Total Alkalinity:\u00a0 Alkalinity was determined using an open cell titration with HCl (Dickson et al., 2007).\u00a0 The pH meter was a Corning model 109 which had been adapted so that the millivolt out was logged by computer through a 14 bit A to D converter.\u00a0 The electrode was an Orion Ross ultra semi-micro glass electrode model 8103-BNUWP.\u00a0 The pH electrode was standardized with accurate pH buffers.\u00a0 The tris buffer ( 2-amino-2-hydroxymethyl-1,3-propanediol) had a pH of about 8.09 depending on temperature.\u00a0 The AMP buffer (2-aminopyridine) had a pH of about 6.79 depending on temperature.\u00a0 Both were dissolved in artificial seawater at S = 35 (Dickson et al., 2007, SOP-6a).\u00a0 Samples and standards were titrated with a 0.15 M HCl solution in 0.45 M NaCl and the temperature was measured to the nearest 0.01C using a NIST calibrated platinum thermometer.\u00a0 The alkalinity standards generally were precise alkalinity/total carbon dioxide seawater standards from Scripps Institute of Oceanography (SIO), but early experiments also used a phosphate buffer standard comprised of an equal molar mixture of KH2PO4\u00a0and Na2HPO4\u00a0-7 H2O in 0.70 M NaCl.\u00a0 This phosphate standard was cross calibrated with the SIO standards.\u00a0 The procedure used generally gave the precision of several replicate standard titrations of 0.06% (standard error of the mean as percent of the mean value).\u00a0 Alkalinities were determined by the fitting procedure described in Dickson et al., 2007 (SOP-3b).
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Total Carbon Dioxide:\u00a0 These concentrations were determined by acid stripping a 1.113 ml volume of water sample or TCO2\u00a0standard, trapping the expelled CO2, and then injecting it into a Shimadzu Model GC-8A gas chromatograph with a thermal conductivity detector (Christensen, 2008).\u00a0 Two standards were employed, ones made from prebaked and freshly made Na2CO3, and the previously mentioned SIO total carbon dioxide seawater standards.\u00a0 This analytical system obtained a precision of about 0.06% (standard error of the mean as percent of the mean).\u00a0 However, in the results listed in this report, precision was less, averaging about 0.25% (standard error of the mean as percent of the mean) because sample analysis time was speeded up causing slightly less efficient trapping of the sample's CO2.\u00a0
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Salinity and Nutrients:\u00a0 Salinity was determined using an Autosal 8400A conductivity salinometer with IAPSO standard seawater standards.\u00a0 Replicate determinations of a single sample were made until two consecutive readings of conductivity matched within +/- 0.002 ppt.\u00a0 Nutrients were determined by autoanalyzer using the methods for nitrate and nitrite of Armstrong et al. (1967) and Pavlou (1972), for ammonium of Koroleff (1970) and Slawyk and MacIsaac (1972), for dissolved inorganic phosphate (Drummond and Maher, 1995), and dissolved silicate (Armstrong et al., 1967).\u00a0 Concentrations were measured in mol L-1\u00a0and converted to mol kg-1\u00a0based on the sample's sigma-t value computed from the sample's salinity and the laboratory temperature during analysis.
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Calculation of Carbonate System Parameters:\u00a0 Carbonate system parameters, include total pH, were calculated from the measured chemistry of the water samples using the carbonate equilibrium model, CO2SYS (DOE, 1994; Lewis and Wallace, 1995).\u00a0 This program employs the equilibrium coefficients of Roy et al. (1993) for carbonate coefficients, K1 and K2, of Weiss (1974) for carbon dioxide, K0, of Dickson (1990a) for borate, of Dickson and Riley (1979) for fluoride, of Dickson (1990b) for sulfate, and of Millero (1995) for phosphate (kp1, kp2, kp3) and silicate.\u00a0 Seawater density at atmospheric pressure was that of UNESCO (1981).
BCO-DMO Processing Notes:
\n- added conventional header with dataset name, PI name, version date
\n- modified parameter names to conform with BCO-DMO naming conventions
\n- hid separator rows (all -99), and duplicate columns