Spatial Distribution, Potential Risks and Sources of Polycyclic Aromatic Hydrocarbons in Sediments of Oleri River, Delta State, Nigeria

The spatial distribution, associated risks and sources of polycyclic aromatic hydrocarbons in sediment of the Oleri River in Delta State were examined in this study. Six sediments were obtained from six locations in the Oleri River and analyzed for the 16 priority PAHs using gas chromatograph coupled with mass spectrometry after extraction with dichloromethane and hexane. The levels of the ∑16-PAHs in the sediment ranged from 73.0-423 µg/kg. The higher molecular weight PAHs were the dominant PAHs in the sediments. The ecological risk assessment indicated that there was no ecological risk from PAHs in the sediment of the Oleri River. The hazard index values indicated that there was no adverse non-carcinogenic risk from human exposure to the PAHs in the sediments of the Oleri River. The total cancer risk values indicated that there was moderate and low carcinogenic risk from PAHs exposure to children and adults respectively. The source apportionment suggested that the PAHs in the Oleri River were from mainly pyrogenic sources such as wood, coal, diesel combustion and traffic emissions.