  
TI: Elemental and major biochemical changes across an oxidation front in a relict turbidite: An oxygen effect
AU: Cowie,-G.L.; Hedges,-J.I.; Prahl,-F.G.; De-Lange,-G.J.
AF: Dep. Oceanogr., Univ. British Columbia, Vancouver, BC V6T 1Z4, Canada
SO: GEOCHIM.-COSMOCHIM.-ACTA 1995 vol. 59, no. 1, pp. 33-46
LA: English
ER: M (Marine)
AB: The elemental and major biochemical compositions of the relict f-turbidite sampled in two cores from the Madeira Abyssal Plain were determined. This fine-grained, distal sequence occurs at ca. 9 m core depth and includes a surficial oxidized horizon defined by a distinct color change. Oxygen diffused downward through sediments above this interface and in ca. 10 kyr destroyed 80% of the organic substances that below the front had survived degradation in the presence of porewater sulfate for ca. 140 kyr. These deposits provide an opportunity to establish the extent and selectivity of oxic sedimentary degradation under natural conditions without the usual complications of bioturbation and varying sources or sedimentation rates. This study demonstrates that prolonged exposure to O sub(2) can lead to organic matter alteration which is far more extensive than that obtained with sulfate alone. In comparison to early diagenesis, however, alteration of the measured biochemicals was largely nonselective. Such oxidation reactions could control the distribution and composition of organic matter in slowly accumulating continental rise and deep-ocean environments.
AN: 3726481

                                                                    361 of 1521  
TI: Rapid bacterial degradation of polysaccharides in anoxic marine systems
AU: Arnosti,-C.; Repeta,-D.J.; Blough,-N.V.
AF: Max-Planck Inst. Mar. Mikrobiol., Fahrenheitstr. 1, D-28359 Bremen, FRG
SO: GEOCHIM.-COSMOCHIM.-ACTA 1994 vol. 58, no. 12, pp. 2639-2652
LA: English
ER: M (Marine)
AB: Extracellular hydrolysis of organic macromolecules is often assumed to be the slow step in remineralization of organic matter. We tested this assumption by comparing the degradation of four polysaccharides (pullulan, laminarin, and two polysaccharides isolated from the marine cyanobacterium Synechococcus WH7335) to determine whether size, linkage position, or anomeric linkage affected rates or mechanisms of carbohydrate degradation by mixed cultures of anaerobic bacteria enriched from marine sediments. NMR spectra showed that preferential hydrolysis occurred at specific chemical linkages, and extracellular enzymatic hydrolysis of polysaccharides occurred far more rapidly than bacterial uptake and remineralization of the lower molecular weight oligosaccharides produced through enzymatic hydrolysis. Substrate size was not a significant determinant of remineralization rate: high molecular weight does not always correlate with slow degradation rate.
AN: 3726453

                                                                    362 of 1521  
TI: Predator-prey interactions between Isochrysis galbana and Oxyrrhis marina. 3. Mathematical modelling of predation and nutrient regeneration
AU: Davidson,-K.; Cunningham,-A.; Flynn,-K.J.*
AF: Algal Res. Unit, Sch. Biol. Sci., Univ. Wales, Swansea, Singleton Park, Swansea SA2 8PP, UK
SO: J.-PLANKTON-RES. 1995 vol. 17, no. 3, pp. 465-492
LA: English
ER: M (Marine)
AB: A mathematical model was derived to simulate ingestion, growth and nitrogen (N) regeneration for the phagotrophic dinoflagellate Oxyrrhis marina. Two types of experimental study were undertaken: prey-deplete O. marina were supplied with Isochrysis galbana in continuous darkness (thus preventing growth of the prey), and the predator-prey interactions were also followed in cultures maintained in a light-dark cycle (allowing growth of the prey). During light-dark cycles, Oxyrrhis volume increased more in the light phase than in the dark. Digestion of Isochrysis lasted  similar to 0.3 days, with an average maximum ingestion rate of 55 prey/predator/day. During active predation, 30% of Oxyrrhis-carbon (C) was lost from the particulate phase: per day, with this loss falling to 10%: per day at the cessation of herbivory when cannibalism became noticeable. Ingestion was modelled as a function of prey density, C-loss and division as functions of cellular predator C, with cannibalism by Oxyrrhis also included. Two N-regeneration expressions were investigated: one proposed by D.A. Caron and J.C. Goldman (Journal of Protozoology, 5, 247-249, 1988) and an alternative function which related N regeneration to intracellular carbon and N based on the concept of an optimal Oxyrrhis C:N ratio. The latter was more successful in simulating batch culture data and did not require a prior calculation of Oxyrrhis gross growth efficiency. The model of Oxyrrhis numbers, C and N contained only nine parameters whose values were fully obtainable from batch culture experiments. By using this model, we were able to use a single parameter set to simulate the transient dynamics of Oxyrrhis ingesting N-replete and N-stressed prey. Further experiments in which Oxyrrhis grew on Isochrysis in light-dark cycles were simulated by combining the Oxyrrhis model with the nutrient-processing model for Isochrysis of K. Davidson et al. (Journal of Plankton Research, 15, 351-359, 1993). The dynamics of the full predator-prey model were found to be sensitive to the level of sophistication of the prey model; the Quota model was found to be less successful than the nutrient-processing prey model. Theoretical model runs indicated the importance of being able to simulate changes in both prey numbers and biomass, and also in including realistic equations for nutrient regeneration from predators in microbial predator-prey models.
AN: 3725499

                                                                    363 of 1521  
TI: The potential of denitrification for intercepting groundwater nitrate in a salt marsh ecosystem
AU: Hee,-C.; Howes,-B.L.; Weiskel,-P.K.
AF: Univ. Scranton, Scranton, PA 18510, USA
CO: 23. Benthic Ecology Meeting, New Brunswick, NJ (USA), 17-19 Mar 1995
SO: TWENTY-THIRD-BENTHIC-ECOLOGY-MEETING. Grassle,-J.P.;Kelsey,-A.;Oates,-E.;Snelgrove,-P.V.-eds. Rutgers-the-State-Univ.,-New-Brunswick,-NJ-USA.-Inst.-Marine-Coastal-Sciences 1995 vp
NT: Abstract only.
LA: English
ER: M (Marine)
AB: The rates and controls of microbial denitrification were studied at Namskaket Marsh, Orleans MA in order to determine the capacity of the marsh to remove nitrate carried by inflowing groundwater. The marsh is located at the discharge of a groundwater nitrate plume generated by a septage treatment plant established in February 1990. Denitrification rates were measured as the disappearance of nitrate over time from water overlying creek bottom sediments in the summer of 1994 (19 C). Rates of denitrification ranged from 277 to 604 umoles/m super(2)/hr. Nitrate and carbon addition experiments were conducted in the creek bottoms and with sediments from below the rooting zone of the vegetated marsh slurried with acetylene. The rate of denitrification was stimulated by both nitrate and carbon additions. Both nitrate and carbon are limiting at current conditions in the creek bottoms and at the seepage front.
AN: 3724277

                                                                    364 of 1521  
TI: Bacterial activity in NW Mediterranean seagrass (Posidonia oceanica) sediments
AU: Lopez,-N.I.; Duarte,-C.M.*; Vallespinos,-F.; Romero,-J.; Alcoverro,-T.
AF: Cent. Estuad. Ave. Blanes, CSIC, Cami St. Barbara s/n, 17300 Blanes, Girona, Spain
SO: J.-EXP.-MAR.-BIOL.-ECOL. 1995 vol. 187, no. 1, pp. 39-49
LA: English
ER: M (Marine)
AB: We examine here the hypothesis that benthic bacterial activity in seagrass [Posidonia oceanica (L.) Delile] meadows is dependent on seagrass growth and availability of inorganic nutrients in the sediments. This was achieved by measuring bacterial activity (ammonification rates, and exoproteolytic and exoglucosidase activities) during an annual cycle in five P. oceanica and meadows in the NW Mediterranean. Benthic bacterial activity was high, and tended to increases with increasing seagrass production. This trend is likely to involve a direct effect derived from the greater supply of organic carbon in productive meadows, and an indirect effect derived from the fact that productive meadows develop over nutrient-rich sediment and yield nutrient-rich detritus. Phosphorus availability to bacteria was low, for plant detritus was deficient in phosphorus relative to bacterial requirements, and bacterial activity was reduced after seagrasses depleted inorganic phosphorus from the sediments at the onset of exponential plant growth. These results indicate that, on local and annual time scales, benthic bacterial activity is directly related to seagrass production in the NW Mediterranean, because of enhanced inputs of organic matter by the seagrasses, while on seasonal scales, bacteria and seagrass metabolism are inversely related, apparently because of competition for inorganic nutrients.
AN: 3724262

                                                                    365 of 1521  
TI: Impact of the soft-shell clam, Mya arenaria burrows on sulfate reduction in an intertidal sediment
AU: Hansen,-K.; King,-G.M.
AF: Inst. Biol., Odense Univ., DK-5230 Odense M, Denmark
CO: 23. Benthic Ecology Meeting, New Brunswick, NJ (USA), 17-19 Mar 1995
SO: TWENTY-THIRD-BENTHIC-ECOLOGY-MEETING. Grassle,-J.P.;Kelsey,-A.;Oates,-E.;Snelgrove,-P.V.-eds. Rutgers-the-State-Univ.,-New-Brunswick,-NJ-USA.-Inst.-Marine-Coastal-Sciences 1995 vp
NT: Abstract only.
LA: English
ER: M (Marine)
AB: The effect of the soft-shell clam Mya arenaria on sulfate reduction and various parameters related to the sulfur cycle was examined in an intertidal sediment (Lowes Cove, Maine). Measurements were made at mm intervals around burrows and extending 25 mm into the ambient sediment. Sulfate reduction rates were 1.5-2 times higher in the inner 1-5 mm region surrounding the burrow, whereas pools of reduced S increased with the distance from the burrow wall, being 1.5 times higher in bulk sediment. Enumeration of sulfate reducing bacteria and thiosulfate-disproportionating bacteria were made using the most-probable-number technique. In both cases highest numbers were found in the innermost zone around burrows relative to bulk sediment. The results suggest that Mya burrows are sites of enhanced microbial activity and a dynamics sulfur cycle with turnover times of reduced sulfur compounds increasing with distance from the burrow wall.
AN: 3724261

                                                                    366 of 1521  
TI: Microbial sulfate reduction in deep-sea sediments at the Guaymas Basin hydrothermal vent area: Influence of temperature and substrates
AU: Elsgaard,-L.; Isaksen,-M.F.; Joergensen,-B.B.; Alayse,-A.-M.; Jannasch,-H.W.
AF: Danish Inst. Plant and Soil Sci., Dep. Soil Sci., Res. Cent. Foulum, P.O. Box 23, DK-8830 Tjele, Denmark
SO: GEOCHIM.-COSMOCHIM.-ACTA 1994 vol. 58, no. 16, pp. 3335-3343
LA: English
ER: M (Marine)
AB: Microbial sulfate reduction was studied by a  super(35)S tracer technique in sediments from the hydrothermal vent site in Guaymas Basin, Gulf of California, Mexico. In situ temperatures ranged from 2.7 degree C in the overlying seawater to > 120 degree C at 30 cm depth in the hydrothermal sediment. The high subsurface rates of sulfate reduction in the hydrothermal vent area was attributed to an enhanced local substrate availability. The overall temperature response of thermophilic sulfate reduction was similar in hydrothermal sediment sampled at different sites. Addition of short-chain fatty acids and yeast extract to the sediment slurries stimulated sulfate reduction rates at all incubation temperatures. No sulfate reduction was detected in the temperature range from 102-120 degree C. Microbial rather than thermochemical sulfate reduction could be a possible source of H sub(2)S in sulfide deposits with formation temperatures at about 100 degree C.
AN: 3722261

                                                                    367 of 1521  
TI: Regeneration rates and potential uptake rates of ammonium in Saginaw Bay water in the presence and absence of zebra mussels during the summer of 1992
AU: Gardner,-W.S.; Cavaletto,-J.F.; Johnson,-J.R.; Cotner,-J.B.,Jr.; Heathe,-R.T.
AF: NOAA Great Lakes Environ. Res. Lab., 2205 Commonwealth Blvd., Ann Arbor, MI 48105, USA
CO: 36. Conf. of the Int. Association for Great Lakes Research, De Pere, WI (USA), 4-10 Jun 1993
SO: OME-36TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH,-JUNE-4-10,-1993.-PROGRAM-AND-ABSTRACTS. 1993 p. 97
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: A series of  super(15)N-NH sub(4) isotope dilution experiments were conducted on waters, collected from southwestern Saginaw Bay at monthly intervals from June to October, 1992, to determine regeneration rates and "potential" uptake rates for ammonium and to examine direct (excretion) and indirect (food web) effects of zebra mussels (Dreissena polymorpha) on these rates. Potential uptake rates peaked in September and corresponded closely with chlorophyll concentrations. The presence of zebra mussels in the bottles (15 per 4-liter bottle) removed some phytoplankton and sometimes caused potential uptake rates to decrease. Ammonium regeneration rates, in the absence of zebra mussel, followed similar seasonal patterns but, as expected, were lower than potential uptake rates. Community ammonium regeneration rates were consistently increased by the presence of zebra mussels indicating that zebra mussel excretion is an important contributor to ammonium regeneration in regions where the bivalve is abundant.
AN: 3721807

                                                                    368 of 1521  
TI: Diatom assemblages as biotic condition indicators within EMAP-Great Lakes
AU: Kreis,-R.G.; Stoermer,-E.F.; Stevenson,-R.J.
AF: USEPA, LLRS/ERL-Duluth, 9311 Groh Rd., Grosse Ile, MI 48138, USA
CO: 36. Conf. of the Int. Association for Great Lakes Research, De Pere, WI (USA), 4-10 Jun 1993
SO: OME-36TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH,-JUNE-4-10,-1993.-PROGRAM-AND-ABSTRACTS. 1993 p. 78
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Diatoms are proposed as indicators of biotic integrity and trophic status in EMAP-GL because of their intrinsic value and the numerous methodological, ecological, and interpretive advantages they offer. Diatoms are a major component of primary producer assemblages in aquatic systems, are often the base of aquatic food webs, are important in biogeochemical cycling, exhibit great diversity, and have public recognition as aesthetic and water intake nuisances. A distinct advantage of using diatoms is the ability to establish the nominal condition using the paleolimnological approach. The paleolimnological approach has wide application, has established methodologies, eliminates the requirement of an index period, will indicate the precultural period of stability, and provide a 200+ year record from a single sampling episode. Multivariate analysis of assemblages will be used to assess deviation from the nominal condition. Metrics such as the proportions of introduced, eutrophic, benthic, cold water, and locally extinct species will also be diagnostically interpreted based on autoecological relationships with water quality parameters as they relate to biotic integrity and trophic status.
AN: 3721790

                                                                    369 of 1521  
TI: The influence of the structure and function of the marine food web on the dynamics of contaminants in Arctic Ocean ecosystems
AU: Alexander,-V.
AF: Inst. Mar. Sci., Sch. Fish. and Ocean Sci., Univ. Alaska, Fairbanks, AK 99775-7220, USA
CO: International Symposium on the Ecological Effects of Arctic Airborne Contaminants, Reykjavik (Iceland), 4-8 Oct 1993
SO: ECOLOGICAL-EFFECTS-OF-ARCTIC-AIRBORNE-CONTAMINANTS. Landers,-D.H.;Christie,-S.J.-eds. vol. 160-161 pp. 593-603
ST: SCI.-TOTAL-ENVIRON. 1995 vol. 160-161
LA: English
ER: M (Marine)
AB: This paper examines some features of arctic marine ecosystems that may render them vulnerable to airborne pollutants. These features include the seasonal and spatial focus of primary productivity, the allocation of a relatively large proportion of the newly fixed carbon to the benthos, the prevalence of large mammals as apex consumers, and relatively high lipid levels in many arctic species. Sea ice is an important factor, since pollutants falling onto the ice surface during the winter months can be concentrated in epontic particulate matter (at the ice/seawater interface), or, more likely, be released through melting of the ice and enter the planktonic system in spring, reaching the benthos via sedimentation. Two ecosystems are discussed in which these processes are likely to be important - the highly productive Chirikov Basin of the northern Bering Sea and the sea ice-associated community north of Svalbard. There is evidence that pollutants are accumulating in arctic marine ecosystems. However, our predictive ability is constrained by the inability to delineate the sites of deposition.
AN: 3721163

                                                                    370 of 1521  
TI: Leakage of industrial lead into the hydrocycle
AU: Erel,-Y.; Patterson,-C.C.
AF: Inst. Earth Sci., Hebrew Univ., Jerusalem, Israel
CO: Topics in Global Geochemistry, Pasadena, CA (USA), 3-4 Dec 1993
SO: GEOCHIM.-COSMOCHIM.-ACTA 1994 vol. 58, no. 15, pp. 3289-3296
LA: English
ER: F (Freshwater)
AB: Quantitative knowledge concerning the contamination effect by industrial Pb migrating through soils into groundwaters has been delineated in a special study carried out in a remote, high altitude mountain valley. Approximately 0.5 ton of industrial Pb has been added in past decades from the atmosphere via precipitation and dry deposition to the 3 km super(2) area of lightly forested and open meadow soil lying within the 13 km super(2) area of the rocky valley. Industrial Pb could be distinguished and its amounts quantitatively determined by use of its unique isotopic composition, which was different from natural Pb in meadow soil. Industrial Pb introduced into the canyon within snow was interacting and exchanging with the larger reservoir of industrial Pb accumulated in canyon soil. Lead in the snow-melt runoff had become attached to soil-derived colloids, and a mixture of industrial and natural particulate Pb was released from the soil to stream water and groundwater. The flux of Pb leached from the accumulated reservoir of industrial Pb in soil could be measured as it flowed through soil pathways into stream runoff waters draining the valley. Such leached industrial Pb comprised about 75% of the total Pb in stream runoff of snow-melt and 20% of the total Pb in stream runoff of groundwater.
AN: 3721114

                                                                    371 of 1521  
TI: Benthic lead fluxes in San Francisco Bay, California, USA
AU: Rivera-Duarte,-I.; Flegal,-A.R.
AF: Earth Sci. Board, Univ. California, Santa Cruz, CA 95064, USA
CO: Topics in Global Geochemistry, Pasadena, CA (USA), 3-4 Dec 1993
SO: GEOCHIM.-COSMOCHIM.-ACTA 1994 vol. 58, no. 15, pp. 3307-3313
LA: English
ER: M (Marine)
AB: Porewater concentration gradients indicate relatively large benthic fluxes of Pb from sediments in the San Francisco Bay estuary. Gradients in total dissolved (<0.45  mu m) Pb concentrations in sediment porewaters, which range from 0.07-19.2 nM, parallel gradients in ammonia and dissolved Fe in sediment cores from the bay. Corresponding Fickian diffusive fluxes range from 2.6 x 10 super(-9) moles/m super(2)/d to 3.1 x 10 super(-8) moles/m super(2)/d in anoxic surface (<2 cm) sediments along the periphery of the estuary. These indicate the net diffusive benthic flux of Pb from sediments in San Francisco Bay (3-31 moles d super(-1)) is at least an order of magnitude greater than the fluvial input of dissolved Pb to the estuary (0.2 moles d super(-1)) during low flow periods. Moreover, estimates of the total benthic Pb flux, which were based on Hammond et al. (1985) irrigation benthic flux model, are two- to six-fold greater (6-186 moles d super(-1)) than the estimates of diffusive fluxes. Therefore, the total benthic flux of Pb from the bay's sediments may be within an order of magnitude of the total anthropogenic flux of Pb to the San Francisco Bay estuary (965-8,410 moles/d).
AN: 3721088

                                                                    372 of 1521  
TI: The effects of ecosystem characteristics on contaminant distribution in northern freshwater lakes
AU: Schindler,-D.W.; Kidd,-K.A.; Muir,-D.C.G.; Lockhart,-W.L.
AF: Dep. Zool., CW312 Biol. Sci. Build., Univ. Alberta, Edmonton, AB T6G 2E9, Canada
CO: International Symposium on the Ecological Effects of Arctic Airborne Contaminants, Reykjavik (Iceland), 4-8 Oct 1993
SO: ECOLOGICAL-EFFECTS-OF-ARCTIC-AIRBORNE-CONTAMINANTS. Landers,-D.H.;Christie,-S.J.-eds. vol. 160-161 pp. 1-17
ST: SCI.-TOTAL-ENVIRON. 1995 vol. 160-161
LA: English
ER: F (Freshwater)
AB: Ecological factors can modify the effect of airborne contaminants in arctic freshwater lakes. The detention time of contaminants in lake catchments can greatly affect concentrations and time-courses of contaminant distribution. Lake sediments typically contain concentrations of contaminants several orders of magnitude higher than those in overlying waters, and appear to contain good temporal records of contaminant deposition. They also indicate general increases in contaminant inputs from north to south and from west to east in North America. The lower mean temperatures of northern lakes render them more efficient as sinks for volatile contaminants than warmer lakes in the south. Lower temperatures also cause lower growth rates in fish, resulting in higher concentrations of contaminants. Conversely, the ratio of methylation to demethylation declines in colder temperatures, favoring lower concentrations of mercury in fish. Bioaccumulation can increase contaminant concentrations by several orders of magnitude in food chains of 4-5 steps. Contaminant levels increase with trophic position and are positively correlated with age and fat content, but negatively correlated with growth rates. Stable isotopes appear to be a useful diagnostic tool for examining biomagnification in arctic food chains. Biological transformation and decomposition affect the quantities and toxicity of some pollutants. The effects of some contaminants can be affected by other human stresses, including acid precipitation, climate change, hydroelectric development, harvesting of fishes and marine mammals, and eutrophication. Management of many contaminants requires tradeoffs, such as the beneficial effects of controlling insect-borne pathogens in the tropics versus the negative effects on northern aboriginal populations relying on wild populations of organisms for food.
AN: 3719470

