Levels, distribution and characterization of Polycyclic Aromatic Hydrocarbons (PAHs) in Ovia river, Southern Nigeria

- Total PAH concentrations in water were generally higher than the WHO guideline value of 0.05 μg/L for PAHs in drinking water.
- Benzo(a)pyrene (BaP) concentrations in fish exceeded the EU recommended safe limit of 2 μg/kg ww for human fish consumption.
- The ratio of specific PAHs compounds reflected mixed patterns of pyrogenic and petrogenic origins in Ovia River.

The concentration and distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in surface water, sediment, and fish (Clarias gariepinus) samples collected from Ovia River, Southern Nigeria were evaluated, to assess the contamination profile of the river. The concentrations of PAHs were measured to reflect the spatial and monthly distribution of PAHs in the matrices. Mean concentrations of total PAHs (∑PAHs) in surface water samples ranged from 2.33 to 25.83 μg/L sediment, 5.25 to 573.33 μg/kg-dry weight (dw) and fish (Clarias gariepinus), 10 to 914.17 μg/kg-wet weight (ww). There was a considerable predominance of the 2 and 3-rings PAHs in all the matrices. Spatial variations showed high concentrations of PAHs in Ekenwan, the downstream station, for all the matrices. The ratios of specific PAHs compounds in sediment reflected the predominance of petrogenic PAHs sources. PAH concentrations in water were observed to be above the guideline value (0.05 μg/L) for PAHs in drinking water which calls for serious pollution concern, as this river serves as drinking water source for people of the community.

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