Distribution and Risk Assessment of Per- and Polyfluoroalkyl Substances from Source Water to Tap Water in the Hubei Section of the Yangtze River Mainstream

• • Total PFAS concentrations in source water ranged from 10.84 to 41.05 ng/L (dry season), nd to 62.60 ng/L (normal), and 6.77 to 29.00 ng/L (wet), indicating seasonal variability with dry season peaks; this informs monitoring frequency and source water management. • • Lake-type water sources had significantly higher PFAS concentrations than river-type sources (p < 0.05), suggesting that stagnant water bodies accumulate PFAS; this necessitates targeted remediation strategies for lake sources. • • PFBS, PFOA, PFHxA, PFBA, and PFOS were the dominant congeners across all seasons, with PFOS and PFOA being legacy compounds; their consistent presence underscores the need for regulatory focus on these specific PFAS. • • Ecological and health risk assessments showed hazard quotients below 1, indicating acceptable risks; however, the potential for mixture effects and future contamination warrants continuous monitoring and risk management.