Assessment of Heavy Metal Contamination in Soils around Cassava Processing Mills in Sub- Urban Areas of Delta State, Southern Nigeria

Abstract

The concentrations, contamination/pollution index, anthropogenic input and enrichment factors for metals in soil in the vicinity of cassava processing mills in sub-urban areas of Delta State of Nigeria were examined. The concentrations of metals in all sites and depths ranged from 0.1 to 383.2 mg kg-1 for Mn, 4.0 to 11.3 mg kg-1 for Ni, 1746.4 to 2839.6 mg kg-1 for Fe, 0.01 to 3.70 mg kg-1 for Cr, 3.7 to 29.5 mg kg-1 for Cu, 21.9 to 97.3 mg kg-1 for Zn, 0.01 to 1.60 mg kg-1 for Cd and <0.01 to <0.01 mg kg-1 for Pb. The concentrations of metals at these sites were below the Department of Petroleum Resources target values for metals in soils except for Cd in some sites. A significant fraction of these metals aroses from anthropogenic sources. The percent anthropogenic fraction of metals in the soil follow the order Cd > Zn > Ni > Cu > Fe > Cr > Pb.

Keywords: Anthropogenic input, cassava, heavy metals, pollution index