Processing Steps |
- Parameter or Variable: Dissolved Inorganic Carbon; Abbreviation: DIC; Observation type: discrete; In-situ / Manipulation / Response variable: In-situ observation; Measured or calculated: Calculated; Detailed sampling and analyzing information: The DIC analytical equipment was set up in a seagoing container modified for use as a shipboard laboratory. The analysis was done by coulometry with two analytical systems (PMEL-1 and PMEL-2) used simultaneously on the cruise. Each system consisted of a 5011 coulometer (UIC, Inc.) coupled with a SOMMA (Single Operator Multiparameter Metabolic Analyzer) inlet system developed by Ken Johnson (Johnson et al., 1985,1987,1993; Johnson, 1992) of Brookhaven National Laboratory (BNL). In the coulometric analysis of DIC, all carbonate species are converted to CO2 (gas) by addition of excess hydrogen to the seawater sample, and the evolved CO2 gas is carried into the titration cell of the coulometer, where it reacts quantitatively with a proprietary reagent based on ethanolamine to generate hydrogen ions. These are subsequently titrated with coulometrically generated OH-. CO2 is thus measured by integrating the total change required to achieve this. Samples were drawn from the Niskin-type bottles into cleaned, precombusted 300-mL Pyrex bottles using Tygon tubing with silicone ends. Bottles were rinsed once and filled from the bottom, overflowing half a volume taking care not to entrain any bubbles. The tube was pinched off and withdrawn, creating a 6-mL headspace, and 0. 2 mL of 50% saturated HgCl2 solution was added as a preservative. The sample bottles were sealed with glass stoppers lightly covered with Apiezon-L grease, and were stored at room temperature for a maximum of 12 hours prior to analysis. A total of 5,233 samples were analyzed for discrete DIC with replicate samples usually taken from the surface, oxygen minimum, and bottom Niskin-type bottles. The replicate samples were interspersed throughout the station analysis for quality assurance of the integrity of the coulometer cell solutions. No systematic differences between the replicates were observed. The overall performance of the instruments was good during the cruise. On PMEL1, valve 5 failed and required replacement. This required a post cruise pipette calibration for this system.; Standardization description: The coulometers were each calibrated by injecting aliquots of pure CO2 (99.99%) by means of an 8-port valve outfitted with two sample loops (Wilke et al., 1993). The instruments were calibrated at the beginning and end of each full station with a set of the gas loop injections. Secondary standards were run throughout the cruise on each analytical system; these standards are Certified Reference Materials (CRMs) consisting of poisoned, filtered, and UV irradiated seawater supplied by Dr. A. Dickson of Scripps Institution of Oceanography (SIO), and their accuracy is determined shoreside manometrically.; CRM batch number: 84.
- Parameter or Variable: Total alkalinity; Abbreviation: TA; Observation type: discrete; In-situ / Manipulation / Response variable: In-situ observation; Measured or calculated: Measured; Curve fitting method: Two titration systems, A and B were used for measuring TA. Each system used a Metrohm 665 Dosimat titrator, an Orion 720A pH meter and a custom designed plexiglass water-jacketed titration cell (Millero et al., 1993a). Both the seawater sample and acid titrant were temperature equilibrated to a constant temperature of 25 +/- 0.1C with a water bath (Neslab, model RTE-17). The water-jacketed cell has a volume of ~200 cm3. Each cell has a fill and drain valve that is electronically activated to increase the reproducibility of the volume of sample. A typical titration recorded the EMF after the readings became stable (deviation less than 0.09 mV) and then enough acid was added to change the voltage a pre-assigned increment (13 mV). A full titration (~25 points) takes about 20 minutes. The electrodes used to measure the EMF of the sample during a titration consisted of a ROSS glass pH electrode (Orion, model 810100) and a double junction Ag, AgCl reference electrode (Orion, model 900200).; Uncertainty: Calibrations of the burette of the Dosimat with water at 25C indicate that the systems deliver 3.000 cm3 (the approximate value for a titration of seawater) to a precision of +/- 0.0004 cm3, resulting in an error of +/- 0.3 μmol/kg-1 in TA.; Method reference: Dickson, A. G. 1981. An exact definition of total alkalinity and a procedure for the estimation of alkalinity and total inorganic carbon from titration data. Deep Sea Research Part A. Oceanographic Research Papers 28: 609.[ https://doi.org/10.1016/0198-0149(81)90121-7] Johansson, O., and M. Wedborg. 1982. On the evaluation of potentiometric titrations of seawater with hydrochloric acid. Oceanol. Acta 5: 209-218 Millero, F. J., J.-Z. Zhang, K. Lee, and D. M. Campbell. 1993. Titration alkalinity of seawater. Marine Chemistry 44: 153.[ https://doi.org/10.1016/0304-4203(93)90200-8].
- Parameter or Variable: pH; Abbreviation: pH; pH scale: SWS @25C; Observation type: discrete; In-situ / Manipulation / Response variable: In-situ observation; Measured or calculated: Measured; Temperature of pH measurement: 25C; Detailed sampling and analyzing information: Measurements of the pH of seawater, on the total scale (pHT) were first made using multi-wavelength spectrophotometric techniques of Clayton and Byrne (1993). The conversion of the pHT (mol/kgH2O) to the seawater scale (mol/kgsol) can be made using equations of Dickson and Millero (1987), Millero et al., 1993b, Dickson and Riley (1979), and Dickson (1990).; Uncertainty: NA.
