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Nitrate reduction rates and soil/ water chemistry from roadside ditches in the Mobile Bay (AL, USA) region (2018-05-23 to 2018-06-08) (NCEI Accession 0211099)

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Ninety-six roadside ditches spanning three landuse types in the Mobile Bay (Alabama, USA) region were sampled in May-June of 2018. Isotope pairing was used to measure nitrate reduction rates (denitrification, anammox, and dissimilatory nitrate reduction to ammonium) on soil slurries. These values were used to calculate the percentage of nitrogen removed in ditch soils. Soil extractable nitrate and ammonium, organic matter content, and plant above/ belowground biomass were measured as well. There was standing water in seventeen of the ditches and it was measured for nitrite, nitrate, ammonium, and phosphate concentrations.

Dataset Citation

Cite as: Tatariw, Corianne; Mason, Olivia U.; Mortazavi, Behzad (2020). Nitrate reduction rates and soil/ water chemistry from roadside ditches in the Mobile Bay (AL, USA) region (2018-05-23 to 2018-06-08) (NCEI Accession 0211099). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. https://www.ncei.noaa.gov/archive/accession/0211099. Accessed [date].

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gov.noaa.nodc:0211099

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Distributor	NOAA National Centers for Environmental Information +1-301-713-3277 ncei.info@noaa.gov
Dataset Point of Contact	NOAA National Centers for Environmental Information ncei.info@noaa.gov

Time Period	2018-05-23 to 2018-06-08
Spatial Bounding Box Coordinates	West: -88.166945 East: -87.74264 South: 30.372541 North: 30.66327
Spatial Coverage Map

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Publication Dates	publication: 2020-07-15
Data Presentation Form	Digital table - digital representation of facts or figures systematically displayed, especially in columns
Dataset Progress Status	Complete - production of the data has been completed Historical archive - data has been stored in an offline storage facility
Data Update Frequency	As needed
Purpose	This dataset is available to the public for a wide variety of uses including scientific research and analysis.
Use Limitations	accessLevel: Public Distribution liability: NOAA and NCEI make no warranty, expressed or implied, regarding these data, nor does the fact of distribution constitute such a warranty. NOAA and NCEI cannot assume liability for any damages caused by any errors or omissions in these data. If appropriate, NCEI can only certify that the data it distributes are an authentic copy of the records that were accepted for inclusion in the NCEI archives.

Dataset Citation	Cite as: Tatariw, Corianne; Mason, Olivia U.; Mortazavi, Behzad (2020). Nitrate reduction rates and soil/ water chemistry from roadside ditches in the Mobile Bay (AL, USA) region (2018-05-23 to 2018-06-08) (NCEI Accession 0211099). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. https://www.ncei.noaa.gov/archive/accession/0211099. Accessed [date].
Cited Authors	Tatariw, Corianne University of Alabama (UA) Mason, Olivia U. Mortazavi, Behzad
Contributors	University of Alabama (UA)
Resource Providers	Corianne Tatariw University of Alabama (UA) University of Alabama (UA)
Points of Contact	Corianne Tatariw University of Alabama (UA)
Publishers	NOAA National Centers for Environmental Information
Acknowledgments	Funding Agency: National Science Foundation

Theme keywords	NODC DATA TYPES THESAURUS AMMONIUM (NH4) LATITUDE LONGITUDE nitrate + nitrite content (concentration) NITROGEN ORGANIC MATTER - WEIGHT PERCENT NODC OBSERVATION TYPES THESAURUS in situ laboratory analyses WMO_CategoryCode oceanography Global Change Master Directory (GCMD) Science Keywords EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > AMMONIA EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > NITRATE EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > NITRITE EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > NITROGEN EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > ORGANIC MATTER Provider Keywords Aboveground Plant Biomass Anammox Rate Belowground Plant Biomass Collection Date DNRA Rate Denitrification Rate Ditch width Extractable NH4+ Extractable NO2+3- Landuse N Removal Soil Chemistry Water Chemistry Water Column NH4+ Water Column NO2- Water Column NO3- Water Column PO43-
Data Center keywords	NODC COLLECTING INSTITUTION NAMES THESAURUS University of Alabama NODC SUBMITTING INSTITUTION NAMES THESAURUS University of Alabama
Instrument keywords	NODC INSTRUMENT TYPES THESAURUS fluorometer spectrophotometer Global Change Master Directory (GCMD) Instrument Keywords FLUOROMETERS > FLUOROMETERS OPTSPEC > Optical Spectrometer Provider Instruments Google Maps Membrane inlet mass spectrometer Muffle furnace, balance Quadrat, balance T-corer, balance Tape measure flurometer
Place keywords	NODC SEA AREA NAMES THESAURUS Coastal Waters of Alabama Gulf of Mexico Global Change Master Directory (GCMD) Location Keywords OCEAN > ATLANTIC OCEAN > NORTH ATLANTIC OCEAN > GULF OF MEXICO Provider Place Names Mobile Bay, Alabama
Project keywords	Provider Project Names CBET 1438092 CBET 1643486
Keywords	NCEI ACCESSION NUMBER 0211099
Keywords	Send2NCEI Submission Package ID 4514GD

