Occurrence and distribution of PFAS in groundwater impacted by various contamination sources in Korea

Per- and polyfluoroalkyl substances (PFAS) contamination in Korean groundwater was investigated using liquid chromatography–tandem mass spectrometry (LC–MS/MS) for 39 target compounds and LC-Orbitrap/MS for suspect and nontarget screening (SNTS). A total of 67 groundwater samples were collected from sites impacted by military, industrial activities, and historical landfill leachate. Total perfluoroalkyl acids (PFAAs) concentrations reached up to 646 ng/L, which is more than ten times higher than the maximum levels previously reported in Korea. Additionally, those of mean concentrations were highest at military sites (121.5 ng/L), followed by industrial areas (69.5 ng/L) and landfill-affected sites (50.5 ng/L). In particular, perfluoroalkyl sulfonic acids (PFSAs) such as PFOS and PFHxS were prevalent in military sites, while short-chain perfluoroalkyl carboxylic acids (PFCAs) were dominant in industrial and historical landfill leachate areas. Precursor and alternative PFAS were detected at concentrations up to 12.9 ng/L, with 6:2 FTS frequently found near military sites and Gen-X predominantly in industrial areas, exhibiting distinct site-specific distribution patterns. SNTS analysis identified 14 PFAS previously unreported in Korean groundwater, including ultrashort-chain PFAS, perfluoroalkane sulfonamidoacetic acids (FASAAs), and perfluoro-4-ethylcyclohexane sulfonate (PFECHS). Short-chain perfluoroalkyl sulfonamides (FASAs) were observed in the sample influenced by firefighting activities, while PFECHS was associated with automobile manufacturing sources. These findings indicate multi-source PFAS contamination in Korean groundwater and underscore the need for source-specific management to protect sustainable water resources.