Concentration and associated risks of polycyclic aromatic hydrocarbons in soils around abandoned oil wellheads in Kolo Creek, Bayelsa State, Nigeria

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are recalcitrant pollutants commonly associated with oil exploration activities. This study assessed the concentration and associated risks of PAHs in soils around abandoned oil wellheads in Kolo Creek, Bayelsa State, Nigeria. The total PAHs concentration varied between 226 - 228.2 µg kg^-1, while that of the most carcinogenic PAH, benzo[a]pyrene (BaP), varied between 58 and 61 µg kg^-1. The concentration of Σ16 PAHs and BaP did not vary significantly (p>0.05) across the four locations. High-molecular-weight PAHs predominated over low-molecular-weight PAHs. The PAHs’ ring-size distribution followed the order: 5-ring > 3-ring > 2-ring > 4-ring. The calculated risk quotient values for individual PAHs were within their permissible limits. Non-cancer risk assessment suggested no immediate non-carcinogenic health risk, with values < 1. However, the estimated incremental lifetime cancer risk exceeded the US EPA acceptable limit for both children and adults exposure scenarios, indicating a health concern in the long-term. These results suggest the need for continuous monitoring and remediation to limit the risks associated with PAHs in the studied areas.