Use Constraints	Cite as: Tatariw, Corianne; Mason, Olivia U.; Mortazavi, Behzad (2020). Nitrate reduction rates and soil/ water chemistry from roadside ditches in the Mobile Bay (AL, USA) region (2018-05-23 to 2018-06-08) (NCEI Accession 0211099). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. https://www.ncei.noaa.gov/archive/accession/0211099. Accessed [date].
Access Constraints	Use liability: NOAA and NCEI cannot provide any warranty as to the accuracy, reliability, or completeness of furnished data. Users assume responsibility to determine the usability of these data. The user is responsible for the results of any application of this data for other than its intended purpose.
Fees	In most cases, electronic downloads of the data are free. However, fees may apply for custom orders, data certifications, copies of analog materials, and data distribution on physical media.

Lineage information for: dataset
Processing Steps	2020-07-15T21:05:15Z - NCEI Accession 0211099 v1.1 was published.
Output Datasets	NCEI Accession 0211099 v1.1 NCEI Accession 0211099 v1.1 (download) published 2020-07-15T21:05:15Z

Lineage information for: dataset
Processing Steps	Parameter or Variable: Collection Date (measured); Units: yyyy-mm-dd; Observation Category: other; Sampling Instrument: calendar; Sampling and Analyzing Method: Ditches were sampled over four dates (23 May 2018, 25 May 2018, 05 June 2018, and 08 June 2018), with eight reaches sampled in each watershed on each date for n=24 per date.. Parameter or Variable: Landuse (measured); Units: none; Observation Category: other; Sampling Instrument: none; Sampling and Analyzing Method: The study was conducted in three watersheds of different predominant land use types surrounding Mobile Bay, Alabama (USA). Fowl River, the southernmost watershed on the west coast of Mobile Bay, was predominantly forested/ wetland (66.7%) (Fowl River Watershed Management Plan 2016). Dog River was a predominantly urban (60.4%) watershed that shares its southern border with Fowl River and includes the City of Mobile. An estimated 16.1% of Dog River watershed was impervious cover (Dog River Watershed Management Plan 2017). The third watershed, Weeks Bay, was located on the east coast of Mobile Bay, and had predominantly agricultural (41.1%) land cover (Final Weeks Bay Watershed Management Plan 2017).. Parameter or Variable: Replicate (measured); Units: none; Observation Category: other; Sampling Instrument: none; Sampling and Analyzing Method: Thirty-two ditch reaches were selected within approximately 90 km2 areas located within the three watersheds. A reach was defined as the length of ditch between two culverts. No reaches were continuous, i.e. no reaches were directly connected by culverts. Ditches were sampled over four dates (23 May 2018, 25 May 2018, 05 June 2018, and 08 June 2018), with eight reaches sampled in each watershed on each date for n=24 per date.. Parameter or Variable: LATITUDE (measured); Units: Decimal Degrees; Observation Category: in situ; Sampling Instrument: Google Maps; Sampling and Analyzing Method: Latitude of each ditch sampled. Ditch location was logged in Google Maps at the time of sampling.. Parameter or Variable: LONGITUDE (measured); Units: Decimal Degrees; Observation Category: in situ; Sampling Instrument: Google Maps; Sampling and Analyzing Method: Longitude of each ditch sampled. Ditch location was logged in Google Maps at the time of sampling.. Parameter or Variable: Ditch width (measured); Units: m; Observation Category: in situ; Sampling Instrument: tape measure; Sampling and Analyzing Method: Ditch width was measured at the location of sampling.. Parameter or Variable: Aboveground Plant Biomass (measured); Units: kg/m^2; Observation Category: laboratory analysis; Sampling Instrument: quadrat, balance; Sampling and Analyzing Method: Aboveground plant biomass was determined by clipping the aboveground plant material to the soil surface within a 0.25 m x 0.25 m quadrat that was randomly thrown into the sampling area. Aboveground samples were oven-dried to constant weight at 60°C.. Parameter or Variable: Belowground Plant Biomass (measured); Units: kg/m^2; Observation Category: laboratory analysis; Sampling Instrument: t-corer, balance; Sampling and Analyzing Method: Belowground biomass in the 0-5 cm depth increment was collected using a t-corer (i.d.