Distribution, sources, and risk of polycyclic aromatic hydrocarbons in soils from rural communities around gas flaring points in the Niger Delta of Nigeria

Abstract

This study investigates the concentrations, sources, and ecological and human health risks resulting from exposure to polycyclic aromatic hydrocarbons (PAHs) in soils of rural communities around gas flaring points in Delta State, Nigeria. PAHs were extracted from these soil samples with hexane/dichloromethane by ultra-sonication and the extracts were cleaned on a silica gel/alumina-packed column. The PAH concentrations in the extracts were quantified by gas chromatography-mass spectrometry (GC-MS). The Σ16 PAH concentrations in soils from these communities varied from 2370–134 000, 461–389 000, and 2130–34 900 μg kg⁻¹ for Emu-Ebendo (EME), Otu-Jeremi (OTJ) and Ebedei (EBD), respectively. The estimated lifetime carcinogenic risk values recorded in this study were above the acceptable limit of 10⁻⁶, indicating a high potential carcinogenic risk resulting from human exposure to PAHs in these soils. The isomeric ratio and principal component analysis results suggest that emissions from high-temperature combustion, potentially gas flaring, vehicular emissions, burning of wood/biomass, and fossil fuel combustion are responsible for the high concentrations of PAHs in soils of these rural communities. This study recommends implementing remediation and source control measures to minimise the impact of PAHs in the affected soils on humans and the environment.