Sources and Fate of Parent and Derivative PAHs in Urban-Industrial Watersheds: A Case Study in Changzhou, China

Polycyclic aromatic hydrocarbons (PAHs) and their alkylated (Me-PAHs) and oxygenated (O-PAHs) derivatives are persistent organic pollutants (POPs) with considerable ecological toxicity and potential human health hazards. A total of 64 regular and derivative PAHs (referred to as polycyclic aromatic compounds, PACs) were quantified in surface water and atmospheric samples from an urban–industrial watershed in Changzhou, located in the Yangtze River Delta, China. Industrial thermal activities were identified as the primary pollution sources, and traffic emission, biomass combustion also contributed to the high PACs concentrations. In addition, photochemical transformation and regional atmospheric transport played vital roles in regulating PAC levels. The air-water fugacity of the PACs indicated that low-ring PAHs tended to volatilize, whereas most O-PAHs exhibited net deposition, suggesting that surface waters serve as an important sink for atmospheric O-PAHs. The coexistence of multiple PACs posed a high risk to the aquatic organisms, whereas the human health risks remained within acceptable levels. These results provide a scientific basis for developing targeted emission control strategies in industrialized watershed systems. • Low-ring structures PACs dominated in Changzhou’s urban–industrial watershed. • Industrial thermal activities were the dominant PAC sources. • PAC composition profiles and spatial distributions reflected source-specific emission patterns. • Surface waters acted as a sink for atmospheric O-PAHs. • PACs posed high ecological risks but low risks to human health.