=7.9 cm). Root material was separated from soil by wet sieving with a 2.0 mm sieve. Root material was oven-dried to constant weight.. Parameter or Variable: Extractable NO2+3- (measured); Units: (µmol g-1); Observation Category: laboratory analysis; Sampling Instrument: spectrophotometer; Sampling and Analyzing Method: Syringe cores (i.d = 1.3 cm) were used to collect soil from the top 5 cm for extractable nitrate + nitrite (NO2+3-). Samples were homogenized by vortexing in 2M potassium chloride (KCl). Following an overnight extraction by horizontal shaking at 70 RPM, samples were centrifuged and the supernatant filtered (VWR filters) into centrifuge tubes and frozen until analysis. Soil extractable NO2+3- was determined colorimetrically by vanadium chloride (detection limit = 0.01 µmol g dry sediment-1).. Parameter or Variable: Extractable NH4+ (measured); Units: (µmol g-1); Observation Category: laboratory analysis; Sampling Instrument: fluorometer; Sampling and Analyzing Method: Syringe cores (i.d = 1.3 cm) were used to collect soil from the top 5 cm for extractable ammonium (NH4+). Samples were homogenized by vortexing in 2M potassium chloride (KCl). Following an overnight extraction by horizontal shaking at 70 RPM, samples were centrifuged and the supernatant filtered (VWR filters) into centrifuge tubes and frozen until analysis.Soil extractable NH4+ was determined fluoremetrically by the OPA method (detection limit = 0.04 µmol g dry sediment-1).. Parameter or Variable: ORGANIC MATTER - WEIGHT PERCENT (measured); Units: %; Observation Category: laboratory analysis; Sampling Instrument: muffle furnace, balance; Sampling and Analyzing Method: Syringe cores (i.d = 1.3 cm) were used to collect soil from the top 5 cm for organic matter content. Cores were oven dried at 60°C. Dried cores were ground using a mortar and pestle and ashed at 600°C for six hours.. Parameter or Variable: Denitrification Rate (measured); Units: µmol N kg dry weight-1 h-1; Observation Category: laboratory analysis; Sampling Instrument: membrane inlet mass spectrometer; Sampling and Analyzing Method: Syringe cores (0-5 cm, i.d. =2.6 cm) were collected to determine denitrification, rates. Soils were extruded into Ziploc bags and transported on ice back to the lab, where they were stored at 4°C overnight. The following day, each sample was slurried with commercial Spring Water (Walmart). Slurries were bubbled with dinitrogen (N2) gas to produce anoxic conditions and siphoned into Exetainer vials (Labco). Following an overnight incubation at room temperature to remove ambient NO3- and oxygen (O2), slurries were spiked to ~50 µM Na15NO3 (99 atom %; Cambridge Isotope Laboratories, Inc.). One half of the slurry tubes were immediately spiked with zinc chloride (ZnCl2, 50% W/V) to stop biological activity. The other half were incubated on a shaker table for ~6 hours at room temperature then spiked with ZnCl2. Denitrification was measured based on the concentration of 29N2 and 30N2 concentrations in slurry water using a membrane inlet mass spectrometer (MIMS) outfitted with a copper reduction column to remove excess oxygen. Denitrification rates from sediment slurries were calculated using the isotope pairing technique.. Parameter or Variable: Anammox Rate (measured); Units: µmol N kg dry weight-1 h-1; Observation Category: laboratory analysis; Sampling Instrument: membrane inlet mass spectrometer; Sampling and Analyzing Method: Syringe cores (0-5 cm, i.d. =2.6 cm) were collected to determine anammox rates. Soils were extruded into Ziploc bags and transported on ice back to the lab, where they were stored at 4°C overnight. The following day, each sample was slurried with commercial Spring Water (Walmart). Slurries were bubbled with dinitrogen (N2) gas to produce anoxic conditions and siphoned into Exetainer vials (Labco). Following an overnight incubation at room temperature to remove ambient NO3- and oxygen (O2), slurries were spiked to ~50 µM Na15NO3 (99 atom %; Cambridge Isotope Laboratories, Inc.). One half of the slurry tubes were immediately spiked with zinc chloride (ZnCl2, 50% W/V) to stop biological activity. The other half were incubated on a shaker table for ~6 hours at room temperature then spiked with