Evaluation of Polycyclic Aromatic Hydrocarbons (PAHs) and Health Risk Assessment of Surface Water and Sediments of River Sasa, Ife North Local Government Area, Nigeria

This study determined the extent of polycyclic aromatic hydrocarbons (PAHs) contamination of the surface water and sediments collected during the dry and wet seasons from River Sasa in Ife-North Local Government Area of Osun State, Nigeria. This was with a view to establishing the pollution status of the studied surface water with PAHs and its safety for drinking. The health risk assessment of the water samples was also established. Water and sediment samples were collected from three sampling points along River Sasa and analysed using standard techniques. Concentration of PAHs in the samples were determined using GC-FID. Fluoranthene (a 4-ring PAH) was the most dominant congener in the sediment for dry (454.35 ng/g) and wet (490.27 ng/g) seasons, while the highest concentrations in water samples for dry and wet seasons respectively were phenanthrene (3-ring) (349.47 ng/L) and fluoranthene (4-ring) (100.68 ng/L). The total PAHs concentrations in the surface water ranging from 777.68 to 2431.39 ng/L (dry season) were significantly greater than 295.46 to 521.16 ng/L (wet season). Sediment samples also showed higher concentrations of PAHs in the dry season with overall mean 3463.52 ± 785.72 ng/g compared to 3247 ± 2427.57 ng/g (wet season). Higher mean concentration of PAHs recorded in the water and sediment samples for dry season was attributed to pyrolytic (or pyrogenic) sources. The study concluded that River Sasa was polluted with PAHs to a level that made the water not safe for drinking and other domestic activities. The health risk assessment results indicated that continuous uses of the surface water over a prolonged period of time could result in grave health challenges such as cancer among the people of the community.