Spatial and temporal trends of per- and polyfluoroalkyl substances (PFASs) in sediments from the Rhône River near Lyon

Prior to 1987, tPFASs concentrations were low (≤ 2 ng g-1 dw), increasing to a maximum of 51 ng g-1 dw in the 1990s and then decreasing from 2002 to the present day (~10 ng g-1 dw). In terms of the PFAS pattern, the proportion of perfluoroalkyl sulfonic acids (PFSAs) has remained stable since the 1980s (~10%), whereas large variations are reported for carboxylic acids (PFCAs). Long chain- (C>8) PFCAs characterized by an even number of perfluorinated carbons represent about 74% of the total PFAS load until 2005.

However, from 2005 to 2013, the relative contribution of long chain- (C>8) PFCAs with an odd number of perfluorinated carbons reaches 80%. Such changes in the PFAS pattern likely highlight a major shift in the industrial production process. This spatial and retrospective study provides valuable insights into the long-term contamination patterns of PFAS chemicals in river basins impacted by both urban and industrial activities.