| Processing Steps |
- Parameter or Variable: Dissolved Inorganic Carbon; Abbreviation: DIC_UMOL_KG; Unit: micro-mol/kg; Observation type: Underway (flow through); In-situ / Manipulation / Response variable: in-situ observation; Measured or calculated: Measured; Sampling instrument: Flow through system and CTD (surface bottle); Analyzing instrument: Two systems consisting of a coulometer (UIC Inc.) coupled with a Dissolved Inorganic Carbon Extractor (DICE) inlet system. DICE was developed by Esa Peltola and Denis Pierrot of NOAA/AOML and Dana Greeley of NOAA/PMEL to modernize a carbon extractor called SOMMA (Johnson et al. 1985, 1987, 1993, and 1999; Johnson 1992); Detailed sampling and analyzing information: Samples for total dissolved inorganic carbon (DIC) measurements were drawn according to procedures outlined in the Guide to best practices for ocean CO2 measurements (Dickson et al., 2007) from the underway system into cleaned 294-ml glass bottles. Bottles were rinsed and filled from the bottom, leaving 6 ml of headspace; care was taken not to entrain any bubbles. After 0.2 ml of 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 to be analyzed within 48 hours of collection. The analysis was done by coulometry with two analytical systems (AOML3 and AOML4) used simultaneously. In the coulometric analysis of DIC, all carbonate species are converted to CO2 (gas) by addition of excess hydrogen ion (acid) to the seawater sample, and the evolved CO2 gas is swept into the titration cell of the coulometer with pure air or compressed nitrogen, where it reacts quantitatively with a proprietary reagent based on ethanolamine to generate hydrogen ions. In this process, the solution changes from blue to colorless, triggering a current through the cell and causing coulometrical generation of OH minus ions at the anode. The OH ions react with the H+, and the solution turns blue again. A beam of light is shone through the solution, and a photometric detector at the opposite side of the cell senses the change in transmission. Once the percent transmission reaches its original value, the coulometric titration is stopped, and the amount of CO2 that enters the cell is determined by integrating the total charge during the titration. The volume of the pipette used to deliver the sample in each system was determined with aliquots of distilled water at known temperature. The weights with the appropriate densities were used to determine the volume of the pipette. Calculation of the amount of CO2 injected was according to the CO2 handbook (Dickson et al., 2007).The instrument has a salinity sensor, but all DIC values were recalculated to a molar weight (micro-mol/kg) using density obtained from the CTD salinity. The DIC values were corrected for dilution by 0.2 ml of saturated HgCl2 used for sample preservation (Measured DIC*1.00037). A correction was also applied for the offset from the CRM. This additive correction was applied for each cell using the CRM value obtained in the beginning of the cell.; Replicate information: In total, 144 underway samples were run, each 250-ml, 18 sets of duplicates.; Standardization description: The coulometers were calibrated by injecting aliquots of pure CO2 (99.99%) by means of an 8-port valve outfitted with two sample loops with known gas volumes bracketing the amount of CO2 extracted from the water samples for the two AOML systems.; Standardization frequency: The stability of each coulometer cell solution was confirmed three different ways: two sets of gas loops were measured at the beginning; also the Certified Reference Material (CRM), supplied by Dr. A. Dickson of UCSD, were measured at the beginning; and the duplicate samples at the beginning, middle, and end of each cell solution. The coulometer cell solution was replaced after 25 mg of carbon was titrated, typically after 9 to 12 hours of continuous use.; CRM manufacturer: Dr. A. Dickson of UCSD; CRM batch number: Batch 188, 192, 194; Preservation method: saturated HgCl2; Preservative volume: 0.2 ml; Preservative correction: The DIC values were corrected for dilution by 0.2 ml of saturated HgCl2 used for sample preservation. The total water volume of the sample bottles was 294 ml (calibrated by Charles Featherstone, AOML). The correction factor used for dilution was 1.00068.; Quality flag convention: WOCE quality control flags are used: 2 = good value, 3 = questionable value, 4 = bad value, 5 = value not reported, 6 = mean of replicate measurements, 9 = sample not drawn.; Method reference: Dickson, A.G., Sabine, C.L. and Christian, J.R. (Eds.) 2007. Guide to best practices for ocean CO2 measurements. PICES Special Publication 3, 191 pp. Johnson, K.M., Kortzinger, A.; Mintrop, L.; Duinker, J.C.; and Wallace, D.W.R. (1999). Coulometric total carbon dioxide analysis for marine studies: Measurement and internal consistency of underway surface TCO2 concentrations. Marine Chemistry 67:123 to 44.Johnson, K.M., Wills, K.D.; Butler, D.B.; Johnson, W.K.; and Wong, C.S. (1993). Coulometric total carbon dioxide analysis for marine studies: Maximizing the performance of an automated gas extraction.Johnson, K.M. (1992). Operator Manual: Single-Operator Multiparameter Metabolic Analyzer (SOMMA) for Total Carbon Dioxide (CT) with Coulometric Detection. Brookhaven National Laboratory, Brookhaven, N.Y. Johnson, K.M.; Williams, P.J.; Brandstrom, L.; and McN. Sieburth, J. (1987). Coulometric total carbon analysis for marine studies: Automation and calibration. Marine Chemistry 21:117 to 33.; Researcher name: Rik Wanninkhof; Leticia Barbero; Researcher institution: Atlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration (NOAA).
