ABSTRACT
Heavy metals like Cd, Pb and Ni, and also As, are strongly poisonous and therefore the highest admissible concentration for these substances is very low (Table 1.1). Enhanced heavy metal concentrations constitute a serious problem for water supplies around the world. Once released to groundwater, the mobility of trace metals is to a large extent controlled by sorption processes. Part of trace metal sorption is due to ion exchange and can be estimated with the formulas from Chapter 6. However, most sorption is connected with specific binding of heavy metals to the variable charge surfaces of oxides and organic matter.
