Risk assessment of heavy metals and polycyclic aromatic hydrocarbons in ground water samples around the vicinity of an asphalt plant in north central, Nigeria

Abstract

ABSTRACT. In this study, the concentration and risk of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in 9 composite samples around the vicinity of an Asphalt plant in North Central, Nigeria, was evaluated. Aqua-regia wet digestion was used for heavy metals extraction in the water samples while atomic absorption spectrometry was used quantification. For PAHs, liquid-liquid extraction was used for extraction while gas chromatography-mass spectrometry was used for quantification of PAHs in the extracts. The risk assessment was estimated using the hazard index (HI) and incremental lifetime cancer risk (ILCR) in all the samples studied. The results showed that Cd and Cr were present in concentrations higher than their permissible limits in water set by World Health Organization, while Pb was not detected. Total concentration of 14 PAHs ranged between 6.47–390 mg L-1 and were within the WHO permissible limits. High molecular weight PAHs were dominant (71.54%) relative to low molecular weight PAHs (28.46%). The risk assessment results revealed that 100% ILCRtotal values recorded for heavy metals were higher than the recommended limit. While 37.5% of ILCRtotal values recorded for PAHs were higher than the recommended values, implying that residents are exposed to health risks from both metals and PAHs. KEY WORDS: Asphalt plant, Heavy metals, Polycyclic aromatic hydrocarbons,Water, Risk assessment Bull. Chem. Soc. Ethiop. 2023, 37(6), 1337-1349. DOI: https://dx.doi.org/10.4314/bcse.v37i6.4