- Parameter or Variable: Total alkalinity; Abbreviation: TA_UMOL_KG; Unit: micro-mol/kg; Observation type: Underway (flow through) and CTD (surface bottle); In-situ / Manipulation / Response variable: in-situ observation; Measured or calculated: Measured; Sampling instrument: Flow through and surface CTD niskin; Analyzing instrument: Two titration systems were used: “System 1” used a Metrohm 765 Dosimat Titrator and an Orion 720A pH meter controlled by a personal computer (Millero et al., 1993). “System 2” used a Metrohm 665 Dosimat Titrator and an Orion 2-Star pH meter. A plexiglass reference electrode (Orion 900200) and a glass pH electrode (Orion 8101BNWP) were used.; Type of titration: Full Titration; Cell type (open or closed): open; Curve fitting method: Least-Square Analysis; Detailed sampling and analyzing information: Samples for total alkalinity (TAlk) measurements were drawn according to procedures outlined in the Guide to best practices for ocean CO2 measurements (Dickson et al., 2007) from the underway system into cleaned 500-ml glass bottles. Bottles were rinsed and filled from the bottom, leaving approximately 6 ml of headspace; care was taken not to entrain any bubbles. After 0.2 ml of 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 analysis onboard within 48 hours of collection. For each measurement, approximately 200 ml of water sample were titrated with an HCl solution in ~0.55 molal NaCl solution provided by Dr. Andrew Dickson of UCSD (0.25175 moles per kilogram-solution).; Replicate information: 124 underway samples each 500-ml, 0 sets of duplicate samples.; Standardization description: 2 CRM samples were run daily on each cell, before and after the seawater samples. The Total Alkalinity for the water samples was corrected using the daily averaged ratios between the certified and measured values of the 2 CRMs run on each cell. This TA titration system has a precision of 0.1 %. All the TA values were directly measured with reference to Certified Reference Material. The accuracy after correction is 0.1%.; Standardization frequency: All values were directly measured with reference to Certified Reference Material (Dickson, UCSD). 2 CRM samples were run daily on each cell.; CRM manufacturer: Dr. A. Dickson of UCSD; CRM batch number: CRM batch: 188, 192, 194; Preservation method: saturated HgCl2; Preservative volume: 0.2 ml; Uncertainty: The precision of this method is better than 0.1% and accuracy is 0.1%.; Quality flag convention: WOCE quality control flags are used: 2 = good value, 3 = questionable value, 4 = bad value, 5 = value not reported, 6 = mean of replicate measurements, 9 = sample not drawn.; Method reference: Millero, F. J., Zhang, J. Z., Lee, K., & Campbell, D. M. (1993). Titration alkalinity of seawater. Marine Chemistry, 44(2), 153-165.; Researcher name: Leticia Barbero; Researcher institution: Atlantic Oceanographic and Meteorological Laboratory, Cooperative Institue for Marine and Atmospheric Studies(CIMAS).
