Legacy and Emerging Per- and Polyfluoroalkyl Substances (PFAS) in Glacial Meltwater from Mt. Everest

Glaciers are recognized as secondary sources of per- and polyfluoroalkyl substances (PFAS) in a warming climate. Yet, the process governing the release of legacy PFAS from glaciers and the occurrence of their emerging homologues in the meltwater remain insufficiently characterized. Here, we measured glacial meltwater from Mt. Everest at elevations of 4,400-5,300 m using a combination of target quantification, the total oxidizable precursor (TOP) assay, and nontarget analysis. Short-chain PFAS, particularly perfluorobutanoic acid (PFBA), dominated at all sites, accounting for over 88% of the total PFAS concentrations. Furthermore, hydrological processes, rather than solar radiation, drive the release of PFAS from glaciers. A modest (∼25%) increase in concentration after the TOP assay suggests a limited pool of oxidizable PFAS precursors in the meltwater. Follow-up nontarget analysis identified four hydrogen-substituted perfluoroalkyl carboxylic acids (H-PFCAs; C5, C7, C8, and C9) and three hydrogen-substituted perfluoroalkanesulfonates (H-PFSAs; C6, C7, and C8). To our knowledge, this is the first study to report the presence of emerging hydrogen-substituted PFAS in glacial meltwater. These findings expand the known suite of PFAS in the cryosphere and underscore the need for optimized analytical strategies to detect trace-level emerging PFAS in high-altitude environments.