Isomers of perfluorooctanesulfonate exhibit preferential infiltration and contrasting ionic associations between surface water and groundwater

We evaluated the spatiotemporal variations of perfluorooctane sulfonate (PFOS) contamination in various environmental matrices of Yorkshire, United Kingdom. The dataset indicates decreasing PFOS concentrations between 2005 and 2023 in the groundwater of Yorkshire, UK. We used statistical methods, including kriging and hydrogeochemical plots, to analyze co-occurring ions, land use influences, and pollution sources. Groundwater exhibited less PFOS concentration, mainly in the form of linear (L) and branched (B) isomers, than surface water. PFOS (B) was more prevalent in groundwater and associated with F, Cr, Cu, Cl, and pH. PFOS pollution in the surface water exhibited source line ionic pairing with Hg, As, and dissolved carbon. Surface water clustering reveals the connection between branched and linear PFOS with Ca-Mg-Cu forms a larger cluster that interacts with major groups like SO4-Na-K and NO3, while the ionic PFOS cluster with As-Cl indicates strong source-level associations, especially in urban areas. Further, isomers were found to be evenly distributed in surface water, which alters during infiltration into groundwater. However, further research is required to provide confirmatory evidence of PFOS pathways linking with surface-groundwater interactions. This study likely represents the first comprehensive analysis of PFOS isomers that provides crucial emphasis on the need for monitoring emerging chemicals, such as PFOS, PFCs, and PFAAs, to establish timely and stringent regulatory guidelines.