- Parameter or Variable: pH; Abbreviation: pH_TS_MEA; pH scale: Total scale (T); Observation type: Surface underway (flow through) and CTD (surface bottle); In-situ / Manipulation / Response variable: in-situ observation; Measured or calculated: Measured; Sampling instrument: Flow through and surface CTD niskin; Analyzing instrument: Agilent 8453 spectrometer setup with a custom-made temperature-controlled cell holder; Detailed sampling and analyzing information: Samples were collected for pH analysis immediately following O2 in the underway sampling sequence. Seawater samples were collected from the underway system directly in 10-cm cylindrical optical cells (~30 mL volume) using a section of silicone tubing (about 15 cm long). One end of the silicone tubing was attached to the optical cell and the other end was attached to the tube of the underway system. Tthe silicone tubing was squeezed to eliminate air bubbles. The optical cell was agitated to eliminate bubbles and, after 15 seconds of sample flow, the cell was capped at one end. The silicone tubing was then detached from the optical cell and, with the water still flowing, the cap was rinsed and used to seal the optical cell. Samples collected this way were not exposed to the atmosphere, and each cell was flushed with approximately three cell volumes of seawater. The samples were collected, taken into the lab, and rinsed with tap water to get rid of salt outside of the cells. The cells were dried and the optical windows were cleaned with Kimwipes. Samples were thermostatted at 25 (±0.05) ºC in a custom made 36-position cell warmer. A custom macro program running on Agilent ChemStation was used to guide the measurements and data processing. The macro automated the procedures of sample input, blank and sample scans, quality control, and data archiving. The quality control steps included checking the baseline shift after dye injection and monitoring the standard deviation of multiple scans. Absorbance blanks were taken for each sample and 10 µL of purified m-cresol purple (10 mmol kg-1) were added for the analysis. pHT (total scale) was calculated according to Liu et al. (2011).; Replicate information: A total of 231 underway samples were taken, 105 duplicate sets.; Standardization description: The pH is calibration-free.; At what temperature was pH reported: 25 degrees Celsius; Uncertainty: Precision was equal to ±0.0004.; Quality flag convention: WOCE quality control flags are used: 2 = good value, 3 = questionable value, 4 = bad value, 5 = value not reported, 6 = mean of replicate measurements, 9 = sample not drawn.; Method reference: Liu, X.; Patsavas, M.C.; and Byrne, R. H. (2011). Purification and characterization of meta-cresol purple for spectrophotometric seawater pH measurements. Environmental Science and Technology, 45(11), 4862-4868. doi: 10.1021/es200665d; Researcher name: Robert Byrne; Researcher institution: University of South Florida.
- Parameter or Variable: pCO2 (fCO2) discrete; Abbreviation: fCO2_measured_UATM; Unit: microatmospheres; Observation type: Surface underway and CTD (surface bottle); In-situ / Manipulation / Response variable: in-situ observation; Sampling instrument: Flow through and surface CTD niskin; Analyzing instrument: LI-COR© (model 840); Storage method: The sample bottles were sealed with glass stoppers lightly covered with Apiezon-L grease and were stored at room temperature for a maximum of twelve hours prior to analysis. When twelve bottles were moved into the primary water bath for analyses, the next twelve bottles were moved into the secondary water bath. No sample bottle spent less than one hour in the secondary water bath prior to being moved to the analytical water bath.; Seawater volume: 500 ml; Headspace volume: 5 mL; Temperature of measurement: 20 ºC; Detailed sampling and analyzing information: Samples were drawn from the underway system into 500 ml glass bottles using Tygon© tubing with a Silicone adapter that fit over the drain cock to avoid contamination of DOM samples. Bottles were rinsed twice, the second time while inverted. They were 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 and tubing of the analytical system. Saturated mercuric chloride solution (0.2 ml) 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 twelve hours prior to analysis.The analyses for fCO2 were done with the discrete samples at 20°C. A primary water bath was kept within 0.03°C of the analytical temperature; a secondary bath was kept within 0.15°C the analytical temperature. The majority of the samples were analyzed in batches of twelve bottles, which with standards took approximately 2.5 hours. When twelve bottles were moved into the primary water bath for analyses, the next twelve bottles were moved into the secondary water bath. No sample bottle spent less than one hour in the secondary water bath prior to being moved to the analytical water bath.; Sample replicate information: A total of 126 underway samples were taken, 0 sets of duplicates.; Gas detector manufacturer: LiCOR 840 infrared analyzer. The system was built by Colm Sweeney and Tim Newberger; Gas detector model: Prototype; Gas detector uncertainty: The average relative standard error was 0.21%, while the median relative error was 0.15%.; Water vapor correction method: The details of the data reduction are described in Pierrot, et.al. (2009).; Temperature correction method: The details of the data reduction are described in Pierrot, et.al. (2009).; At what temperature was pCO2 reported: 20 ºC; Uncertainty: The average relative standard error was 0.21%, while the median relative error was 0.15%.; Quality flag convention: WOCE quality control flags are used: 2 = good value, 3 = questionable value, 4 = bad value, 5 = value not reported, 6 = mean of replicate measurements, 9 = sample not drawn.; Method reference: Wanninkhof, R.; and Thoning, K. (1993). Measurement of fugacity of CO2 in surface water using continuous and discrete sampling methods. Mar. Chem., v. 44, no. 2-4, pp. 189-205.Pierrot, D.; Neill, C.; Sullivan, K.; Castle, R.; Wanninkhof, R.; Luger, H.; Johannessen, T.; Olsen, A.; Feely, R.A.; and Cosca, C.E. (2009). Recommendations for autonomous underway pCO2 measuring systems and data-reduction routines. Deep-Sea Res., II, v. 56, pp. 512-522.; Researcher name: Rik Wanninkhof; Researcher institution: Atlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration.
