Levels, Distribution, Sources, Ecological and Health risk assessment of polyaromatic hydrocarbons in surface and groundwater within and around Gosa dumpsite, Abuja, Nigeria

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are persistent and potentially toxic contaminants that may migrate from municipal solid-waste dumpsites into surrounding aquatic environments. This study assessed the levels, distribution, possible sources, ecological implications and human health risks of PAHs in surface water, lake water and groundwater within and around Gosa dumpsite, Abuja, Nigeria. Water samples were collected from eight stream locations (SSW1–SSW8), four lake locations (LW1–LW4), one shallow hand-dug well (SHDW) and three boreholes (BW1–BW3). Sixteen priority PAHs were extracted and quantified using gas chromatography–mass spectrometry, while physicochemical parameters, diagnostic molecular ratios, toxic-equivalent quantities (TEQs), Pearson correlation and human-health risk indices were evaluated. Total PAH concentrations in stream water ranged from 0.220 to 1.090 µg/mL, while lake water ranged from 0.380 to 1.330 µg/mL; concentrations of 1.360, 1.360, 0.330 and below detection limit were reported for SHDW, BW1, BW2 and BW3, respectively. The highest reported total TEQ was 0.023 at SSW7, followed by 0.0069 at SSW5. Total adult carcinogenic risks reached 0.014 at SSW7, 0.0054 at BW2, 0.0040 at SSW5 and 0.0019 at SSW1, while corresponding child risks were 0.0043, 0.0017, 0.0012 and 0.00062, respectively. Significant correlations occurred between naphthalene and anthracene (r = 0.486), acenaphthene and fluorene (r = 0.499), and fluoranthene and benzo[a]anthracene (r = −0.490; p < 0.05). The findings demonstrate spatially heterogeneous PAH contamination and indicate potential exposure concerns for aquatic resources surrounding Gosa dumpsite. Regular monitoring, improved leachate and runoff management, and protection of nearby water resources are therefore warranted.