Chemical Modeling of Ion Adsorption in Soils

Adsorption occurs in soil when aqueous solutes accumulate on mineral surfaces, their coatings, or particulate organic matter. Adsorption is a fundamental process in soil that influences nutrient concentrations, the retardation of microcontaminants, the heterogeneous nucleation of secondary solid phases, and the stability of the colloidal fraction. Proton adsorption controls charge development on soil oxides, hydrous oxides, layer silicate edges, and organic matter, which, in turn, influences the adsorption of other solutes. Weathering, an integral component of the global carbon cycle and soil formation, is driven by adsorption of H+, CO2(g), organic acids of biotic origin, and reductants/oxidants that destabilize and promote release of structural cations such as Al (III) or Fe (II,III).