                                                                    373 of 1521  
TI: Litter accession and accumulation in a Melaleuca quinquenervia (Cav.) S.T. Blake wetland in south-eastern Queensland
AU: Greenway,-M.
AF: Fac. Environ. Sci., Griffith Univ., Nathan, Qld 4111, Australia
SO: AUST.-J.-MAR.-FRESHWAT.-RES. 1994 vol. 45, no. 8, pp. 1509-1519
NT: Special issue: Plants and processes in wetlands.
LA: English
ER: F (Freshwater)
AB: Litterfall and litter accumulation were investigated over two years in a Melaleuca quinquenervia wetland in south-eastern Queensland. In 1992, a seasonally wet year, litterfall was 809  plus or minus  135 g/m super(2)/yr at the floodplain site and 764  plus or minus  192 g/m super(2)/yr at the riparian site, of which Melaleuca leaf litter made up 65% and 56% respectively. Litterfall was significantly lower and more variable in 1993, a drought year, being 725  plus or minus  106 g/m super(2)/year and 675  plus or minus  216 g/m super(2)/year. There was a distinct seasonal pattern, with peak leaf litterfall occurring in spring in 1992 but extending into summer in 1993. Melaleuca leaf fall was significantly lower in 1993, possibly because drought conditions caused greater leaf longevity. Litter accumulation on the forest floor was 3457 g/m super(2) at the floodplain site and 2320 g/m super(2) at the riparian site; there was no significant difference between years, although the organic matter content of the litter was lower in 1992, possibly as a result of leaching during flooding. Carbon content decreased with decreasing particle size of the litter, whereas nitrogen and phosphorus increased. There was no evidence to suggest leaching of nitrogen or phosphorus, and the high C:N:P ratios indicate slow rates of litter decay. The high accumulation of litter mass suggests that these woody wetlands may function as nutrient sinks.
AN: 3719403

                                                                    374 of 1521  
TI: Methane flux from beds of Baumea arthrophylla (Nees) Boeckeler and Triglochin procerum R. Br. at Bool Lagoon, South Australia
AU: Muller,-K.L.; Ganf,-G.G.; Boon,-P.I.
AF: Dep. Bot., Univ. Adelaide, Adelaide, SA 5005, Australia
SO: AUST.-J.-MAR.-FRESHWAT.-RES. 1994 vol. 45, no. 8, pp. 1543-1553
NT: Special issue: Plants and processes in wetlands.
LA: English
ER: F (Freshwater)
AB: The flux of methane from freshwater wetlands is likely to be influenced by the presence of emergent macrophytes. The plants generate an organic loading, which should increase methanogenesis, yet they also aerate the sediment, creating oxic zones inimical to the obligately anaerobic methanogenic bacteria and promoting the oxidation of methane by methanotrophic bacteria. Moreover, emergent plants can act as a conduit for methane to be vented to the atmosphere. Depth profiles of oxygen in beds of B. arthrophylla and T. procerum at Bool Lagoon, South Australia, showed that water at the sediment surface was anoxic during the night but became oxygenated during the latter part of the day. Redox profiles of the sediment gave values that ranged from -50 to +250 mV, indicating a sediment that was not highly reducing. Despite these conditions, the wetlands were sources of significant methane emissions, with total water-atmosphere fluxes ranging from <0.01 to 1.05 mmol m super(-2) h super(-1). The presence of B. arthrophylla, but not that of T. procerum, affected the bubble concentration of methane in the sediments. Diel variations in ebullitive or total methane fluxes were not detected, but emissions varied according to water depth and time of year. Treatments that removed macrophytes reduced total methane fluxes to rates approximately equivalent to ebullition, indicating that the plants were acting as a major pathway for the release of methane to the atmosphere. The lack of a clear diel pattern in emissions suggests that diffusion, rather than convective flow, is the mechanism for this flux through the plants.
AN: 3719401

                                                                    375 of 1521  
TI: A preliminary mass balance model of primary productivity and dissolved oxygen in the Mississippi River plume/Inner Gulf Shelf region
AU: Bierman,-V.J.,Jr.; Hinz,-S.C.; Zhu,-Dong-Wei; Wiseman,-W.J.,Jr.; Rabalais,-N.N.; Turner,-R.E.
AF: Limno-Tech, Inc., 20780 S. Gatehouse Dr., South Bend, IN 46637, USA
SO: ESTUARIES 1994 vol. 17, no. 4, pp. 886-899
NT: Special issue dedicated to papers from NOAA's Nutrient Enhanced Coastal Ocean Productivity Study.
LA: English
ER: M (Marine)
AB: A deterministic, mass balance model for phytoplankton, nutrients, and dissolved oxygen was applied to the Mississippi River Plume/Inner Gulf Shelf (MRP/IGS) region. The model was calibrated to a comprehensive set of field data collected during July 1990 at over 200 sampling stations in the northern Gulf of Mexico. The spatial domain of the model is represented by a three-dimensional, 21-segment water-column grid extending from the Mississippi River Delta west to the Louisiana-Texas border, and from the shoreline seaward to the 30-60 m bathymetric contours. Diagnostic analyses and numerical experiments were conducted with the calibrated model to better understand the environmental processes controlling primary productivity and dissolved oxygen dynamics in the MRP/IGS region. Underwater light attenuation appears relatively more important than nutrient limitation in controlling rates of primary productivity. Chemical-biological processes appear relatively more important than advective-dispersive transport processes in controlling bottom-water dissolved oxygen dynamics. Oxidation of carbonaceous material in the water column, phytoplankton respiration, and sediment oxygen demand all appear to contribute significantly to total oxygen depletion rates in bottom waters. The estimated contribution of sediment oxygen demand to total oxygen-depletion rates in bottom waters ranges from 22% to 30%. Primary productivity appears to be an important source of dissolved oxygen to bottom waters in the region of the Atchafalaya River discharge and further west along the Louisiana Inner Shelf. Dissolved oxygen concentrations appear very sensitive to changes in underwater light attenuation due to strong coupling between dissolved oxygen and primary productivity in bottom waters. The Louisiana Inner Shelf in the area of the Atchafalaya River discharge and further west to the Texas border appears to be characterized by significantly different light attenuation-depth-primary productivity relationships than the area immediately west of the Mississippi Delta. Nutrient remineralization in the water column appears to contribute significantly to maintaining chlorophyll concentrations on the Louisiana Inner Shelf.
AN: 3719304

                                                                    376 of 1521  
TI: Environmental and substrate controls over carbon and nitrogen mineralization in northern wetlands
AU: Updegraff,-K.; Pastor,-J.; Bridgham,-S.D.; Johnston,-C.A.
AF: Nat. Resour. Res. Inst., Univ. Minnesota, Duluth, MN 55811, USA
SO: ECOL.-APPL. 1995 vol. 5, no. 1, pp. 151-163
LA: English
ER: F (Freshwater)
AB: Northern wetlands may be a potential carbon source to the atmosphere upon global warming, particularly with regard to methane. However, recent conclusions have largely been based on short-term field measurements. We incubated three wetland soils representing a range of substrate quality for 80 wk in the laboratory under both aerobic and anaerobic conditions at 15 degree  and 30 degree C. The soils were obtained from a Scirpus-Carex-dominated meadow in an abandoned beaver pond and from the surface and at 1 m depth of a spruce (Picea)-Sphagnum bog in Voyageurs National Park, Minnesota. Substrate quality was assessed by fractionation of carbon compounds and summarized using principal components analysis. Nitrogen and carbon mineralization, the partitioning of carbon between carbon dioxide and methane, pH, and Eh were measured periodically over the course of the incubation. The responses of nitrogen mineralization, carbon mineralization, and trace gas partitioning to both temperature and aeration depended strongly on the substrate quality of the soils. Sedge meadow soil had the highest nitrogen and carbon mineralization rates and methane production under anaerobic conditions, and carbon mineralization under aerobic conditions, but the surface peats had the highest nitrogen mineralization rates under aerobic conditions. Methanogenesis was highest in the sedge soil but less sensitive to temperature than in the peats. A double exponential model showed that most of the variation in nitrogen and carbon mineralization among the soils and treatments was accounted for by differences in the size and kinetics of a relatively small labile pool. The kinetics of this pool were more sensitive to changes in temperature and aeration than that of the larger recalcitrant pool. Principal components analysis separated the soils on the basis of labile and recalcitrant carbon fractions. Total C and N mineralization correlated positively with the factor representing labile elements, while methanogenesis also showed a negative correlation with the factor representing recalcitrant elements. Estimates of atmospheric feedbacks from northern wetlands upon climatic change must account for extreme local variation in substrate quality and wetland type; global projections based on extrapolations from a few field measurements do not account for this local variation and may be in error.
AN: 3719257

                                                                    377 of 1521  
TI: Phosphorus and nitrogen mass budgets for Green Bay, 1987-1988 from the Green Bay Mass Balance Study
AU: Warren,-G.; Hughes,-P.E.
AF: U.S. EPA, 77 W. Jackson Blvd., Chicago, IL 60604, USA
CO: 36. Conf. of the Int. Association for Great Lakes Research, De Pere, WI (USA), 4-10 Jun 1993
SO: OME-36TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH,-JUNE-4-10,-1993.-PROGRAM-AND-ABSTRACTS. 1993 p. 64
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: Total phosphorus and total soluble phosphorus, nitrite-nitrate and ammonia nitrogen concentration information was gathered to support the Green Bay Mass Balance Study. These concentrations, tributary flow and precipitation data are used to calculate loads of nutrients from river and atmospheric sources. This information is combined with ambient Green Bay concentrations from surface water samples taken from the R/V Roger Simons to arrive at a mass budget for nitrogen and phosphorus for the Bay. A comparison of load history for a short period prior to Green Bay sampling surveys will be used to describe the mass movement of the nutrients through the Green Bay system.
AN: 3719191

                                                                    378 of 1521  
TI: Climatically linked carbon isotope variation during the past 430,000 years in Southern Ocean sediments
AU: Singer,-A.J.; Shemesh,-A.
AF: Dep. Environ. Sci. and Energy Res., Weizmann Inst. Sci., Rehovot, Israel
SO: PALEOCEANOGRAPHY 1995 vol. 10, no. 2, pp. 171-177
LA: English
ER: M (Marine)
AB: We use the isotopic composition of carbon from organic matter enclosed within diatom frustules as a proxy for paleoproductivity and paleo-dissolved carbon dioxide concentrations in ocean surface waters. A Southern Ocean record from south of the Antarctic Polar Front and spanning 430,000 years of carbon isotopic variation in diatomaceous organic matter is presented for the first time. The most refractory diatomaceous organic matter fraction was extracted and analyzed to avoid problems associated with diagenesis. The results clearly indicate cyclic changes in organic carbon isotopic ratios, with  super(13)C depleted values associated with all of the last five glacial periods, reflecting changes in surface water properties and primary productivity. Changes in dissolved carbon dioxide concentrations are the most probable cause of these cycles, but the possible effect of seawater pH changes cannot be excluded.
AN: 3719187

                                                                    379 of 1521  
TI: A phosphorus mass balance for the Green Bay ecosystem
AU: Klump,-J.V.; Sager,-P.; Edgington,-D.N.
AF: Cent. Great Lakes Stud., Univ. Wisconsin, Milwaukee, WI, USA
CO: 36. Conf. of the Int. Association for Great Lakes Research, De Pere, WI (USA), 4-10 Jun 1993
SO: OME-36TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH,-JUNE-4-10,-1993.-PROGRAM-AND-ABSTRACTS. 1993 p. 63
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: The tributaries of Green Bay, primarily the lower Fox River, have long recognized as major sources of phosphorus in the Lake Michigan basin. The status of Green Bay as a sink or source of phosphorus for Lake Michigan proper has been less well defined. Data on external phosphorus loading to the bay are examined in relation to sediment fluxes of phosphorus in the bay to arrive at a simple model of the phosphorus budget for Green Bay. Tributary loadings are estimated at more than 660,000 kg/y, 75% of which is from the Fox River. At least 50% of the Fox River load in turn originates in the upper watershed above Lake Winnebago, significantly broadening the area of concern for phosphorus control. Sediment flux data leave a substantial portion of the phosphorus load unaccounted for in the southern half of the bay, requiring that either northern Green Bay or Lake Michigan is a significant phosphorus sink.
AN: 3719186

                                                                    380 of 1521  
TI: Mechanisms controlling primary production in Lake Michigan
AU: Brooks,-A.S.; Edgington,-D.N.
AF: Dep. Biol. Sci., Geosci. Cent. Great Lakes Stud., Univ. Wisconsin, Milwaukee, WI, USA
CO: 36. Conf. of the Int. Association for Great Lakes Research, De Pere, WI (USA), 4-10 Jun 1993
SO: OME-36TH-CONFERENCE-OF-THE-INTERNATIONAL-ASSOCIATION-FOR-GREAT-LAKES-RESEARCH,-JUNE-4-10,-1993.-PROGRAM-AND-ABSTRACTS. 1993 p. 36
NT: Summary only.
LA: English
ER: F (Freshwater)
AB: A three-year study, 1986-1988, has revealed a biogeochemical, climatically-coupled mechanism controlling spring primary production in Lake Michigan. The mass of total phosphorus in the water increases from 1.3 to 3.5  mu mole-P cm in concert with increases in chlorophyll-a and organic nitrogen and decreases in nitrate and soluble Si. During spring, solar irradiance, wind-driven mixing and the onset of thermal stratification determine the magnitude of the spring bloom. The rate of production is determined by the geochemical flux of P from the sediments to the overlying water. The sequestration of P by the primary producers displaces the geochemical equilibrium, which allows more P to be released from the sediments to the water. Primary production measurements made in Lake Michigan will be compared with those in Lake Ontario.
AN: 3719091

                                                                    381 of 1521  
TI: Microbial community structure at the U.S.-Joint Global Ocean Flux study station ALOHA: Inverse methods for estimating biochemical indicator ratios
AU: Christian,-J.R.; Karl,-D.M.
AF: Sch. Ocean and Earth Sci. and Technol., Univ. Hawaii at Manoa, Honolulu, HI 96822, USA
SO: J.-GEOPHYS.-RES.-C-OCEANS 1994 vol. 99, no. C7, pp. 14,269-14,276
LA: English
ER: M (Marine)
AB: Modeling biogeochemical fluxes in the marine plankton requires the application of factors for extrapolation of biomass indicators measured in the field (chlorophyll a, adenosine triphosphate, bacterial counts) to biomass carbon or nitrogen. These are often inferred from culture studies and are poorly constrained for natural populations. A least squares inverse method with a simple linear model constrains the values of several common indicator ratios, giving self-consistent solutions that provide useful information about the structure of the microbial community at our North Pacific Ocean study site (Station ALOHA (A Long-term Oligotrophic Habitat Assessment)). These results indicate that the fraction of the microbial biomass that is autotrophic (pigmented) is greater in the mixed layer than at the deep chlorophyll maximum layer and that heterotrophic bacteria are a significant but not necessarily predominant component of the microbial community in the euphotic zone.
AN: 3718044

                                                                    382 of 1521  
TI: Physical processes affecting availability of dissolved silicate for diatom production in the Arabian Sea
AU: Young,-D.K.; Kindle,-J.C.
AF: Oceanogr. Div. Nav. Res. Lab., Stennis Space Cent., MS, USA
SO: J.-GEOPHYS.-RES.-C-OCEANS 1994 vol. 99, no. C11, pp. 22,619-22,632
LA: English
ER: M (Marine)
AB: A passive tracer to represent dissolved silicate concentrations, with biologically realistic uptake kinetics, is successfully incorporated into a three-dimensional, eddy-resolving, ocean circulation model of the Indian Ocean. Hypotheses are tested to evaluate physical processes which potentially affect the availability of silicate for diatom production in the Arabian Sea. An alternative mechanism is offered to the idea that open ocean upwelling is primarily responsible for the high, vertical nutrient flux and consequent large-scale phytoplankton bloom in the northwestern Arabian Sea during the southwest monsoon. Model results show that dissolved silicate in surface waters available for uptake by diatoms is primarily influenced by the intensity of nearshore upwelling from southwest monsoonal wind forcing and by the offshore advective transport of surface waters. The absence of diatoms in sediments of the eastern Arabian Basin is consistent with modeled distributional patterns of dissolved silicate resulting from limited westward advection of upwelled coastal waters from the western continental margin of India and rapid uptake of available silicate by diatoms.
AN: 3717689

                                                                    383 of 1521  
TI: Particle-associated PCBs in Lake Ontario
AU: Mudroch,-A.; Kaiser,-K.L.E.; Comba,-M.E.; Neilson,-M.
AF: Lakes Res. Branch, Natl. Water Res. Inst., Burlington, ON L7R 4A6, Canada
SO: SCI.-TOTAL-ENVIRON. 1994 vol. 158, pp. 113-125
LA: English
ER: F (Freshwater)
AB: A study was carried out to evaluate the role of the nepheloid layer in the transport and cycling of PCBs in Lake Ontario in 1987-89 and 1991. Water, suspended matter, and bottom sediment samples were collected at eleven stations in Lake Ontario. The concentrations of t-PCBs in the suspended matter in the nepheloid layer ranged from 151 to 728 ng/g (dry wt) in 1987-1989, and were greater than those in most of the top 3-cm sediments (< 1-405 ng/g dry wt). The suspended matter in the nepheloid layer contained more lower chlorinated biphenyls, particularly tetra- and pentachlorobiphenyls, than the bottom sediments. The greatest concentrations (up to 4100 ng/g dry wt) existed in the suspended matter at 15 m above the lake bottom after the development of the nepheloid layer. The results of the study indicated the association of t-PCBs with allochthonous particles originating mainly during the summer months in the surface water which were sinking through the water column and accumulated in the nepheloid layer in late August and September.
AN: 3717607

                                                                    384 of 1521  
TI: Development and field validation of a microcosm to simulate the mercury cycle in a contaminated pond
AU: Saouter,-E.; Gillman,-M.; Turner,-R.; Barkay,-T.*
AF: U.S. EPA, Environ. Res. Lab., 1 Sabine Island Dr., Gulf Breeze, FL 32561, USA
SO: ENVIRON.-TOXICOL.-CHEM. 1995 vol. 14, no. 1, pp. 69-77
LA: English
ER: F (Freshwater)
AB: A microcosm consisting of water, sediment, and air compartments was used to simulate mercury geochemical cycling in a mercury-contaminated ( mu g/L) pond at Oak Ridge, Tennessee. Total and dissolved mercury and total methylmercury were analyzed in water and sediment; total gaseous mercury and head-space mercury were analyzed in the water and head space, respectively. The production of gaseous mercury was correlated to dissolved mercury (0.2- mu m filtration), and methyl-mercury was mainly produced in the sediment compartment. Addition of mercuric chloride to the system increased the production of head-space mercury by a factor of 10 but did not affect the methylation rate. Saturation of gaseous mercury in microcosm water varied from 480 to 1,500% of the solubility of elemental mercury and was controlled by unidentified factors. The microcosm maintained stable conditions for up to 3 weeks, and a mass balance indicated that it reasonably simulated the cycling of mercury in the pond. This microcosm could be used to test remedial treatments aimed at decreasing the amount of mercury that is available for accumulation by biota.
AN: 3715076

                                                                    385 of 1521  
TI: Concentration and transport of nitrate by the mat-forming sulphur bacterium Thioploca
AU: Fossing,-H.; Gallardo,-V.A.; Joergensen,-B.B.; Huettel,-M.; Nielsen,-L.P.; Schulz,-H.; Canfield,-D.E.; Forster,-S.; Glud,-R.N.; Gundersen,-J.K.; Kuever,-J.; Ramsing,-N.B.; Teske,-A.; Thamdrup,-B.; Ulloa,-O.
AF: Max Planck Inst. Mar. Microbiol., Fahrenheitstr. 1, D-28359 Bremen, FRG
SO: NATURE 1995 vol. 374, no. 6524, pp. 713-715
LA: English
ER: M (Marine)
AB: Marine species of Thioploca occur over 3,000 km along the continental shelf off Southern Peru and North and Central Chile. These filamentous bacteria live in bundles surrounded by a common sheath and form thick mats on the sea floor under the oxygen-minimum zone in the upwelling region, at between 40 and 280 m water depth. The metabolism of this marine bacterium remained a mystery until long after its discovery. We report here that Thioploca cells are able to concentrate nitrate to up to 500 mM in a liquid vacuole that occupies > 80% of the cell volume. Gliding filaments transport this nitrate 5-10 cm down into the sediment and reduce it, with concomitant oxidation of hydrogen sulphide, thereby coupling the nitrogen and sulphur cycles in the sediment.
AN: 3714388

                                                                    386 of 1521  
TI: Biogeochemical processes of the sulphur cycle at early stages of sediment diagenesis along the Enisei River--Kara Sea profile.
OT: Biogeokhimicheskie protsessy tsikla sery na rannikh stadiyakh diageneza osadkov na profile reka Enisej--Karskoe more
AU: Lein,-A.Yu.; Miller,-Yu.M.; Namsaraev,-B.B.; Pavlova,-G.A.; Pimenov,-N.V.; Rusanov,-I.I.; Savvichev,-A.S.; Ivanov,-M.V.
AF: Inst. Geokhim. Anal. Khim. RAN, Moscow, Russia
SO: OKEANOLOGIYA 1994 vol. 34, no. 5, pp. 681-692
LA: Russian
ER: M (Marine); F (Freshwater)
AB: The paper presents data on the chemical composition of pore water, content of different sulphur compounds, their isotope composition and the rate of sulphate reduction in sediment samples collected during the 49th cruise of the R/V Dmitrij Mendeleev in August-September 1993. The rate of sulphate reduction in the profile sediments was found to differ by an order of magnitude. It is at a maximum (1.5 mg S/kg day) and comparable to that in the shallow water sediments from the North Sea in the Enisei delta deposits and in the northern part of the profile. The sediments from the river offing show much lower rates of bacterial sulphate reduction (0.03-0.06 mg S/kg day). The annual production of reduced sulphur in the sediments is estimated at 24 times 10 super(6) tons and only 2% of this amount is buried. The annual expenditure of organic carbon for sulphate reduction in the Enisei mouth zone is 17.6 times 10 super(6) tons.
AN: 3714383

                                                                    387 of 1521  
TI: A high-resolution Sr/Ca and  delta  super(18)O coral record from the Great Barrier Reef, Australia, and the 1982-1983 El Nino
AU: McCulloch,-M.T.; Gagan,-M.K.; Mortimer,-G.E.; Chivas,-A.R.; Isdale,-P.J.
AF: Res. Sch. Earth Sci., Australian Natl. Univ., Canberra, A.C.T. 0200, Australia
SO: GEOCHIM.-COSMOCHIM.-ACTA 1994 vol. 58, no. 12, pp. 2747-2754
LA: English
ER: M (Marine)
AB: A high-resolution (near weekly) Sr/Ca and oxygen isotopic record is presented for a coral from the Pandora Reef in the Great Barrier Reef (GBR) of Australia during the period 1978 to 1984. The records are well correlated except for periods of high rainfall when river runoff has significantly modified the  delta  super(18)O value of seawater. Using the Sr/Ca temperature calibration of De Villiers et al. (1994), the Sr/Ca records exhibit seasonally controlled cyclical SST (sea surface temperature) variations of from  similar to 21 to  similar to 28 degree C. During the very strong El Nino of 1982-1983, the Sr/Ca systematics indicate a sharp drop in the winter SST to  similar to 18.5 degree C. Due to the extremely low ( similar to 10 super(-3)) Sr and Ca contents of river runoff relative to seawater, it is possible to use the Sr/Ca thermometer to calculate temperatures independent of major floods and hence deconvolve the combined effects in the oxygen isotopic record of variable temperature and the  delta  super(18)O value of seawater. Using this approach it is possible to quantitatively reproduce the volume of runoff from the Burdekin River during the periods of major flooding that occurred in early 1979 and 1981. The results of this study demonstrate that the combined use of high-resolution Sr/Ca and  delta  super(18)O systematics in scleractinian corals is a powerful tool for providing quantitative constraints on past climate.
AN: 3714331

