RESUMEN
Polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in groundwater and leachate around selected waste dumpsites from two southwestern states of Nigeria were investigated. Samples were Soxhlet-extracted using hexane/methylene chloride mixture and cleaned-up with preconditioned solid-phase extraction cartridges. The ∑PAHs (PCBs) (all in µg/L) in the boreholes, leachate, and hand-dug well across all locations ranged from below detection limit (BDL) to 0.62 (BDL to 0.067), 1.16 to 9.96 (0.003 to 0.041), and BDL to 0.01 (0.001-0.031), respectively. Low molecular weight-PAHs accounted for ≥61% of ∑PAHs detected across all locations. The highly chlorinated hexa-PCBs [2,2',3,4,4',5'-HeCB(#180), 2,2',3,4',5',6-HeCB(#34) and 2,2',4,4',5,5'-HeCB(#153)] dominated the entire congener profiles. Pyrene and 2,3',4,4',5-PeCB(#118) constituted 56% and 58% of the ∑PAHs and ∑PCBs, respectively. Sampled water is not adequately safe for drinking and may pose cancer risk. This study should be sustained for health risk and sustenance of an enduring ecological integrity.
Asunto(s)
Monitoreo del Ambiente/métodos , Agua Subterránea/química , Bifenilos Policlorados/análisis , Hidrocarburos Policíclicos Aromáticos/análisis , Instalaciones de Eliminación de Residuos , Contaminantes Químicos del Agua/análisis , Nigeria , Pirenos/análisisRESUMEN
Samples of fish and shellfish (periwinkles, mussel, and snail) collected from the rapidly contaminated Ogbese River, Ondo State, Nigeria, were analyzed for their polycyclic aromatic hydrocarbon (PAH) levels by gas chromatography-mass spectrometry after cleanup using solid-phase extraction. The rank order of concentration of ΣPAHs in fish follows: gills >> eggs >>> muscle. The dry weight concentrations (µg/g) of total PAHs ranged from < 0.001 to 2.06, 0.01 to 18.67, 0.01 to 9.56, and 0.01 to 8.28 in fish muscle, periwinkle, snail, and mussel respectively. Accumulation levels of PAHs in the biota were used to calculate biota-sediment (or porewater) accumulation factors (BSAF (BPwAF)) and bioaccumulation factor (BAF). The lower molecular weight PAHs constitute major components (≥ 87% in each case) of PAH congener profiles. Bioaccumulation was greatest for PAHs with log Kow values between 5.0 and 5.6. However, the study did not show a good correlation between log Kow of individual PAH and the corresponding BSAFs/BPwAF for the biota. The study indicates that significantly greater (p < 0.05) BSAFs for ΣPAHs were observed in the three bottom dwellers than in fish muscle which suggests that the sediment-feeding behavior largely affected the extent of PAH bioaccumulation in the aquatic organisms. The calculated potency equivalent concentration (PEC) of total PAHs was above the recommended screening value (SV) in US EPA guidelines, suggesting great concern for human consumption. However, estimated excess cancer risk (ECR) induced by dietary exposure only suggests potential cancer risk. The study suggests urgent remediation of the river to safeguard public health.