- Parameter or Variable: bottle dissolved oxygen; Abbreviation: OXYGEN_UMOL_KG; Unit: micromol/kg; Observation type: Surface underway (flow through) and CTD (surface bottle); In-situ / Manipulation / Response variable: in-situ observation; Measured or calculated: Measured; Sampling instrument: Flow through and surface CTD niskin; Analyzing instrument: Automated oxygen titrator using amperometric end-point detection (Langdon 2010).; Detailed sampling and analyzing information: Samples were drawn from the underway system into volumetrically calibrated 125 ml iodine titration flasks using Tygon tubing with a silicone adaptor that fit over the petcock to avoid contamination of DOC samples. Bottles were rinsed three times and filled from the bottom, overflowing three volumes while taking care not to entrain any bubbles. The draw temperature was taken using a digital thermometer with a flexible thermistor probe that was inserted into the flask while the sample was being drawn during the overflow period. These temperatures were used to calculate concentrations. One ml of MnCl2 and one ml of NaOH/NaI were added immediately after drawing of the sample was concluded using a Repipetor, the flasks were then stoppered and shaken well. DIW was added to the neck of each flask to create a water seal. The flasks were stored in the lab in plastic totes at room temperature for at least 1 hour before analysis. Twenty-four samples plus duplicates were drawn from each station except the shallow coastal stations where fewer samples were drawn depending on the depth or as directed by the chief scientist. Dissolved oxygen analyses were performed with an automated oxygen titrator using amperometric end-point detection (Langdon 2010). The titration of the samples and the data logging and graphical display was performed on a PC running a LabView program written by Ulises Rivero of AOML. The titrations were performed in a climate controlled lab at 18.5°C-20°C. Thiosulfate was dispensed by a 2 ml Gilmont syringe driven with a stepper motor controlled by the titrator. Tests in the lab were performed to confirm that the precision and accuracy of the volume dispensed were comparable or superior to the Dosimat 665. The whole-bottle titration technique of Carpenter (1965) with modifications by Culberson et al. (1991) was used. Four to three replicate 10 ml iodate standards were run 13 times during the cruise. The reagent blank was determined at the beginning and end of the cruise. A titration was made to 1 ml of iodate standard. The volume of thiosulfate required for the titration is V1. An additional 1 ml of standard was added to the titrated sample and titrated again. The volume of thiosulfate used for the second titration is V2. The reagent blank was determined as the difference between V1 and V2.; Replicate information: A total of 124 underway samples were taken, 0 duplicate sets.; Uncertainty: A total of 14 standardizations were performed (mean=706.120, mean SD=0.359 uL). Reagent blanks were run at the beginning of the cruise (2.1±1.0 uL), and at the end. The average standard deviation of all duplicates was 0.164 µmol kg-1.; Quality flag convention: WOCE quality control flags are used: 2 = good value, 3 = questionable value, 4 = bad value, 5 = value not reported, 6 = mean of replicate measurements, 9 = sample not drawn.; Method reference: Carpenter, J.H. (1965). The Chesapeake Bay Institute technique for the Winkler dissolved oxygen method. Limnol. Oceanogr. 10: 141-143Culberson, C.H. and Huang, S. (1987). Automated amperometric oxygen titration. Deep-Sea Res. 34: 875-880.Culberson, C.H.; Knapp, G.; Stalcup, M.; Williams, R.T. and Zemlyak, F. (1991). A comparison of methods for the determination of dissolved oxygen in seawater. WHP Operations and Methods.Langdon, C. (2010). Determination of dissolved oxygen in seawater by Winkler titration using the amperometric technique. The GO-SHIP Repeat Hydrography Manual: A Collection of Expert Reports and Guidelines. E. M. Hood, C. L. Sabine and B. M. Sloyan, IOCCP Report Number 14, ICPO Publication Series Number 134.; Researcher name: Chris Langdon; Researcher institution: Rosenstiel School of Marine, Atmospheric, & Earth Science/University of Miami.