                                                                    388 of 1521  
TI: Carbon isotope variations in a solar pond microbial mat: Role of environmental gradients as steering variables
AU: Schidlowski,-M.; Gorzawski,-H.; Dor,-I.
AF: Max-Planck-Inst. Chem., Saarstr. 23, D-55020 Mainz, FRG
SO: GEOCHIM.-COSMOCHIM.-ACTA 1994 vol. 58, no. 10, pp. 2289-2298
LA: English
ER: M (Marine)
AB: A biogeochemical traverse is presented for a juvenile benthic mat covering the depth profile of an artificially stratified and eutrophicated hypersaline heliothermal pond with known gradients of temperature, salinity, pH, and light transmission. It can be shown that visual mat development depends primarily on temperature and salinity as main environmental steering variables whose increase with depth goes along with the attenuation and final disappearance of a visible microbial film in the pond's hypolimnic compartment. Recorded biogeochemical parameters (C sub(org) content, cell numbers, chlorophyll-a content) evidently reflect, as either biomass- or productivity-related index functions, the visually perceptible growth gradient of the microbial ecosystem along the pond slope. The observed coincidence of maxima in these index functions with maxima in  delta  super(13)C sub(org) identifies high rates of primary productivity as the agent ultimately responsible for the generation of  super(13)C-enriched biomass in these and related environments.
AN: 3714294

                                                                    389 of 1521  
TI: Mangroves as filters of shrimp pond effluent: Predictions and biogeochemical research needs
AU: Robertson,-A.I.; Phillips,-M.J.
AF: Australian Inst. Mar. Sci., PMB No. 3, Townsville MC, Qld. 4810, Australia
CO: Asia-Pacific Symposium on Mangrove Ecosystems, (Hong Kong), 1-3 Sep 1993
SO: PROCEEDINGS-OF-THE-ASIA-PACIFIC-SYMPOSIUM-ON-MANGROVE-ECOSYSTEMS. Wong,-Yuk-Shan;Tam,-N.F.Y.-eds. 1995 vol. 295, no. 1-3 pp. 311-321
ST: HYDROBIOLOGIA vol. 295, no. 1-3
LA: English
ER: M (Marine); B (Brackish)
AB: Preliminary estimates of the ratio of mangrove forest:shrimp pond area necessary to remove nutrients from shrimp pond effluent are made using budgets of nitrogen and phosphorus output for semi-intensive and intensive shrimp ponds combined with estimates of total net primary production in Rhizophora-dominated mangrove forests in tropical coastal areas. If effluent is delivered directly to mangrove forest plots, it is estimated that, depending on shrimp pond management, between 2 and 22 hectares of forest are required to filter the nitrogen and phosphorus loads from effluent produced by a 1 hectare pond. While such ratios may apply to small scale, integrated shrimp aquaculture-mangrove forestry farming systems, the variability in mangrove hydrodynamics makes it difficult to apply such ratios at a regional scale. Before mangroves can be used to strip shrimp pond effluent more research is required on the effects that high ammonia and particulate organic matter loads in pond effluent have on nutrient transformations in mangrove sediments and on forest growth.
AN: 3714239

                                                                    390 of 1521  
TI: Temporary and definitive fixation of atmospheric lead in deep-sea sediments of the western Mediterranean Sea
AU: Fernex,-F.; Migon,-C.
AF: Lab. Geodyn. Sous-Mar., CNRS U.A. 132 Geosci. Environ., La Darse, BP 48, F-06230 Villefranche-sur-Mer, France
SO: MAR.-POLLUT.-BULL. 1994 vol. 28, no. 12, pp. 727-734
LA: English
ER: M (Marine)
AB: Most lead brought to the Mediterranean Sea has an anthropogenic origin and is mainly transported through the atmosphere. Atmospheric Pb was continuously collected at Cap Ferrat in 1986 and 1987. From this study, the estimation of the anthropogenic Pb flux on the whole Western Mediterranean was, averaged on 1986 and 1987 data, 4080 t. Assuming that the atmospheric anthropogenic Pb input varied in this course of time similarly to the consumption of Pb added to gasolines in France, the mean annual flux could be calculated: 3.95 kg/km super(2)/yr, that is an annual input of 3360 t/yr. Reaching the sea, this metal seems to become rapidly bound to phytoplankton. Grazing by zooplankton leads to the production of faecal pellets which frequently contain rather high metal concentrations. The sinking rate of pellets of various zooplankton species is high; within a few days pellets may reach deep-sea sediments. After deposition, Pb is released from this organic-rich material during early diagenesis. In most cases, it, therefore, returns to the overlaying water body by ascending diffusion. But, in a deep-sea area of approximately 80 000 km super(2) where Mn oxide precipitation occurs in surficial sediments, Pb seems to remain stored by coprecipitation processes. By considering the lead stored in 'excess' in the surficial sediment of the deep-sea area, we estimate that a mean annual anthropogenic Pb amount ranging from 800 up to 1080 t was stored every year from 1950. On the same area, taking into account the Pb loss at the straits, the 'direct' atmospheric input to the sea bottom is, on average, 184 t/yr. The remaining part, that is (800-1080)-184 = (616-896) t/yr, corresponds to an additional 'indirect' Pb flux in water due to Pb released from sediments of the surrounding areas where it does not remain stored.
AN: 3713049

                                                                    391 of 1521  
TI: Activity of methanotrophic bacteria in Green Bay sediments
AU: Buchholz,-L.A.; Klump,-J.V.; Collins,-M.L.P.; Brantner,-C.A.; Remsen,-C.C.*
AF: Cent. Great Lakes Stud., Univ. Wisconsin, 600 E. Greenfield Ave., Milwaukee, WI 53204, USA
SO: FEMS-MICROBIOL.-ECOL. 1995 vol. 16, no. 1, pp. 1-8
LA: English
ER: F (Freshwater)
AB: Sediment pore water samples obtained from a 19 m station in Green Bay in Lake Michigan were examined for levels of ambient dissolved methane and copper, and for the potential for in situ methane oxidation by methanotrophs found within surface sediments. The in situ methane concentration in the upper oxic sediment layer ranged from 20-150  mu mol/l at this station. The activity of methanotrophs and the kinetics of methane oxidation in these sediments were demonstrated by the uptake of radiolabeled methane. K sub(s) values varied between 4.1-9.6 nmol/cm super(3) of sediment slurry. High V sub(max) values (12.7-35.2 nmol/cm super(3)/h) suggest a large population of methanotrophs in the sediments. An average methane flux to the oxic sediments of 0.24 mol/m super(2)/year was calculated from the pore water methane gradients. Pore water concentrations of copper in the upper sediment layer ranged from 10-120 nmol/l. Based upon the copper concentration, other measured parameters, and equilibrium conditions defined by WATEQF4, an estimate for dissolved free Cu super(2+) concentration of 5-38 nmol/l pore water was obtained. Several factors control the rate of methane oxidation, including oxygen, methane, and the bioavailability of free Cu super(2+).
AN: 3712971

                                                                    392 of 1521  
TI: The silica balance in the world ocean: A reestimate
AU: Treguer,-P.; Nelson,-D.M.; Van-Bennekom,-A.J.; DeMaster,-D.J.; Leynaert,-A.; Queguiner,-B.
AF: URA, CNRS 1513, Inst. Univ. Bretagne Occidentale, 6 Ave. Le Gorgeu, BP 809, F-29285 Brest Cedex, France
SO: SCIENCE-WASH. 1995 vol. 268, no. 5209, pp. 375-379
LA: English
ER: M (Marine)
AB: The net inputs of silicic acid (dissolved silica) to the world ocean have been revised to 6.1  plus or minus  2.0 teramoles of silicon per year (1 teramole = 10 super(12) moles). The major contribution (about 80 percent) comes from rivers, whose world average silicic acid concentration is 150 micromolar. These inputs are reasonably balanced by the net ouputs of biogenic silica aof 7.1  plus or minus  1.8 teramoles of silicon per year in modern marine sediments. The gross production of biogenic silica (the transformation of dissolved silicate to particulate skeletal material) in surface waters was estimated to be 240  plus or minus  40 teramoles of silicon per year, and the preservation ratio (opal accumulation in sediment/gross production in surface waters) averages 3 percent. In the world ocean the residence time of silicon, relative to total biological uptake in surface waters, is about 400 years.
AN: 3711989

                                                                    393 of 1521  
TI: Maldanid polychaetes as vehicles for rapid subduction of phytodetritus on the North Carolina slope
AU: Levin,-L.; Blair,-N.; Plaia,-G.; DeMaster,-D.; Martin,-C.; Fornes,-W.
AF: Scripps Inst. Oceanogr., La Jolla, CA 92093-0218, USA
CO: 23. Benthic Ecology Meeting, New Brunswick, NJ (USA), 17-19 Mar 1995
SO: TWENTY-THIRD-BENTHIC-ECOLOGY-MEETING. Grassle,-J.P.;Kelsey,-A.;Oates,-E.;Snelgrove,-P.V.-eds. Rutgers-the-State-Univ.,-New-Brunswick,-NJ-USA.-Inst.-Marine-Coastal-Sciences 1995 vp
NT: Abstract only.
LA: English
ER: M (Marine)
AB: Maldanids, which often live head down, are typically considered to be conveyor belt feeders that transport deposits from deep in the sediment column to the sediment surface. However hoeing of surface material has been described in at least one shallow water species (Dobbs and Whitlatch 1982). We have observed rapid subduction of an experimentally-placed tracer mixture containing  super(13)C-labeled diatoms Thalassiosira pseudonona, kaolinite clay, glass beads and  super(113)Sn-labeled slope sediments, by the maldanid Praxillella sp. at an 850-m site off Cape Hatteras, NC. After 1.5 da. material placed on the surface was observed at 10-13 cm depths in the sediment column near maldanid tube bases, in maldanid guts, and incorporated into maldanid tubes. Praxillella sp. occurs at densities of  similar to 450 ind./m super(2) at our study site and maldnids are common in bathyal sediments throughout the world's oceans. Through surface feeding, caching, and tube construction, maldanids may cause significant vertical advection of labile carbon below the sediment surface, with important biogeochemical consequences.
AN: 3711690

                                                                    394 of 1521  
TI: Nitrogen fixation and photosynthesis in high arctic forms of Nostoc commune
AU: Lennihan,-R.; Chapin,-D.M.*; Dickson,-L.G.
AF: EA Eng., Sci. Technol., Inc., 8577 154th Ave. NE, Redmond, WA 98052, USA
SO: CAN.-J.-BOT.-REV.-CAN.-BOT. 1994 vol. 72, no. 7, pp. 940-945
LA: English
ER: F (Freshwater)
AB: Nostoc commune, a colonial cyanobacterium, has been suggested as an important contributor of nitrogen to terrestrial ecosystems in the Canadian High Arctic, yet little is known about the ecophysiology of this organism in arctic environments. This study focused on the physiological performance of macroscopic colonies of N. commune found on Devon Island, N.W.T. The objectives were to examine the influence of temperature, colony morphology, and seasonal phenology on nitrogen fixation rates and the effects of light and temperature on photosynthesis. Maximum rates of acetylene reduction in N. commune (2119 nmol C sub(2)H sub(4)/g/h) were higher than those previously recorded for arctic N. commune but lower than values reported for temperate populations. Depending on the time of the growing season, the temperature optimum for acetylene reduction varied from 15 degree C to greater than 20 degree C. Photosynthetic temperature optima did not occur below 20-25 degree C (the highest temperatures measured). Light saturation of photosynthesis was reached at low levels of irradiance (100-150  mu mol/m super(2)/s PPFD). Acetylene reduction rates varied strongly with colony morphology. Thin, fragile, flattened colonies had higher rates than thicker, more resilient, flattened colonies or spherical colonies. Cold post-thaw temperatures appeared to delay the recovery of maximum nitrogen fixation rates for 2-3 weeks following the onset of the growing season. Compared with two other species of cyanobacteria present on Truelove Lowland (Gloeocapsa alpina and Gleotrichia sp.), N. commune had higher rates of nitrogen fixation.
AN: 3711655

                                                                    395 of 1521  
TI: A comparison of sites in the EXMAN project, with respect to atmospheric deposition and the chemical composition of the soil solution and foliage
AU: Farrell,-E.P.; Cummins,-T.; Collins,-J.F.; Beier,-C.; Blanck,-K.; Bredemeier,-M.; De-Visser,-P.H.B.; Kreutzer,-K.; Rasmussen,-L.; Rothe,-A.; et-al.
AF: Dep. Environ. Resour. Manage., University Coll. Dublin, Eire
CO: Symposium on Experimental Manipulations of Biota and Biogeochemcial Cycling in Ecosystems, Copenhagen (Denmark), May 1992
SO: FOR.-ECOL.-MANAGE. 1994 vol. 68, no. 1, pp. 3-14
LA: English
AB: Forest stands, throughfall and the composition of the soil solution in six coniferous forest plantations in Europe were compared as part of the EXMAN project, which was established to quantify biogeochemical cycles and the effects of atmospheric deposition on coniferous forest ecosystems. Even though the EXMAN stands and sites are broadly similar, they represent a wide range of climatic conditions and levels of pollutant deposition. The EXMAN project incorporates treatment of forest plots and in this paper the untreated control plots are compared. The results show marked differences in ionic composition of water between sites, most clearly expressed in throughfall fluxes. At the German and Dutch sites, ionic inputs demonstrate a strong human influence. Throughfall at the Danish and Irish sites is dominated by ions of marine origin. Hydrogen ions are not the most important cations in precipitation at any site, and at only one site (Solling, Germany) was the hydrogen ion flux in throughfall greater than in precipitation. The influence of atmospheric deposition on the composition of the soil water is very evident for most major ions. Exceptions to this are ammonium and nitrate, the complexity of whose behaviour demonstrates the need for greater understanding of nitrogen transformation and uptake in coniferous forest ecosystems.
AN: 3710645

                                                                    396 of 1521  
TI: Measurements of the total CO sub(2) concentration and partial pressure of CO sub(2) in seawater during WOCE expeditions in the South Pacific Ocean. Progress report, (January 1, 1993--December 31, 1993)
AU: Takahashi,-T.; Goddard,-J.G.; Chipman,-D.W.; Rubin,-S.I.
CA: Lamont-Doherty Earth Observatory, Palisades, NY (USA)
SO: 1993 14 pp
NT: NTIS Order No.: DE93018158XSP.
RN: ID No: DOEER615391 (NoDOEER615391)
LA: English
ER: M (Marine)
AB: During the first year of the grant, we participated in three WOCE expeditions (a total of 152 days at sea) in the South Pacific Ocean, and the field phase of the proposed investigation has been successfully completed. The total CO sub(2) concentration and pCO sub(2) were determined at sea in 4419 water samples collected at 422 stations. On the basis of the shipboard analyses of SIO Reference Solutions for CO, and a comparison with the results of previous expeditions, the overall precision of our total CO sub(2) determinations is estimated to be about +2  mu M/kg. The deep water data indicate that there is a CO sub(2) maximum centered about 2600 meters deep. This appears to represent a southward return flow from the North Pacific. The magnitude and distribution of the CO, maximum observed along the 135.0 degree W meridian differ from those observed along the 150.5 degree W meridian due to Tuamotu Archipelago, a topographic high which interferes with the southward return flow. The surface water pCO sub(2) data indicate that the South Pacific sub-tropical gyre water located between about 15 degree S and 50 degree S is a sink for atmospheric CO sub(2).
AN: 3708404

                                                                    397 of 1521  
TI: Inuit exposure to organochlorines through the aquatic food chain in Arctic Quebec
AU: Dewailly,-E.; Ayotte,-P.; Bruneau,-S.; Laliberte,-C.; Muir,-D.C.G.; Norstrom,-R.J.*
AF: Environ. Health Serv., Public Health Cent. (Quebec Reg.)-CHUL, 2050 Blvd. Rene-Levesque, Ste-Foy, PQ G1V 2K8, Canada
SO: ENVIRON.-HEALTH-PERSPECT. 1993 vol. 101, no. 7, pp. 618-620
LA: English
AB: Inuit people (Eskimos) are likely exposed to persistent organochlorine compounds because their traditional diet includes fatty tissues of the arctic marine biota. Here we present the results of organochlorine compound analysis in milk fat samples from arctic Quebec Inuit women and in fat tissues from various animal species inhabiting that region. The total concentration of polychlorinated biphenyl congeners in Inuit milk fat was similar to that of the beluga, while the profile of the 10 congeners resembled that of the polar bear. Mean concentrations of various organochlorines in milk-fat samples from Inuit women were between 2 and 10 times greater than those found in samples previously collected from southern Quebec women. The Inuit mothers exhibit the greatest body burden known to occur from exposure to organochlorine residues present in the environment by virtue of their location at the highest trophic level of the arctic food web.
AN: 3708370

                                                                    398 of 1521  
TI: Freshwater sediments: Sinks and sources of bromine
AU: Song,-Y.; Mueller,-G.
AF: Inst. Sedimentforschung der Univ., D-69020 Heidelberg, FRG
SO: NATURWISSENSCHAFTEN 1993 vol. 80, no. 12, pp. 558-560
LA: English
ER: F (Freshwater)
AB: With 2.5 mg/kg in crustal rocks bromine is forty-sixth in order of abundance. Like chlorine, the largest natural sources of bromine are the oceans which contain 65 mg/l. Amongst salt lakes the Dead Sea is extremely enriched in bromine with concentrations exceeding 4000 mg/l. In contrast to seawater or water of saline lakes, bromine concentrations in freshwater rivers and lakes are extremely low: in 126 water samples from rivers in the inland area of Finland, bromine concentrations were in the range of 0.006-0.108 mg/l, similar concentrations (0.005-0.146 mg/l) were found in 25 rivers of the (former) USSR. The water of the Danube near Regensburg contained 0.013 mg/l, three small rivers entering the Soese water reservoir in the Harz mountains had Br concentrations between 0.008 and 0.020 mg/l. Within the framework of investigations of sediment/interstitial water interactions in freshwater sediments applying in-situ dialysis methods for the collection of pore water, locations in the Neckar river drainage area were studied.
AN: 3708330

                                                                    399 of 1521  
TI: Biogenic production and consumption of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) in the marine epipelagic zone: A review
AU: Groene,-T.
AF: Environ. Inst. (TP 272), Joint Res. Cent., 21020 Ispra (Va), Italy
SO: J.-MAR.-SYST. 1995 vol. 6, no. 3, pp. 191-209
LA: English
ER: M (Marine)
AB: Dimethylsulfide (DMS) is the dominating sulfur gas in surface marine waters. The flux of DMS to the atmosphere plays an important role in the natural sulfur cycle and in the formation of acidic components and condensation nucleii in the remote oceanic atmosphere and is likely to be of climatic significance. This article reviews the biologic production and consumption processes of DMS and its precursor dimethylsulfoniopropionate (DMSP) in ocean surface waters. The description of relevant processes in this paper is complemented by rate estimates where such data are available. The literature on a region in the Northeast Atlantic Ocean is reviewed to provide information on DMS and DMSP pools in situ and their regional and seasonal variations.
AN: 3708251

                                                                    400 of 1521  
TI: Biogenic silica fluxes and accumulation rates in the Gulf of California
AU: Thunell,-R.C.; Pride,-C.J.; Tappa,-E.; Muller-Karger,-F.E.
AF: Dep. Geol. Sci., Univ. South Carolina, Columbia, SC 29208, USA
SO: GEOLOGY 1994 vol. 22, no. 4, pp. 303-306
LA: English
ER: M (Marine)
AB: The Gulf of California, though small in size, plays an important role in the global silica cycle. The seasonal pattern of biogenic silica flux in the gulf is closely related to that of phytoplankton biomass levels and is controlled by changes in weather and hydrographic conditions. The highest opal fluxes ( similar to 0.35 g/m super(2)/d) occur during winter and spring, and they are comparable to those measured in some of the most productive ecosystems of the world. Approximately 15%-25% of the biogenic silica produced in surface waters is preserved in gulf sediments, a figure significantly higher than the average global ocean preservation rate. However, the flux of opal at 500 m water depth is less than 25% of that being produced at the surface, suggesting that most of the recycling of biogenic silica in the Gulf of California occurs in the upper water column.
AN: 3705681

                                                                    401 of 1521  
TI: Original mineralogy of carboniferous worm tubes: Evidence for changing marine chemistry and biomineralization: Comment and reply
AU: Weedon,-M.J.; Taylor,-P.D.
AF: Dep. Palaeontol., Nat. Hist. Mus., London SW7 5BD, UK
SO: GEOLOGY 1994 vol. 22, no. 3, pp. 281-282
LA: English
ER: M (Marine)
AB: In a stimulating paper, Railsback (1993) claimed that serpulid tube mineralogy changed from calcitic in the Mississippian to aragonitic in the Pennsylvanian, concluding that this change (1) supported evidence from abiotic carbonates that marine chemistry underwent a significant change at the end of the Mississippian; (2) illustrated the susceptibility of biologically induced biomineralization to long-term environmental change; and (3) raised the possibility that similar mineralogical changes might be found in other organisms in response to changing marine chemistry. However, several criticisms cast doubt on these three conclusions. The putative change from calcitic serpulids in the Mississippian to aragonitic serpulids in the Pennsylvanian obviously depends upon all of the studied fossils being identified correctly as serpulids which belong to an evolutionary lineage or at least the same taxonomic group. Neither of these essential prerequisites is convincingly demonstrated in the paper.
AN: 3705649

