SEDIMENT QUALITY ASSESSMENT OF OKE-ITOKU RIVER, ABEOKUTA, SOUTHWEST NIGERIA
Abstract
This research investigated contamination of sediments due to continuous tie and dye effluents discharge into Oke-Itoku River, Abeokuta, Nigeria. Surface and subsurface sediment samples were collected upstream, at point of discharge and downstream. The contamination factor (Cf), degree of contamination (Cd) and geo-accumulation index (Igeo) were also determined. Physico-chemical parameters such as Temperature, Total Dissolve Solids (TDS), Electrical Conductivity (EC), pH, Dissolved Oxygen (DO) and five selected heavy metals: Chromium (Cr), Copper (Cu), Cobalt (Co) and Lead (Pb) were measured. Results revealed mean TDS, EC, Temperature and DO pollution of 485.6±134.66 mg/L, 2153.6±1122.19 µS/cm, 32.46±0.570C and 4.01±0.43 mg/L respectively at the discharge point. The heavy metal concentrations for the surface and subsurface sediments obtained had a range of 11.5-18.3, 30.1-39 mg/L for Cr; 12.6-27.0, 23.8-42 mg/L for Cu; 16.2-31.0, 23.8-42.0 for Co and 1.8-3.2, 1.8-3.5 mg/L for Pb in surface and subsurface sediment respectively. Heavy metal contamination in the sediments of Oke-Itoku river showed order of enrichment of Co>Cu>Cr>Pb according to Cf, Cd and Igeo for the study area. There are only natural inputs of chromium and copper into the river while Cd, Co and Pb concentrations are due to anthropogenic input mainly from tie and dye by-products.
