Risk Assessment and Distribution of Heavy Metals in Water and Sediments along Ibelebiri Axis of Kolo Creek, Ogbia Local Government Area, Niger Delta Region of Nigeria

Abstract

Pollution arising from uncontrollable combustion processes, including artisanal refineries are common in communities through which Kolo Creek traverses. Previous studies have centered on the effect of oil and gas production on Kolo Creek at shell flow station at Imiringi. Therefore, the aim of this study is to investigate the risk and distribution of heavy metals (Zn, Ni, Cr, Cu, Pb, Co, and Cd) in water and sediments along Ibelebiri axis of Kolo creek in Ogbia L.G.A., Niger Delta region of Nigeria. Water and sediment samples were collected at locations upstream, within and downstream at Ibelebiri community, and also from a control site.  Generally, heavy metal concentrations showed a decreasing trend of Cu˃Zn˃Pb˃Cr˃Cd˃Co˃Ni for water samples. The mean concentration of these metals: Ni, Cr, Zn and Cu  recorded in this study was below international recommended limits.  But, Pb, Cd levels in locations LC1, LC3 and LC4 are above the international recommended limits. The heavy metals in the sediments showed a decreasing trend of Zn˃Pb˃Cu˃Co˃Cr˃Ni˃Cd. The concentrations of these metals Cd, Pb, Ni, Cr, Cu and Zn are below the permissible limit set by Department of Petroleum Resources (DPR). However, Co values at locations LC3 and LC4 are slightly above the DPR target value of 20 mg/kg for sediments. Using the geoaccumulation index (Igeo) classification, the sediments across the four locations are uncontaminated with Cd, Cr, Cu, Zn, Co and Ni. But, the sediments in locations LC1, LC3 and LC4 are moderately contaminated with Pb. Similarly, the contamination factor (CF) classification, revealed low contamination of Cd, Cr, Cu, Zn, Ni and Co across the four locations;  moderate contamination of Pb in the four locations. Finally, principal component analysis  (PCA) identified two major factors.