                                                                    402 of 1521  
TI: Effects of agricultural development on processing of tussock leaf litter in high country New Zealand streams
AU: Young,-R.G.; Huryn,-A.D.; Townsend,-C.R.
AF: Dep. Zool., Univ. Otago, P.O. Box 56 Dunedin, New Zealand
SO: FRESHWAT.-FORUM 1994 vol. 32, no. 2, pp. 413-427
LA: English
ER: F (Freshwater)
AB: The authors compare the rates and mechanisms of processing of tussock (Chionochloa spp.) leaf litter in six New Zealand streams draining grassland catchments that contrast in the extent to which they have been developed for pasture. Rates of processing, measured as rate of weight loss of leaf packs and rate of leaf softening, were at the slow end of the spectrum for vascular plant processing. Processing was faster at developed sites, mediated mainly through the influence of oxidized nitrogen concentration on microbial activity. Few invertebrate shredders colonized leaf packs and it is unlikely that invertebrates had an appreciable effect on leaf processing in our study streams, which do not effectively retain leaf litter. Very small headwater tributaries appear to retain leaf litter and possess a more abundant shredder community. The authors discuss the potential for using rate of leaf litter processing as a method of bioassessment.
AN: 3705235

                                                                    403 of 1521  
TI: Assessment of the eutrophication of Al Massira Reservoir (Morocco) by means of a survey of the biogeochemical balance of phosphate
AU: Alaoui-Mhamdi,-M.; Aleya,-L.*
AF: Lab. Zool. Protistol., URA CNRS 138 Aubiere Cedex, France
SO: HYDROBIOLOGIA 1995 vol. 297, no. 1, pp. 75-82
NT: Special issue: Sediment-water Interaction 5.
LA: English
ER: F (Freshwater)
AB: The biogeochemical balance of phosphate was studied in Al Massira reservoir (Morocco) from February 1991 to end January 1992. The study concerned P-supplies and losses by the Oum errbia river, sedimentation rate and water-sediment exchange. Supply and loss of phosphate were calculated from samples collected every 48 hours. Phosphate sedimentation rate was measured with sediment traps. The assessment of phosphate release at the water-sediment interface during either low oxic or anoxic conditions was made in situ with a benthic chamber. The results showed that phosphate input was higher than phosphate output resulting in a progressive increase of the internal phosphorus stock. The sedimentation flux ranged between 9 and 19 mg/m super(2)/d of P. Release of phosphate depended on the oxygen concentration in the water. We suggest that a drastic control of phosphate input into the water must be achieved through a programmed of dephosphorylation of the tributaries to avoid accumulation of calcium-bound phosphate which may become a source of upward release of bioavailable phosphate. Further investigations of this flux should be carried out to check the quantitative influence on phytoplankton community dynamics.
AN: 3704320

                                                                    404 of 1521  
TI: A bloom of Dunaliella parva in the Dead Sea in 1992: Biological and biogeochemical aspects
AU: Oren,-A.; Gurevich,-P.; Anati,-D.A.; Barkan,-E.; Luz,-B.
AF: Div. Microb. Mol. Ecol., Alexander Silberman Inst. Life Sci., Hebrew Univ. Jerusalem, 91904 Jerusalem, Israel
SO: HYDROBIOLOGIA 1995 vol. 297, no. 3, pp. 173-185
LA: English
ER: B (Brackish)
AB: A bloom of the unicellular green alga Dunaliella parva (up to 15 000 cells/ml) developed in the upper 5 m of the water column of the Dead Sea in May-June 1992. This was the first mass development of Dunaliella observed in the lake since 1980, when another bloom was reported (up to 8800 cells/ml). For a bloom of Dunaliella to develop in the Dead Sea, two conditions must be fulfilled: the salinity of the upper water layers must become sufficiently low as a result of dilution with rain floods, and phosphate must be available. During the period 1983-1991 the lake was holomictic, hardly any dilution with rainwater occurred, and no Dunaliella cells were observed. Heavy rain floods in the winter of 1991-1992 caused a new stratification, in which the upper 5 m of the water column became diluted to about 70% of their former salinity. Measurements of the isotopic composition of inorganic carbon in the upper water layer during the bloom ( delta  super(13)C = 5.1ppt) indicate a strong fractionation when compared with the estimated -3.4ppt prior to the bloom. The particulate organic carbon formed was highly enriched in light carbon isotopes ( delta  super(13)C = -13.5ppt). The algal bloom rapidly declined during the months June-July, probably as a result of the formation of resting stages, which sank to the bottom. A smaller secondary bloom (up to 1850 cells/ml) developed between 6 and 10 m depth at the end of the summer. Salinity values at this deep chlorophyll maximum were much beyond those conductive for the growth of Dunaliella, and the factors responsible for the development of this bloom are still unclear.
AN: 3704319

                                                                    405 of 1521  
TI: Application of organic carbon and nitrogen stable isotope and C/N ratios as source indicators of organic matter provenance in estuarine systems: Evidence from the Tay Estuary, Scotland
AU: Thornton,-S.F.; McManus,-J.
AF: Sch. Earth Sci., Univ., Birmingham B15 2TT, UK
SO: ESTUAR.-COAST.-SHELF-SCI. 1994 vol. 38, no. 3, pp. 219-233
LA: English
ER: B (Brackish)
AB: The source of particulate organic matter (POM) in lacustrine and estuarine sediments from the Tay River catchment has been evaluated using stable carbon and nitrogen isotope and elemental C/N ratios. The  delta  super(13)C,  delta  super(15)N and C/N compositions of POM from the two environments were statistically distinct, enabling, by use of a simple two component mixing equation, assessment of the ability of each tracer to estimate the terrigenous flux to the estuarine organic matter pool. Estuarial mixing of terrigenous, indigenous estuarine and marine derived organics, recorded by  delta  super(13)C data, was only partly confirmed by equivalent  delta  super(15)N and C/N compositions which reflected greater control by organic matter diagenesis and biological processing. Limited data indicate sewage derived contributions are insignificant. Of the three tracers employed, only  delta  super(13)C ratios are reliable as provenance indicators. Both  delta  super(15)N and C/N ratios are limited because the original POM source signature may be lost or overprinted by biochemical alteration prior to and/or soon after deposition. The simultaneous application of these tracers provides substantially more information regarding the source, quality and turnover of sedimentary POM in these contrasting systems than could be achieved using one technique alone.
AN: 3704287

                                                                    406 of 1521  
TI: PCR for direct detection of indigenous uncultured magnetic cocci in sediment and phylogenetic analysis of amplified 16S ribosomal DNA
AU: Thornhill,-R.H.; Burgess,-J.G.; Matsunaga,-T.*
AF: Dep. Biotechnol., Tokyo Univ. Agric. and Technol., Koganei, Tokyo 184, Japan
SO: APPL.-ENVIRON.-MICROBIOL. 1995 vol. 61, no. 2, pp. 495-500
LA: English
ER: M (Marine)
AB: PCR primers specific to the 16S ribosomal DNA (rDNA) of magnetic cocci were designed and used to amplify DNA from magnetically isolated magnetic cocci. The PCR products were subcloned by ligation into plasmid vector pCRII, and five clones containing approximately 270-bp fragments of amplified DNA were sequenced. The specific primers were also used to detect magnetic coccus 16S rDNA in environmental samples. Magnetic coccus 16S rDNA was amplified from the water column above sediment kept in an anoxic environment in the laboratory, but little was amplified from a water column in an anoxic environment had migrated there from the sediment as a response to the microoxic or anoxic conditions, rather than having been present previously in a nonmagnetic form and having become magnetic due to these conditions. The specific primers were also used to detect magnetic cocci in aquatic sediment. DNA was extracted from sediment by direct lysis and purified for use as a PCR template by electrophoresis on an agarose-polyvinylpyrrolidone gel. 16S rDNA was then amplified and subcloned, and two clones were sequenced. The clones were screened for chimeric DNA by comparing sections of each with the GenBank database.
AN: 3704236

                                                                    407 of 1521  
TI: The stoichiometry of N and P in the pelagic zone of Castle Lake, California
AU: Elser,-J.J.; George,-N.B.
AF: Dep. Zool., Arizona State Univ., Tempe, AZ 85287, USA
SO: J.-PLANKTON-RES. 1993 vol. 15, no. 8, pp. 977-992
LA: English
ER: F (Freshwater)
AB: We measured the concentrations, as well as lake-wide amounts, of nitrogen (N) and phosphorus (P) in dissolved, seston and zooplankton pools throughout the water column of Castle Lake, California, during summer, 1991. This allowed us to determine the stoichiometric ratios of important elements in each pool (C:N, C:P, N:P) as well as for the entire lake. Dissolved and seston pools were the predominant storage compartments for both N and P; zooplankton never contained >5% of N or 10% of P lake wide. However, by late summer, the concentrations of P in seston and in zooplankton were similar in the upper portions of the water column, suggesting that changes in food web structure that alter zooplankton biomass and community composition (and hence elemental storage in the zooplankton) may produce significant shifts in nutrient storage among pelagic pools. Lake-wide levels of dissolved N were largely constant over the study period; however, lake-wide dissolved P increased. These dynamics suggested that the majority of nutrients stored in dissolved pools were unavailable for phytoplankton growth. N:P and C:P ratios indicated that Castle Lake phytoplankton became severely deficient in P during the course of our observations. These ratios also greatly exceeded recently reported threshold values for elemental constraints on growth and reproduction for several species of zooplankton. The ratio of N to P in the zooplankton pool was relatively constant and consistently lower than that in the sestion. As a result, the predicted N:P ratio of zooplankton-regenerated nutrients exceeded the N:P ratio of the seston, implying that zooplankton nutrient regeneration further skewed N and P supply ratios, and potentially enhanced P limitation of phytoplankton in Castle Lake.
AN: 3699797

                                                                    408 of 1521  
TI: The plankton multiplier -- positive feedback in the greenhouse
AU: Woods,-J.; Barkmann,-W.
AF: Nat. Environ. Res. Counc., Polaris House, Swindon SN2 1EU, UK
SO: J.-PLANKTON-RES. 1993 vol. 15, no. 9, pp. 1053-1074
LA: English
ER: M (Marine)
AB: The plankton multiplier is a positive feedback mechanism linking the greenhouse effect and biological pump. As pollution increases the atmospheric concentration of carbon dioxide, the enhanced greenhouse effect induces radiative forcing of the ocean, which diminishes the depth of winter convection, reducing the annual resupply of nutrients to the euphotic zone and therefore the annual primary production. That weakens the biological pump, which contributes to oceanic uptake of CO sub(2). As the ocean takes up less CO sub(2), more remains in the atmosphere, accelerating the rise in radiative forcing. We have used a mathematical model of the upper ocean ecosystem, based on the Lagrangian Ensemble method, to estimate the sensitivity of the biological pump to radiative forcing, which lies at the heart of the plankton multiplier. We conclude that increasing radiative forcing by 5 W m super(-2) (equivalent to doubling atmospheric CO sub(2)) reduces the deep flux of particulate carbon by 10%. That sensitivity is sufficient to produce significant positive feedback in the greenhouse. It means that the plankton multiplier will increase the rate of climate change in the 21st Century. It also suggests that the plankton multiplier is the mechanism linking the Milankovich effect to the enhanced greenhouse effect that produces global warming at the end of ice ages.
AN: 3699776

                                                                    409 of 1521  
TI: Biogeological mineralization in deep-sea hydrothermal deposits
AU: Cook,-T.L.; Stakes,-D.S.
AF: Monterey Bay Aquar. Res. Inst., 160 Central Ave., Pacific Grove, CA 93950, USA
SO: SCIENCE-WASH. 1995 vol. 267, no. 5206, pp. 1975-1979
LA: English
ER: M (Marine)
AB: Oriented drill cores retrieved from active massive sulfide edifices at the Endeavour Segment of the Juan de Fuca Ridge contain an abundance of fossilized tube structures associated with vestimentiferan and annelid worms. The petrological evolution of these biogeological structures and their presence deep inside the edifice walls demonstrate that an initial, worm-mediated texture directly affects the subsequent steps of inorganic precipitation, wall infilling, and outward growth of these black smoker deposits. The presence of fossilized structures in hydrothermal discharge sites that are 2 kilometers apart and their similarity to structures observed in other modern and ancient deposits suggest that these biogeological processes are general phenomena.
AN: 3699633

                                                                    410 of 1521  
TI: Biogeochemical cycles of carbon, sulfur, and free oxygen in a microbial mat
AU: Canfield,-D.E.; Des-Marais,-D.J.
AF: Sch. Earth Atmosp. Sci., Georgia Inst. Technol., Atlanta, GA 30332-0340, USA
SO: GEOCHIM.-COSMOCHIM.-ACTA 1993 vol. 57, no. 16, pp. 3971-3984
LA: English
ER: M (Marine); B (Brackish)
AB: Complete budgets for carbon and oxygen have been constructed for cyanobacterial mats dominated by Microcoleus chthonoplastes from the evaporating ponds of a salt works located in Guerrero Negro, Baja California Sur, Mexico. Included in the budget are measured rates of O sub(2) production, sulfate reduction, and elemental exchange across the mat/brine interface, day and night, at various temperatures and times of the year. We infer from this data the various sinks for O sub(2), as well as the sources of carbon for primary production. To summarize, although seasonal variability exists, a major percentage of the O sub(2) produced during the day did not diffuse out of the mat but was used within the mat to oxidize both organic carbon and the sulfide produced by sulfate production. At night, most of the O sub(2) that diffused into the mat was used to oxidize sulfide, with  sub(2) respiration of minor importance. During the day, the internal mat processes of sulfate reduction and O sub(2) respiration generated as much or more inorganic carbon (DIC) for primary production as diffusion into the mat. Also, oxygenic photosynthesis was the most important process of carbon fixation, although anoxygenic photosynthesis may have been important at low light levels during some times of the year. At night, the DIC lost from the mat was mostly from sulfate reduction. Elemental fluxes across the mat/brine interface indicated that carbon with an oxidation state greater than zero was taken up by the mat during the day and liberated from the mat at night. Overall, carbon with an average oxidation state of near zero accumulated in the mat. Both carbon fixation and carbon oxidation rates varied with temperature by a similar amount. These mats are thus closely coupled systems where rapid rates of photosynthesis both require and fuel rapid rates of heterotrophic carbon oxidation.
AN: 3699462

                                                                    411 of 1521  
TI: The biogeochemistry of potassium at Hubbard Brook
AU: Likens,-G.E.; Driscoll,-C.T.; Buso,-D.C.; Siccama,-T.G.; Johnson,-C.E.; Lovett,-G.M.; Ryan,-D.F.; Fahey,-T.; Reiners,-W.A.
AF: Inst. Ecosyst. Stud., Millbrook, NY 12545, USA
SO: BIOGEOCHEMISTRY 1994 vol. 25, no. 2, pp. 61-125
LA: English
ER: F (Freshwater)
AB: A synthesis of the biogeochemistry of K was conducted during 1963-1992 in the reference and human-manipulated watershed-ecosystems of the Hubbard Brook Experimental Forest (HBEF), NH. Results showed that during the first two years of the study (1963-65), which coincided with a drought period, the reference watershed was a net sink for atmospheric inputs of K. During the remaining years, this watershed has been a net source of K for downstream ecosystems. There have been long-term declines in volume-weighted concentration and flux of K at the HBEF; however, this pattern appears to be controlled by the relatively large inputs during the initial drought years. Net ecosystem loss (atmospheric deposition minus stream outflow) showed an increasing trend of net loss, peaking during the mid-1970s and declining thereafter. This pattern of net K loss coincides with trends in the drainage efflux of SO sub(4) super(2-) and NO sub(3) super(-), indicating that concentrations of strong acid anions may be important controls of dissolved K loss from the site. There were no long-term trends in streamwater concentration or flux of K. A distinct pattern in pools and fluxes of K was evident based on biotic controls in the upper ecosystem strata (canopy, boles, forest floor) and abiotic controls in lower strata of the ecosystem (mineral soil, glacial till). Clearcutting disturbance resulted in large losses of K in stream water and from the removal of harvest products. Stream losses occur from release from slash, decomposition of soil organic matter and displacement from cation exchange sites. Elevated concentrations of K persist in stream water for many years after clearcutting. Of the major elements, K shows the slowest recovery from clearcutting disturbance.
AN: 3698183

                                                                    412 of 1521  
TI: Nutrient retention in riparian ecotones
AU: Vought,-L.B.-M.; Dahl,-J.; Pedersen,-C.L.; Lacoursiere,-J.O.
AF: Limnol., Dep. Ecol., Ecol. Build., Univ. Lund, S-223 62 Lund, Sweden
SO: AMBIO 1994 vol. 23, no. 6, pp. 342-348
LA: English
ER: F (Freshwater)
AB: Nutrient retention mechanisms in riparian buffer strips are reviewed with emphasis on surface runoff and subsurface flows, the main pathways of exchanges between the stream and its surroundings. Unique physical and biogeochemical properties prevailing in these riparian ecotones dictate the flux of water, nutrients and other exogenous substances between the upland areas and the stream. Removal of nutrients from surface inflows is induced by deposition of sediment bound nutrients and exchange of dissolved nutrients with the soil/litter surface. Removal of nitrogen in subsurface flows can partly be explained by vegetation uptake, but the main mechanism for removal is usually denitrification. In channelized streams, the subsurface inflows have, in most cases, been altered to discharges via drainage tiles, with the exchange flows (water leaving and re-entering the open-channel via the stream bed and banks) being greatly decreased. Consequently, to improve nitrogen removal in these systems, these flows have to be intercepted or reestablished either through restoration of the old stream valley or through managed structures in the buffer strips.
AN: 3697346

                                                                    413 of 1521  
TI: Nitrogen retention in forest wetlands
AU: Jacks,-G.; Joelsson,-A.; Fleischer,-S.
AF: Dep. Civ. and Environ. Eng., KTH, S-100 44 Stockholm, Sweden
SO: AMBIO 1994 vol. 23, no. 6, pp. 358-362
LA: English
ER: F (Freshwater)
AB: Forests in southern Sweden are receiving nitrogen depositions that are about twice the critical load. There are indications that nitrogen losses from forest land are increasing. Forest wetlands may in this perspective become important traps for nitrogen, thus, protecting streams, lakes and marine environments from eutrophication. A number of forest wetlands in southwestern Sweden have been investigated with the aim of assessing their efficiency as nitrogen traps. Nitrogen retention is small in undisturbed upland forest. However, increased nitrate flux from a clearcut area was largely retained in one of the studied wetlands. In the spruce, which is the dominating tree in southern Sweden, the large-scale damages due to soil acidification or climatic causes cannot be excluded and it is advocated that forest wetlands should not be subject to drainage.
AN: 3697345

                                                                    414 of 1521  
TI: Nitrogen retention in artificially flooded meadows
AU: Leonardson,-L.; Bengtsson,-L.; Davidsson,-T.; Persson,-T.; Emanuelsson,-U.
AF: Limnol., Dep. Ecol., Ecol. Build., S-223 62 Lund, Sweden
SO: AMBIO 1994 vol. 23, no. 6, pp. 332-341
LA: English
ER: F (Freshwater)
AB: Investigations of nitrogen retention in artificially flooded wetlands were performed in southern Sweden during 1991-1993. The purpose of the study was to investigate whether artificial flooding of meadows would be a possible means of reducing the nitrogen content in streams and rivers. Two case studies are presented, one from a sandy/organic soil, one from a peaty soil. Overall nitrogen retention was estimated by mass balance. Denitrification activity and plant biomass incorporation of nitrogen were used to complement and verify the mass-balance data. The study shows that artificial flooding of meadows did not contribute significantly to nitrogen retention in the introduced river water under the irrigation regimes utilized. The technique stimulated mineralization of the soil nitrogen pool to an extent which corresponded to the reduction of nitrate caused by denitrification. In the sandy/organic soil, denitrification was enhanced by the artificial flooding, while in the peat area the activity was lower than in a nonflooded reference area. Plant uptake of nitrogen was stimulated by flooding.
AN: 3697344

                                                                    415 of 1521  
TI: Stoichiometric nutrient balance and origin of coastal eutrophication
AU: Justic,-D.; Rabalais,-N.N.; Turner,-R.E.
AF: Coast. Ecol. Inst., Louisiana State Univ., Baton Rouge, LA 70803, USA
SO: MAR.-POLLUT.-BULL. 1995 vol. 30, no. 1, pp. 41-46
LA: English
ER: M (Marine)
AB: We present here an analysis of the stoichiometry of dissolved nutrients in 10 large world rivers, Amazon, Changjiang, Huanghe, Mackenzie, Mississippi, Po, Rhine, Seine, Yukon and Zaire, and in two river-dominated coastal ecosystems prone to eutrophication, the northern Adriatic Sea and the northern Gulf of Mexico. Our analysis suggests that proportions of dissolved silica (Si), nitrogen (N) and phosphorus (P) in rivers carrying nutrients of anthropogenic origin, as well as in the coastal waters strongly influenced by those rivers, have changed historically in a way that now closely approximates the Redfield ratio (Si:N:P=16:16:1). It is likely that coastal phytoplankton productivity has increased under these favourable nutrient conditions and was accompanied by an increasing incidence of noxious phytoplankton blooms and bottom water hypoxia.
AN: 3697313

                                                                    416 of 1521  
TI: Biochemical feedbacks in the oceanic carbon cycle
AU: Klepper,-O.; De-Haan,-B.J.; Van-Huet,-H.
AF: Natl. Inst. Public Health Environ. Prot., Cent. Math. Methods, P.O. Box 1, 3720 BA Bilthoven, Netherlands
CO: 8. Conference of the International Society for Ecological Modelling, Kiel (Germany), 28 Sep-2 Oct 1992
SO: ECOL.-MODEL. 1994 vol. 75-76, pp. 459-469
LA: English
ER: M (Marine)
AB: This paper presents the results of a coupled ocean circulation and biochemical model to study carbon uptake of the oceans by chemical buffering and primary production. The circulation model is a 2-dimensional model (latitudinally averaged per ocean basin with a 20 degree  resolution, and 12 vertical layers). The biochemical model includes the elements C (as inorganic, particulate and dissolved organic), N, O, Ca and  super(14)C, and models the fluxes between the various species (atmospheric exchange, physical transport, primary production, calcification, decomposition and dissolution). Steady-state results show good agreement with measurements. The model is then used in a sensitivity analysis to study the effect of possible changes in biochemical processes by running it to the year 2070 (projected atmospheric CO sub(2) doubling under "business as usual" scenario). It turns out that most of the feedbacks are positive, i.e.: ocean uptake capacity decreases more rapidly than in the simulation with constant process rates. As a result, atmospheric pCO sub(2) may rise considerably faster than is currently predicted using no-feedback ocean models.
AN: 3697117

