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Method Description:
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Total C02 Data:
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TCO2 Analysis Method:
The coulometric analysis system which was used to measure the TCO2 concentration in seawater samples during the expedition is similar to the one described by Johnson et al. (1985). This system consists of a coulometer (Model 5011) manufactured by the UIC Inc. (Jollies, IL) and a sample introduction/CO2 extraction system of the LDEO design, which differs from the Single Operator Multiparameter Metabolic Analyzer (SOMMA) system used by most of the other participants of the DOE/CO2 program. In the LDEO system (Chipman et al., 1993), a precisely known volume of seawater sample is introduced manually into an CO2 extraction vessel using a calibrated syringe, instead of an automated pipette used by the SOMMA system.
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Standardization Technique:
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Technique Description:
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Sample Volume:
250 mL
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CRM Info:
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Correction Magnitude:
Measured values are not corrected for CRM
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Batch Number:
6
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CRM Analysis Info:
The precision of the total CO2 measurements was further tested by analyzing the Certified Reference Solutions each day along with the seawater samples. CRMs were provided by Dr. A. G. Dickson of SIO and their shipboard measurements yielded a mean value of 2303.2 ± 1.5 µmol/kg (N = 156), which compares with 2304.6 ± 1.6 µmol/kg (N = 9) determined manometrically by the staff of C. D. Keeling.
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Field Replicate Info:
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Poisoning Info:
All samples were poisoned with 200 uL of 50% saturated mercuric chloride solution to prevent biological alteration of the TCO2, and were analyzed within 24 hours of collection. 200 uL
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Poisoning Correction Description:
All samples were poisoned with 200 uL of 50% saturated mercuric chloride solution to prevent biological alteration of the TCO2, and were analyzed within 24 hours of collection.
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Poison Volume:
200 uL
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Accuracy Info:
Our shipboard measurements yielded a mean value of 2303.2 ± 1.5 µ mol/kg (N = 156), which compares with 2304.6 ± 1.6 µ mol/kg (N = 9) determined manometrically by the staff of C. D. Keeling. Although our value is smaller than the Keeling value by 1.4 µ mol/kg, these mean values overlap within one standard deviation. Thus, the total CO2 concentration values reported in this report are consistent with the manometric values within ± 1.5 µmol/kg. The total CO2 values listed in this report are not corrected for the systematic difference of 1.4 µmol/kg.
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Method References:
Chipman, D. W., J. Marra, and T. Takahashi. 1993. Primary production at 47oN and 20oW in the North Atlantic Ocean: A comparison between the 14C incubation method and the mixed layer carbon budget. Deep-Sea Res. 40:151-69. Johnson, K. M., A. E. King, and J. McN. Sieburth. 1985. Coulometric TCO2 analyses for marine studies: An introduction. Mar. Chem. 16:61-82. Millero, F.J., C.-T. Chen, A. Bradshaw, and K. Schleicher. 1980. A new high pressure equation of state for seawater. Deep.Sea Res. 27:255-64. Takahashi, T., J. G. Goddard, S. Rubin, D. W. Chipman, and S. C. Sutherland. 1993. Investigation of Carbon Dioxide in the Central South Pacific Ocean (WOCE Sections P-16C and P-17C) during the TUNES/2 Expedition of the R/V Thomas Washington, July August, 1991. Final Technical Report for grant DE-FGO2-90-ER60983, LDEO of Columbia University, Palisades, N.Y.
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Citations:
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Alkalinity:
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Curve Fitting Method:
The TALK concentration in 139 samples was determined on shore at the laboratory of C. Goyet of WHOI.
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Type of Titration:
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Description of Other Titration:
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Cell Type:
Closed
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CRM cale:
Millero
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Sample Volume:
250 mL
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Magnitude of Blank Correction:
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Accuracy Info:
The precision of the measurements was estimated to be better than 0.1%.
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Method References:
Bradshaw, A. L., P. G. Brewer, D. K. Shafer, and R. T. Williams. 1981. Measurements of total carbon dioxide and alkalinity by potentiometric titration in the GEOSECS program. Earth Planet. Sci. Lett. 55:99-115. Brewer, P. G., A. L. Bradshaw, and R. T. Williams. 1986. Measurements of total carbon dioxide and alkalinity in the North Atlantic Ocean in 1981. pp. 358-81. In D. Reiche (ed.), The Global Carbon Cycle: Analysis of the Natural Cycle and Implications of Anthropogenic Alterations for the Next Century. Springer, New York. Dyrssen D. 1965. A gran titration of sea water on board SAGITTA. Acta Chemica Scand. 19:1265
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Citations:
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pCO2 Data:
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Analysis:
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pCO2 Analysis Method:
A fully automated equilibrator-gas chromatograph system was used during the expedition for the determination of partial pressure of CO2 exerted by the seawater samples, and its design has been described by Chipman et al. (1993).
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Sample Volume:
500 mL
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Headspace_Volume:
3-5 mL
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Measurement_Temperature:
20 degree C
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Temperature Normalization:
20 degree C
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Temperature Correction Method:
constant temperature water bath
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Variable Reported:
pCO2
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Gas:
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Standard Gas Concentrations:
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Frequency of Standardization:
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Field Replicate Info:
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Storage Method:
The samples were poisoned with 200 µl of 50% saturated mercuric chloride solution to prevent biological modification of the pCO2, and were stored in the dark until measurement, which normally was performed within 24 hours of sampling.
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Accuracy Info:
The overall precision of the pCO2 measurement has been estimated to be about ± 0.10% based on the reproducibility of replicate equilibrations.
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Method References:
Chipman, D. W., J. Marra, and T. Takahashi. 1993. Primary production at 47oN and 20oW in the North Atlantic Ocean: A comparison between the 14C incubation method and the mixed layer carbon budget. Deep-Sea Res. 40:151-69. Weiss, R.F. 1981. Determination of CO2 and methane by dual catalyst flame ionization chromatography and nitrous oxide by electron capture chromatography. Jour. of Chromatogr. Sci. 19:611-616. Takahashi, T., D. Chipman, N. Schechtman, J. Goddard, and R. Wanninkof. 1982. Measurements of the partial pressure of CO2 in discrete water samples during the North Atlantic Expedition, the Transient Tracers of Oceans Project. Technical Report to NSF, Lamont-Doherty Geol. Obs., Palisades, NY.
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pH Data:
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pH Scale:
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pH Analysis Method:
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Calibration Info:
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Calibration Description:
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In Situ Temperature:
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Temperature of Analysis:
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Temperature Normalization:
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In Situ Pressure:
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Accuracy Info:
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Method References:
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Citation:
| Takahashi, T., J. G. Goddard, S. Rubin, D. W. Chipman, S. C. Sutherland, and C. Goyet. 1995. Carbon Dioxide, Hydrographic, and Chemical Data Obtained in the Central South Pacific Ocean (WOCE Sections P17S and P16S) During the TUNES-2 Expedition of the R/V Thomas Washington, July-August, 1991. ORNL/CDIAC-86, NDP-054. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee. doi:10.3334/CDIAC/otg.ndp054 |
Metadata Summary
