ABSTRACT
The major inorganic contaminants in soil are heavy metal(loid)s and nutrients. Some heavy metal(loid)s are biologically essential elements that they are required in low concentrations and hence are known as trace elements or micronutrients (e.g., Co, Cu, Cr, Mn, Se, and Zn) (Kesler 1994). Some nonessential heavy metal(loid)s are phytotoxic, zootoxic, or both, and hence are known as toxic elements (e.g., As, Cd, Pb, and Hg). Both groups are toxic to plants, animals, and humans at exorbitant concentrations. The two most important elemental nutrients that lead to pollution and environmental degradation are N and P (Carpenter et al. 1998).