- Parameter or Variable: Orthosilicic acid; Abbreviation: SILICATE_UMOL_KG; Unit: micromol/kg; Observation type: Surface underway (flow through) and CTD (surface bottle); In-situ / Manipulation / Response variable: in-situ observation; Measured or calculated: Measured; Sampling instrument: Flow through and surface CTD niskin; Analyzing instrument: Continuous flow analyzer (CFA) using the standard and analysis protocols for the WOCE hydrographic program as set forth in the manual by L.I. Gordon, et al. (1993).; Detailed sampling and analyzing information: Nutrient samples were collected from the underway system, after at least three seawater rinses. Sample analysis typically began within a few hours of sample collection after the samples had warmed to room temperature. Those samples not analyzed within 3 hours were refrigerated for later analysis. Samples were analyzed for phosphate (PO4− 3), nitrate (NO3−), nitrite (NO2−) and orthosilicic acid (H4SiO4). Silicic acid was analyzed using a modification of Armstrong et al. (1967). The sample is reacted with ammonium molybdate in an acidic solution to form molybdosilicic acid. The molybdosilicic acid was then reduced with ascorbic acid to form molybdenum blue. The absorbance of the molybdenum blue was measured at 660 nm.; Uncertainty: A mixed stock standard consisting of silicic acid, phosphate and nitrate was prepared by dissolving high purity standard materials (KNO3, KH2PO4 and Na2SiF6) in deionized water using a two step dilution for phosphate and nitrate. This standard was stored at room temperature. A nitrite stock standard was prepared dissolving NaNO2 in distilled water, and this standard was stored in the ship’s refrigerator. Working standards were prepared fresh daily by diluting the stock solutions in low nutrient seawater. The mixed standards were verified against commercial standards, and in-lab standards.; Quality flag convention: WOCE quality control flags are used: 2 = good value, 3 = questionable value, 4 = bad value, 5 = value not reported, 6 = mean of replicate measurements, 9 = sample not drawn.; Method reference: Armstrong, F.A.J., Stearns, C.R. and Strickland, J.D.H. (1967). The measurement of upwelling and subsequent biological processes by means of the Technicon AutoAnalyzer and associated equipment. Deep-Sea Res. 14:381-389.Gordon, L.I., Jennings Jr., J.C., Ross, A.A. and Krest, J.M. (1993). A suggested protocol for the continuous automated analysis of seawater nutrients (phosphate, nitrate, nitrite and silicic acid) in the WOCE Hydrographic program and the Joint Global Ocean Fluxes Study. WOCE Operations Manual, vol. 3: The Observational Programme, Section 3.2: WOCE Hydrographic Programme, Part 3.1.3: WHP Operations and Methods. WHP Office Report WHPO 91-1; WOCE Report No. 68/91. November 1994, Revision 1, Woods Hole, MA., USA, 52 loose-leaf pages.; Researcher name: Jia-Zhong Zhang; Researcher institution: Atlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration.
