Occurrence and source apportionment of novel and legacy poly/perfluoroalkyl substances in Hai River basin in China using receptor models and isomeric fingerprints

Abstract

A variety of fluorinated alternatives are being manufactured and applied as a consequence of stringent regulations on legacy poly/perfluoroalkyl substances (PFASs). In this study, 26 emerging and legacy PFASs were measured in the surface water (including dissolved phase and suspended particulate matter) and sediments taken from Hai River basin, China. The total concentrations of PFASs (∑PFASs) ranged from 1.74 to 172 ng/L, with perfluorooctanonate (PFOA) as the dominant compound (15.2% of the ∑PFASs, median value). Emerging PFASs, such as dimer acid of hexafluoropropylene oxide dimer acid (HFPO-DA) and trimer acid (HFPO-TA), were widely detected in the water samples. Specifically, chlorinated polyfluorinated ether sulfonate (F–53B) was observed to be predominant in some sediment samples. A receptor model, Unmix, was introduced to identify the sources of PFASs in the surface water, and the results indicated that fire-fighting foam/fluoropolymer processing aids (36.6%) were the dominant source. The field-based sediment-water (organic carbon normalized) coefficients, Koc, were correlated to the carbon chain lengths of the PFASs. A technique coupling one-way analysis of variance with chemical mass balance model was developed to trace the manufacturing sources of PFOA. Electrochemical fluorination (ECF) was the major PFOA manufacturing source with considerable contribution by telomerization. For the first time, the isomers of perfluorooctane sulfonamide (PFOSA) were quantified in the environmental samples. The lower proportion of branched (br-) PFOSA isomers and higher percentage of br-perfluorooctane sulfonate (PFOS) isomers in the water samples relative to their corresponding commercial products, provided more direct evidences that br-PFOSA isomers were biotransformed more easily than n-PFOSA, explaining the observed enrichment of br-PFOS in the aquatic environment.