Global Multidimensional Ecological Risk Assessment of Per- and Polyfluoroalkyl Substances in Groundwater and Associated Influencing Factors

Per- and polyfluoroalkyl substances (PFAS) are widely present in global groundwater and pose ecological risks. However, existing studies have mainly focused on local regions, resulting in limited understanding of global risk distributions and environmental impacts. In this study, global groundwater PFAS monitoring data from 2010 to 2024 were collected to summarize the analytical techniques involved. A concentration probability distribution-based ecological risk assessment framework was established by integrating the Weibull probability distribution model with predicted no-effect concentration (PNEC), and PFAS ecological risks were evaluated from three dimensions: spatial distribution, pollution sources, and environmental factors. The results showed that: (1) Due to their strong polarity, ionic properties, and low volatility, PFAS are more suitable for liquid-phase separation coupled with mass spectrometry detection. Therefore, current groundwater PFAS analysis mainly relies on LC-MS/MS (96.3%–100%) and LC-HRMS (0–3.7%). (2) PFOA, PFOS, and PFHxS exhibited relatively high detection frequencies (69.6%, 76.8%, and 75.8%, respectively) due to their widespread applications and environmental persistence. Short-chain PFAS showed lower detection frequencies (59.6%–63.6%) due to fewer historical emissions, while 6:2 FTSA exhibited the lowest detection frequency (50.2%), possibly due to its susceptibility to transformation during migration. (3) Compared with PFOS and PFOA, the lower toxicity of short-chain PFAS may be related to their limited bioaccumulation potential, whereas the lower toxicity of 6∶2 FTSA is attributed to its weaker cytotoxicity and protein-binding affinity. (4) At the global scale, the ecological risk exceedance rate of groundwater PFAS was 40.2%, with PFOS (16.9%) and PFOA (10.2%) identified as the major risk contributors. Short-chain PFAS and 6:2 FTSA exhibited lower risks (0–6.1%), which were associated with PFAS contamination levels and ecological toxicity. However, 6∶2 FTSA presents a potential risk due to its transformation into more toxic PFAS. (5) Regarding spatial distribution and pollution sources, Oceania (53.7%) and Asia (34.8%) showed higher exceedance rates, and aqueous film-forming foam (AFFF)-related contamination exhibited the highest risk (46.8%). (6) Environmental analysis indicated that high clay content (21%–57%), moderate cation exchange capacity (CEC) (9–22 cmol/kg), and medium-to-low annual precipitation (163–1090 mm/a) represent high-risk environmental conditions for groundwater PFAS contamination. These findings provide important insights into understanding the drivers of global PFAS distribution and identifying priority areas for risk management and control.