Empirical equations for correction to in situ pressure

The pressure dependence of the various carbonate equilibrium constants is less well defined than the temperature dependence, with the result that less attention has been devoted to empirical equations for the pressure dependence of pH. Millero (1979) quotes the following equation for the NBS pH scale as a function of pressure P  

No corresponding equation is available for the total and seawater pH scales, but given the uncertainties involved in these pressure corrections this equation can be used to give reasonable estimates of corrections to in situ pressures on these scales also. 

(1973), Determination of pH. Theory and Practice. New York Wiley-lnterscience, 

Culberson, C. (1981), in Marine Electrochemistry Whitfield, M., Jagner, D. (Eds.), Chichester John Wiley, 1981 pp.187-261. 

UNESCO (1987). Thermodynamics of the carbon dioxide system in seawater. Report by the Carbon Dioxide Sub-Panel of the Joint Panel on Oceanographic Tables and Standards, Techn. Pap. Mar. Sci., No. 51, Paris. 

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