ABSTRACT
A number of studies have been made on the behavior of heavy metals in different compartments of the environment. It is observed that each metal behaves in a different way in the ecosystem due to different thermodynamic and physico chemical properties. For example, Cd is deposited on soils in the particulate forms, e.g., in the solid phase, whereas Hg and As exist in the atmosphere pre dominantly in the vapor phase. Consequently, Hg has a tendency to be re-emitted to the air once deposited on the surface of soils (5). Deposition rate of Cd is maximal in industrial countries, but in other regions of the planet where industri alization is limited, Cd enters into soil compartments through fertilizers, mostly manure, sewage sludge, and biosolids (6). It has been suggested that anthropo genic deposition of Cd is maximum (7,8), but there is some uncertainly when considering the partitioning of emissions of Cd and other heavy metals between natural and anthropogenic sources (9). It is clear that on the global scale atmo spheric deposition of heavy metals to soils is most important, whereas on a local or regional scale, other sources may be more significant from the perspective of soil pollution.
