Ecological Risk Assessment of Soils Contaminated with Polycyclic Aromatic Hydrocarbons and Polychlorinated Biphenyls in Industrial Sites of Rivers State, Nigeria

Polycyclic Aromatic Hydrocarbons (PAHs) and Polychlorinated biphenyls (PCBs) are Persistent Organic Pollutants that can accumulate in soil and pose ecological risks. This study investigated the ecological risks associated with PAHs and PCBs in soil around selected industrial sites in Rivers State. Soil samples were collected from one non-industrial and four industrial sites and analyzed for PAHs and PCBs using Gas Chromatography-Mass Spectrometry (GC-MS). The results showed that the soil samples from non-industrial site (control) had PAH and PCB concentrations below detection limit (<0.01mg/kg). PAH and PCB concentrations in industrial sites ranged from 0.41±0.04mg/kg to 32.27±0.15mg/kg and 1.09±0.03mg/kg to 5.55±0.01mg/kg respectively. PAH Risk Quotient for the Petrochemical company and Electronics market gave values >1 indicative of potential ecological risks while Transformer oil storage site and Colour Academy gave Risk Quotient <1 indicative of low risk. Petrochemical Company with Ecological Risk Index (ERI) of 192.08 showed high risk from PAH contamination while other sites revealed ERI values <150 indicative of low risk. Similarly, Risk Quotient obtained from PCB concentrations in all industrial sites gave values >1 indicative of significant risks. Ecological Risk Index revealed values <150 all indicative of low risks from PCB contamination. The study revealed that Ecological Risk Assessment for PAH and PCB concentrations in all industrial sites have values that spanned from low to high risk ratings. PAH and PCB contamination in soil can bioaccumulate and not only affect the health of individual organisms but also have wider impacts on biodiversity and ecosystem dynamics. Thus, it is recommended that regular monitoring and remediation of contaminated soil sites should be carried out to reduce human health and ecological risk associated with unsafe PAH and PCB levels.