                                                                    417 of 1521  
TI: Seasonal variability and biogeochemistry of phosphorus in the Scheldt Estuary, south-west Netherlands
AU: Zwolsman,-J.J.G.
AF: Delft Hydraul., P.O. Box 177, 2600 MH Delft, Netherlands
SO: ESTUAR.-COAST.-SHELF-SCI. 1994 vol. 39, no. 3, pp. 227-248
LA: English
ER: B (Brackish)
AB: The geochemistry of phosphate in the highly polluted Scheldt Estuary has been studied during eight cruises in 1987-88. Property-salinity plots show significant seasonal variability in the environmental conditions which trigger phosphate behaviour, such as dissolved oxygen, pH and phytoplankton activity. Consequently, the behaviour of orthophosphate differs from season to season. During autumn and winter, when phytoplankton activity is low or negligible, the orthophosphate profiles show the occurrence of a buffering mechanism, probably caused by desorption of particle-bound phosphorus in response to the increase in pH with increasing salinity. During spring and summer, the geochemistry of orthophosphate is influenced by the presence of anoxic headwaters. High phosphate concentrations are observed in the anoxic river water entering the estuary, probably reflecting release from the sediments. However, phosphate is rapidly removed from solution in the low-salinity zone due to co-precipitation with iron oxyhydroxides, formed by reoxidation in the water column. Seaward from the low-salinity high-turbidity zone, phosphate is-removed from solution during phytoplankton blooms, especially during spring. Blooms also affect the suspended matter composition, in that a shift towards biogenic elements (POC, N, P) at the expense of lithogenic elements (Fe, Al) occurs. Moreover, the speciation of particulate phosphorus shifts from iron- and aluminium-bound forms to POC-bound phosphate in zones of high primary productivity. These findings have implications for the future management of the Scheldt Estuary, as nutrient reduction policies are being implemented.
AN: 3696297

                                                                    418 of 1521  
TI: Potential rates of methanogenesis in sawgrass marshes with peat and marl soils in the Everglades
AU: Bachoon,-D.; Jones,-R.D.*
AF: Dep. Biol. Sci., Florida Int. Univ., Miami, FL 33199, USA
SO: SOIL-BIOL.-BIOCHEM. 1992 vol. 24, no. 1, pp. 21-27
LA: English
ER: F (Freshwater)
AB: Comparisons of methanogenesis in two sawgrass wetlands of the Florida Everglades revealed that marl soils had a much greater potential rate of methanogenesis than peat soils. In these wetlands methanogenesis decreased rapidly with increased soil depth, increased at higher temperatures, increased with lower Eh, was stimulated by organic compounds (cellulose, glucose and acetate), and remained unaffected by ammonium and phosphate. Lowering the Eh in peat and marl soils with sulfide or sulfate stimulated methanogenesis. Methanogenesis potentials decreased to undetectable values when water levels dropped below the surface, and peaked 1 month after heavy rainfall in November 1989.
AN: 3696288

                                                                    419 of 1521  
TI: Autotrophic picoplankton in southern Lake Baikal: Abundance, growth and grazing mortality during summer
AU: Nagata,-T.; Takai,-K.; Kawanobe,-K.; Kim,-D.; Nakazato,-R.; Guselnikova,-N.; Bondarenko,-N.; Mologawaya,-O.; Kostrnova,-T.; Drucker,-V.; Satoh,-Y.; Watanabe,-Y.
AF: Inst. Hydrosp.-Atmos. Sci., Nagoya Univ., Chikusa, Nagoya 464-01, Japan
SO: J.-PLANKTON-RES. 1994 vol. 16, no. 8, pp. 945-959
LA: English
ER: F (Freshwater)
AB: Autotrophic picoplankton were highly abundant during the thermal stratification period in late July in the pelagic area (water depth 500-1300 m) of southern Lake Baikal; maximum numbers were 2 x 10 super(6) cells/ml in the euphotic zone ( similar to  15 m). Unicellular cyanobacteria generally dominated the picoplankton community, although unidentified picoplankton that fluoresced red under blue excitation were also abundant (maximum numbers 4 x 10 super(5) cells/ml) and contributed up to  similar to  40% of the total autotrophic picoplankton on occasions. Carbon and nitrogen biomasses of autotrophic picoplankton estimated by conversion from biovolumes were 14-84  mu g C/L and 3.6-21  mu g N/L. These were comparable to or exceeded the biomass of heterotrophic bacteria. Autotrophic picoplankton and bacteria accounted for as much as 33% of particulate organic carbon and 81% of nitrogen in the euphotic zone. Measurements of the photosynthetic uptake of [ super(14)C]bicarbonate and the growth of picoplankton in diluted or size-fractionated waters revealed that 80% of total primary production was due to picoplankton, and that much of this production was consumed by grazers in the < 20  mu m cell-size category. These results suggest that picoplankton-protozoan trophic coupling is important in the pelagic food web and biogeochemical cycling of Lake Baikal during summer.
AN: 3696278

                                                                    420 of 1521  
TI: Linkages between organic matter mineralization and denitrification in eight riparian wetlands
AU: Seitzinger,-S.P.
AF: Rutgers Univ., Inst. Mar. and Coast. Sci., P.O. Box 231, New Brunswick, NJ 08903-0231, USA
SO: BIOGEOCHEMISTRY 1994 vol. 25, no. 1, pp. 19-39
LA: English
ER: F (Freshwater)
AB: Denitrification (N sub(2) production) and oxygen consumption rates were measured at ambient field nitrate concentrations during summer in sediments from eight wetlands (mixed hardwood swamps, cedar swamps, health dominated shrub wetland, herbaceous peatland, and a wetland lacking live vegetation) and two streams. The study sites included wetlands in undisturbed watersheds and in watersheds with considerable agricultural and/or sewage treatment effluent input. Denitrification rates measured in intact cores of water-saturated sediment ranged from  less than or equal to 20 to 260  mu mol N m super(-2)/h among the three undisturbed wetlands and were less variable (180 to 260  mu mol N m super(-2)/h) among the four disturbed wetlands. Denitrification rates increased when nitrate concentrations in the overlying water were increased experimentally (1 up to 770  mu M), indicating that nitrate was an important factor controlling denitrification rates. However, rates of nitrate uptake from the overlying water were not a good predictor of denitrification rates because nitrification in the sediments also supplied nitrate for denitrification. Regardless of the dominant vegetation, pH, or degree of disturbance, denitrification rates were best correlated with sediment oxygen consumption rates (r super(2) = 0.912) indicating a relationship between denitrification and organic matter mineralization and/or sediment nitrification rates. Rates of denitrification in the wetland sediments were similar to those in adjacent stream sediments. Rates of denitrification in these wetlands were within the range of rates previously reported for water-saturated wetland sediments and flooded soils using whole core  super(15)N techniques that quantify coupled nitrification/denitrification, and were higher than rates reported from aerobic (non-saturated) wetland sediments using acetylene block methods.
AN: 3693285

                                                                    421 of 1521  
TI: The effect of pressure on leucine and thymidine incorporation by free-living bacteria and by bacteria attached to sinking oceanic particles
AU: Turley,-C.M.
AF: Plymouth Mar. Lab., Citadel Hill, Plymouth PL1 2PB, UK
SO: DEEP-SEA-RES.-A-OCEANOGR.-RES.-PAP. 1993 vol. 40, no. 11-12, pp. 2193-2206
LA: English
ER: M (Marine)
AB: The effect of pressure on upper ocean free-living bacteria and bacteria attached to rapidly sinking particles was investigated through studying their ability to synthesize DNA and protein by measuring their rate of  super(3)H-thymidine and  super(3)H-leucine incorporation. Studies were carried out on samples from the NE Atlantic under the range of pressures (1-430 atm) encountered by sinking aggregates during their journey to the deep-sea bed. Thymidine and leucine incorporation rates per bacterium attached to sinking particles from 200 m were about six and ten times higher, respectively, than the free-living bacterial assemblage. The ratio of leucine incorporation rate per cell to thymidine incorporation rate per cell was significantly different between the larger attached (18.9:1) and smaller free-living (10.4:1) assemblages. The rates of leucine and thymidine incorporation decreased exponentially with increasing pressure for the free-living and linearly for attached bacteria, while there was no significant influence of pressure on cell numbers. At 100 atm leucine and thymidine incorporation rate per free-living bacterium was reduced to 73 and 20%, respectively, relative to that measured at 1 atm. Pressure of 100 atm reduced leucine and thymidine incorporation per attached bacterium to 94 and 70%, and at 200 atm these rates were reduced to 34 and 51%, respectively, relative to those measured at 1 atm. There was no significant uncoupling of thymidine and leucine incorporation for either the free-living or attached bacterial assemblages with increasing pressure, indicating that the processes of DNA and protein synthesis may be equally affected by increasing pressure. It is therefore unlikely that bacteria, originating from surface waters, attached to rapidly sinking particles play a role in particle remineralization below approximately 1000-2000 m. These results may help to explain the occurrence of relatively fresh aggregates on the deep-sea bed that still contain sufficient organic carbon to fuel the rapid growth of benthic micro-organisms; they also indicate that the effect of pressure on microbial processes may be important in oceanic biogeochemical cycles.
AN: 3693223

                                                                    422 of 1521  
TI: Phaeopigment distribution during the 1990 spring bloom in the northeastern Atlantic
AU: Barlow,-R.G.; Mantoura,-R.F.C.; Gough,-M.A.; Fileman,-T.W.
AF: Plymouth Mar. Lab., Prospect Place, West Hoe, Plymouth PL1 3DH, UK
SO: DEEP-SEA-RES.-A-OCEANOGR.-RES.-PAP. 1993 vol. 40, no. 11-12, pp. 2229-2242
LA: English
ER: M (Marine)
AB: The temporal and depth distributions of phaeopigments were determined during a spring bloom in the northeastern Atlantic in 1990 using reverse phase high performance liquid chromatography. Phaeopigment concentrations were very low (<8% by mole relative to chlorophyll a) and two forms of phaeophorbide and two forms of phaeophytin were separated and quantified. Phaeophorbides were the dominant phaeopigments, accounting for 80% of the total phaeopigment molar concentration, and phaeopigments closely tracked the variations in chlorophyll a by increasing during the development phase of the bloom and declining in the post bloom stage. Production of phaeopigments was found to occur predominantly at night, and these rates exceeded the rates of phaeopigment destruction during the day. Lower phaeopigment-chlorophyll a ratios were determined for the surface waters, suggesting that photodegradation was possibly the primary mechanism of phaeopigment disappearance in the euphotic zone. A comparison of phaeopigment data and phyto- and zooplankton structure indicates that greater phaeopigment production and grazing pressure occurred in the development phase when diatoms dominated, while grazing and phaeopigment production declined in the post bloom stage dominated by prymnesiophytes.
AN: 3693194

                                                                    423 of 1521  
TI: Direct observations of advective nutrient and oxygen fluxes at 24 degree N in the Pacific Ocean
AU: Robbins,-P.E.; Bryden,-H.L.
AF: MIT/WHOI Joint Program Oceanogr., Woods Hole Oceanogr. Inst., Woods Hole, MA 02543, USA
SO: DEEP-SEA-RES.-A-OCEANOGR.-RES.-PAP. 1994 vol. 41, no. 1, pp. 143-168
LA: English
ER: M (Marine)
AB: Meridional oxygen and nutrient flux in the Pacific Ocean are estimated using a hydrographic transect at 24 degree N. A velocity field is diagnosed from the observed density structure using a least-squares inversion which insures mean net upwelling across isopycnal surfaces in the Pacific basin north of the transect. Uncertainties in the velocity field prevent the determination of a non-zero flux of nitrate and dissolved silica at 24 degree N. Net oxygen flux is southward owing to atmospheric exchange in conjunction with the temperature dependent gas solubility. Although net flux is poorly determined, the structure of the nutrient flux at 24 degree N is robust to uncertainties in the circulation: the surface wind driven circulation imports nutrients to the north Pacific while the deep overturning thermohaline circulation exports nutrients in the deep waters. Estimates of basin-scale nutrient remineralization and oxygen utilization rates are in agreement with published values derived from other methods. Mechanisms which contribute to the large scale nutrient budgets are quantitatively examined and horizontal advection is found to play a significant role.
AN: 3693193

                                                                    424 of 1521  
TI: Comparison of anaerobic and aerobic biodegradation of mineralized skeletal structures in marine and estuarine conditions
AU: Simon,-A.; Poulicek,-M.; Velimirov,-B.; Mackenzie,-F.T.
AF: Lab. Morphol., Syst. et Ecol. Anim., Univ. Liege. Inst. Zool., Quai Van Beneden 22, B-4020 Liege, Belgium
SO: BIOGEOCHEMISTRY 1994 vol. 25, no. 3, pp. 167-195
LA: English
ER: M (Marine); B (Brackish)
AB: The knowledge of the biodegradation rates is essential to studies of the biogeochemistry and ecology of aquatic systems. It helps us to quantify the production and uptake rates of chemical components and their recycling, and to understand the mechanisms and rates of organic matter accumulation in sediments. Experimental studies of biodegradation processes in six types of mineralized skeletons were performed in shallow-marine waters of Calvi Bay, Corsica and in estuarine waters of Roscoff, Brittany. Three types of mollusk shells, sea urchin skeletal plates, crab cuticle and fish vertebrae were exposed to oxic and anoxic conditions over periods of 15 days to 30 months. After recovery of the substrates, protein assays, bacterial counts and organic carbon analyses were performed. Quantitative protein assays and bacterial counts indicate that biodegradation of mineralized skeletal structures occurs at a slower rate in anoxic conditions than in oxic conditions. Bacterial analysis showed that in anoxic environment, less than 0.5% of the consumed organic matter is converted into bacterial biomass. The aerobic biodegradation rate was positively correlated with the organic content of the skeletons. Anoxic biodegradation of skeletons occurred at much slower rates in estuarine sediments than in shallow marine sediments. Preservation of skeletal structures in estuarine conditions appears to be correlated with the abundance of dissolved organic matter rather than with high sedimentation rates.
AN: 3693038

                                                                    425 of 1521  
TI: Allochthonous input of organic matter from different riparian habitats of an agriculturally impacted stream
AU: Delong,-M.D.; Brusven,-M.A.
AF: Biol. Dep., Winona State Univ., Winona, MN 55987, USA
SO: ENVIRON.-MANAGE. 1994 vol. 18, no. 1, pp. 59-71
LA: English
ER: F (Freshwater)
AB: Lapwai Creek, an agriculturally impacted stream in northern Idaho, was examined to determine longitudinal patterns of particulate allochthonous input from different riparian vegetation types. The stream, characterized by extensive removal of mature vegetation, was classified as having four riparian vegetation types: herbaceous, herbaceous-shrub mix, shrubs, and deciduous trees. Litterfall from each vegetation type was measured monthly for two years at eight locations along Lapwai Creek using 0.1-m super(2) baskets. Litterfall was lowest for herbaceous habitats and highest for deciduous tree habitats. Annual litterfall was low in the headwaters, which flow through an open meadow and deep canyon, and increased from the canyon-floodplain transition downstream to the first fifth-order site. Annual litterfall decreased markedly at the last two fifth-order stream sections. Differences in annual input rates between section 6 and sections 7 and 8, all of which are fifth order, can be attributed to removal of climax riparian vegetation. Estimates of actual and potential annual allochthonous income for each site suggest that current detrital inputs to Lapwai Creek are less than could be achieved if greater quantities of climax vegetation were still present. Lower rates of allochthonous inputs to Lapwai Creek may result in a system with detrital dynamics and macroinvertebrate communities different from that of comparable undisturbed streams of this region.
AN: 3692757

                                                                    426 of 1521  
TI: Total organic carbon in streamwater from four long-term monitored catchments in Norway
AU: Lydersen,-E.; Henriksen,-A.
AF: Norw. Inst. Water Res., 0411 Oslo, Norway
SO: ENVIRON.-INT. 1994 vol. 20, no. 6, pp. 713-729
LA: English
ER: F (Freshwater)
AB: By linear regression analyses, flux, concentration, and net charge (NC in  mu eq/mg C) of total organic carbon (TOC) have been related to different physico-chemical parameters present in air/precipitation and streamwater at four long-term monitored catchments in Norway, during the period 1986-1992. The catchments vary a lot with respect to annual water input, acid rain, and the streamwater concentration of TOC. Thus, relationships between concentration/NC of TOC and chemical compounds in precipitation and streamwater were often catchment-specific. However, seasonal climatic changes, like air temperature and hydrology, were found to be important for the concentration variations of TOC. The correlation between concentration of nonmarine base cations ( capital sigma BC*) and concentration of TOC at the four sites was far more significant (r=0.86) than the corresponding correlation between nonmarine sulphate (SO sub(4)*) and  capital sigma BC* (r=0.57). This indicates the important role of organic matter in weathering reactions in the catchment. Concerning weathering and cation leaching of aluminum, the correlation between concentration of total aluminum (RAL) and SO sub(4)* was far more significant (r=0.93) compared with the corresponding correlation between RAL and TOC (r=0.40). This should be expected, because a high concentration of SO sub(4)* means a low pH, which is needed to dissolve substantial amounts of Al from soils. The NC of TOC was found to be most affected by compounds in precipitation, primarily the inputs of sea salts. In the most acidified areas, the influence from strong acid inputs also affects the NC of TOC, but less significantly. The concentration of Na super(+) in precipitation is much higher and the variations much larger compared with the concentration of H super(+) in precipitation in the coastal areas, like Birkenes and especially Kaarvatn. Thus, it is reasonable that the variations in sea salt inputs (primarily NaCl) are more important for the temporary variation in NC of TOC compared with H super(+) ions at these sites. Only at Langtjern, the most TOC-influenced site, a significant and positive correlation was found between H super(+) and the concentration of TOC in streamwater. This indicates that at a certain TOC level, the weak organic acids may affect the streamwater pH. A comparison between measured and calculated concentrations of organic Al indicated that the dissociation constants (pK-values) of the organic acids present at Birkeness must be higher and/or the Al-complexing constants lower compared with the constants given by the programme. At the three other sites, it was the other way around. This may explain why a negative correlation between concentrations of TOC and labile Al was present at Birkenes, while the other sites exhibited a corresponding positive correlation with respect to labile Al or  capital sigma Al super(n+). The comparison also documented larger differences in these constants between the sites, compared with monthly variations in the constants at one single site.
AN: 3692755

                                                                    427 of 1521  
TI: Production of isoprene by marine phytoplankton cultures
AU: Moore,-R.M.; Oram,-D.E.; Penkett,-S.A.
AF: Dep. Oceanogr., Dalhousie Univ., Halifax, NS B3H 4J1, Canada
SO: GEOPHYS.-RES.-LETT. 1994 vol. 21, no. 23, pp. 2507-2510
LA: English
ER: M (Marine)
AN: 3691433

                                                                    428 of 1521  
TI: Climatic warming and the decline of zooplankton in the California Current
AU: Roemmich,-D.; McGowan,-J.
AF: Mar. Life Res. Group, Scripps Inst. Oceanogr., Univ. California at San Diego, La Jolla, CA 92093-0230, USA
SO: SCIENCE-WASH. 1995 vol. 267, no. 5202, pp. 1324-1326
LA: English
ER: M (Marine)
AB: Since 1951, the biomass of macrozooplankton in waters off southern California has decreased by 80 percent. During the same period, the surface layer warmed-by more than 1.5 degree C in some places--and the temperature difference across the thermocline increased. Increased stratification resulted in less lifting of the thermocline by wind-driven upwelling. A shallower source of upwelled waters provided less inorganic nutrient for new biological production and hence supported a smaller zooplankton population. Continued warming could lead to further decline of zooplankton.
AN: 3691033

                                                                    429 of 1521  
TI: Spring-neap tidal contrasts and nutrient dynamics in a marsh-dominated estuary
AU: Voeroesmarty,-C.J.; Loder,-T.C.,III
AF: Inst. Study Earth, Oceans, Space, Morse Hall, Univ. New Hampshire, Durham, NH 03824, USA
SO: ESTUARIES 1994 vol. 17, no. 3, pp. 537-551
LA: English
ER: B (Brackish)
AB: This contribution presents a new perspective on water chemistry and its relation to tidal hydrology in marsh-dominated estuaries. Results are derived from both field and modeling experiments. A heuristic model based on a tidally-averaged advection-dispersion equation is used in conjunction with source-sink terms (for benthic, marsh surface, and open-water exchanges) to make predictions of nutrient concentrations in the water column. Spring-neap tidal contrasts are associated with significant changes in water-column chemistry for a variety of nutrients sampled during the growing season in the Parker River estuary (Massachusetts). For ammonium, phosphate, nitrate plus nitrite, total dissolved N, and total dissolved P, concentrations are significantly lower during spring tides (marshes flooded) than during neap tides (marshes unflooded). Model results indicate that physical changes and open-water processing are insufficient to produce the observed effect, and that explicit biogeochemical processing on marsh surfaces is required. Field observations of changes in nutrient to nutrient ratios with the onset of marsh inundation also support this conclusion. As tides progress from the neap to spring condition, a "spectrum" of trajectories emerges in salinity-nutrient plots developed from both observational datasets and model output. Care must therefore be exercised in designing sampling programs for water chemistry in marsh-dominated ecosystems and in interpreting the resulting mixing diagrams.
AN: 3690700

                                                                    430 of 1521  
TI: Internal nutrient budget in a shallow hypereutrophic lake
AU: Reddy,-K.R.; Gale,-P.M.
AF: Soil Water Sci. Dep., Univ. Florida, Gainesville, FL 32611, USA
CO: 14. Annu. International Symposium of the North American Lake Management Society, Orlando, FL (USA), 31 Oct-5 Nov 1994
SO: LAKE-RESERV.-MANAGE. 1994 vol. 9, no. 2, pp. 107-108
NT: Abstract only.
LA: English
ER: F (Freshwater)
AB: Nutrient processing by aquatic biota and bottom sediments can be a major factor in determining the trophic status of a lake. The role of bottom sediments in nutrient release or retention becomes increasingly important in regulating water quality. The objective of this study was to determine the role of bottom sediments in overall nutrient budget of Lake Apopka, a shallow hypereutrophic lake located in Central Florida. As the head waters of the Oklawaha River system, Lake Apopka's water quality can significantly effect that of the lakes downstream. Since the lake has a large surface area and is quite shallow (mean depth of 2 m), stratification of the water column does not occur, as wind driven events can completely mix the system. Although point sources of nutrients such as raw citrus wastes and sewage have been eliminated, the drainage water pumpage from adjacent agricultural fields and the bottom sediments themselves continue to contribute to the nutrient load of the lake. Using the data obtained in the laboratory and field experiments on C, N and P cycle processes in sediment-water column of Lake Apopka, simple nutrient budgets were developed. These budgets suggest that external nutrient inputs to the lake are not always high enough to support the high level of primary productivity currently being measured in the lake. Thus, internal cycling of nutrients between the sediment and the overlying water column apparently contributes to the nutrient requirements of the algae. The lake is functioning as a net sink for C, N and P by transforming inorganic pools of nutrients into organic forms and depositing them on the sediment surface. In short-term, reduction in external loading may not result in significant changes in eutrophic status of the lake. The nutrient release due to diffusive and resuspension flux from bottom sediments can potentially supply most of the nutrient requirements of the algae. However, if the external nutrient loadings are curtailed, over a several year period of time nutrient limitation may occur in the lake as a result of reduction in nutrient supply from bottom sediments. The time period required to achieve nutrient limitation in the lake depends on the effectiveness of the restoration techniques implemented both within the lake and in the drainage basin.
AN: 3690172

