| Processing Steps |
- Parameter or Variable: pH (measured); Units: total; Observation Category: laboratory analysis; Sampling Instrument: Niskin bottle; Sampling and Analyzing Method: Measurements are reported as PH_TOT. Seawater was drawn from the Niskin bottles into 250ml borosilicate bottles, following best practices. Bottles were rinsed 3 times, filled from the bottom over 10-15 seconds, and overflowed for approximately another 10-15 seconds. No headspace was left, and the bottle stopper was gently placed in to minimize gas exchange. All samples were run within 2 hours of collection while preferentially measuring near surface waters first, thus, samples were not poisoned. At least one duplicate sample was drawn every cast to assess precision. pH was measured spectrophotometrically (Clayton and Byrne, 1993) using purified m-cresol purple dye (Liu et al. 2011), and reported on the total scale. Dye solution of 2mM was prepared in 0.7M NaCl background, and pH was adjusted to ~7.8 and dye addition correction was characterized prior to the cruise; at sample pH of 7.4, perturbation was on the magnitude of 0.001-0.002 pH. A semi-automated system was utilized based on the design from Carter et al. 2013. Briefly, a Kloehn syringe pump is used to transfer sample into a 10-cm jacketed cell, controlled to 20°C using a recirculating water bath. Water temperature of the outflow of the jacketed component was measured. Absorbance spectra was measured using an Agilent 8453 spectrophotometer, and three spectra each were measured for the ‘blank’ and ‘sample’, and averaged. Samples were kept in a water bath that was temperature controlled to ~20°C for at least 30 minutes prior to analysis.; Data Quality Method: Precision of the pH measurement is estimated to be ± 0.002 (1 σ), based on the differences between duplicate samples (mean difference was -0.0001 ± 0.002, n = 44). The reproducibility of the measurements were assessed through routine measurements of Certified Reference Material (CRMs) for DIC and TA (Batch 183). The mean difference between measured and calculated pH (measured minus calculated; using constants from Leuker et al. 2000) was -0.0076 ± 0.001 (1 σ, n = 20). From this, we conclude that pH measurements were stable to better than 0.002 throughout the cruise. WOCE water sample quality codes are used for PH_TOT_FLAG_W: 2 = acceptable measurement, 3 = questionable measurement, 4 = bad measurement, 5 = not reported, 6 = mean of replicate measurements, 9 = sample not drawn for measurement from this Niskin bottle. Quality flags were assigned using several criteria. Measurements were flagged 3 (questionable) if the baseline absorbance changed by more than 0.004 between blank and sample, or if there was indication that a bubble was in the optical path. Furthermore, the data were flagged 4 (bad) if the sample clearly did not fit the shape of the expected profile, and no coincident changes in O2 or DIC were observed, or flagged 3 (questionable) if the shape of the profile deviated slightly from expectation.
