Quantifying the Ecological Risk Posed by Heavy Metals in Oil Spill Remediated Soil and Sediment in Parts of the Niger Delta
Publication Date : 24/05/2022
The metal pollution status of soil and sediment was assessed using ecological risk posed by trace heavy metals in oil spill remediated soil and sediment in parts of the Niger Delta. Remediated soil (0-15cm top and 15-30 cm bottom) and sediment samples collected between 2010-2018 were evaluated for Lead (Pb), Cadmium (Cd), Chromium (Cr), Nickel (Ni), Vanadium (V) Copper Cu, and Zinc (Zn) in line with the Department of Petroleum Resources guideline in Environmental Guideline and Standard for Petroleum Industries in Nigeria. Descriptive univariate analysis which preceded the single ecological risk index (Ei) and the potential ecological risk index (PERI) were used to evaluate the average concentration trends of heavy metals, trace heavy metal pollution status of the study area and the impact of the remedial measures on soil and sediment over years. With respect to their DPR target values, the result revealed reduction in the concentration of Cr, Cd, Ni, and Zn in the topsoil and upward trend in the average concentration levels of Cu and Pb. In the bottom soil and sediment, Zn showed an upward but its average values were much below the given target.Similarly, sediment samples from remediated sites showed downward trends in concentration levels of Cr, Pb, Cu, Cd and Ni Cd showed downward trend intop, bottom soil and sediment although with concentration values above the DPR target.70% and 73% of the remediated soil sites (topsoil and bottom) and sediment, respectively, had low ecological risk index. The general pollution status of the study area with respect to heavy metal pollution showed increasing improvement in soil and sediment qualities in recent years.
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