Occurrence， characteristics， and risk assessment of legacy and novel per- and polyfluoroalkyl substances in drinking water sources of Eastern China

Per- and polyfluoroalkyl substances（PFAS） are notorious environmental contaminants that are often referred to as “forever chemicals”. Eastern China is a major region that produces and utilizes PFAS. These substances can enter the environment and migrate to drinking water sources， thereby posing potential ecological and health risks. To investigate the occurrence and potential risks of both legacy and novel PFAS in the drinking water sources of this region， a study was conducted on water samples collected from 13 drinking water sources. Anion exchange solid-phase extraction coupled with ultra performance liquid chromatography-triple quadrupole mass spectrometry（UPLC-MS/MS） was used to determine PFAS in water. The pollution levels and spatial distribution characteristics of 50 legacy and novel PFAS in these drinking water sources were studied in detail and their ecological and health risks were also assessed. Twenty-six types of PFAS were detected in the drinking water sources of the eastern region， with total mass concentrations ranging from 80.0 to 282 ng/L and a median mass concentration of 153 ng/L. The relatively high concentrations of PFAS in these drinking water samples is likely due to heavy industrial activities in this region. Nevertheless， the levels of perfluorooctanoic acid（PFOA） and perfluorooctanesulfonic acid（PFOS） in all sampling sites were far below the limits of national drinking water standards of China. The detected PFAS in drinking water sources were predominantly short-chain compounds， such as perfluorobutanoic acid（PFBA） and perfluorobutanesulfonic acid（PFBS）， which accounted for 27.6% and 20.8% of the total PFAS concentration， respectively. In contrast， long-chain PFAS（with more than nine carbons） constituted less than 2% of the total PFAS concentration. The observed higher proportions of short-chain PFAS are rationalized by their somewhat higher mobilities in aquatic environments. Low levels of various novel PFAS， such as hexafluoropropylene oxide dimer acid（HFPO-DA）， 1<italic>H</italic>，1<italic>H</italic>，2<italic>H</italic>，2<italic>H</italic>-perfluorooctanesulfonic acid（6∶2 FTS）， perfluoro（2-ethoxyethane）sulfonic acid（PFEESA）， 9-chlorohexadecafluoro-3-oxanonane-1-sulfonic acid（9Cl-PF3ONS）， and perfluorooctanesulfonamide（FOSA） were detected to varying degrees in the drinking water sources. This indicated that novel PFAS are being increasingly produced and used as alternatives to those restricted by international and Chinese regulations. The overall PFAS pollution levels and compositions in the drinking water sources of Eastern China are significantly influenced by nearby industrial activities， with wastewater discharged from chemical industrial parks and related enterprises contributing significantly to the elevated PFAS levels in the drinking water sources. Pearson correlation analysis suggested that the PFAS in these drinking water sources likely arise from common pollution sources. Ecological risk-assessment data reveal that the PFAS risk quotient in the abovementioned drinking water sources ranged from 9.7×10^-6 to 8.9×10^-³， which suggests that the PFAS levels at the sampling sites in this study evidently pose no ecological risks. The hazard indices for perfluorohexanoic acid（PFHxS）， perfluorononanoic acid（PFNA）， HFPO-DA， and PFBS in the examined drinking water sources ranged from 0.16 to 0.89. The detected levels of these four PFAS are compliant with the limits set by the national primary drinking water regulations of the United States. This study furnishes foundational data that provide a comprehensive understanding of the pollution profiles of PFAS in drinking water sources in Eastern China. Continuous monitoring is necessary to ensure drinking-water safety for residents given the widespread occurrence of both legacy and novel PFAS in drinking water.