A NEW METHOD FOR DETERMINING THE TOTAL CARBONATE ION CONCENTRATION IN SALINE WATERS1

A new method of determining total carbonate ion content of saline waters requires measurement of the partial pressure of carbon dioxide gas (Pco2) in equilibrium with an initial solution, plus two more Pco2 measurements made after adding a known amount of strong base and after further adding boric acid. These three Pco2 measurements, plus the total inorganic carbon concentration (∑CO2) are used to compute the total carbonate ion concentration of the original solution, without the use of any system of apparent dissociation constants. Experimental data for seawater samples using this method yield total carbonate ion concentrations in agreement with those calculated using Lyman’s apparent dissociation constants for carbonic and boric acids. The method can be equally well applied to other saline natural waters.