- Parameter or Variable: DISSOLVED INORGANIC CARBON (DIC) (measured); Units: micromole/kilogram; Observation Category: laboratory analysis; Sampling Instrument: Niskin bottle; Sampling and Analyzing Method: PLEASE NOTE: DIC may be referred to as TCO2, TCARBN, or C(sub)T in other data sets. We report DIC measurements as TCARBN. All of these abbreviations refer to the total dissolved inorganic carbon concentration (i.e., the combined concentration of dissolved CO2, bicarbonate ion, and carbonate ion). Seawater was drawn from the Niskin bottles into 250ml borosilicate bottles, following best practices. Bottles were rinsed 3 times, filled from the bottom over 10-15 seconds, and overflowed for approximately another 10-15 seconds. No headspace was left, and the bottle stopper was gently placed in to minimize gas exchange. All samples were run within 3 hours of collection while preferentially measuring near surface waters first, thus, samples were not poisoned. At least one duplicate sample was drawn every cast to assess precision. DIC measurements were made using a custom system based on O’Sullivan et al. 1998, using an Infrared detector (LiCOR7000). Briefly, 1.5 ml of sample is injected and acidified in a stripping chamber. N2 was used as the carrier gas, and dried using Nafion tubing prior to reaching the analyzer. All samples were measured in triplicate. Samples were kept in a temperature controlled bath (~20°C) for at least 30 minutes prior to, and during analysis. Certified Reference Materials (CRM batch 183) were measured every ~hour to calibrate the system. A new bottle was opened for a new station or every 6 hours, whichever was shorter, and recapped in between. Laboratory tests demonstrated negligible drift in CRM DIC over this time period, so long as the solution was undisturbed.; Data Quality Method: Precision of the DIC measurement is estimated to be ± 1.8 μmol kg-1 (1 σ), based on the differences between duplicate samples (mean difference was -0.4 ± 1.8 μmol kg-1, n = 62). Accuracy is estimated to be ± 2 μmol kg-1. WOCE water sample quality codes are used for TCARBN_FLAG_W: 2 = acceptable measurement, 3 = questionable measurement, 4 = bad measurement, 5 = not reported, 6 = mean of replicate measurements, 9 = sample not drawn for measurement from this Niskin bottle. Data were flagged 4 (bad) if the sample clearly did not fit the shape of the expected profile, and no coincident changes in O2 or pH were observed, or flagged 3 (questionable) if the shape of the profile deviated slightly from expectation. TA
- Parameter or Variable: total alkalinity (measured); Units: micromole/kilogram; Observation Category: laboratory analysis; Sampling Instrument: Niskin bottle; Sampling and Analyzing Method: Measurements are reported as ALKALI. Seawater was drawn from the Niskin bottles into 250ml borosilicate bottles, following best practices. Bottles were rinsed 3 times, filled from the bottom over 10-15 seconds, and overflowed for approximately another 10-15 seconds. Approximately 1% headspace was left by pinching the sampling tube before slowly removing. Samples were preserved using 0.1 ml of saturated mercuric chloride solution and sealed following best practices. Samples were analyzed back in the laboratory within 2 months of collection. Due to bottle shortages, duplicate samples were not taken. TA was measured using an open cell titration with a modified gran approach to calculate the endpoint, following best practices. A modified Metrohm 855 autotitrator was used. All samples were run in triplicate, and the average value is reported. 35 ml of sample was delivered to a temperature controlled beaker using a 50 ml Dosino syringe pump, calibrated gravimetrically. Titrant was 0.1 M HCl in 0.6M NaCl background, and was calibrated using frequent measurements of Certified Reference Materials (CRMs; batch 185).; Data Quality Method: Precision of the TA measurement was estimated from the average precision from the triplicate measurements made on each sample (defined as 1 σ), and is estimated to be ± 1.08 μmol kg-1. This is likely a slight underestimate of the true precision of the measurement, as it only accounts for instrumental precision and not the sampling process. Thus, we estimate the accuracy as double this number, and to be ± 2.16 μmol kg-1. WOCE water sample quality codes are used for ALKALI_FLAG_W: 2 = acceptable measurement, 3 = questionable measurement, 4 = bad measurement, 5 = not reported, 6 = mean of replicate measurements, 9 = sample not drawn for measurement from this Niskin bottle. Data from the first 4 stations are flagged as 3 (questionable), due to the larger than expected precision and reproducibility. Additionally, data were flagged 4 (bad) if the sample clearly did not fit the shape of the expected profile, and no coincident changes in O2 or salinity were observed, or flagged 3 (questionable) if the shape of the profile deviated slightly from expectation.
