Spatiotemporal distribution, sources apportionment and ecological risks of PAHs: a study in the Wuhan section of the Yangtze River

This study investigated the sources, contamination and ecological risks of polycyclic aromatic hydrocarbons (PAHs) based on their spatiotemporal distribution in aquatic environment in the Wuhan section of the Yangtze River (WYR). The fugacity ratio evaluation indicated that sediment was secondary release sources of two- and three-ring PAHs and sinks of four- and five-ring PAHs. The total concentrations of PAHs (sigma(16)PAHs) ranged from 2.51 to 102.5 ng/L in water with the dominant contribution of 47.8% by two-ring PAHs. sigma(16)PAHs in sediments varied from 5.90 to 2926 ng/g with the contribution of 35.4% by four-ring PAHs. The higher levels of PAHs occurred around developed industrial areas during the wet season, which was related to local industrial emissions and influenced by rainfall/runoff. Annual flux of sigma(16)PAHs was estimated of 28.77 t. The PMF model analysis revealed that petroleum and industrial emissions were the dominant sources in water accounting for 58.5% of the total pollution, although traffic emission was the main source for sediment accounting for 44.6%. Risk assessments showed that PAHs in water were at low risks, whereas about 44% of the sediments were identified as medium risks. Therefore, energy structure adjustment and further implement of regulation and monitoring are necessary to reduce PAH emissions.

Automated summary

This study examined the sources, pollution, and ecological risks of PAHs in the Wuhan section of the Yangtze River. Sediment was found to be a secondary release source for two- and three-ring PAHs and a sink for four- and five-ring PAHs. The dominant contribution of PAHs in water was from two-ring PAHs, while in sediments, it was from four-ring PAHs. Higher levels of PAHs were observed around industrial areas during the wet season, influenced by local industrial emissions and rainfall/runoff. Risk assessments showed low risks in water but medium risks in 44% of the sediments. Energy structure adjustment and stricter regulations are necessary to reduce PAH emissions.