ABSTRACT
Adsorption is arguably the most important of the physical-chemical processes responsible for the retention of inorganic and organic substances in the soil environment. The soil solution composition of inorganic and organic substances is controlled by surface or near-surface processes. With respect to trace elements, the activities of aqueous metal ions in equilibrium with an adsorbed phase are controlled to levels that can be orders of magnitude lower than levels controlled by even the most stable mineral phases.
