Abstract

River Usuma was used as a substrate through which toxic elements and their sources were identified and measured due to anthropogenic activities in Federal Capital Territory (FCT), Abuja. It makes good public health sense, good economic and environmental sense to prevent water contamination at the source. Concentrations of heavy metals [Zinc (Zn), Manganese (Mn), Copper (Cu), Cadmium (Cd), Lead (Pb), Iron (Fe), and Chromium (Cr)] were measured in water and two fish species, catfish-Synodontis membranaceus andtilapia-Oreochromis niloticus, from River Usuma, FCT Abuja, Nigeria. As an attempt to understand metal bioavailability and assess the potential impact on aquatic biota, a study of seasonal variations of heavy metals fractionation in water column was achieved. In comparison to some organizations tolerable values, relatively high levels of total and dissolved Mn, Cu, Pb, and Fe were found in water samples. Availability of metals in water column established were in the rank: Cr < Fe < Pb < Zn < Cu < Mn. In addition, the potential toxicity of the metals was studied by evaluating correlations of the concentration of the metals in fish tissues and in water. High Cu and Fe levels were observed in liver tissue of both species, in agreement with higher total content of these metals in water. Correlations among metals’ content in catfish’s tissues and different fractions of metals in water were found.

Key words: Metal pollution, water, fish, speciation.