The dissociation constants of carbonic acid in seawater at salinities 5 to 45 and temperatures 0 to 45°C

Rabindra N. Roy, Lakshimi N. Roy, Kathleen M. Vogel, C. Porter-Moore, Tara Pearson, Catherine E. Good, Frank J. Millero, Douglas M. Campbell

Research output: Contribution to journalArticle

485 Scopus citations

Abstract

The pK1* and pK2* for the dissociation of carbonic acid in seawater have been determined from 0 to 45°C and S = 5 to 45. The values of pK1* have been determined from emf measurements for the cell:Pt](1 - X)H2 + XCO2|NaHCO3, CO2 in synthetic seawater|AgC1; Ag where X is the mole fraction of CO2 in the gas. The values of pK2* have been determined from emf measurements on the cell: Pt, H2(g, 1 atm)|Na2CO3, NaHCO3 in synthethic seawater|AgC1; Ag The results have been fitted to the equations: lnK*1 = 2.83655 - 2307.1266/T - 1.5529413 lnT + (-0.20760841 - 4.0484/T)S0.5 + 0.08468345S - 0.00654208S1 InK*2 = -9.226508 - 3351.6106/T- 0.2005743 lnT + (-0.106901773 - 23.9722/T)S0.5 + 0.1130822S - 0.00846934S1.5 where T is the temperature in K, S is the salinity, and the standard deviations of the fits are σ = 0.0048 in lnK1* and σ = 0.0070 in lnK2*. Our new results are in good agreement at S = 35 (±0.002 in pK1* and ±0.005 in pK2*) from 0 to 45°C with the earlier results of Goyet and Poisson (1989). Since our measurements are more precise than the earlier measurements due to the use of the Pt, H2|AgCl, Ag electrode system, we feel that our equations should be used to calculate the components of the carbonate system in seawater.

Original languageEnglish (US)
Pages (from-to)249-267
Number of pages19
JournalMarine Chemistry
Volume44
Issue number2-4
DOIs
StatePublished - Dec 1993

    Fingerprint

ASJC Scopus subject areas

  • Oceanography
  • Chemistry(all)
  • Environmental Chemistry
  • Water Science and Technology

Cite this

Roy, R. N., Roy, L. N., Vogel, K. M., Porter-Moore, C., Pearson, T., Good, C. E., Millero, F. J., & Campbell, D. M. (1993). The dissociation constants of carbonic acid in seawater at salinities 5 to 45 and temperatures 0 to 45°C. Marine Chemistry, 44(2-4), 249-267. https://doi.org/10.1016/0304-4203(93)90207-5