ZnCl2. Anammox was measured based on the concentration of 29N2 and 30N2 concentrations in slurry water using a membrane inlet mass spectrometer (MIMS) outfitted with a copper reduction column to remove excess oxygen. Background NO2+3- concentrations were used to determine the fraction enrichment (FN) for anammox.. Parameter or Variable: DNRA Rate (measured); Units: µmol N kg dry weight-1 h-1; Observation Category: laboratory analysis; Sampling Instrument: membrane inlet mass spectrometer; Sampling and Analyzing Method: Syringe cores (0-5 cm, i.d. =2.6 cm) were collected to determine dissimilatory nitrate reduction to ammonium (DNRA) rates. Soils were extruded into Ziploc bags and transported on ice back to the lab, where they were stored at 4°C overnight. The following day, each sample was slurried with commercial Spring Water (Walmart). Slurries were bubbled with dinitrogen (N2) gas to produce anoxic conditions and siphoned into Exetainer vials (Labco). Following an overnight incubation at room temperature to remove ambient NO3- and oxygen (O2), slurries were spiked to ~50 µM Na15NO3 (99 atom %; Cambridge Isotope Laboratories, Inc.). One half of the slurry tubes were immediately spiked with zinc chloride (ZnCl2, 50% W/V) to stop biological activity. The other half were incubated on a shaker table for ~6 hours at room temperature then spiked with ZnCl2. DNRA was measured based on 15NH4 production using a hypobromite reduction. DNRA tubes were bubbled with N2 to purge 29N2 and 30N2 produced by denitrification and anammox. Samples were then amended with 200 µL sodium hypobromite, which converts NH4+ to N2. The resulting 29N2 and 30N2 concentrations were measured on the MIMS.. Parameter or Variable: N Removal (calculated); Units: %; Observation Category: other; Sampling Instrument: none; Sampling and Analyzing Method: The percent of nitrogen removed of total nitrate reduced was calculated as: [((denitrification+anammox))/(denitrification+anammox+DNRA)]×100 .. Parameter or Variable: Water Column NO2- (measured); Units: µmol/L; Observation Category: laboratory analysis; Sampling Instrument: spectrophotometer; Sampling and Analyzing Method: Seventeen of the 96 ditches had standing water at the time of sampling. Water was collected with a syringe and filtered through a nylon membrane filter (0.45 µm, VWR) into a centrifuge tube. Water samples were stored on ice for transport to the lab and frozen until analysis. Nitrite (NO2-) concentrations were determined photometrically on a Genesys 10S UVVis spectrophotometer (Thermo Scientific).. Parameter or Variable: Water Column NO3- (measured); Units: µmol/L; Observation Category: laboratory analysis; Sampling Instrument: spectrophotometer; Sampling and Analyzing Method: Seventeen of the 96 ditches had standing water at the time of sampling. Water was collected with a syringe and filtered through a nylon membrane filter (0.45 µm, VWR) into a centrifuge tube. Water samples were stored on ice for transport to the lab and frozen until analysis. Nitrate-nitrite (NO2+3 -) concentrations were determined microphotometrically via vanadium(III) chloride reduction. Nitrate (NO3-) concentrations were determined by subtracting NO2- from NO2+3 – concentrations.. Parameter or Variable: Water Column NH4+ (measured); Units: µmol/L; Observation Category: laboratory analysis; Sampling Instrument: flurometer; Sampling and Analyzing Method: Seventeen of the 96 ditches had standing water at the time of sampling. Water was collected with a syringe and filtered through a nylon membrane filter (0.45 µm, VWR) into a centrifuge tube. Water samples were stored on ice for transport to the lab and frozen until analysis. NH4+ was determined fluorometrically with the OPA method.. Parameter or Variable: Water Column PO43- (measured); Units: µmol/L; Observation Category: laboratory analysis; Sampling Instrument: spectrophotometer; Sampling and Analyzing Method: Seventeen of the 96 ditches had standing water at the time of sampling. Water was collected with a syringe and filtered through a nylon membrane filter (0.45 µm, VWR) into a centrifuge tube. Water samples were stored on ice for transport to the lab and frozen until analysis. PO43- concentrations were determined photometrically on a Genesys 10S UVVis spectrophotometer (Thermo Scientific)..