- Parameter or Variable: DISSOLVED OXYGEN (measured); Units: micromole/kilogram; Observation Category: laboratory analysis; Sampling Instrument: Niskin bottle; Sampling and Analyzing Method: Measurements are reported as OXYGEN. Seawater was drawn from the Niskin bottles into 125 ml borosilicate Iodine flasks, following best practices, and analyzed via Winkler Titration. Bottles were rinsed 3 times, filled from the bottom slowly while removing any visible bubbles. Water was allowed to overflow 3 times its volume to ensure the flask was at thermal equilibrium. The tube was withdrawn without turbulence to maintain an overfull bottle. A bottletop pump dispenser was used to add 1 ml of MgCl2 and 1 ml of NaOH-NaI mixture to precipitate out O2. The flask was capped gently without introducing any bubbles, and mixed thoroughly to homogenize the solution. DI water was added to the lid to minimize gas exchange. Solution was remixed approximately 30 minutes later, and samples were analyzed approximately 6 hours after collection. The titration followed best practices (Dickson, 2003), using a custom built instrument with a photometric endpoint detection. Titrant concentration was determined directly before and after the cruise through gravimetric addition of KIO3 standard, which was recrystallized 4 times and dried in the oven for > 24 hours for improved accuracy. No drift in titrant concentration was observed. Titrant was added using an automated Dosino burette, and the endpoint was detected automatically. Each Iodine flask volume was calibrated gravimetrically, and temperature and salinity from the CTD was used to convert concentration to micromole-per-kilogram.; Data Quality Method: Precision of the O2 measurement is estimated to be ± 0.6 μmol kg-1 (1 σ), based on the differences between duplicate samples (mean difference was -0.04 ± 0.64 μmol kg-1, n = 27). Accuracy is estimated to be ± 1 μmol kg-1, because KIO3 standards were recrystallized (Emerson 1990). WOCE water sample quality codes are used for OXYGEN_FLAG_W: 2 = acceptable measurement, 3 = questionable measurement, 4 = bad measurement, 5 = not reported, 6 = mean of replicate measurements, 9 = sample not drawn for measurement from this Niskin bottle. Data were flagged 3 (questionable) if any bubbles existed in the pickled sample prior to analysis. Additionally, data were flagged 4 (bad) if the sample clearly did not fit the shape of the expected profile, and no coincident changes in pH or DIC were observed, or flagged 3 (questionable) if the shape of the profile deviated slightly from expectation.
- Parameter or Variable: NITRATE (measured); Units: micromole/liter; Observation Category: laboratory analysis; Sampling Instrument: Niskin bottle; Sampling and Analyzing Method: Measurements are reported as NITRAT. Samples were collected in 20 ml PTFE bottles with PTFE conical caps, and immediately frozen in a -80°C freezer. Samples were analyzed within 1 year of collection in the laboratory at MBARI using an Alpkem Astoria-Pacific Rapid Flow Analysis (RFA) system.; Data Quality Method: WOCE water sample quality codes are used for NITRAT_FLAG_W: 2 = acceptable measurement, 3 = questionable measurement, 4 = bad measurement, 5 = not reported, 6 = mean of replicate measurements, 9 = sample not drawn for measurement from this Niskin bottle. Data were flagged 4 (bad) if the sample clearly did not fit the shape of the expected profile, and no coincident changes in pH or O2 were observed, or flagged 3 (questionable) if the shape of the profile deviated slightly from expectation.
- Parameter or Variable: phosphate (measured); Units: micromole/liter; Observation Category: laboratory analysis; Sampling Instrument: Niskin bottle; Sampling and Analyzing Method: Measurements are reported as PHSPHT. Samples were collected in 20 ml PTFE bottles with PTFE conical caps, and immediately frozen in a -80°C freezer. Samples were analyzed within 1 year of collection in the laboratory at MBARI using an Alpkem Astoria-Pacific Rapid Flow Analysis (RFA) system.; Data Quality Method: WOCE water sample quality codes are used for PHSPT_FLAG_W: 2 = acceptable measurement, 3 = questionable measurement, 4 = bad measurement, 5 = not reported, 6 = mean of replicate measurements, 9 = sample not drawn for measurement from this Niskin bottle. Data were flagged 4 (bad) if the sample clearly did not fit the shape of the expected profile, and no coincident changes in pH or O2 were observed, or flagged 3 (questionable) if the shape of the profile deviated slightly from expectation.
