Polycyclic Aromatic Hydrocarbons: Evaluation of concentrations in environmental media in Bayelsa State

Abstract

Background and aim Artisanal refining of crude oil is an illegal refining process that contributes to environmental pollution through the release of Polycyclic Aromatic Hydrocarbons (PAHs). PAHs compounds are known for their destructive effects on the environment as well as their harmful effects on human health. This study thus assessed the concentrations of PAHs in water, soil, and fish in communities where artisanal refining of crude oil is practiced in Bayelsa State. Materials and methods This descriptive, comparative study was conducted in Sampou (mildly exposed community), Gbarain, and Nembe (severely exposed communities) in Bayelsa State. Water, fish, and soil samples were collected using pre-existing environmental media collection guidelines and sent to the laboratory for GC-FID determination of the PAH concentrations. The data obtained were analyzed using the Statistical Package for Social Sciences (SPSS) software. Results Mean and (total) PAHs concentration in water samples obtained from Sampou was 3.50 ± 4.51 (59.59) μg/L; Gbarain 1.76 ± 4.35 (29.87) μg/L and Nembe 1.90 ± 4.20 (32.25) μg/L. A significant difference in the concentrations was also identified p-value: of 0.021. The mean concentration of PAHs in soil samples obtained from Sampou was 10.73 ± 15.53 (183.38) μg/kg; Gbarain 12.00 ± 19.57 (204.32) μg/kg and Nembe was 8.49 ± 10.07 (144.48) μg/kg. Finally, the mean concentration in fish samples obtained from Sampou was 5.62 ± 5.92 (95.43) μg/kg; Gbarain 3.81 ± 5.57 (64.75) μg/kg and Nembe 4.61 ± 5.33 (78.35) μg/kg. The difference in these concentrations was however not significant. Source diagnostic ratios of the PAHs in the water included Flt/(Flt + Pyr) ratio of 0.23, 0.16, and 0.21; Ant/(Ant + Phe) ratio of 0.87, 0.76, and 0.87 as well as BaA/(BaA + Chr) ratio of 0.43, 0.51 and 0.66 in Sampou, Gbarain and Nembe respectively. Conclusion Concentrations of total PAHs in water and fish samples obtained from the three communities exceeded the acceptable limits for ƩPAHs of 2.0 μg/L and 2 μg/kg in water and fish respectively stipulated by the United States Environmental Protection Agency and the Nigerian Petroleum Regulatory Authority. ƩPAHs concentrations from the samples obtained from Sampou were also higher than the other two communities. There is a need for regular environmental monitoring of PAH concentrations, especially in oil-producing communities, and a shift of focus toward the elimination of pyrolytic sources of PAH pollution.