Effects of power station and abattoir on PAH input into sediments of Oji River: ecological and human health exposure risks

This study investigated the concentration and sources of polycyclic aromatic hydrocarbons (PAHs) in the sediments of Oji River due to point sources of pollution from abattoir and power plant and determined the ecological and human health risks associated with the PAHs in the sediments. Oji River in Nigeria receives contaminants from anthropogenic activities relating to waste tires used in singeing cow meats in abattoir and preparing hides and skin for local consumption. It also receives contaminants from power distribution station where the defunct coal power plant used to be situated. These activities have the potential to release polycyclic aromatic hydrocarbons that could accumulate in the river sediments. The PAHs were measured using gas chromatography-mass spectrometry (GC-MS). This study found that the abattoir is responsible for the occurrence of benzo[b]fluoranthene, benzo[k]fluoranthene and benzo[a]pyrene in the sediments around the abattoir. The occurrence and distribution of PAHs around the area affected by the power station was profound as among all the 16 priority PAHs; only naphthalene benzo[g,h,i]perylene, dibenzo[a,h]anthracene and indeno[1,2,3-cd]pyrene were not detected. The five-member ring PAHs were predominant in this section of the river affected by power station. Ecological risks of the PAHs due to the effects of the power station are significant. The total toxicity equivalence (TEQ) of the PAHs upstream the abattoir is insignificant but significant around the abattoir and within the area impacted by the power station. The values of the hazard index (HI) and risk index (RI) indicate insignificant carcinogenic and non-carcinogenic human health risks in all the locations except the area within the influence of the power station where there are insignificant non-carcinogenic risks but significant carcinogenic risks.