- Parameter or Variable: Nitrite; Abbreviation: NITRITE_UMOL_KG; Unit: micromol/kg; Observation type: Surface underway (flow through) and CTD (surface bottle); In-situ / Manipulation / Response variable: in-situ observation; Measured or calculated: Measured; Sampling instrument: Flow through and surface CTD niskin; Analyzing instrument: Continuous flow analyzer (CFA) using the standard and analysis protocols for the WOCE hydrographic program as set forth in the manual by L.I. Gordon, et al. (1993).; Detailed sampling and analyzing information: Nutrient samples were collected from the underway system, after at least three seawater rinses. Sample analysis typically began within a few hours of sample collection after the samples had warmed to room temperature. Those samples not analyzed within 3 hours were refrigerated for later analysis. Samples were analyzed for phosphate (PO4− 3), nitrate (NO3−), nitrite (NO2−) and orthosilicic acid (H4SiO4). Nitrite was determined by diazotizing the sample with sulfanilamide and coupling with N-1 naphthyl ethylenediamine dihydrochloride to form an azo dye. The color produced is measured at 540 nm.; Uncertainty: A mixed stock standard consisting of silicic acid, phosphate and nitrate was prepared by dissolving high purity standard materials (KNO3, KH2PO4 and Na2SiF6) in deionized water using a two step dilution for phosphate and nitrate. This standard was stored at room temperature. A nitrite stock standard was prepared dissolving NaNO2 in distilled water, and this standard was stored in the ship’s refrigerator. Working standards were prepared fresh daily by diluting the stock solutions in low nutrient seawater. The mixed standards were verified against commercial standards, and in-lab standards.; Quality flag convention: WOCE quality control flags are used: 2 = good value, 3 = questionable value, 4 = bad value, 5 = value not reported, 6 = mean of replicate measurements, 9 = sample not drawn.; Method reference: Armstrong, F.A.J., Stearns, C.R. and Strickland, J.D.H. (1967). The measurement of upwelling and subsequent biological processes by means of the Technicon AutoAnalyzer and associated equipment. Deep-Sea Res. 14:381-389.Gordon, L.I., Jennings Jr., J.C., Ross, A.A. and Krest, J.M. (1993). A suggested protocol for the continuous automated analysis of seawater nutrients (phosphate, nitrate, nitrite and silicic acid) in the WOCE Hydrographic program and the Joint Global Ocean Fluxes Study. WOCE Operations Manual, vol. 3: The Observational Programme, Section 3.2: WOCE Hydrographic Programme, Part 3.1.3: WHP Operations and Methods. WHP Office Report WHPO 91-1; WOCE Report No. 68/91. November 1994, Revision 1, Woods Hole, MA., USA, 52 loose-leaf pages.; Researcher name: Jia-Zhong Zhang; Researcher institution: Atlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration.
- Parameter or Variable: nitrate; Abbreviation: NITRATE_UMOL_KG; Unit: micromol/kg; Observation type: Surface underway (flow through) and CTD (surface bottle); In-situ / Manipulation / Response variable: in-situ observation; Measured or calculated: Measured; Sampling instrument: Flow through system and CTD (surface bottle); Analyzing instrument: Continuous flow analyzer (CFA) using the standard and analysis protocols for the WOCE hydrographic program as set forth in the manual by L.I. Gordon, et al. (1993).; Detailed sampling and analyzing information: Nutrient samples were collected from the underway system, after at least three seawater rinses. Sample analysis typically began within a few hours of sample collection after the samples had warmed to room temperature. Those samples not analyzed within 3 hours were refrigerated for later analysis. Samples were analyzed for phosphate (PO4− 3), nitrate (NO3−), nitrite (NO2−) and orthosilicic acid (H4SiO4). Samples for nitrate analysis were passed through a cadmium column, which reduced nitrate to nitrite, and the resulting nitrite concentration (i.e. the sum of nitrate + nitrite which is signified as N+N) was then determined as described above. Nitrate concentrations were determined from the difference of N+N and nitrite.; Uncertainty: A mixed stock standard consisting of silicic acid, phosphate and nitrate was prepared by dissolving high purity standard materials (KNO3, KH2PO4 and Na2SiF6) in deionized water using a two step dilution for phosphate and nitrate. This standard was stored at room temperature. A nitrite stock standard was prepared dissolving NaNO2 in distilled water, and this standard was stored in the ship’s refrigerator. Working standards were prepared fresh daily by diluting the stock solutions in low nutrient seawater. The mixed standards were verified against commercial standards, and in-lab standards.; Quality flag convention: WOCE quality control flags are used: 2 = good value, 3 = questionable value, 4 = bad value, 5 = value not reported, 6 = mean of replicate measurements, 9 = sample not drawn.; Method reference: Armstrong, F.A.J., Stearns, C.R. and Strickland, J.D.H. (1967). The measurement of upwelling and subsequent biological processes by means of the Technicon AutoAnalyzer and associated equipment. Deep-Sea Res. 14:381-389.Gordon, L.I., Jennings Jr., J.C., Ross, A.A. and Krest, J.M. (1993). A suggested protocol for the continuous automated analysis of seawater nutrients (phosphate, nitrate, nitrite and silicic acid) in the WOCE Hydrographic program and the Joint Global Ocean Fluxes Study. WOCE Operations Manual, vol. 3: The Observational Programme, Section 3.2: WOCE Hydrographic Programme, Part 3.1.3: WHP Operations and Methods. WHP Office Report WHPO 91-1; WOCE Report No. 68/91. November 1994, Revision 1, Woods Hole, MA., USA, 52 loose-leaf pages.; Researcher name: Jia-Zhong Zhang; Researcher institution: Atlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration.