                                                                    431 of 1521  
TI: Factors affecting nitrogen loss in experimental wetlands with different hydrologic loads
AU: Phipps,-R.G.; Crumpton,-W.G.
AF: Dep. Bot., Iowa State Univ., Ames, IA 50011, USA
SO: ECOL.-ENG. 1994 vol. 3, no. 4, pp. 399-408
NT: Special issue: Creating freshwater marshes in a riparian landscape.
LA: English
ER: F (Freshwater)
AB: Constructed or restored wetlands have great potential for reducing nonpoint source contamination of surface and ground waters by agricultural chemical contaminants. The work reported here combines field and experimental studies of factors affecting nitrogen loss in the Des Plaines River Experimental Wetlands, northeastern Illinois, USA. These wetlands receive approximately 5-36 cm/week of pumped river water with significant but seasonally variable loads of nitrate and organic nitrogen. On an annual basis, the wetlands removed 78-95% of the nitrate and 54-75% of the total nitrogen received. At the low hydrologic loading rate, organic nitrogen exports approximately equalled imports. However at the higher hydrologic loading rate, the wetlands exported 22-31% more organic nitrogen than received. Seasonal variation in nitrate and organic nitrogen loads had significant effects on the effectiveness of the wetlands as sinks for total nitrogen. The wetlands were nitrogen sinks during periods of high nitrate loading and nitrogen sources during periods of low nitrate loading. Experimental studies demonstrated the effects of nitrate concentration, temperature, and location on rates of nitrate loss. Results suggest that nitrate loading rates might influence not only nitrate loss rates but also loss rate coefficients.
AN: 3689468

                                                                    432 of 1521  
TI: Respiration and dissolution in the sediments of the western North Atlantic: Estimates from models of in situ microelectrode measurements of porewater oxygen and pH
AU: Hales,-B.; Emerson,-S.; Archer,-D.
AF: Univ. Washington Sch. Oceanogr., WB-10, Seattle, WA 98195, USA
SO: DEEP-SEA-RES.-A-OCEANOGR.-RES.-PAP. 1994 vol. 41, no. 4, pp. 695-719
LA: English
ER: M (Marine)
AB: We present in situ microelectrode measurements of sediment formation factor and porewater oxygen and pH from six stations in the North Atlantic varying in depth from 2159 to 5380 m. A numerical model of the oxygen data indicates that fluxes of oxygen to the sediments are as much as an order of magnitude higher than benthic chamber flux measurements previously reported in the same area. Model results require dissolution driven by metabolic CO sub(2) production within the sediments to explain the pH data; even at the station with the most undersaturated bottom waters >60% of the calcite dissolution occurs in response to metabolic CO sub(2). Aragonite dissolution alone cannot provide the observed buffering of porewater pH, even at the shallowest station. A sensitivity test of the model that accounts for uncertainties in the bottom water saturation state and the stoichiometry between oxygen consumption and CO sub(2) production during respiration constrains the dissolution rate constant for calcite to between 3 and 30%/day, in agreement with earlier in situ determinations of the rate constant. Model results predict that over 35% of the calcium carbonate rain to these sediments dissolves at all stations, confirmed by sediment trap and CaCO sub(3) accumulation data.
AN: 3689424

                                                                    433 of 1521  
TI: Causes and consequences of variability in the timing of spring phytoplankton blooms
AU: Townsend,-D.W.; Cammen,-L.M.; Holligan,-P.M.; Campbell,-D.E.; Pettigrew,-N.R.
AF: Dep. Oceanogr., Univ. Maine, Orono, ME 04469, USA
SO: DEEP-SEA-RES.-A-OCEANOGR.-RES.-PAP. 1994 vol. 41, no. 5-6, pp. 747-765
LA: English
ER: M (Marine)
AB: Established conceptual models of the initiation and progression of spring phytoplankton blooms are reconsidered in light of recent observations. We use biological simulation modelling as a tool for the analysis of spring plankton blooms in shallow, coastal waters in temperate latitudes of the North Atlantic. The model shows that interannual variability in the timing of bloom initiation arises from year-to-year differences in incident irradiation, as determined by weather (cloudiness). This variability in timing results in some years when the spring bloom occurs in cold water temperatures near 0 degree C. Model results suggest that due to low temperature inhibition of heterotrophic consumption, more fresh organic material is delivered to the benthos in these cold-water blooms than when the bloom occurs in waters only 3 degree C warmer. Thus we suggest that variable bloom timing can be important to the trophodynamic fate of bloom products. We suggest that variability in timing of spring phytoplankton blooms in offshore and open ocean waters is also related to weather, through controls on the light field and wind mixing. Our analyses of wind-driven vertical mixing demonstrate such blooms can begin following the winter period of deep convection, and prior to the vernal development of stratification, provided that wind speed is below a certain, predictable threshold, which we estimate. In such cases, there may be several spring bloom pulses, each interrupted by self-shading light limitation or vertical mixing events. Eventually the seasonal thermocline develops and nutrient exhaustion curtails bloom production. This means that the spring phytoplankton bloom in offshore and open ocean areas may be significantly more productive, result in more export production, and be more important to the carbon cycle, than has been previously assumed. Furthermore, these features of temperate marine planktonic ecosystems are not only sensitive to annual variations in weather, but also any trends that might result from greenhouse warming or other factors that affect the climate system.
AN: 3689412

                                                                    434 of 1521  
TI: The impact of a coccolithophore bloom on oceanic carbon uptake in the Northeast Atlantic during summer 1991
AU: Robertson,-J.E.; Robinson,-C.; Turner,-D.R.; Holligan,-P.; Watson,-A.J.; Boyd,-P.; Fernandez,-E.; Finch,-M.
AF: Plymouth Mar. Lab., Prospect Pl., Plymouth PL1 3DH, UK
SO: DEEP-SEA-RES.-A-OCEANOGR.-RES.-PAP. 1994 vol. 41, no. 2, pp. 297-314
LA: English
ER: M (Marine)
AB: Measurements of the carbonate system in the surface waters of the northeast Atlantic during summer 1991, following the main growth phase of a bloom of the coccolithophore Emiliania huxleyi are presented. We examine the perturbation of the carbonate system and assess the effect of calcification on the air-sea gradient of dissolved carbon dioxide in the surface ocean. An estimate of 1:1 organic to inorganic carbon uptake is calculated using the measurements of the surface carbonate parameters which is consistent with other estimates for E. huxleyi populations using radio-tracer methods. Using the changing ratio of dissolved carbon dioxide to nitrate concentration we demonstrate a relative increase in dissolved carbon dioxide due to calcification with evidence of this increase supported by estimates of the buffer factor and C:N assimilation ratios. Within the E. huxleyi bloom the effect of calcification on alkalinity appears to have reduced the air-sea gradient by  similar to 15  mu atms (corrected to a constant temperature) using measurements from a 440 km section along the 20 degree W meridian. This reduction could prove to be significant in terms of the overall drawdown of carbon during the spring-summer season in this area.
AN: 3687928

                                                                    435 of 1521  
TI: Global oceanic and atmospheric oxygen stability considered in elation to the carbon cycle and to different time scales
AU: Duursma,-R.K.; Boisson,-M.P.R.M.
AF: Residence Les Marguerites, Appt. 15, 1305, Chemin des Rivoires, 06320 La Turbie, France
SO: OCEANOL.-ACTA 1994 vol. 17, no. 2, pp. 117-141
LA: English
ER: M (Marine)
AB: This paper constitutes an overview and synthesis concerning atmospheric and oceanic oxygen and related carbon dioxide, particular attention being paid to potential regulation mechanisms on different time scales. The world atmospheric oxygen reserve is remarkably large, so that a lack of oxygen will not easily occur, whether in confined spaces or in major conurbations. Atmospheric oxygen production began some 3.2 billion years ago, and has resulted in a net total amount of 5.63 x 10 super(20) mol (1.8 x 10 super(22) g) of oxygen, of which 3.75 x 10 super(19) mol is present as free oxygen in the atmosphere and 3.1 x 10 super(17) mol as dissolved oxygen in the oceans, the remainder being stored in a large number of oxidized terrestrial and oceanic compounds. The present global atmospheric oxygen level remains remarkably constant at a level of 20.946  plus or minus  0.006 vol %, with a slight decrease of 0.0004 O sub(2) vol %/yr (4 ppmv/yr) which is counter-correlated to CO sub(2) produced by fossil-fuel and biomass burning. The atmosphere-ocean exchange budget of CO sub(2) is dominated by the fossil-fuel and biomass fire-derived CO sub(2), of which 39 % is due to CO sub(2) increase in the atmosphere, 30 % is taken up by the oceans, the remainder possibly being recovered by biomass growth. Compared to the atmosphere-ocean flux of CO sub(2), the biogenic ocean fluxes of carbon ("oceanic biological pumps") are lower by a factor of at least ten (burial of organic matter and foraminifers, and reef growth).
AN: 3686514

                                                                    436 of 1521  
TI: Designing a simple microbiological-physical model for a coastal embayment
AU: Tett,-P.; Grenz,-C.
AF: Univ. Wales, Bangor: Sch. Ocean Sci., Menai Bridge, Gwynedd LL59 5EY, UK
SO: VIE-MILIEU 1994 vol. 44, no. 1, pp. 39-58
LA: English
ER: M (Marine)
AB: Numerical modelling provides a means of studying the processes that cycle nutrients and organic material as they pass through the coastal zone on their way from the land to the sea. The Gulf of Fos is an embayment on the Mediterranean coast of France, receiving part of the discharge of the Rhone river. We discuss the design of a simple numerical model for the Gulf. The model couples the physical processes of estuarine circulation, density stratification, and particulate resuspension, with the microbiological processes of light - and nutrient - controlled growth of pelagic micro-algae, bacteria and protozoans, and the detrital remineralisation of nutrients in water-column and sediment. Simple numerical experiments are used to show (1) the role of the Gulf in cycling land-derived nutrients before they reach the open sea; (2) the importance of particulate resuspension in controlling light availability for photosynthesis and the export of organic material; and (3) the high frequency of variability in this shallow, wind-forced system.
AN: 3686497

                                                                    437 of 1521  
TI: Influence of aquatic macrophytes on phosphorus and sediment porewater chemistry in a freshwater wetland
AU: Moore,-B.C.; Lafer,-J.E.; Funk,-W.H.
AF: Dep. Nat. Resour. Sci., Washington State Univ., Pullman, WA 99164-6410, USA
SO: AQUAT.-BOT. 1994 vol. 49, no. 2-3, pp. 137-148
LA: English
ER: F (Freshwater)
AB: The influence of the emergent aquatic macrophyte, Menyanthes trifoliata L. on sediment interstitial porewater chemistry, particularly on the distribution of soluble reactive phosphorus (SRP), was investigated at Silver Lake in southwestern Washington (Cowlitz County). Menyanthes trifoliata and many other wetland species create an oxygenated rhizosphere by translocation of oxygen to the roots. Close interval diffusion sampling showed that SRP, total soluble phosphorus (TSP), and concentrations of other redox-sensitive species such as T-Fe, Fe super(2+), and T-Mn were reduced in interstitial waters when macrophytes were present. Total alkalinity and pH also were lower and oxidation-reduction potentials were higher in sediments with plants than those in which the plants were removed. Rhizosphere oxidation appears to provide wetland species with a mechanism for sequestering phosphorus and for creating favorable concentration gradients within the root zone.
AN: 3684435

                                                                    438 of 1521  
TI: Sulfate reduction and sediment metabolism in Tomales Bay, California
AU: Chambers,-R.M.; Hollibaugh,-J.T.; Vink,-S.M.
AF: Tiburon Cent. Environ. Stud., San Francisco State Univ., P.O. Box 855, Tiburon, CA 94920, USA
SO: BIOGEOCHEMISTRY 1994 vol. 25, no. 1, pp. 1-18
LA: English
ER: B (Brackish)
AB: Sulfate reduction rates (SRR) in subtidal sediments of Tomales Bay, California, were variable by sediment type, season and depth. Higher rates were measured in near-surface muds during summer (up to 45 nmol cm super(-3)/h), with lower rates in sandy sediments, in winter and deeper in the sediment. Calculations of annual, average SRR throughout the upper 20 cm of muddy subtidal sediments (about 30 mmol S m super(-2)/d) were much larger than previously reported net estimates of SRR derived from both benthic alkalinity flux measurements and bay wide, budget stoichiometry (3.5 and 2.6 mmol m super(-2)/d, respectively), indicating that most reduced sulfur in these upper, well-mixed sediments is re-oxidized. A portion of the net alkalinity flux across the sediment surface may be derived from sulfate reduction in deeper sediments, estimated from sulfate depletion profiles at 1.5 mmol m super(-2)/d. A small net flux of CO sub(2) measured in benthic chambers despite a large SRR suggests that sediment sinks for CO sub(2) must also exist (e.g., benthic microalgae).
AN: 3680775

                                                                    439 of 1521  
TI: Recent advances in freshwater ecology
AU: Jones,-J.G.
AF: Freshwat. Biol. Assoc., Ferry House, Far Sawrey, Ambleside Cumbria LA22 0LP, UK
CO: 2. Reunion Argentina de Limnologia, La Plata (Argentina), Nov 1991
SO: CONFERENCES-ON-LIMNOLOGY.#CONFERENCIAS-DE-LIMNOLOGIA. Boltovsky,-A.;Lopez,-H.L.-eds. 1993 pp. 159-169
LA: Spanish
ER: F (Freshwater)
AB: The paper examines aspects of current research in freshwater ecology at three levels. The application of techniques of molecular biology has permitted significant advances, not least in the area of bacterial population ecology. At the other end of the scale these methods will permit us to determine the degree of relatedness of different fish stocks. The analysis of phytoplankton populations has now reached the stage where the results of several long term programmes can be combined to produce truly predictive models. Finally the knowledge that has been gained during the study of biogeochemical cycles can now be applied in the active management of lakes and reservoirs. This has been particularly successful when management strategies have been employed to counter the acidity of both natural and man-made water bodies.
AN: 3680215

                                                                    440 of 1521  
TI: Carbonate systems in the Baltic and Weddell Seas: Inventories and influences by man
AU: Ohlson,-M.
CA: Goeteborg Univ./Chalmers Univ. of Technology (Sweden). Dep. of Analytical and Marine Chemistry
SO: 1991 32 pp
NT: NTIS Order No.: DE92506616/GAR. Thesis (FD). 28 refs.
RN: NEI-SE-94 (NEISE94)
LA: English
ER: M (Marine)
AB: The result of recent measurements of the total alkalinity and calcium in the Baltic Sea are presented. The 1986 investigation gives a significantly different calcium to total alkalinity ratio (0.691) compared to literature values (0.41). Explanations for the difference in calcium to total alkalinity ratio are offered, based on reactions in the drainage basins including decay of organic matter, precipitation of acid rain and dissolution of carbonate minerals. From later investigations a more reasonable explanation seems that the shift is due to chemical patchiness in the Baltic proper. In spite of the acidic precipitation and the increased partial pressure of carbon dioxide in the atmosphere it seems that the carbonate system has not changed dramatically during the century. Existing fluctuations are mainly depending on the season and the inflow of dense water from the Kattegat/North Sea. A carbonate model has been coupled to a one-dimensional physical and biogeochemical model of the Baltic proper. The considered regulating mechanisms have been the atmospheric carbon dioxide pressure, the river run-off concentration of total alkalinity and total carbonate, and the total alkalinity in the precipitation. With the present concentrations of the above regulating mechanisms the uptake of atmospheric carbon dioxide by the Baltic proper gets about 12 g C/m(sup 2)/year and the net sedimentation gets about 8 g C/m(sup 2)/year. Total carbonate data from the southern Weddell Sea, collected during the Swedish Antarctic Expedition in 1988-1989, have been investigated with respect to the contribution of anthropogenic carbon dioxide. The anthropogenic carbon dioxide mean concentration varies in the different water masses from about 36 (mu)mol/kg in the Ice Shelf water to 8 (mu)mol/kg in the Antarctic bottom water. The evaluated annual transport of anthropogenic carbon amounts to 8x10(sup 12) g for this special area. [U.S. Sales Only.] (DBO)
AN: 3679965

                                                                    441 of 1521  
TI: Interhemispheric transport of carbon through the ocean
AU: Broecker,-W.S.; Peng,-T.H.
CA: Oak Ridge Natl. Lab., TN (USA)
SO: 1991 22 pp
NT: NTIS Order No.: DE92007246/GAR.
RN: CONF-9109340-2 (CONF91093402)
LA: English
ER: M (Marine)
AB: A case is made that the Atlantic's conveyor circulation carries roughly 0.6 gigatons of carbon (as (Sigma)CO(sub 2)) from the northern to the southern hemisphere. The return transport of this carbon (as CO(sub 2)) through the atmosphere would maintain a 1.6 ppm south to north gradient in atmospheric CO(sub 2) content. Such a gradient would go a long way toward explaining the current lower than expected fossil fuel CO(sub 2) supported north to south atmospheric gradient and hence would alleviate the necessity for the large northern hemisphere terrestrial sink proposed by Tans et al., 1990. [Contract AC05-84OR21400. Ciocco global cycle meeting (2nd), Ciocco (Italy), 8-20 Sep 1991. Sponsored by Department of Energy, Washington, DC.] (DBO)
AN: 3679892

                                                                    442 of 1521  
TI: Simulations of the carbon cycle in the oceans. (Part 3): (Annual report)
AU: Siegenthaler,-U.
CA: Bern Univ. (Switzerland)
SO: 1991 18 pp
NT: NTIS Order No.: DE91017410/GAR.
RN: DOE/ER/61054-1 (DOEER610541)
LA: English
ER: M (Marine)
AB: Our original goal of modelling the impact of seasonality on CO(sub 2) uptake in the ocean should be completed during the next year, now that the study of the effect of iron fertilization on global CO(sub 2) levels has been completed. The analysis of existing 3D nitrogen circulation models is nearing completion, and will produce two manuscripts. A combined carbon/nitrogen mixed layer ecosystem model has been completed and the equations were made available for inclusion in the Princeton North Atlantic General Circulation Model. A coupled air/sea model of anthropogenic CO(sub 2) uptake is currently under development, and development of this model is our highest priority in the next year. (MHB). [Contract FG02-90ER61054. Sponsored by Department of Energy, Washington, DC.] (DBO)
AN: 3679803

                                                                    443 of 1521  
TI: Dynamics of phosphorus in lake systems
AU: Kenney,-B.C.
CA: Inland Waters Dir., Ottawa, ON (Canada)
SO: 1990 55 pp
NT: NTIS Order No.: MIC-91-02049/GAR.
LA: English
ER: F (Freshwater)
AB: The phosphorus loading concept is examined within the framework of equilibrium input-output models. Some theoretical and practical shortcomings of several phosphorus models are then discussed. Finally, the dynamics of total phosphorus in lakes is explored using first-order linear theory with time-dependent coefficients.
AN: 3677651

                                                                    444 of 1521  
TI: Climate-related variations in denitrification in the Arabian Sea from sediment  super(15)N/ super(14)N ratios
AU: Altabet,-M.A.; Francois,-R.; Murray,-D.W.; Prell,-W.L.
AF: Mar. Chem. and Geochem. Dep., Woods Hole Oceanogr. Inst., Woods Hole, MA 02543, USA
SO: NATURE 1995 vol. 373, no. 6514, pp. 506-509
LA: English
ER: M (Marine)
AB: Denitrification--the process by which nitrate is reduced to gaseous nitrogen species (usually N sub(2) or N sub(2)O)--is the dominant mechanism for removal of fixed nitrogen from the biosphere. In the oceans, denitrification is mediated by bacteria in suboxic environments and, by controlling the supply of fixed nitrogen, is an important limiting factor for marine productivity. Denitrification produces substantial  super(15)N enrichment in subsurface nitrate, which is reflected in the isotopic composition of sinking particulate nitrogen; sediment  super(15)N/ super(14)N ratios in regions with suboxic water columns may therefore provide a record of past changes in denitrification intensity. Here we report nitrogen isotope data for sediment cores from three sites in the Arabian Sea. At all three sites we find large, near-synchronous downcore variations in  super(15)N/ super(14)N, which are best explained by regional changes in the isotopic composition of subsurface nitrate, and hence denitrification. Moreover, these variations are synchronous with Milankovitch cycles, thereby establishing a link with climate. We argue that these large, climate-linked variations, in a region that contributes significantly to global marine denitrification, are likely to have perturbed marine biogeochemical cycles during the Late Quaternary period.
AN: 3676502

                                                                    445 of 1521  
TI: Beyond global warming: Ecology and global change
AU: Robert,-H.; MacArthur,-A.L.
AF: Dep. Biol. Sci., Stanford Univ., Stanford, CA 94305, USA
SO: ECOLOGY 1994 vol. 75, no. 7, pp. 1861-1876
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: While ecologists involved in management or policy often are advised to learn to deal with uncertainty, there are a number of components of global environmental change of which we are certain--certain that they are going on, and certain that they are human-caused. Some of these are largely ecological changes, and all have important ecological consequences. Three of the well-documented global changes are: increasing concentrations of carbon dioxide in the atmosphere; alterations in the biogeochemistry of the global nitrogen cycle; and ongoing land use/land cover change. These three and other equally certain components of global environmental change are the primary causes of anticipated changes in climate, and of ongoing losses of biological diversity. They are caused in turn by the extraordinary growth in size and resource use of the human population. On a broad scale, there is little uncertainty about any of these components of change or their causes. However, much of the public believes the causes--even the existence--of global change to be uncertain and contentious topics. By speaking out effectively, we can help to shift the focus of public discussion towards what can and should be done about global environmental change.
AN: 3676293

