THE DISSOCIATION-CONSTANTS OF CARBONIC-ACID IN SEAWATER AT SALINITIES5 TO 45 AND TEMPERATURES 0-DEGREES-C TO 45-DEGREES-C

The pK(1) and pK(2)* for the dissociation of carbonic acid in seawate r have been determined from 0 to 45 degrees C and S = 5 to 45. The val ues of pK(1) have been determined from emf measurements for the cell: Pt\(l - X)H-2 + XCO(2)\NaHCO3, CO2 in synthetic seawater\AgCl; Ag whe re X is the mole fraction of CO2 in the gas. The values of pK(2) have been determined from emf measurements on the cell: Pt, H-2(g, 1 atm)N a2CO3, NaHCO3 in synthethic seawater\AgCl;Ag The results have been fit ted to the equations: InK1 = 2.83655 - 2307.1266/T - 1.5529413 lnT (-0.20760841 - 4.0484/T)S-0.5 + 0.08468345S - 0.00654208S(1) InK2 = - 9.226508 - 3351.6106/T - 0.2005743 InT + (-0.106901773 - 23.9722/T)S-0 .5 + 0.1130822S - 0.00846934S(1.5) where T is the temperature in K, S is the salinity, and the standard deviations of the fits are sigma = 0 .0048 in InK1 and sigma = 0.0070 in InK2*. Our new results are in goo d agreement at S = 35 (+/-0.002 in pK(1) and +/-0.005 in pK(2)*) from 0 to 45 degrees C with the earlier results of Goyet and Poisson (1989 ). Since our measurements are more precise than the earlier measuremen ts due to the use of the Pt, H-2\AgCl, Ag electrode system, we feel th at our equations should be used to calculate the components of the car bonate system in seawater.