Speciation Studies On Sediments From Asa River, Ilorin, Kwara State, Nigeria

Abstract

Sediments from a stretch Asa River, in Ilorin, Kwara State of Nigeria were sequentially extracted to determine the variations in heavy metal binding fractions of Mn, Fe, Pb, Zn and Cu (exchangeable, bound to carbonate, bound to Mn and Fe oxides, bound to organic matter and the residual). The choice of sample locations was based on land use along the Asa River with a view to determining the impact of such activities on the various levels metal contamination. The observed mobility based on the percentage of metal extracted in the first step were, Cu > Pb > Cr > Zn > Mn > Fe. The order of existence of the trace metals could be ranked thus: residuals > oxido-reducible > bioavailable.
From experimental findings, the sediments of Asa River does not pose serious health risk. It is however recommended that regular monitoring of the sediments be carried out as there is notable increase in the level of human and industrial activities along the course of the river.


Key words: speciation, sequential, mobility, bioavailable

Ife Journal of Science Vol. 7(1) 2005: 139-146