Occurrence of polycyclic aromatic hydrocarbons in the Soan River, Pakistan: Insights into distribution, composition, sources and ecological risk assessment

• Surface water samples were collected from the Soan River, Pakistan for investigation of PAHs.
• No significant differences in ∑PAHs concentration were observed in the main river and tributaries.
• Vehicular exhaust, coal and coke combustion, and waste from industries were the major sources.
• Risk assessment illustrated that ecological integrity of the Soan River is under lower risk due to PAHs.

Present study investigates the occurrence, distribution and sources of ∑17 polycyclic aromatic hydrocarbons (PAHs) in the surface water of Soan River, Pakistan. The concentrations of total PAHs ranged from 61 to 207 ng/l. Low molecular weight (LMW) PAHs were recorded higher in concentrations (64.7 percent) as compared to high molecular weight (HMW) PAHs (35.6 percent). Principal component analysis (PCA) revealed domestic and industrial wastewater discharge, vehicular exhaust, petroleum residues and biomass combustion as the main sources for PAHs contamination. Using the USEPA toxic equivalency factor (TEF) approach: Benzo(a)Pyrene and Dibenzo(a,h)Anthracene contributed highly carcinogenic exposure equivalent. The surface water of the Soan River is found to be slightly polluted with PAHs thereby posing health risks to aquatic bodies.

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