Assessment of Heavy Metals Pollution in Freshly Deposited Sediments of Asa River, Ilorin, Kwara State, Nigeria

Abstract

Concentrations of metals such as Cu, Cr, Co, Fe, Mn, Ni, Pb, Zn and Cd were determined in freshly deposited sediments of Asa River in Ilorin. The choice of sample locations was based on the land use pattern along the Asa River with a view to determine the impact of such activities on the various levels of metal pollution. Seven locations along the river bank were selected particularly areas that receives effluents into the river. Sediment samples were collected when water level of the Asa River was low. In order to minimize the grain-size dependencies of metal concentration, a grain-size fraction <20μm was used for sediments in this study. Geoaccumulation index method and enrichment factor interpretations shows that Asa River sediments are highly polluted with iron and cadmium and moderately polluted with lead which suggest their anthropogenic inputs including effluents from nearby industries as well as agricultural activities such as the use of fertilizers, pesticides. Regular monitoring of sediments of the Asa River should be carried out as there is notable increase in the level of human and industrial activities along the course of the river.