ABSTRACT

Metals are ubiquitous in the environment. Many are essential for mediating biological functions in biota. Essential trace metals, such as Co, Cu, Fe, Mn, Ni, and Zn, are involved in many of the enzymatic and metabolic reactions that take place within an organism, either as a component or an activator of enzymes (Lehninger, 1982). However, some metals, such as Hg, Pb, and U, have no known biological function, and are therefore classified as non essential. All metals, whether essential or non-essential to an organism, become toxic beyond certain threshold concentrations (Depledge et al., 1994).