- Parameter or Variable: Sum of nitrate + nitrite; Abbreviation: NITRATE_and_NITRITE_UMOL_KG; Unit: micromol/kg; Observation type: Surface underway (flow through) and CTD (surface bottle); In-situ / Manipulation / Response variable: in-situ observation; Measured or calculated: Measured; Sampling instrument: Flow through and surface CTD niskin; Analyzing instrument: Continuous flow analyzer (CFA) using the standard and analysis protocols for the WOCE hydrographic program as set forth in the manual by L.I. Gordon, et al. (1993).; Detailed sampling and analyzing information: Nutrient samples were collected from the underway system, after at least three seawater rinses. Sample analysis typically began within a few hours of sample collection after the samples had warmed to room temperature. Those samples not analyzed within 3 hours were refrigerated for later analysis. Samples were analyzed for phosphate (PO4− 3), nitrate (NO3−), nitrite (NO2−) and orthosilicic acid (H4SiO4). Samples were passed through a cadmium column, which reduced nitrate to nitrite, and the resulting nitrite concentration (i.e. the sum of nitrate + nitrite which is signified as N+N) was then determined as described above.; Uncertainty: A mixed stock standard consisting of silicic acid, phosphate and nitrate was prepared by dissolving high purity standard materials (KNO3, KH2PO4 and Na2SiF6) in deionized water using a two step dilution for phosphate and nitrate. This standard was stored at room temperature. A nitrite stock standard was prepared dissolving NaNO2 in distilled water, and this standard was stored in the ship’s refrigerator. Working standards were prepared fresh daily by diluting the stock solutions in low nutrient seawater. The mixed standards were verified against commercial standards, and in-lab standards.; Quality flag convention: WOCE quality control flags are used: 2 = good value, 3 = questionable value, 4 = bad value, 5 = value not reported, 6 = mean of replicate measurements, 9 = sample not drawn.; Method reference: Armstrong, F.A.J., Stearns, C.R. and Strickland, J.D.H. (1967). The measurement of upwelling and subsequent biological processes by means of the Technicon AutoAnalyzer and associated equipment. Deep-Sea Res. 14:381-389.Gordon, L.I., Jennings Jr., J.C., Ross, A.A. and Krest, J.M. (1993). A suggested protocol for the continuous automated analysis of seawater nutrients (phosphate, nitrate, nitrite and silicic acid) in the WOCE Hydrographic program and the Joint Global Ocean Fluxes Study. WOCE Operations Manual, vol. 3: The Observational Programme, Section 3.2: WOCE Hydrographic Programme, Part 3.1.3: WHP Operations and Methods. WHP Office Report WHPO 91-1; WOCE Report No. 68/91. November 1994, Revision 1, Woods Hole, MA., USA, 52 loose-leaf pages.; Researcher name: Jia-Zhong Zhang; Researcher institution: Atlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration.