- Parameter or Variable: silicate (measured); Units: micromole/liter; Observation Category: laboratory analysis; Sampling Instrument: Niskin bottle; Sampling and Analyzing Method: Measurements are reported as SILCAT. Samples were collected in 20 ml PTFE bottles with PTFE conical caps, and immediately frozen in a -80°C freezer. Samples were analyzed within 1 year of collection in the laboratory at MBARI using an Alpkem Astoria-Pacific Rapid Flow Analysis (RFA) system.; Data Quality Method: WOCE water sample quality codes are used for SILCAT_FLAG_W: 2 = acceptable measurement, 3 = questionable measurement, 4 = bad measurement, 5 = not reported, 6 = mean of replicate measurements, 9 = sample not drawn for measurement from this Niskin bottle. Data were flagged 4 (bad) if the sample clearly did not fit the shape of the expected profile, and no coincident changes in pH or O2 were observed, or flagged 3 (questionable) if the shape of the profile deviated slightly from expectation.
- Parameter or Variable: NITRITE (measured); Units: micromole/liter; Observation Category: laboratory analysis; Sampling Instrument: Niskin bottle; Sampling and Analyzing Method: Measurements are reported as NITRIT. Samples were collected in 20 ml PTFE bottles with PTFE conical caps, and immediately frozen in a -80°C freezer. Samples were analyzed within 1 year of collection in the laboratory at MBARI using an Alpkem Astoria-Pacific Rapid Flow Analysis (RFA) system.; Data Quality Method: WOCE water sample quality codes are used for NITRIT_FLAG_W: 2 = acceptable measurement, 3 = questionable measurement, 4 = bad measurement, 5 = not reported, 6 = mean of replicate measurements, 9 = sample not drawn for measurement from this Niskin bottle. Data were flagged 4 (bad) if the sample clearly did not fit the shape of the expected profile, and no coincident changes in pH or O2 were observed, or flagged 3 (questionable) if the shape of the profile deviated slightly from expectation.
- Parameter or Variable: HYDROSTATIC PRESSURE recorded from CTD at depth where the sample is taken (measured); Units: dbars; Observation Category: in situ; Sampling Instrument: Sea-Bird Scientific SBE 9plus CTD; Sampling and Analyzing Method: Pressure was measured using the pressure sensor on the CTD. Data were processed using SBE proprietary software, and values from the .btl file were used.; Data Quality Method: No data flags were applied to CTD pressure data
- Parameter or Variable: WATER TEMPERATURE recorded from CTD at depth where the sample is taken (measured); Units: Celsius ITS-90 Scale; Observation Category: in situ; Sampling Instrument: Sea-Bird Scientific SBE 9plus CTD; Sampling and Analyzing Method: Temperature was measured using the thermometer on the CTD. Data were processed using SBE proprietary software, and values from the .btl file were used.; Data Quality Method: No data flags were applied to CTD pressure data
- Parameter or Variable: SALINITY from the CTD (calculated); Units: 1978 practical salinity scale; Observation Category: in situ; Sampling Instrument: Sea-Bird Scientific SBE4 CTD; Sampling and Analyzing Method: Measurements are reported as CTDSAL. Salinity was calculated from conductivity measurements using factory calibration coefficients on the CTD, with SBE software. Outputs from the .btl file were used.; Data Quality Method: WOCE water sample quality codes are used for CTDSAL_FLAG_W: 2 = acceptable measurement, 3 = questionable measurement, 4 = bad measurement, 5 = not reported, 6 = mean of replicate measurements, 9 = sample not drawn for measurement from this Niskin bottle. Data were visually inspected, salinity values were compared between the two CTDs. CTDSAL was compared to discrete salinity, and the median difference was -0.0045 ± 0.0073 with a near constant offset trend. Therefore a constant offset of +0.0045 was applied to CTDSAL.
