Trace Metal Distribution in Fish, Sediment and Water Samples from Nkisa River, Nigeria

Aims: Contamination of surface water, sediment and fish samples by heavy metals have been a problem of developing countries as a result of growing rate of industrialization. This study was aimed at determining the level of heavy metal toxicants in water, sediment and fish samples from Nkisa River. The effect of these elemental contaminants and the associated health hazards were examined.
Study Design: Unicam 919 Atomic Absorption Spectrophotometer (AAS) was used for the determination of heavy metals in water, sediment and fish samples.
Place and Duration of Study: Department of Chemistry, Federal University of Technology, Owerri, Nigeria, between October and December, 2012.
Methodology: Water samples were pre-treated by repeated evaporation with analar grade nitric acid (HNO3) and heavy metal contaminant in the water samples were determined using Unicam 919 AAS. The wet sediment samples were ashed at 555ºC. 5 g of dried sediment was weighed into a Teflon crucible and 1 cm3 of (HNO3/HCl 1:3 v/v) and 6 cm3 hydrofluoric acid were added into the crucible. The resulting solution after digestion was collected in volumetric flask containing 2.7 g of boric acid. The digested sample was analyzed using Unicam 919 AAS. The whole fish were dried in an electric oven at 70-80ºC. A homogenized 2 g of the ground fish samples were put in flasks and 10 ml each of concentrated HNO3 and HCl were added. After digestion the samples were analyzed using Unicam 919 AAS.
Results: The result of this study revealed that water, sediment and fish samples were contaminated with heavy metals such as Cr, Pb, Cd, Fe, Mn. The study indicates that heavy metal contaminant were observed more in the sediment of the river. The associated health hazards of the metals were examined.
Conclusion: This study revealed that Nkisa River is contaminated with heavy metals from crude oil pipeline leakages and vandalization. This study gives an idea to the mechanisms of depletion and possible extinction of fish species in Nkisa River.