Contamination of the urban river network with perfluoroalkyl acids (PFAAs) introduced during river regulations

River regulation has a key role in water resource management, but the introduced pollutants cannot be underestimated. This study reported spatiotemporal variations of perfluoroalkyl acids (PFAAs) significantly affected by river regulations in a standard example of urban river network with bidirectional flow in China. Perfluoroalkyl sulfonic acids (PFSAs), mostly of domestic origin, dominated during discharge, and perfluoroalkyl carboxylic acids (PFCAs), industrial pollutants, during diversion. The estimated PFAA flux into the Yangtze River during discharge was 1.22 × 10² kg with 62.5 % from Taihu Lake and 37.5 % from the river network. And that from the Yangtze River during diversion was 90.2 kg with 72.2 % into Taihu Lake and 27.8 % into the river network. Our findings show that PFAAs can exert pressure on regional water security that most of the urban river network was at medium risk. This study improves understandings of the role of river regulations in urban water networks and provides solid reference for risk assessment.