- Parameter or Variable: DISSOLVED OXYGEN from the CTD (measured); Units: micromole/kilogram; Observation Category: in situ; Sampling Instrument: Sea-Bird Scientific SBE43; Sampling and Analyzing Method: Measurements are reported as CTDOXY. Oxygen was measured using a profiling Clark electrode O2 sensor (SBE43), and processed using factory calibrations with SBE software. Outputs from the .btl file were used.; Data Quality Method: WOCE water sample quality codes are used for CTDOXY_FLAG_W: 2 = acceptable measurement, 3 = questionable measurement, 4 = bad measurement, 5 = not reported, 6 = mean of replicate measurements, 9 = sample not drawn for measurement from this Niskin bottle. The CTDOXY was calibrated based on comparisons to bottle oxygen measured with Winkler titrations, and the following linear correction was applied: CTDOXY_corrected = CTDOXY * 1.0648 + 0.995
- Parameter or Variable: CHLOROPHYLL A CONCENTRATION from fluorometery (measured); Units: microgram/liter; Observation Category: laboratory analysis; Sampling Instrument: Niskin bottle; Sampling and Analyzing Method: Measurements are reported as CHL_GFF. Chlorophyll-a and phaeopigments were collected in 280-ml polyethylene bottles and filtered onto 25-mm Whatmann GF/F filters. Chlorophyll-a was assayed with the standard fluorometric procedure of Holm-Hansen et al. (1965), modified such that phaeopigments are extracted in acetone in a freezer over at least 24 hours (Venrick and Hayward, 1984; Chavez et al., 1991). Analysis was performed as possible during the cruise or at MBARI immediately following the cruise on a Turner 10AU fluorometer.; Data Quality Method: WOCE water sample quality codes are used for CHLPHAEO_FLAG_W: 2 = acceptable measurement, 3 = questionable measurement, 4 = bad measurement, 5 = not reported, 6 = mean of replicate measurements, 9 = sample not drawn for measurement from this Niskin bottle. Quality flags were applied based on visual inspection of the profile
- Parameter or Variable: PHAEOPIGMENTS from fluorometery (measured); Units: microgram/liter; Observation Category: laboratory analysis; Sampling Instrument: Niskin bottle; Sampling and Analyzing Method: Measurements are reported as CHLPHAEO_GFF. Chlorophyll-a and phaeopigments were collected in 280-ml polyethylene bottles and filtered onto 25-mm Whatmann GF/F filters. Chlorophyll-a was assayed with the standard fluorometric procedure of Holm-Hansen et al. (1965), modified such that phaeopigments are extracted in acetone in a freezer over at least 24 hours (Venrick and Hayward, 1984; Chavez et al., 1991). Analysis was performed as possible during the cruise or at MBARI immediately following the cruise on a Turner 10AU fluorometer.; Data Quality Method: WOCE water sample quality codes are used for CHLPHAEO _FLAG_W: 2 = acceptable measurement, 3 = questionable measurement, 4 = bad measurement, 5 = not reported, 6 = mean of replicate measurements, 9 = sample not drawn for measurement from this Niskin bottle. Quality flags were applied based on visual inspection of the profile.
- Parameter or Variable: SALINITY from a salinometer (measured); Units: 1978 practical salinity scale; Observation Category: laboratory analysis; Sampling Instrument: Niskin bottle; Sampling and Analyzing Method: Measurements are reported as SALNTY. Samples were collected into 200 ml borosilicate bottles; typically 2 samples were collected per station. Samples were analyzed within 3 months of the cruise on a Guildline 8400B Autosal salinometer in the laboratory at MBARI.; Data Quality Method: WOCE water sample quality codes are used for SALNTY_FLAG_W: 2 = acceptable measurement, 3 = questionable measurement, 4 = bad measurement, 5 = not reported, 6 = mean of replicate measurements, 9 = sample not drawn for measurement from this Niskin bottle.
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