the great impetus for the study of removal mechanisms of ion from seawater was the publication of AA (1961) equilibrium model. The basic postulate of this model was that the cationic ratios in seawater were controlled by equilibria among the major solid phases present in marine sediments; thus, for example, the [Mg2+]/[H+] ratio would be determined by equilibrium between chlorite and quartz (a similar reaction can be written for an aluminous chlorite, with kaolinite as a product on the right-hand side):