Lineage information for: dataset

Processing Steps

Parameter or Variable: Collection Date (measured); Units: yyyy-mm-dd; Observation Category: other; Sampling Instrument: calendar; Sampling and Analyzing Method: Ditches were sampled over four dates (23 May 2018, 25 May 2018, 05 June 2018, and 08 June 2018), with eight reaches sampled in each watershed on each date for n=24 per date..
Parameter or Variable: Landuse (measured); Units: none; Observation Category: other; Sampling Instrument: none; Sampling and Analyzing Method: The study was conducted in three watersheds of different predominant land use types surrounding Mobile Bay, Alabama (USA). Fowl River, the southernmost watershed on the west coast of Mobile Bay, was predominantly forested/ wetland (66.7%) (Fowl River Watershed Management Plan 2016). Dog River was a predominantly urban (60.4%) watershed that shares its southern border with Fowl River and includes the City of Mobile. An estimated 16.1% of Dog River watershed was impervious cover (Dog River Watershed Management Plan 2017). The third watershed, Weeks Bay, was located on the east coast of Mobile Bay, and had predominantly agricultural (41.1%) land cover (Final Weeks Bay Watershed Management Plan 2017)..
Parameter or Variable: Replicate (measured); Units: none; Observation Category: other; Sampling Instrument: none; Sampling and Analyzing Method: Thirty-two ditch reaches were selected within approximately 90 km2 areas located within the three watersheds. A reach was defined as the length of ditch between two culverts. No reaches were continuous, i.e. no reaches were directly connected by culverts. Ditches were sampled over four dates (23 May 2018, 25 May 2018, 05 June 2018, and 08 June 2018), with eight reaches sampled in each watershed on each date for n=24 per date..
Parameter or Variable: LATITUDE (measured); Units: Decimal Degrees; Observation Category: in situ; Sampling Instrument: Google Maps; Sampling and Analyzing Method: Latitude of each ditch sampled. Ditch location was logged in Google Maps at the time of sampling..
Parameter or Variable: LONGITUDE (measured); Units: Decimal Degrees; Observation Category: in situ; Sampling Instrument: Google Maps; Sampling and Analyzing Method: Longitude of each ditch sampled. Ditch location was logged in Google Maps at the time of sampling..
Parameter or Variable: Ditch width (measured); Units: m; Observation Category: in situ; Sampling Instrument: tape measure; Sampling and Analyzing Method: Ditch width was measured at the location of sampling..
Parameter or Variable: Aboveground Plant Biomass (measured); Units: kg/m^2; Observation Category: laboratory analysis; Sampling Instrument: quadrat, balance; Sampling and Analyzing Method: Aboveground plant biomass was determined by clipping the aboveground plant material to the soil surface within a 0.25 m x 0.25 m quadrat that was randomly thrown into the sampling area. Aboveground samples were oven-dried to constant weight at 60°C..
Parameter or Variable: Belowground Plant Biomass (measured); Units: kg/m^2; Observation Category: laboratory analysis; Sampling Instrument: t-corer, balance; Sampling and Analyzing Method: Belowground biomass in the 0-5 cm depth increment was collected using a t-corer (i.d.=7.9 cm). Root material was separated from soil by wet sieving with a 2.0 mm sieve. Root material was oven-dried to constant weight..
Parameter or Variable: Extractable NO2+3- (measured); Units: (µmol g-1); Observation Category: laboratory analysis; Sampling Instrument: spectrophotometer; Sampling and Analyzing Method: Syringe cores (i.d = 1.3 cm) were used to collect soil from the top 5 cm for extractable nitrate + nitrite (NO2+3-). Samples were homogenized by vortexing in 2M potassium chloride (KCl). Following an overnight extraction by horizontal shaking at 70 RPM, samples were centrifuged and the supernatant filtered (VWR filters) into centrifuge tubes and frozen until analysis. Soil extractable NO2+3- was determined colorimetrically by vanadium chloride (detection limit = 0.01 µmol g dry sediment-1)..