                                                                    446 of 1521  
TI: Simulation model of the coupling between nitrification and denitrification in a freshwater sediment
AU: Blackburn,-T.H.; Blackburn,-N.D.; Jensen,-K.; Risgaard-Petersen,-N.
AF: Dep. Microb. Ecol., Inst. Biol. Sci., Univ. Aarhus, Ny Munkegade, DK-8000 Aarhus C, Denmark
SO: APPL.-ENVIRON.-MICROBIOL. 1994 vol. 60, no. 9, pp. 3089-3095
LA: English
ER: F (Freshwater)
AB: A model was constructed to simulate the results of experiments which investigated nitrification and denitrification in the freshwater sediment of Lake Vilhelmsborg, Denmark. The model output faithfully represented the profiles of O sub(2) and NO sub(3) super(-) and rates of nitrification, denitrification, and O sub(2) consumption as the O sub(2) concentration in the overlying water was increased from 10 to 600  mu M. The model also accurately predicted the response, to increasing O sub(2) concentrations, of the integrated (micromoles per square meter per hour) rates of nitrification and denitrification. The simulated rates of denitrification of NO sub(3) super(-) diffusing from the overlying water (D sub(w)) and of NO sub(3) super(-) generated by nitrification within the sediment (D sub(n)) corresponded to the experimental rates as the O sub(2) concentration in the overlying water was altered. The predicted D sub(w) and D sub(n) rates, as NO sub(3) super(-) concentration in the overlying water was changed, closely resembled those determined experimentally. The model was composed of 41 layers 0.1 mm thick, of which 3 represented the diffusive boundary layer in the water. Large first-order rate constants for nitrification and denitrification were required to completely oxidize all NH sub(4) super(+) diffusing from the lower sediment layers and to remove much of the NO sub(3) super(-) produced. In addition to the flux of NH sub(4) super(+) from below, the model required a flux of an electron donor, possibly methane. Close coupling between nitrification and denitrification, achieved by allowing denitrification to tolerate some O sub(2) ( similar to 10  mu M), was necessary to reproduce the real data. Spatial separation of the two processes (no toleration by denitrification of O sub(2)) resulted in too high NO sub(3) super(-) concentrations and too low rates of denitrification.
AN: 3673347

                                                                    447 of 1521  
TI: Changes in oceanic and terrestrial carbon uptake since 1982
AU: Francey,-R.J.; Tans,-P.P.; Allison,-C.E.; Enting,-I.G.; White,-J.W.C.; Trolier,-M.
AF: CSIRO Div. Atmos. Res., Priv. Bag 1, Mordialloc, Vic. 3195, Australia
SO: NATURE 1995 vol. 373, no. 6512, pp. 326-330
LA: English
AB: Changes in the carbon isotope ratio ( delta  super(13)C) of atmospheric CO sub(2) can be used in global carbon-cycle models to elucidate the relative roles of oceanic and terrestrial uptake of fossil-fuel CO sub(2). Here we present measurements of  delta  super(13)C made at several stations in the Northern and Southern hemispheres over the past decade. Focusing on the highest-quality data from Cape Grim (41 degree S), which also provide the longest continuous record, we observed a gradual decrease in  delta  super(13)C from 1982 to 1993, but with a pronounced flattening from 1988 to 1990. There is an inverse relationship between CO sub(2) growth rate and El Nino/Southern Oscillation (ENSO) events which is not reflected in the isotope record. Thus, for the ENSO events in 1982, 1986 and 1991-92, we deduce that net ocean uptake of CO sub(2) increased, whereas during La Nina events, when equatorial sea surface temperatures are lower, upwelling of carbon-rich water increases the release of CO sub(2) from the oceans. The flattening of the trend from 1988 to 1990 appears to involve the terrestrial carbon cycle, but we cannot yet ascribe firm causes. We find that the large and continuing decrease in CO sub(2) growth starting in 1988 involves increases in both terrestrial and oceanic uptake, the latter persisting through 1992.
AN: 3671992

                                                                    448 of 1521  
TI: Ecosystem changes in the North Pacific Subtropical Gyre attributed to the 1991-92 El Nino
AU: Karl,-D.M.; Letelier,-R.; Hebel,-D.; Tupas,-L.; Dore,-J.; Christian,-J.; Winn,-C.
AF: SOEST, Dep. Oceanogr., Univ. Hawaii, Honolulu, HI 96822, USA
SO: NATURE 1995 vol. 373, no. 6511, pp. 230-234
LA: English
ER: M (Marine)
AB: Subtropical ocean gyres are considered to be the marine analogues of terrestrial deserts because of chronic nutrient depletion and low standing stocks of organisms. Despite their presumed low rates of primary and export production, oligotrophic habitats contribute significantly to global productivity because of their large extent. Therefore, even small changes in ecosystem production can produce large effects in the global carbon cycle. The North Pacific Subtropical Gyre has generally been thought to support a homogeneous, stable biological community, but recent investigations have suggested instead that the ecosystem of this gyre is temporally and spatially variable. The causes of this variability are not well understood. Here we present evidence of a major change in the structure and productivity of the pelagic ecosystem in the Subtropical North Pacific Ocean, an effect that we attribute to the 1991-92 El Nino-Southern Oscillation (ENSO) event. Decreased upper-ocean mixing and a change in circulation resulted in an increased abundance and activity of nitrogen-fixing micro-organisms and a shift from a primarily nitrogen-limited to a primarily phosphorus-limited habitat with attendant changes in total and export production and in nutrient cycling pathways and rates.
AN: 3671939

                                                                    449 of 1521  
TI: Iron limitation and the cyanobacterium Synechococcus in equatorial Pacific waters
AU: Wells,-M.L.; Price,-N.M.; Bruland,-K.W.
AF: Inst. Mar. Sci. Univ. California, Santa Cruz, CA 95064, USA
SO: LIMNOL.-OCEANOGR. 1994 vol. 39, no. 6, pp. 1481-1486
LA: English
ER: M (Marine)
AB: Iron enrichments in bottle experiments in high nutrient, low chlorophyll (HNLC) surface waters typically stimulate the net growth of nanophytoplankton (2.0-20  mu m) but not picophytoplankton (<2.0  mu m), suggesting either that picophytoplankton are not Fe limited or that any increased picophytoplankton growth is balanced by increased microzooplankton grazing rates. Using a novel approach in which we diminish iron availability in seawater with the fungal siderophore deferriferrioxamine B, we demonstrate that growth of the abundant picoplanktonic cyanobacterium Synechococcus is not strongly rate limited by Fe in the HNLC equatorial Pacific Ocean. However, experiments at the equator and 5 degree S show an unsuspected non-uniformity in iron nutrition within this HNLC region. Furthermore, our results indicate that a major portion of "dissolved" (<0.4  mu m) iron in these waters is unavailable to Synechococcus, providing the first evidence that a significant fraction of dissolved iron occurs in forms other than the simple hydroxy species predicted by thermodynamic models. Deferriferrioxamine B affords a powerful new tool for probing the iron nutrition of marine phytoplankton and can provide unique insight into the role of iron in marine biogeochemical cycles.
AN: 3670139

                                                                    450 of 1521  
TI: Effects of sinking and zooplankton grazing on the release of elements from planktonic debris
AU: Lee,-B.-G.; Fisher,-N.S.*
AF: Mar. Sci. Res. Cent., State Univ. of New York, Stony Brook, NY 11794-5000, USA
SO: MAR.-ECOL.-PROG.-SER. 1994 vol. 110, no. 2-3, pp. 271-281
NT: Bibliogr.: 55 ref.
LA: English
ER: M (Marine)
AB: Laboratory radiotracer experiments compared the effects of zooplankton grazing and microbial decomposition on the release of organic C and Ag, Cd, Co, Pb and Po from phytoplankton cells. After 40 h incubation of diatoms with copepods + microorganisms, 70% of the diatom cellular C was remineralized to CO sub(2) (40%), assimilated in copepod tissue (20%), excreted in fecal pellets (5%) or released as DOC (5%); microorganisms alone removed half this amount of diatom C. Copepod grazing enhanced the conversion of Ag from diatom cells to other forms (particulate and dissolved) by 27%, Po by 25 %, Pb by 20% Cd by 13%, and Co by 10%, over those cells incubated with only microorganisms; zooplankton grazing increased by 5 to 15%, the release of elements from diatom cells into the dissolved phase. Decomposing copepod fecal pellets, held free-falling on a spinning wheel, lost about 20% more C, Ag, Co and Pb than did undisturbed fecal pellets, while no appreciable difference was observed for release of metals from copepod carcasses treated similarly. The results suggest that retention of an element contained primarily in the cytoplasm of phytoplankton cells (such as C or Cd) is largely governed by microbial activity and leaching. Microbial activity has a smaller effect on particle-reactive elements (Ag and Pb) bound to structural components of cells; zooplankton are effective in removing these unassimilable elements by grazing and packaging them into rapidly sinking fecal pellets.
AN: 3668626

                                                                    451 of 1521  
TI: Grazer-mediated regeneration and assimilation of Fe, Zn and Mn from planktonic prey
AU: Hutchins,-D.A.; Bruland,-K.W.
AF: Mar. Sci. Res. Cent., SUNY Stony Brook, NY 11794-5000, USA
SO: MAR.-ECOL.-PROG.-SER. 1994 vol. 110, no. 2-3, pp. 259-269
NT: Bibliogr.: 45 ref.
LA: English
ER: M (Marine)
AB: Experiments were performed to investigate grazer remineralization and assimilation of Fe, Zn and Mn from autotrophic and heterotrophic plankton prey. Metal isotope activity incorporated into planktonic prey was added to bottles containing crustacean zooplankton grazers, and distribution of the added metals into dissolved, fecal pellet and grazer fractions was monitored over time. At the end of a 9 to 10 h grazing period, concentrations of dissolved metal isotopes were approximately 3 to 7 times higher in bottles with grazers than in control bottles without grazers. An experiment in which flagellate grazers were fed Fe-labeled cyanobacteria suggested that protozoans may also remineralize trace metals ingested with prey. Metal assimilation efficiencies from diatom and flagellate prey were determined in crustacean grazers; efficiencies energy creased in the order Zn > Fe > Mn. These experiments indicate that biologically required trace metals behave much like major nutrients during grazing, and suggest that biologically mediated regeneration and recycling could be an important part of the marine biogeochemical cycles of Fe, Zn and Mn.
AN: 3668625

                                                                    452 of 1521  
TI: Coexistence of sulfate reduction and methane production in an organic-rich sediment
AU: Holmer,-M.; Kristensen,-E.
AF: Dep. Life Sci. and Chem., Roskilde Univ., P.O. Box 260, DK-4000 Roskilde, Denmark
SO: MAR.-ECOL.-PROG.-SER. 1994 vol. 107, no. 1-2, pp. 177-184
NT: Bibliogr.: 35 ref.
LA: English
ER: M (Marine)
AB: Anaerobic mineralization processes were studied over a period of 40 d in an organic-rich sediment amended with labile organic matter (fish food pellets). Although measured sulfate reduction rates (SRR) were high (up to  similar to 2400 nmol/cm super(3)/d), a coexistence between sulfate-reducing bacteria (SRB) and methane-producing bacteria (MPB) was evident. Methane production rates (MPR) of the same order of magnitude as SRR (up to  similar to 1300 nmol/cm super(3)/d) occurred even when sulfate was present in high concentrations (5 to 60 mM). Acetate was an important substrate for the SRB initially, but its role diminished after 180 h of incubation, indicating that SRB used other substrates than acetate. There was only minor competition for acetate between SRB and MPB, as indicated by the lack of effect on MPR by inhibition of SRB with molybdate. This provides a possible explanation for the coexistence between SRB and MPB; in this organic-rich sediment the concentration of competitive substrates either exceeds the competition level or substrates are used noncompetitively.
AN: 3668462

                                                                    453 of 1521  
TI: A comparative study on 5'- nucleotidase (5'-nase) and alkaline phosphatase (APA) activities in two lakes
AU: Siuda,-W.; Guede,-H.
AF: Dep. Microbiol. Ecol., Inst. Microbiol., Univ. Warsaw, Ul. Karowa 18, Warsaw, Poland
SO: ARCH.-HYDROBIOL. 1994 vol. 131, no. 2, pp. 211-229
NT: Bibliogr.: 52 ref.
LA: English
ER: F (Freshwater)
AB: Phosphorus regeneration by 5'-nucleotidase (5'-nase) and alkaline phosphatase (APA) was studied in the pelagic zones of two German lakes. The obtained results supported the existence of an enzymatic mechanism of phosphorus-regeneration in pelagic lake water, which appears to be distinct from APA and is presumed to be represented by 5'-nucleotidases of bacterial origin. These enzymes exhibit a high substrate-affinity and a high specificity for nucleotides. In contrast to APA, no inhibition of activity by inorganic phosphorus (Pi) was observed. However, the enzymes could be strongly inhibited by Ni super(2+) ions and to some extent by Glucose-6-Phosphate. As was exemplified with ATP as substrate, the Pi released by these enzymes was much in excess of the uptake capacities of the plankton community at high substrate concentrations. At these conditions the majority of the planktonic uptake of the released Pi occurred in the algal size fraction. However, the coupling between release and uptake became much stronger at lower substrate concentrations, coinciding with an increased percentage of bacterial uptake. The obtained results suggest that regeneration of orthophosphate by the 5'-nase system may be more significant for the phosphorus dynamics of the whole planktonic community as compared to Pi liberation by APA activities.
AN: 3668441

                                                                    454 of 1521  
TI: Seasonal variation in sediment urea turnover in a shallow estuary
AU: Therkildsen,-M.S.; Lomstein,-B.A.
AF: Dep. Microbial Ecol., Inst. Biol. Sci., Univ. Aarhus, DK-8000 Aarhus, Denmark
SO: MAR.-ECOL.-PROG.-SER. 1994 vol. 109, no. 1, pp. 77-82
NT: Bibliogr.: 33 ref.
LA: English
ER: M (Marine)
AB: A seasonal study of sediment urea turnover rates was carried out in a shallow Danish estuary. Turnover, rates decreased with sediment depth (0 to 16 cm) and were within the range 1.2 to 424.8 nmol N/cm super(3)/d. Integrated (0 to 16 cm depth) turnover rates varied between 1.5 and 16.9 mmol N/m super(2)/d with a maximum in July and a minimum in January. Urea turnover followed first-order rate kinetics, as the urea turnover rate constant, k sub(urea), was independent of the urea concentration, and the urea turnover rates were positively related to the latter. The urea turnover rate and rate constant were positively related to temperature. Urea production was stimulated by availability of high quality organic material (low C/N) and temperature. Urea production rates and urea concentrations in the sediment reached a maximum in July, when C-mineralization, temperature, and the quality of organic material were maximal, and there was a high benthic macrofaunal biomass. Secondary maxima in urea concentrations matched major phytoplankton sedimentation events in spring and autumn. Urea-N accounted for 7 to 55%, of the total N pool (urea + NH sub(4) super(+) + N0 sub(3) super(-) + NO sub(2) super(-)) in the sediment surface (0 to 1 cm.) The NH sub(4) super(+) pool was positively related to the urea turnover rate ( sigma 0 to 16 cm). Urea turnover accounted for a major part of the NH sub(4) super(+) production in the sediment.
AN: 3668397

                                                                    455 of 1521  
TI: Network analysis on nitrogen cycling in a coastal lagoon
AU: Fores,-E.; Christian,-R.R.; Comin,-F.A.; Menendez,-M.
AF: Dep. Ecol., Fac. Biol., Univ. Barcelona, Diagonal 645, E-08028 Barcelona, Spain
SO: MAR.-ECOL.-PROG.-SER. 1994 vol. 106, no. 3, pp. 283-290
NT: Bibliogr.: 33 ref.
LA: English
ER: M (Marine)
AB: Network analysis was applied to nitrogen cycling data from 6 ecosystem components (phytoplankton, Potamogeton pectinatus, Ruppia cirrhosa, detritus plus heterotrophs, sediment, and dissolved inorganic nitrogen) in Tancada Lagoon (Ebro River delta, NE Spain) to ascertain (1) the relative importance of internal recycling versus external exchanges, (2) the main biogeochemical processes and (3) the fate of nitrogen imported to the lagoon. We compared cycling from 2 periods of the year: May-October, dominated by freshwater inputs, and November-April, dominated by seawater. Nitrogen recycling in the lagoon is equal to or more important than exchanges with other ecosystems, as indicated by the Finn Cycling Index (FCI). FCI values are the percentage of total flow in the network which is associated with internal cycles and not with imports or exports. These internal cycles involve flows from a compartment that can be traced through 1 or more other compartments and back to the original. FCI values were 62% during the freshwater period and 52% during the seawater period. Nitrogen input to the lagoons was mainly as detritus plus heterotroph nitrogen (0.81 and 0.51 mmol N m super(-2) d super(-1) during the fresh- and seawater periods respectively). Most nitrogen export was as phytoplankton (0.2 mmol N m super(-2) d super(-1) during both periods). Denitrification rates were comparable to other exports (0.17 and 0.09 mmol m super(-2) d super(-1) during the fresh- and seawater periods respectively). Sediment played a key role in the international recycling of nitrogen. A total of 80% of the phytoplankton nitrogen flow came indirectly from ammonium fluxes between sediment and water during the freshwater period, and 60% during the seawater period. Thus several differences were noted in the N cycles between these 2 periods involving both the amount of recycling and the relative importance of different processes to the fate of nitrogen.
AN: 3668123

                                                                    456 of 1521  
TI: Simulated degradation of phytodetritus in deep-sea sediments of the NE Atlantic (47 degree N, 19 degree W)
AU: Poremba,-K.
AF: Inst. Meereskd., Univ. Kiel, Abt. Mar. Mikrobiol., Duesternbrooker Weg 20, D-24105 Kiel, FRG
SO: MAR.-ECOL.-PROG.-SER. 1994 vol. 105, no. 3, pp. 291-299
NT: Bibliogr.: 54 ref.
LA: English
ER: M (Marine)
AB: The degradation of phytodetritus in the deep sea was studied in sediment samples of the NE Atlantic in spring and summer 1992 using  super(14)C-labelled algal cells (Anacystis) fed to the benthic population in ship-board experiments and measuring the liberation of labelled  super(14)CO sub(2) over time. The mineralization process showed a 2-step behaviour with an initial rapid rate which later slowed down, indicating the initial attack of easily degradable material of the complex food and the later utilization of less labile matter. The profile of degradation activity with sediment depth showed no clear vertical gradient in March, but in August the activity in the top horizon increased by a factor of 6.1 to 7.8, which was coherent with increased bacterial numbers or biomass (factor of 1.3 to 1.7), respectively, and might be caused by the seasonal input of phytodetritus to the deep-sea bottom. The degradation measured was positively influenced by elevated incubation pressure mostly in summer, indicating that the summer stimulation of microbial activity in 1992 was based on the metabolic activation of the indigenous benthic community, while surface-derived organisms attached to sedimented particles were of lesser importance with respect to consumption of phytodetritus.
AN: 3668115

                                                                    457 of 1521  
TI: Past and present biomineralization processes. Considerations about the carbonate cycle. IUCN-COE Workshop, Monaco, 15-16 November 1993
AU: Doumenge,-F.; Allemand,-D.; Toulemont,-A.-(eds.)
AF: Musee Oceanogr. Monaco, Monaco
CO: Past and Present Biomineralization Processes. Considerations about the Carbonate Cycle. IUCN-COE Workshop, Monaco (Monaco), 15-16 Nov 1993
SO: BULL.-INST.-OCEANOGR.-MONACO MONACO-MONACO MUSEE-OCEANOGRAPHIQUE 1994 no. Spec. Iss. 13, 196 pp
LA: English
ER: M (Marine)
AB: Two days of open pluridisciplinary workshops were organized (on November 15 and 16) to appraise the information required and suggest new hypotheses and directions for research in all the areas relating to carbon and carbonate cycles. These six colloquia, each organized and directed by a guest speaker, highlighted various regulatory mechanisms for maintaining life on earth, despite the episodic distortions of the space-time continuum. Today, the time has come to proceed with a broad pluridisciplinary platform so as to reinterpret the major palaeontological crises in the light of current mechanisms. In this context, our guest speakers stimulated a general discussion on some key phenomena: The unity of these contributions lies in a common concern for: 1) introducing original ideas and approaches to open new directions for research; 2) identifying the state of current knowledge, along with often considerable gaps, thus revealing areas for research; 3) supplying accurate information on each topic from a pluridisciplinary viewpoint, with abundant bibliographic references and illustrations. The lively and always productive discussions following these presentations reflect the broad interest of the scientific community and provide ample food for thought. The outcome of these two days is particularly stimulating. It is a clear encouragement to pursue structured research projects through networks - formal and informal - ensuring collaboration between researchers and providing further support for scientific institutions. Our hope is not only that this work supplies an effective tool for information and reflection, but that it also acts as a catalyst for all the good intentions expressed during this exceptionally productive symposium.
AN: 3666664

                                                                    458 of 1521  
TI: Strategies for the study of climate forcing by calcification
AU: Westbroek,-P.; Buddemeier,-B.; Coleman,-M.; Kok,-D.J.; Fautin,-D.; Stal,-L.
AF: Dep. Chem., Leiden Univ., P.O. Box 9502, 2300 RA Leiden, Netherlands
CO: Past and Present Biomineralization Processes. Considerations about the Carbonate Cycle. IUCN-COE Workshop, Monaco (Monaco), 15-16 Nov 1993
SO: PAST-AND-PRESENT-BIOMINERALIZATION-PROCESSES.-CONSIDERATIONS-ABOUT-THE-CARBONATE-CYCLE.-IUCN-COE-WORKSHOP,-MONACO-MONACO,-15-16-NOVEMBER-1993. Doumenge,-F.;Allemand,-D.;Toulemont-A.-eds. MONACO-MONACO MUSEE-OCEANOGRAPHIQUE 1994 no. Spec. Iss. 13 pp. 37-60
ST: BULL.-INST.-OCEANOGR.-MONACO no. Spec. Iss. 13
LA: English
ER: M (Marine)
AB: The massive biological intervention in the climate system and the complexity of the biological response to global change call for a coordinated and well-organised scientific effort. In this paper we propose a hierarchical systems approach to study one particular aspect of geosphere-biosphere interactions - the marine cycle of calcium carbonate. The bulk ocean tends to be supersaturated with respect to this mineral. Yet, as ambient crystallization inhibitors and active biological 'anti-calcification' prevent physico-chemical precipitation of calcium carbonate, its production depends on the ecological and evolutionary success of the calcifying biota. As the most efficient method to study this intricate process, a series of integrated experimental and modeling studies is proposed, at three levels. Level I studies the general role of calcium carbonate mineralisation in biogeochemical cycling, using microbial mats as the key experimental system. The major calcium carbonate generating biological systems are then studied separately at Level II. Procedures for two of these studies are worked out in some detail, i.e., for coral reefs and coccolithophores. In the former case, selected reef communities are used as model systems, in the second the cosmopolitan species Emiliania huxleyi plays this exemplary role. Finally, at Level III, the results of the previous studies are combined, resulting in a realistic model of the marine calcium carbonate cycle. We suggest that our model systems approach is also applicable to aspects of geosphere-biosphere interactions other than carbonate biogeochemistry.
AN: 3666614

