| Summary: | Per- and polyfluoroalkyl substances (PFAS) are a group of persistent organic contaminants. Some are toxic and bioaccumulative, and pose a hazard to human and environmental health. This thesis aims to further understand the sources and environmental processes of PFAS in the Arctic terrestrial cryosphere. This was achieved by analysing PFAS in an ice core (spanning 2006 – 2019) from the remote Lomonosovfonna ice cap and surface snow samples collected seasonally (January – August 2019) on Svalbard (Norwegian Arctic). These samples were used to assess the levels, sources, and the significance of photochemical processes in the atmospheric transformations of PFAS. In addition, the extent of PFAS contamination from local sources in the settlement of Longyearbyen, Svalbard, was investigated. PFAS contamination is widespread in the remote Arctic, since more than 26 compounds were detected, including C2 – C11 perfluoroalkyl carboxylic acids (PFCAs), perfluorohexane sulfonic acid (PFHxS) and perfluorooctane sulfonic acid (PFOS). In the Lomonosovfonna ice core, PFCAs are thought to come from the atmospheric degradation of fluorotelomer alcohols (FTOHs) and chlorofluorocarbon (CFC) replacement products such as hydrofluorocarbons (HFCs). High levels of trifluoroacetic acid (TFA) contribute to 71% of C2 – C11 PFCAs in the ice core. Neither the ice core nor surface snow indicate that marine aerosols are a source of PFAS deposition in the Arctic. Hexafluoropropylene oxide dimer acid (HFPO-DA or GenX) and trifluoromethane sulfonic acid (TFMS) are widespread in surface snow, but the source of TFMS is unknown. During 24-hour daylight, the deposition fluxes of C2 – C11 PFCAs, PFHxS, PFOS and HFPO-DA (GenX) were 2 – 38 times higher in surface snow. Several PFCAs, PFOS and HFPO-DA are found to correlate with solar radiation which indicates that photochemical processes likely contribute to the atmospheric formation of these PFAS. Further investigation suggests that bromine radicals are a significant additional oxidant for the degradation of precursors (e.g. FTOHs, HFCs) in the atmosphere during Arctic Springtime.
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