A Comparative Analysis on the Concentration and Potential Risk of Polycyclic Aromatic Hydrocarbons in Surface Water, Sediment and Soil from a Non-crude Oil and a Crude Oil Explosion Site in the Niger Delta, Nigeria

In this study, a comparative evaluation of the concentration, sources and potential health risk of polycyclic aromatic hydrocarbons (PAHs) in surface water, sediments and soils from a non-crude oil (Udu River) and a crude oil explosion site (Okpare River) in the Niger Delta area of Nigeria were determined. Samples were extracted using a mixture of n-hexane and methylene chloride. Water samples were extracted using a separatory funnel while sediment and soil samples were extracted with the aid of a sonicator. Gas chromatography-mass spectrometry was used for quantification of PAHs in the extracts. The total concentration of 16PAHs in surface waters ranged from < 0.01 to 19,920 mu g L-1, and from 2130 to 11,070 mu g L-1 for the Udu and Okpare Rivers, respectively. For sediments, PAHs concentration (mu g kg(-1)) ranged from 390 to 4570 in Udu River and from 3940 to 8610 in Okpare River, while for soils, PAHs concentration (mu g kg(-1)) ranged from 346 to 9114 in Udu River and from 110 to 4842 in Okpare River. High molecular weight (HMW) PAHs were predominant in surface waters of these Rivers. The HMW PAHs were also the most prevalent in sediments of Okpare River, while low molecular weight (LMW) PAHs occurred the most in soils of the Udu River. Principal component analysis revealed that PAHs in sediments and soils originated primarily from high-temperature processes. Incremental lifetime carcinogenic risk assessment showed very high potential carcinogenicity in humans arising from the intentional and incidental ingestion of water from the studied Rivers. Comparatively, the concentration of 16PAHs in the studied matrices were significantly higher in Okpare River relative to Udu River, with increased potential health risk. Crude oil explosions are therefore a significant point source of PAHs in the environment.