Environmental levels and distribution of structural isomers of perfluoroalkyl acids after aqueous fire-fighting foam (AFFF) contamination

Environmental context Perfluoroalkyl acids are used in many products and have spread into the environment where their persistence and potential toxicity pose a threat to humans and wildlife. The present study describes environmental contamination from usage of aqueous film forming foams, and investigates the distribution of structural isomers of perfluoroalkyl acids from a point source to the surrounding environment. Isomer patterns might be used to track contamination sources since isomer composition differs in the various products containing perfluoroalkyl acids. The environmental behaviour of these structural isomers is described, and limitations of their use to track contamination sources are identified. Abstract The environment (soil, water, sediment, fish, crab and mussel) around a training facility using aqueous film forming foams (AFFFs) was studied with respect to perfluorinated alkyl acids (PFAAs) and 6 : 2 fluorotelomer sulfonate (FTS) and their structural isomers. High levels of many PFAAs and 6 : 2 FTS were detected in soil, seepage water, sediment and fish liver. Structural isomers were found for sulfonates, except PFBuS, and for PFOA. Quantification using authentic standards revealed an isomer pattern of 63% linear PFOS (L-PFOS) and 80% linear PFOA (L-PFOA) in the soil at the contamination site, which indicated a source produced by electrochemical fluorination (ECF). The 6 : 2 FTS was 100% linear in all compartments thus coming from a telomerisation product. Enrichment of the linear structure of PFOS and PFOA in soil was seen with increasing distance from the training centre, and an enrichment of branched isomers for both compounds could be found in the seepage water. Sorption to sediment and accumulation in fish liver led to an enrichment of L-PFOS whereas all PFOA remained in the water body.