Evaluation of Heavy Metal Contamination of Soil from Petroleum Crude Oil at an Illegal Refinery Site: A Case Study of Oshika Community in the Niger Delta Region of Nigeria

Authors: *Achadu, M.A., Dimkpa, I.H. And Dimkpa, C.A.

DOI Info: http://doi.org/10.5281/zenodo.10442805

ABSTRACT

The study was carried out at Oshika community of Rivers State in the Niger Delta region of Nigeria where petroleum crude oil illegal refining activity was terminated. Soil samples were collected at two different points at depths of 15 cm, 45 cm and 90 cm with a control for analysis of heavy metal pollutants (Pb, Cd, Cr, As, Zn, Cu, Ni, Co). The results from the analysis show that all the heavy metals investigated were present with their mean concentration values for top soil as 56.48±0.01 mg/kg, 53.49±0.00 mg/kg. 53.49±0.00 mg/kg, 84.75±0.01 mg/kg, 39.44±9.01 mg/kg, 35.46±0.00 mg/kg, 66.61±0.03 mg/kg and 40.66±0.00 mg/kg respectively which are all higher than the control values. Contamination factor, pollution index and geo-accumulation index were applied as index models for the evaluation of the extent and intensity of heavy metal contamination and pollution of the illegal refining at the site. All the index models used showed that the soil at the site was heavily contaminated and polluted by Cd and As, while also the result of the soil from the analysis indicated uncontaminated and unpolluted by Pb, Co, Ni, Cu, Cr and Zn. The toxicity of these heavy metals and the adverse impact on the health of the community cannot be over emphasized and the paper therefore advocated for discouraging illegal refining and implementation of integration policy into the modular refinery system.

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