Fingerprinting PFAS pollution in European surface waters

Robin Schröder, Jens Prothmann, Tobias Licha, Hans Hermann Dürr, Martina Flörke

Per- and polyfluoroalkyl substances (PFAS) comprise a large group of synthetic chemical substances used across industries and find application in a diverse range of consumer products. Owing to their ubiquitous use and ongoing emissions, such substances are distributed throughout the environment. PFAS and their metabolites pose considerable risk to environmental and human health due to their high persistence, toxicity, and bioaccumulation.
However, PFAS in European surface waters have not been systematically investigated across multiple substances. We compiled and harmonised daily concentration data from multiple open data sources for the years 2019 to 2026, comprising 1,907,309 samples from 9,072 sites and 34 substances. We used factor-rotated principal component analysis and hierarchical clustering to characterise co-occurrence patterns, identified hotspots as nearby clusters of samples above substance-specific 85th-percentile concentrations, and screened potential ecological risk.
Recurring co-occurrence patterns involved short-chain perfluoroalkyl carboxylic acids (PFCAs), PFOS and PFHxS, PFBA and PFBS, and the long-chain PFCA pair PFNA and PFDA. TFA and HFPO-DA showed relatively distinct loading patterns, indicating that their co-occurrence profiles differed from those of other compounds in the analysis. Potential hotspots involving multiple compounds were identified in Belgium, Germany and Italy. These findings illustrate the complexity of PFAS co-occurrence patterns in European surface waters and support the need for coordinated monitoring that includes both legacy and emerging substances. The patterns identified here can inform future research, while source attribution should be treated as tentative because co-occurrence patterns alone do not establish sources or pathways.