                                                                    459 of 1521  
TI: Demethylation and cleavage of dimethylsulfoniopropionate in marine intertidal sediments
AU: Visscher,-P.T.; Kiene,-R.P.; Taylor,-B.F.
AF: U.S. Geol. Survey-MS 465, 345 Middlefield Rd., Menlo Park, CA 94025, USA
SO: FEMS-MICROBIOL.-ECOL. 1994 vol. 14, no. 2, pp. 179-190
LA: English
ER: M (Marine)
AB: Demethylation and cleavage of dimethylsulfoniopropionate (DMSP) was measured in three different types of intertidal marine sediments: a cyanobacterial mat, a diatom-covered tidal flat and a carbonate sediment. Consumption rates of added DMSP were highest in cyanobacterial mat slurries (59  mu mol DMSP/1 slurry/h) and lower in slurries from a diatom mat and a carbonate tidal sediment (24 and 9  mu mol DMSP/1/h, respectively). Dimethyl sulfide (DMS) and 3-mercaptopropionate (MPA) were produced simultaneously during DMSP consumption, indicating that cleavage and demethylation occurred at the same time. Viable counts of DMSP-utilizing bacteria revealed a population of 2 x 10 super(7) cells/cm super(3) sediment (90% of these cleaved DMSP to DMS, 10% demethylated DMSP to MPA) in the cyanobacterial mat, 7 x 10 super(5) cells/cm super(3) in the diatom mat (23% cleavers, 77% demethylators), and 9 x 10 super(4) cells/cm super(3) (20% cleavers and 80% demethylators) in the carbonate sediment. In slurries of the diatom mat, the rate of MPA production from added 3-methiolpropionate (MMPA) was 50% of the rate of MPA formation from DMSP. The presence of a large population of demethylating bacteria and the production of MPA from DMSP suggest that the demethylation pathway, in addition to cleavage, contributes significantly to DMSP consumption in coastal sediments.
AN: 3665770

                                                                    460 of 1521  
TI: Regeneration of inorganic phosphorus and nitrogen from decomposition of seston in a freshwater sediment
AU: Andersen,-F.O.; Jensen,-H.S.
AF: Dep. Biol., Odense Univ., DK-5230 Odense M, Denmark
SO: HYDROBIOLOGIA 1992 vol. 228, no. 1, pp. 71-81
NT: Spec. Iss.: Sediment-Water Interaction.
LA: English
ER: F (Freshwater)
AB: The mineralization of phosphorus and nitrogen from seston was studied in consolidated sediment from the shallow Lake Arreskov (July and November) and in suspensions without sediment (July). In the suspension experiment, phosphorus and nitrogen were mineralized in the same proportions as they occurred in the seston. During the 30 days suspension experiment, 47 and 43% of the particulate phosphorus and nitrogen, respectively, was mineralized with constant rates. Addition of seston to the sediment had an immediate enhancing effect on oxygen uptake, phosphate and ammonia release, whereas nitrate release decreased due to denitrification. The enhanced rates lasted for 2-5 weeks, while the decrease in nitrate release persisted throughout the experiment. The increase in oxygen uptake (equivalent to 21% of the seston carbon) was, however, only observed in the July experiment. The release of phosphorus and nitrogen from seston decomposing on the sediment surface differed from the suspension experiments. Thus, between 91 and 111% of the phosphorus in the seston was released during the experiments. Due to opposite directed effects on ammonium and nitrate release, the resulting net release of nitrogen was relatively low. A comparison of C/N/P ratios in seston, sediment and flux rates indicated that nitrogen was mineralized faster than phosphorus and carbon. Some of this nitrogen was lost through denitrification and therefore not measurable in the flux of inorganic nitrogen ions. This investigation also suggests that decomposition of newly settled organic matter in sediments have indirect effects on sediment-water exchanges (e.g. by changing of redox potentials and stimulation of denitrification) that modifies the release of mineralized phosphate and nitrogen from the sediment.
AN: 3663821

                                                                    461 of 1521  
TI: Biogeochemical processes in Amazon Shelf sediments
AU: Aller,-R.C.; Aller,-J.Y.; Blair,-N.E.; Mackin,-J.E.; Rude,-P.D.; Stupakoff,-I.; Patchineelam,-S.; Boehme,-S.E.; Knoppers,-B.
AF: Mar. Sci. Res. Cent., SUNY, Stony Brook, NY 11794, USA
SO: OCEANOGRAPHY 1991 vol. 4, no. 1, pp. 27-32
LA: English
ER: M (Marine)
AB: Each year the Amazon River delivers approximately 1 billion metric tons of sediment to the equatorial Atlantic. A portion of this debris is highly weathered and contains abundant reactive Fe, Mn, Al, and Si oxides. The associated terrestrial organic matter is biologically refractory. Upon entering the Amazon Shelf region, particles are exposed to seawater brine, mixed with labile planktonic organic matter, and incorporated into the seabed where a variety of geochemical reactions take place. Major research efforts within the AmasSeds Project include elucidating the types and rates of these diagenetic reactions, their governing factors, and their influence on the properties of overlying water and preserved deposits. Modern views of early diagenetic processes in shallow marine sediments have largely derived from studies of temperate estuaries and shelves, particularly along the coasts of North America and Europe. In these environments, sedimentary organic matter is decomposed through the general sequential series of biogeochemical oxidants (O sub(2), NO super(-) sub(3), Mn, Fe, SO super(=) sub(4), CO sub(2)), although reactions are typically dominated over large vertical intervals by sulfate reduction or methanogenesis. Oxygen is often relegated to a largely indirect role as an oxidant of anaerobic metabolites. Other potential oxidants of organic matter such as NO super(-) sub(3), Mn and Fe oxides, are of minor importance. The chemical properties of sediments and patterns of authigenic mineral formation in deposits reflect these reaction paths, as well as diagenetic transport regimes strongly influenced by the bioturbation activities of benthic organisms. In contrast, early studies of Amazon Shelf sediments demonstrated extensive zones of suboxic reactions associated with Fe,Mn reduction and oxidation cycles, and little evidence of macrobenthic activity. Unlike other shelf deposits of similar organic content, sulfate depletion is limited, dissolved sulfide is undetectable, and sulfide minerals are minor in the upper few meters. High concentrations of dissolved Fe super(++) and Mn super(++) in pore water (0.1-1 mM) are found throughout the upper 0.5-2 m of Amazon deposits compared with vertical intervals 0.01-0.05-m thick in many shelves. These suboxic zones extend across the Amazon Shelf for  similar to 100 km, encompassing an area of at least 40,000 km super(2) off Brazil alone. Because Fe and Mn oxides and their reduction products are carrier phases for numerous minor and trace elements, their redox cycling can critically influence oceanic chemistry. The input of highly weathered debris and massive physical mobility/reworking of sediments are apparently critical factors determining these patterns. (DBO)
AN: 3663539

                                                                    462 of 1521  
TI: AmasSeds: An interdisciplinary investigation of a complex coastal environment
AU: Nittrouer,-C.A.; DeMaster,-D.J.; Figueiredo,-A.G.; Rine,-J.M.
AF: Mar. Sci. Res. Cent., SUNY, Stony Brook, NY 11794, USA
SO: OCEANOGRAPHY 1991 vol. 4, no. 1, pp. 3-7
LA: English
ER: M (Marine)
AB: A multidisciplinary Amazon Shelf SEDiment Study (AmasSeds) is being undertaken on the continental shelf near the mouth of the Amazon River. Details of the AmasSeds international research project are described in the five papers which follow. The present paper outlines the justification, background and approach of the overall project. On the Amazon shelf, between the Para estuary and the Brazil-French Guiana Border, material input and energy expenditure are enormous. This situation produces a myriad of complex interdependent oceanic processes. Sediment is a common link between the diverse processes, because most of them affect and/or are affected by the particles found on the Amazon shelf. The fundamental justification for AmasSeds research is that a number of unique oceanic processes are active near the mouths of very large rivers, and that these processes cannot be understood solely by extrapolation from observations of smaller river systems. For example, the papers which follow will demonstrate that biological productivity and cycling of many geochemical components are largely controlled by the immense discharge of sediment particles. The freshwater discharge of the Amazon displaces typical estuarine circulation from the river mouth into the three-dimensional setting of the shelf, where it is superimposed on marine circulation. Extremely high supply rates of sediment to the Amazon shelf create fluid muds which severely affect marine sediment transport and create an extensive subaqueous delta with special morphologic and stratigraphic character. In addition to being unique, oceanic processes in coastal environments near the mouths of large rivers are very important. They control the fate of the material that is discharged, and in this way affect global budgets. On a worldwide basis, the Amazon discharges 18% of all river water, 10% of fluvial sediment and 8% of dissolved solids. How and whether this material reaches the rest of the world ocean is dependent upon oceanic processes operating on the Amazon shelf. AmasSeds also will provide valuable new insights into some special attributes of the Amazon shelf, such as its location in an equatorial setting. Terrestrial and marine equatorial environments are especially sensitive to world climatic conditions, and the strata preserved at the mouth of the Amazon record the histories of both environments. Chemical weathering in equatorial settings produces lateritic soils and iron-rich sediments, which cause unusual geochemical signatures in the marine portions of the Amazon dispersal system. In addition, important changes to the basic physics of ocean circulation result when river effluent is released at the equator in the absence of Coriolis forces. The Amazon shelf is an ideal study area to investigate the detailed operation of interdisciplinary oceanic processes for reasons described above, and because results from previous research allowed the design of an intricate field and laboratory study. (DBO)
AN: 3663530

                                                                    463 of 1521  
TI: Swimmers: A recapitulation of the problem and a potential solution
AU: Karl,-D.M.; Knauer,-G.A.
SO: OCEANOGRAPHY 1989 vol. 2, no. 1, pp. 32-35
LA: English
ER: M (Marine)
AB: We read, with great interest, the article by Lee et al. (1988) concerning the effects of "swimmers" on the measurement of particulate organic matter flux in the marine environment. Generally swimmers are either: (1) acknowledged and their impact reduced by manually removing the carcasses ("picking") before further sample processing, (2) acknowledged, but trap contents analyzed unaltered, or (3) totally ignored. None of these three options is acceptable, if the desired outcome is to obtain accurate particle flux estimates. As Lee et al. (1988) discuss in their review, the swimmer problem is exacerbated in near-surface waters ( less than or equal to 500 m). Unfortunately, the measurement of particulate organic matter flux in the upper water column is crucial to our understanding of biogenic element cycles, including the rates and mechanisms of nutrient regeneration and, consequently, crucial to addressing the Global Ocean Flux Study (GOFS) program objectives. Because sediment traps are now recognized as the only method for estimating the passive downward flux of organic matter in the sea (SCOR WG-71 report on "Particulate Biogeochemical Processes," S. Krishnaswami, chairman), our progress toward a resolution of these important oceanic processes is stalled at this time. So, to provide a brief answer to the rhetorical question posed in their title, "Are 'Swimmers' a Problem?," we believe the reply is an overwhelming affirmative. (DBO)
AN: 3663177

                                                                    464 of 1521  
TI: Joint Global Ocean Flux Study: The 1989 North Atlantic Bloom Experiment
AU: Ducklow,-H.W.
AF: Horn Point Environ. Lab., Univ. Maryland Cent. Environ. Estuar. Stud., Box 775, Cambridge, MD 21613, USA
SO: OCEANOGRAPHY 1989 vol. 2, no. 1, pp. 4-8
LA: English
ER: M (Marine)
AB: In 1989, JGOFS begins a six-nation, eight month investigation of biogeochemical processes in the North Atlantic Ocean. This experiment will emphasize observation of the spring phytoplankton bloom and its biogeochemical consequences along longitude 20 degree W, between 15 degree  and 60 degree N latitude, from March to October. The North Atlantic Bloom Experiment is intended to be a pilot study for future JGOFS experiments. (DBO)
AN: 3663176

                                                                    465 of 1521  
TI: The effect of substrate stoichiometry on microbial activity and carbon degradation in humic lakes
AU: Hessen,-D.O.; Nygaard,-K.; Salonen,-K.; Vaehaetalo,-A.
AF: Univ. Oslo, Dep. Biol., Box 1027 Blindern, N-0315 Oslo, Norway
CO: 4. Nordic Symp. on Humic Substances, Loen (Norway), 7-9 Jun 1993
SO: ENVIRON.-INT. 1994 vol. 20, no. 1, pp. 67-76
LA: English
ER: F (Freshwater)
AB: Studies of bacterial growth and community respiration in water from two humic lakes indicated a balanced supply of C relative to N and P under periods with low loads of allochthonous C (humus). A predominant mineral nutrient limitation existed when external C supply was high. During autumn, both nitrogen and phosphorus additions stimulated bacterial growth, while community respiration was stimulated by N and P combined, but not N alone. Additions of excess labile carbon (glucose) never stimulated either bacterial growth or respiration, while glucose and mineral nutrients combined gave rise to a vigorous production, suggesting that a strict C limitation is unlikely for heterotrophic bacteria in these lakes. Increased anthropogenic loadings of N and P may thus stimulate heterotrophic activity in humic lakes, increase degradation of humic matter, and finally increase CO sub(2) outputs to the atmosphere. A prevailing mineral nutrient limitation of the bacteria would strongly affect the algal-bacterial competition and constrain phytoplankton production.
AN: 3662108

                                                                    466 of 1521  
TI: An ecological perspective on methane emissions from northern wetlands
AU: Bubier,-J.L.; Moore,-T.R.
AF: Dep. Geogr., McGill Univ., 805 Sherbrooke St. W., Montreal, PQ H3A 2K6, Canada
SO: TRENDS-ECOL.-EVOL. 1994 vol. 9, no. 12, pp. 460-464
LA: English
ER: F (Freshwater)
AB: Wetlands are significant sources of atmospheric methane, an important radiatively active "greenhouse" gas that accounts for an estimated 12% of total greenhouse warming. Since global climate models predict the greatest temperature and precipitation changes at high latitudes, and as the largest areas of wetland (346 x 10 super(6) ha) are in the boreal and subarctic regions (40-70 degree N), recent research has focused on identifying the factors that control methane emission from northern wetlands. Over the past few years, the database has expanded tremendously, and much progress has been made in understanding the environmental controls on methane emission at small spatial and temporal scales. However, we now need to broaden our understanding of regional differences in methane emission, ecological responses of northern wetlands to climate change, and the effect of other perturbations such as drainage and flooding.
AN: 3661940

                                                                    467 of 1521  
TI: The production of  super(34)S-depleted sulfide during bacterial disproportionation of elemental sulfur
AU: Canfield,-D.E.; Thamdrup,-B.
AF: Sch. Earth and Atmos. Sci., Georgia Inst. Technol., Atlanta, GA 30332, USA
SO: SCIENCE-WASH. 1994 vol. 266, no. 5193, pp. 1973-1975
LA: English
AB: Bacteria that disproportionate elemental sulfur fractionate sulfur isotopes such that sulfate is enriched in sulfur-34 by 12.6 to 15.3 per mil and sulfide is depleted in sulfur-34 by 7.3 to 8.6 per mil. Through a repeated cycle of sulfide oxidation to S super(0) and subsequent disproportionation, these bacteria can deplete sedimentary sulfides in sulfur-34. A prediction, borne out by observation, is that more extensive sulfide oxidation will lead to sulfides that are more depleted in sulfur-34. Thus, the oxidative part of the sulfur cycle creates circumstances by which sulfides become more depleted in sulfur-34 than would be possible with sulfate-reducing bacteria alone.
AN: 3661577

                                                                    468 of 1521  
TI: Problems in the quantitative analysis of submicron particles in marine waters
AU: Ruiz,-J.; Rodriguez,-J.
AF: Fac. Cienc. Mar, Univ. Cadiz, Puerto Real, Cadiz, Spain
CO: NATO Experimental Workshop on the Size Structure and Metabolism of the Marine Microbial Food Web, Malaga (Spain), 25 Jan-5 Feb 1993
SO: THE-SIZE-STRUCTURE-AND-METABOLISM-OF-THE-PELAGIC-ECOSYSTEM. Rodriguez,-J.;Li,-W.K.W-eds. BARCELONA-SPAIN INSTITUTO-DE-CIENCIAS-DEL-MAR 1994 vol. 58, no. 1-2 pp. 81-86
ST: SCI.-MAR.-BARC. vol. 58, no. 1-2
LA: English
ER: M (Marine)
AB: A procedure is described to avoid artifacts due to instabilities when measuring submicron particles (SMP) by mean of resistance pulse instruments (Coulter registered  principle). The sample has to flow for at least half an hour before recording the counts given by the equipment. The concentrations of SMP obtained with this procedure are similar to those obtained with image analysis by Sieracki & Viles (1992) but more than one order of magnitude lower than those given by Koike et al. (1990). The discrepancies with the results of Koike et al. (op. cit.) are concentrated in the smallest SMP. Therefore, our results leads us to suggest caution when considering the role of SMP in the biogeochemical cycling of elements in the ocean.
AN: 3661463

                                                                    469 of 1521  
TI: Particle-solution behaviour of plutonium in an estuarine environment, Esk Estuary, UK
AU: Hamilton-Taylor,-J.; Kelly,-M.; Titley,-J.G.; Turner,-D.R.
AF: Cent. Adv. Anal. Chem., Priv. Mail Bag 7, Menai, NSW 2234, Australia
SO: GEOCHIM.-COSMOCHIM.-ACTA 1993 vol. 57, no. 14, pp. 3367-3381
LA: English
ER: B (Brackish)
AB: The particle-solution (K sub(d)) relationships of Pu(III,IV) in the Esk Estuary are investigated, using new experimental data together with a synthesis of our earlier work. Adsorption of  super(236)Pu(IV) by a suspension of intertidal mud (40 mg/L) from the Esk Estuary was determined after 1 h, as a function of salinity and pH, in a series of controlled laboratory experiments. Desorption of  super(239,240)Pu(III,IV) from this environmentally contaminated sediment was determined concurrently. The short term (i.e., within a tidal cycle) non-conservative behaviour of Pu(III,IV) in both the laboratory experiments and the estuary appears to be dominated by a rapid, reversible surface complexation reaction, although only a small fraction (<5%) of the  super(239,240)Pu(III,IV) activity of the environmentally contaminated sediment is able to participate in the reaction. The existence of this exchangeable or labile fraction can explain the apparent dependence of Pu(III,IV) K sub(d) on sediment concentration. Thus, a single K sub(d) value is able to describe both the observed adsorption and desorption behaviour and the effect of sediment concentration, when desorption is expressed with respect to the labile  super(239,240)Pu(III,IV) fraction. For example, in R. Esk water, the adsorption of  super(236)Pu(III,IV) and the desorption of  super(239,240)Pu(III,IV), over a two order of magnitude concentration range of unwashed Esk Estuary sediment, can be accounted for by a single K sub(d) of  similar to 3 x 10 super(3) L/kg. The K sub(d) for the labile Pu(III,IV) fraction varies mainly as a function of salinity. pH is not an important factor over the pH range 4-9, although H super(+) ion exchange does occur, probably through a similar surface complexation reaction. The kinetic and equilibrium characteristics of the Pu(III,IV) sorption behaviour conform to the pattern observed by Jannasch et al. (1988) and other workers for a range of trace elements.
AN: 3661288

                                                                    470 of 1521  
TI: Seasonal and geographic variations of methanesulfonic acid in the Arctic troposphere
AU: Li,-S.-M.; Barrie,-L.A.; Talbot,-R.W.; Harriss,-R.C.; Davidson,-C.I.; Jaffrezo,-J.-L.
AF: Atmos. Environ. Serv., 4905 Dufferin St., Downsview, ON, Canada
SO: ATMOS.-ENVIRON.,-PART-A 1993 vol. 27A, no. 17-18, pp. 3011-3024
NT: Special Issue: Arctic Air, Snow and Ice Chemistry.
LA: English
ER: M (Marine); B (Brackish); F (Freshwater)
AB: Measurements in the Arctic troposphere over several years show that MSA concentrations in the atmospheric boundary layer, 0.08-6.1 parts per trillion (ppt, molar mixing ratio), are lower than those over mid-latitude oceans. The seasonal cycle of MSA at Alert, Canada (82.5 degree N, 62.3 degree W), has two peaks of 6 ppt in March-April and July-August and minima of 0.3 ppt for the rest of the year. At Dye 3 (65 degree N, 44 degree W) on the Greenland Ice Sheet, a similar seasonal MSA cycle is observed although the concentrations are much lower with a maximum of 1 ppt. Around Barrow, Alaska (71.3 degree N, 156.8 degree W), MSA is between 1.0 and 25 ppt in July, higher than 1.5  plus or minus  1.0 ppt in March-April. The mid-tropospheric MSA level of 0.6-1 ppt in the summer Arctic is much lower than about 6 ppt in the boundary layer. At Alert, the ratio of MSA to non-sea-salt (nss) SO sub(4) super(2-) ranges from 0.02 to 1.13 and is about 10 times higher in summer than in spring. The summer ratios are higher than found over mid-latitude regions and, when combined with reported sulfur isotope compositions from the Arctic, suggest that on average a significant fraction (about 16-23%) of Arctic summer boundary layer sulfur is marine biogenic. The measurements show that the summer Arctic boundary layer has a significantly higher MSA/nss-SO sub(4) super(2-) ratio than aloft.
AN: 3660466

                                                                    471 of 1521  
TI: Chemosynthetic bacterial mats at cold hydrocarbon seeps, Gulf of Mexico continental slope
AU: Sassen,-R.; Roberts,-H.H.; Aharon,-P.; Larkin,-J.; Chinn,-E.W.; Carney,-R.
AF: Geochem. Environ. Res. Gr., Texas A&M Univ., College Station, TX 77845, USA
SO: ORG.-GEOCHEM. 1993 vol. 20, no. 1, pp. 77-89
