Pollution characteristics and priority substance screening of PFASs in typical drinking water systems of the lower Yangtze River

Per- and polyfluoroalkyl substances （PFASs） are frequently detected at elevated concentrations in water bodies of the lower Yangtze River， posing risks to drinking water safety and human health. This study investigated the occurrence of 23 typical PFASs in source water， treated water， and tap water from eight drinking water treatment plants （DWTPs） in the lower reaches of the Yangtze River. The removal efficiency of PFASs by the treatment processes and their priority for control were also assessed. The results revealed the presence of 19 PFASs across the eight DWTPs， with total concentrations ranging from 32.02 to 167.68 ng/L and an average of 85.86 ng/L. Among these， 14 long-chain and 5 short-chain PFASs were identified， contributing 35.7% and 64.3% to the total concentration， respectively， indicating that short-chain PFASs were the predominant pollutants. The major contaminant monomers were perfluorooctanoic acid （PFOA）， perfluorobutanoic acid （PFBA）， perfluorobutanesulfonic acid （PFBS）， and perfluorohexanoic acid （PFHxA）. The overall removal efficiency of PFASs by the drinking water treatment processes was 17.8%， with a removal efficiency of 22.2% for long-chain and 15.1% for short-chain congeners. Notably， concentrations of 14 PFASs increased during distribution from the treatment plant to the tap， resulting in an overall rebound rate of 39.6%. PFBA， PFOA， and PFBS were the primary contributors， accounting for over 92.8% of this concentration increase. Modeling assessment identified PFOA， perfluorononanoic acid （PFNA）， perfluorododecanoic acid （PFDoA）， and perfluorooctanesulfonic acid （PFOS） as priority PFASs requiring enhanced monitoring and control measures.