Objective This study aimed to provide a scientific basis for the safety management of drinking water by assessing the contamination levels of 21 per- and polyfluoroalkyl substances (PFASs) in water samples collected from the Yangtze River Delta region.
Methods Solid-phase extraction coupled with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was employed to determine 21 PFASs in 6 source water samples, 20 treated water samples, and 60 tap water samples collected from 5 administrative districts in the Yangtze River Delta region across four seasons in 2023. The Kruskal-Wallis H test was used to compare differences in PFAS concentrations among the three types of water samples, followed by post hoc pairwise comparisons with Bonferroni correction. Removal efficiencies of target compounds were also calculated.
Results Among the 86 samples, 14 PFASs were detected, with 7 compounds detected in 100% of samples. The total concentrations of PFASs in source water, treated water, and tap water ranged from 63.85 to 190.54 ng·L-¹, 55.75 to 774.36 ng·L-¹, and 40.72 to 689.80 ng·L-¹, respectively. The compounds with the highest median concentrations were perfluorobutanoic acid (PFBA) (40.19, 15.20, and 14.05 ng·L-¹), perfluorohexanoic acid (PFHxA) (29.69, 32.62, and 34.24 ng·L-¹), perfluorooctanoic acid (PFOA) (17.65, 39.45, and 36.83 ng·L-¹), and potassium perfluorobutanesulfonic acid (PFBS) (16.99, 24.38, and 23.89 ng·L-¹). Notably, concentrations of PFOA (7.71‒71.63 ng·L-¹) and PFOS (<LoD‒5.36 ng·L-¹) in tap water were below the regulatory limits specified in GB 5749‒2022 Standards for Drinking Water Quality (PFOA: 0.000 08 mg·L-1, PFOS: 0.000 04 mg·L-1). Significant seasonal variations in PFAS concentrations were observed, with total PFAS levels in March being higher than those in September and November (adjusted P<0.001, and P=0.006), and levels in May being higher than those in September (adjusted P=0.037). The removal efficiencies of PFASs in the water treatment plants ranged from -14% to 34%.
Conclusion PFAS contamination is widespread in source water, treated water, and tap water in the Yangtze River Delta region, and concentrations of PFOA and PFOS in all tested water samples comply with the Chinese national standards for drinking water quality (GB 5749‒2022). The use of PFASs should be continuously regulated to ensure water safety.
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