Temporal trends and sediment-water partitioning of per- and polyfluoroalkyl substances (PFAS) in lake sediment.

The use of per- and polyfluoroalkyl substances (PFAS) containing aqueous film forming foams (AFFF) at fire training facilities can have an adverse impact on the surrounding environment. The aim of the present study was to study the distribution and temporal trend of 26 PFAS in water and sediment cores for a lake and a pond affected by AFFF release from a fire training facility in Luleå, northern Sweden. In the aqueous phase, maximum ΣPFAS concentration was 1.700 ± 90 ng L-1. Dominant PFAS groups were perfluoroalkane sulfonates (PFSAs) with 70% of the ΣPFAS, followed by perfluoroalkyl carboxylates (PFCAs, 29%), whereas the contribution of 6:2 fluorotelomer carboxylate (FTSAs) was low (<1%). In the sediment core samples, ΣPFAS concentrations ranged between <1 μg kg-1 dry weight (dw) and 76 μg kg-1 dw, where perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) had an average contribution of ∼71% and ∼23% of the ΣPFAS. The sediment core analysis indicated that the PFAS contamination began about 1994 and the highest accumulation rate was observed for the period 2003-2009. The PFAS flux increased from 2.3 μg m-2 yr-1 dw in 1994 to 12 μg m-2 yr-1 dw by 2009. Over the accumulation period 1994-2009, the lake sediment surface received 213 μg m-2 dw for ƩPFAS, where PFOS contributed with 125 μg m-2 yr-1 dw and PFHxS with 65 μg m-2 dw. Results point to that sediment cores collected near PFAS hotspot areas can be used as a contamination record to reconstruct release history.