- Parameter or Variable: pCO2 (fCO2) discrete; Abbreviation: fCO2; Observation type: discrete; In-situ / Manipulation / Response variable: In-situ observation; Measured or calculated: Measured; Storage method: Samples were drawn from Niskin bottles into 500 ml volumetric flasks using Tygono tubing with a Silicone adapter that fit over the petcock to avoid contamination of DOM samples. Bottles were rinsed while inverted and filled from the bottom, overflowing half a volume while taking care not to entrain any bubbles. About 5 ml of water was withdrawn to allow for expansion of the water as it warms and to provide space for the stopper, tubing, and frit of the analytical system. Saturated mercuric chloride solution (0.2 ml) was added as a preservative. The sample bottles were sealed with a screw cap containing a polyethylene liner. The samples were stored in coolers at room temperature generally for no more than 5 hours.; Seawater volume: 500 mL; Headspace volume: 120 mL; Temperature of measurement: 20C; Detailed sampling and analyzing information: Analyses were done by equilibrating water samples in 500-ml glass volumetric flasks at a fixed temperature of 20C. Headspace created with gas of known concentration was bubbled through the water and circulated through a LiCor 6252 infrared analyzer (IR). Details of the analysis and instrumental setup can be found in Wanninkhof and Thoning (1993). The analysis was done shipboard in the main laboratory that had poor temperature control which is believed to contribute to the variability in results.; Sample replicate information: Generally when samples were taken, flasks were drawn on all the Niskins including four duplicates. Two of the duplicates were analyzed at different temperatures; Temperature correction method: See Peng et al., 1987; Uncertainty: The constants of Mehrbach as refit by Dickson and Millero (1987), along with other constants referenced therein are used in the calculations using the code based on Lewis and Wallace (1998) as ported to Excel by Pierrot. Silicate and phosphate values as provided by the nutrient group were used to determine the alkalinity. The final fCO2 values are not sensitive to the range of reported errors in DIC, SiO2, or PO4 that are used as input to calculate the fCO2 values.; Method reference: Wanninkhof, R., & Thoning, K. (1993). Measurement of fugacity of CO2 in surface water using continuous and discrete sampling methods. Marine Chemistry, 44(2–4), 189–204. https://doi.org/10.1016/0304-4203(93)90202-y.
- Parameter or Variable: CTDTMP; Abbreviation: CTDTMP; Unit: DEG_C; Controlled vocabulary name: WATER TEMPERATURE; In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: CTDSAL; Abbreviation: CTDSAL; Controlled vocabulary name: SALINITY; In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: SALNTY; Abbreviation: SALNTY; Controlled vocabulary name: SALINITY; In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: CTDOXY; Abbreviation: CTDOXY; Unit: UMOL/KG; Controlled vocabulary name: DISSOLVED OXYGEN; In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: OXYGEN; Abbreviation: OXYGEN; Unit: UMOL/KG; Controlled vocabulary name: DISSOLVED OXYGEN; In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: SILCAT; Abbreviation: SILCAT; Unit: UMOL/KG; Controlled vocabulary name: silicate; In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: NITRAT; Abbreviation: NITRAT; Unit: UMOL/KG; Controlled vocabulary name: NITRATE; In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: NITRIT; Abbreviation: NITRIT; Unit: UMOL/KG; Controlled vocabulary name: NITRITE; In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: PHSPHT; Abbreviation: PHSPHT; Unit: UMOL/KG; Controlled vocabulary name: phosphate; In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: CFC-11; Abbreviation: CFC-11; Unit: PMOL/KG; Controlled vocabulary name: CHLOROFLUOROCARBON-11 (CFC-11); In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: CFC-12; Abbreviation: CFC-12; Unit: PMOL/KG; Controlled vocabulary name: CHLOROFLUOROCARBON-12 (CFC-12); In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: SF6; Abbreviation: SF6; Unit: FMOL/KG; Controlled vocabulary name: Sulfur Hexaflouride (SF6); In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: CCL4; Abbreviation: CCL4; Unit: PMOL/KG; Controlled vocabulary name: Carbon tetrachloride (CCL4); In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: TCARBN; Abbreviation: TCARBN; Unit: UMOL/KG; Controlled vocabulary name: DISSOLVED INORGANIC CARBON (DIC); In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: ALALI; Abbreviation: ALALI; Unit: UMOL/KG; Controlled vocabulary name: total alkalinity; In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: FCO2; Abbreviation: FCO2; Unit: UATM; Controlled vocabulary name: partial pressure of carbon dioxide - water; In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: FCO2_TMP; Abbreviation: FCO2_TMP; Unit: DEG_C; Controlled vocabulary name: partial pressure of carbon dioxide - water; In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: PH_SWS; Abbreviation: PH_SWS; Unit: @25C; Controlled vocabulary name: pH; In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: PH_TMP; Abbreviation: PH_TMP; Unit: DEG_C; Controlled vocabulary name: pH; In-situ / Manipulation / Response variable: in-situ.
- Parameter or Variable: DOC; Abbreviation: DOC; Unit: UMOL/KG; Controlled vocabulary name: DISSOLVED ORGANIC CARBON; In-situ / Manipulation / Response variable: in-situ .
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