Parameter or Variable: Extractable NH4+ (measured); Units: (µmol g-1); Observation Category: laboratory analysis; Sampling Instrument: fluorometer; Sampling and Analyzing Method: Syringe cores (i.d = 1.3 cm) were used to collect soil from the top 5 cm for extractable ammonium (NH4+). Samples were homogenized by vortexing in 2M potassium chloride (KCl). Following an overnight extraction by horizontal shaking at 70 RPM, samples were centrifuged and the supernatant filtered (VWR filters) into centrifuge tubes and frozen until analysis.Soil extractable NH4+ was determined fluoremetrically by the OPA method (detection limit = 0.04 µmol g dry sediment-1)..
Parameter or Variable: ORGANIC MATTER - WEIGHT PERCENT (measured); Units: %; Observation Category: laboratory analysis; Sampling Instrument: muffle furnace, balance; Sampling and Analyzing Method: Syringe cores (i.d = 1.3 cm) were used to collect soil from the top 5 cm for organic matter content. Cores were oven dried at 60°C. Dried cores were ground using a mortar and pestle and ashed at 600°C for six hours..
Parameter or Variable: Denitrification Rate (measured); Units: µmol N kg dry weight-1 h-1; Observation Category: laboratory analysis; Sampling Instrument: membrane inlet mass spectrometer; Sampling and Analyzing Method: Syringe cores (0-5 cm, i.d. =2.6 cm) were collected to determine denitrification, rates. Soils were extruded into Ziploc bags and transported on ice back to the lab, where they were stored at 4°C overnight. The following day, each sample was slurried with commercial Spring Water (Walmart). Slurries were bubbled with dinitrogen (N2) gas to produce anoxic conditions and siphoned into Exetainer vials (Labco). Following an overnight incubation at room temperature to remove ambient NO3- and oxygen (O2), slurries were spiked to ~50 µM Na15NO3 (99 atom %; Cambridge Isotope Laboratories, Inc.). One half of the slurry tubes were immediately spiked with zinc chloride (ZnCl2, 50% W/V) to stop biological activity. The other half were incubated on a shaker table for ~6 hours at room temperature then spiked with ZnCl2. Denitrification was measured based on the concentration of 29N2 and 30N2 concentrations in slurry water using a membrane inlet mass spectrometer (MIMS) outfitted with a copper reduction column to remove excess oxygen. Denitrification rates from sediment slurries were calculated using the isotope pairing technique..
Parameter or Variable: Anammox Rate (measured); Units: µmol N kg dry weight-1 h-1; Observation Category: laboratory analysis; Sampling Instrument: membrane inlet mass spectrometer; Sampling and Analyzing Method: Syringe cores (0-5 cm, i.d. =2.6 cm) were collected to determine anammox rates. Soils were extruded into Ziploc bags and transported on ice back to the lab, where they were stored at 4°C overnight. The following day, each sample was slurried with commercial Spring Water (Walmart). Slurries were bubbled with dinitrogen (N2) gas to produce anoxic conditions and siphoned into Exetainer vials (Labco). Following an overnight incubation at room temperature to remove ambient NO3- and oxygen (O2), slurries were spiked to ~50 µM Na15NO3 (99 atom %; Cambridge Isotope Laboratories, Inc.). One half of the slurry tubes were immediately spiked with zinc chloride (ZnCl2, 50% W/V) to stop biological activity. The other half were incubated on a shaker table for ~6 hours at room temperature then spiked with ZnCl2. Anammox was measured based on the concentration of 29N2 and 30N2 concentrations in slurry water using a membrane inlet mass spectrometer (MIMS) outfitted with a copper reduction column to remove excess oxygen. Background NO2+3- concentrations were used to determine the fraction enrichment (FN) for anammox..
