Distribution and enrichment of metals in sediments of the Ogun River within Abeokuta, south-western Nigeria

Abstract

The distribution and enrichment of metals in the sediments of Ogun River within Abeokuta City, south-western Nigeria, were assessed in 2007. Replicate samples of sediments were collected from 10 sampling sites along the length of the river within the city. Concentrations of Cd, Zn, Cr, Fe, Ni and Pb ranged between 0.03 and 0.66 mg kg⁻¹, 1.75 and 12.63 mg kg⁻¹, 5.19 and 28 mg kg⁻¹, 156 and 750.50 mg kg⁻¹, 17.50 and 60.00 mg kg⁻¹, and 0.73 and 4.5 mg kg⁻¹, respectively, all, with the exception of Fe, being lower than sediment quality guideline values. Sediment pollution assessment was carried out using enrichment factor (EF) and geoaccumulation index (I_geo). On average, EF values indicated that Ogun River sediments were moderately contaminated with Cd. I_geo values suggest that the sediment was moderately polluted with Cd, Zn, Fe, Mn and Pb.

Keywords:

• contamination
• enrichment factor
• geoaccumulation index