Abstract

<p>This study assessed polycyclic aromatic hydrocarbons (PAHs) and heavy metals in the Bonny River by analyzing water, sediment, and biota samples from fifteen strategically selected stations: Jetty to Mguodeya, Eagle Island opposite Emenike waterfront, 107 Emenike Str waterfront by slaughter, Waterfront by Hospital Management Board, Abonnema Wharf Rd, Oil terminal, Wait and Bush Jetty, Nembe Jetty, Old PH Tourist Beach 1, PH Tourist Beach 2, Borokiri Sandfill 1, Fed. Housing Estate (Jetty), Fed. Housing Estate (Abandoned House), Rd 2 Old PH TWP, 42 Eastern Bye-pass, and Amadi Sandfill. The research design adopted in this study was a descriptive approach aimed at analyzing the presence and concentration of polycyclic aromatic hydrocarbons (PAHs) in surface water, sediments, and biota samples from the selected sampling points along the Bonny River. Standard sampling methods were followed. Sample collection involved obtaining 15 surface water samples, 15 sediment samples, and 15 biota samples, ensuring a comprehensive representation of the aquatic environment. The collected samples were preserved and prepared for analysis, with selected physicochemical parameters of the water, sediments and biota measured using suitable laboratory equipment. PAHs were extracted from the samples using appropriate solvents and methods, followed by a clean-up process to eliminate impurities and unwanted compounds, ensuring accuracy in the subsequent analysis. The concentration of PAHs were determined using Gas Chromatography-Mass Spectrometry (GC-MS). Principal Component Analysis (PCA) was employed for source apportionment of the PAHs. The heavy metals were analysed using the Atomic Absorbtion Spectrophotometer (AAS). The ecological risk assessment was conducted to evaluate the potential impact on the environment. Findings revealed significant pollution with electrical conductivity (5850.7±0.15-16490.80±2.15 µS/cm), total dissolved solids (2925.37±2.14-8245.38±3.14 mg/L), and other contaminants exceeding permissible limits, indicating serious environmental contamination. Heavy metal analysis highlighted high levels of cadmium (mean 1.535±3.22 mg/kg) and lead (mean 29.279±3.12 mg/kg) in sediments, with seafood such as crabs showing elevated cadmium (mean 0.182±0.02 mg/kg), chromium (mean 0.972 mg/kg), and lead (mean 4.391±0.18 mg/kg). Carcinogenic risk indices for seafood ranged from 1.99E-04 to 1.50E-03 for adults and from 7.80E-04 to 5.83E-03 for children, exceeding safety thresholds. Ecological risk assessments indicated significant bioaccumulation in oysters, crabs, and periwinkles, with non-carcinogenic risk values and carcinogenic indices surpassing acceptable limits. PAH analysis showed elevated B(a)Pteq values, with oysters having the highest levels and exceeding EU limits for PAHs in smoked fish, underscoring the need for enhanced monitoring and pollution control to protect public health.</p>