Parameter or Variable: DNRA Rate (measured); Units: µmol N kg dry weight-1 h-1; Observation Category: laboratory analysis; Sampling Instrument: membrane inlet mass spectrometer; Sampling and Analyzing Method: Syringe cores (0-5 cm, i.d. =2.6 cm) were collected to determine dissimilatory nitrate reduction to ammonium (DNRA) rates. Soils were extruded into Ziploc bags and transported on ice back to the lab, where they were stored at 4°C overnight. The following day, each sample was slurried with commercial Spring Water (Walmart). Slurries were bubbled with dinitrogen (N2) gas to produce anoxic conditions and siphoned into Exetainer vials (Labco). Following an overnight incubation at room temperature to remove ambient NO3- and oxygen (O2), slurries were spiked to ~50 µM Na15NO3 (99 atom %; Cambridge Isotope Laboratories, Inc.). One half of the slurry tubes were immediately spiked with zinc chloride (ZnCl2, 50% W/V) to stop biological activity. The other half were incubated on a shaker table for ~6 hours at room temperature then spiked with ZnCl2. DNRA was measured based on 15NH4 production using a hypobromite reduction. DNRA tubes were bubbled with N2 to purge 29N2 and 30N2 produced by denitrification and anammox. Samples were then amended with 200 µL sodium hypobromite, which converts NH4+ to N2. The resulting 29N2 and 30N2 concentrations were measured on the MIMS..
Parameter or Variable: N Removal (calculated); Units: %; Observation Category: other; Sampling Instrument: none; Sampling and Analyzing Method: The percent of nitrogen removed of total nitrate reduced was calculated as: [((denitrification+anammox))/(denitrification+anammox+DNRA)]×100 ..
Parameter or Variable: Water Column NO2- (measured); Units: µmol/L; Observation Category: laboratory analysis; Sampling Instrument: spectrophotometer; Sampling and Analyzing Method: Seventeen of the 96 ditches had standing water at the time of sampling. Water was collected with a syringe and filtered through a nylon membrane filter (0.45 µm, VWR) into a centrifuge tube. Water samples were stored on ice for transport to the lab and frozen until analysis. Nitrite (NO2-) concentrations were determined photometrically on a Genesys 10S UVVis spectrophotometer (Thermo Scientific)..
Parameter or Variable: Water Column NO3- (measured); Units: µmol/L; Observation Category: laboratory analysis; Sampling Instrument: spectrophotometer; Sampling and Analyzing Method: Seventeen of the 96 ditches had standing water at the time of sampling. Water was collected with a syringe and filtered through a nylon membrane filter (0.45 µm, VWR) into a centrifuge tube. Water samples were stored on ice for transport to the lab and frozen until analysis. Nitrate-nitrite (NO2+3 -) concentrations were determined microphotometrically via vanadium(III) chloride reduction. Nitrate (NO3-) concentrations were determined by subtracting NO2- from NO2+3 – concentrations..
Parameter or Variable: Water Column NH4+ (measured); Units: µmol/L; Observation Category: laboratory analysis; Sampling Instrument: flurometer; Sampling and Analyzing Method: Seventeen of the 96 ditches had standing water at the time of sampling. Water was collected with a syringe and filtered through a nylon membrane filter (0.45 µm, VWR) into a centrifuge tube. Water samples were stored on ice for transport to the lab and frozen until analysis. NH4+ was determined fluorometrically with the OPA method..
Parameter or Variable: Water Column PO43- (measured); Units: µmol/L; Observation Category: laboratory analysis; Sampling Instrument: spectrophotometer; Sampling and Analyzing Method: Seventeen of the 96 ditches had standing water at the time of sampling. Water was collected with a syringe and filtered through a nylon membrane filter (0.45 µm, VWR) into a centrifuge tube. Water samples were stored on ice for transport to the lab and frozen until analysis. PO43- concentrations were determined photometrically on a Genesys 10S UVVis spectrophotometer (Thermo Scientific)..

Acquisition Information (collection)
Instrument	fluorometer spectrophotometer

Last Modified: 2024-10-15T12:55:45Z
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Nitrate reduction rates and soil/ water chemistry from roadside ditches in the Mobile Bay (AL, USA) region (2018-05-23 to 2018-06-08) (NCEI Accession 0211099)

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