Solubility of minerals and forms of lead existence in seawater

The values of the thermodynamical solubility product for lead sulfate, hydr oxochloride, and chromate in seawater are determined experimentally. From t he experimental data, the values of the total activity coefficients of Pb2 ions in seawater are estimated to be 0.0128 at pH = 5.90; 0.0094 at pH = 7 .05, and 0.0012 at pH = 7.9. It is shown that the share of free Pb2+ ions d ecreases from 4 to 0.6% as the pH value increases from 7 to 8. The essentia l forms of Pb2+ in seawater are chloride and sulfate complexes amounting to 95% of the sum of all forms of the lead dissolved.