Author(s)

Adedoyin Olubunmi Bankole^1*, Akinyemi Olufemi Ogunkeyede¹, Harrison Agboro², Prince Alex Ekhorutomwen², Osasenaga Israel Otuomagie², Khadijah Ateda Isimekhai³, Ekaette Akpan Fadairo⁴, Efe Jeffery Isukuru¹

¹Department of Environmental Management and Toxicology, College of Science, Federal University of Petroleum Resources, Effurun, Nigeria.
²Department of Biology and Environmental Science, College of Arts and Sciences, University of New Haven, West Haven, USA.
³Department of Chemistry, University of Abuja, Abuja, Nigeria.
⁴Department of Science Laboratory Technology, Petroleum Training Institute, Effurun, Nigeria.

Crude oil spills have inflicted extensive disruption upon the Niger Delta ecosystem, resulting in crop loss and severe environmental damage. Such spills exacerbate heavy metal concentration within soil due to the presence of metallic ions. The Okpare-Olomu community has borne the brunt of crude oil pollution from illicit bunkering, sabotage, and equipment malfunction. This study targets an evaluation of ecological hazards linked to heavy metals (HMs) in crude oil impacted agriculturally soils within Okpare-Olomu in Ughelli South LGA of Delta State. In this study, 24 topsoil samples were obtained from areas affected by crude oil pollution; the heavy metal content was evaluated through atomic absorption spectrometry. The concentration ranges for HMs (mg/kg) in soil were: 24.1 - 23,174 (Cu); 0.54 - 37.1 (Cd); 9.05 - 54 (Cr); 12 - 174 (Ni); 18.5 - 8611 (Pb); and 148 - 9078 (Zn) at a soil depth of 0 - 15 cm. Notably, metal concentrations were recorded to be above permissible World Health Organization limits. Predominantly, Zn and Pb recorded higher heavy metal concentration when compared to other heavy metals analysed, notably at sampling points PT7 through PT24. Zinc and Pb contamination exhibited highly significant contamination factors, and contamination severity was evidenced across all sample points, signifying a grave risk level. Pollution load indices indicated pervasive extreme pollution levels. Geoaccumulation indices signaled moderate to strong pollution, mainly by Pb and Zn. Ecological risk assessments revealed variable levels of heavy metal contamination, from low to very high, with potential ecological risk reflecting markedly elevated levels. This study underscores the imperative for soil remediation to rectify ecological imbalances in agriculturally affected soil constituents.

Heavy Metals, Crude Oil, Pollution, Degree of Contamination, Potential Risk Index

Bankole, A.O., Ogunkeyede, A.O., Agboro, H., Ekhorutomwen, P.A., Otuomagie, O.I., Isimekhai, K.A., Fadairo, E.A. and Isukuru, E.J. (2024) Heavy Metal Levels and Ecological Risk in Crude Oil-Contaminated Soils from Okpare-Olomu, Niger Delta, Nigeria. Journal of Environmental Protection, 15, 415-438. doi: 10.4236/jep.2024.154024.