Introduction
In aquatic systems, heavy metals have received
considerable attention due to their toxicity and
accumulation in biota (Mason, 1991). Metals
generally enter the aquatic environment through
atmospheric deposition, erosion of the geological
matrix, or due to anthropogenic activities caused by
industrial effluents, domestic sewage, and mining
wastes (Tarvainen et al., 1997; Stephen et al., 2000).