- Parameter or Variable: phosphate; Abbreviation: PHOSPHATE_UMOL_KG; Unit: micromol/kg; Observation type: Surface underway (flow through) and CTD (surface bottle); In-situ / Manipulation / Response variable: in-situ observation; Measured or calculated: Measured; Sampling instrument: Flow through and surface CTD niskin; Analyzing instrument: Continuous flow analyzer (CFA) using the standard and analysis protocols for the WOCE hydrographic program as set forth in the manual by L.I. Gordon, et al. (1993).; Detailed sampling and analyzing information: Nutrient samples were collected from the underway system, after at least three seawater rinses. Sample analysis typically began within a few hours of sample collection after the samples had warmed to room temperature. Those samples not analyzed within 3 hours were refrigerated for later analysis. Samples were analyzed for phosphate (PO4− 3), nitrate (NO3−), nitrite (NO2−) and orthosilicic acid (H4SiO4). Phosphate was determined by reacting the sample with molybdic acid to form phosphomolybdic acid. This complex was subsequently reduced with hydrazine, and the absorbance of the resulting phosphomolybdous acid was measured at 820 nm.; Uncertainty: A mixed stock standard consisting of silicic acid, phosphate and nitrate was prepared by dissolving high purity standard materials (KNO3, KH2PO4 and Na2SiF6) in deionized water using a two step dilution for phosphate and nitrate. This standard was stored at room temperature. A nitrite stock standard was prepared dissolving NaNO2 in distilled water, and this standard was stored in the ship’s refrigerator. Working standards were prepared fresh daily by diluting the stock solutions in low nutrient seawater. The mixed standards were verified against commercial standards, and in-lab standards.; Quality flag convention: WOCE quality control flags are used: 2 = good value, 3 = questionable value, 4 = bad value, 5 = value not reported, 6 = mean of replicate measurements, 9 = sample not drawn.; Method reference: Armstrong, F.A.J., Stearns, C.R. and Strickland, J.D.H. (1967). The measurement of upwelling and subsequent biological processes by means of the Technicon AutoAnalyzer and associated equipment. Deep-Sea Res. 14:381-389.Gordon, L.I., Jennings Jr., J.C., Ross, A.A. and Krest, J.M. (1993). A suggested protocol for the continuous automated analysis of seawater nutrients (phosphate, nitrate, nitrite and silicic acid) in the WOCE Hydrographic program and the Joint Global Ocean Fluxes Study. WOCE Operations Manual, vol. 3: The Observational Programme, Section 3.2: WOCE Hydrographic Programme, Part 3.1.3: WHP Operations and Methods. WHP Office Report WHPO 91-1; WOCE Report No. 68/91. November 1994, Revision 1, Woods Hole, MA., USA, 52 loose-leaf pages.; Researcher name: Jia-Zhong Zhang; Researcher institution: Atlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration.
- Parameter or Variable: carbonate ion concentration; Abbreviation: CARBONATE_UMOL_KG; Unit: micromol/kg; Observation type: Surface underway (flow through) and CTD (surface bottle); In-situ / Manipulation / Response variable: in-situ observation; Measured or calculated: Measured; Sampling instrument: Flow through and surface CTD niskin; Analyzing instrument: Agilent 8453 spectrometer setup with a custom-made temperature-controlled cell holder.; Detailed sampling and analyzing information: The carbonate ion samples were sampled into quartz cells in the same manner as the pH samples. After the pH samples were taken, the quartz cells were attached to the silicone tubing to collect samples for carbonate ion concentration measurements. Samples were analyzed on an Agilent 8453 spectrophotometer. A UV blank was taken for each sample and 20 µL of 0.022 M PbClO4 were added (Acros Organics, Lot A0301399 – 99% purity). Absorbances, A, were measured at two wavelengths (1λ = 234 nm and 2λ = 250 nm), along with the absorbance at a non-absorbing wavelength (350 nm).; Replicate information: A total of 196 underway samples were taken, 70 sets up duplicates.; Uncertainty: All spectrophotometric CO32- measurements were tentatively flagged if the baseline shifted more than 0.002absorbance units for carbonate ion measurements. A series of at least five spectra were averaged for each determination and samples were rerun if the overall standard deviations were higher than 0.001. This process was repeated until the standard deviation of multiple readings was within 0.001. Absorbance values were saved so that the quality criteria can be evaluated in the future.Data for directly measured carbonate are reported in terms of both concentrations and the R-Ratios taken at 250 nm and 234 nm. Data for CO32-, are reported at the analysis temperature of 25 ºC.; Quality flag convention: WOCE quality control flags are used: 2 = good value, 3 = questionable value, 4 = bad value, 5 = value not reported, 6 = mean of replicate measurements, 9 = sample not drawn.; Method reference: Byrne, R.H.; & Yao, W. (2008). Procedures for measurement of carbonate ion concentrations in seawater by direct spectrophotometric observations of Pb(II) complexation. Marine Chemistry, 112(1-2), 128-135. Clayton, T.D.; & Byrne, R.H. (1993). Spectrophotometric seawater pH measurements: total hydrogen ion concentration scale calibration of m-cresol purple and at-sea results. Deep Sea Research Part I: Oceanographic Research Papers, 40(10), 2115-2129. doi: 10.1016/0967-0637(93)90048-8Liu, X.; Patsavas, M.C.; & Byrne, R. H. (2011). Purification and characterization of meta-cresol purple for spectrophotometric seawater pH measurements. Environmental Science & Technology, 45(11), 4862-4868. doi: 10.1021/es200665d.; Researcher name: Robert Byrne; Researcher institution: University of South Florida .
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