Source tracking of per- and polyfluoroalkyl substances (PFAS) from perch in Kvädöfjärden: Report 7:2024

Elevated PFAS concentrations have consistently been found in perch from the Kvädöfjärden monitoring station (Original station) since monitoring of this chemical group started in 2016. In this project we 1) investigated the temporal variability of PFAS in Kvädöfjärden by retrospective analysis of perch from 1981 until 2015, 2) investigated the spatial variability of PFAS concentrations in perch from ten locations collected in the Kvädöfjärden region in 2023 and 3) mapped various harmful activities in the surrounding area of Kvädöfjärden. The results show that PFOS and several PFCAs has continuously increased from the 1980s. We further see a change in the PFAS homologue fingerprint between 2005 and 2010 that suggests a change from a more marine influence to the influence of a local source. All perch from the spatial survey have a fractional pattern of the PFAS homologues similar to the Original station, but the PFAS concentrations show high spatial variability. The Original station has the highest PFAS concentrations but elevated concentrations were also seen in perch in Licknevarpfjärden, north of the Original station. The ratio of PFUnDA/PFDA suggest that firefighting foam is not the source of the increasing PFAS concentrations. Moreover, we could not identify any harmful activities in the Kvädöfjärden region that potentially could affect the PFAS concentrations. We are therefore not able to identify the exact source of the elevated PFAS concentrations. To track a possible source area, we suggest perch samples are collected between the Original station and Licknevarpfjärden. In addition, we suggest that water samples could be collected in the region as a supplement.