Seasonal Shift in Exposure and Accumulation of PFAS and Heavy Metals in High Arctic Reindeer

Seasonal fluctuations in contaminant concentrations are an important, yet often overlooked, aspect of Arctic wildlife monitoring, particularly in species like the Svalbard reindeer (<i>Rangifer tarandus platyrhynchus</i>), which exhibit annual fattening and fasting cycles. While seasonal variation in metal concentrations has been observed in this species, little is known about how other contaminant groups, such as per- and poly-fluoroalkyl substances (PFAS), vary with season. In the present study, we report concentrations of total mercury (THg), cadmium (Cd), lead (Pb), and 13 PFAS in the liver and muscle of Svalbard reindeer culled in August 2022 and October 2023. Seasonal differences were observed, with higher concentrations of THg, Cd, and several PFAS in October, likely reflecting an extended foraging time following the winter fasting. The PFAS profiles, dominated by PFOS and long-chain PFCAs, primarily suggest exposure to long-range transported contaminants rather than local sources, highlighting that even remote terrestrial wildlife is affected by emissions from industrialized regions. While Cd and Pb concentrations have decreased compared to levels reported in the 1980s, PFAS concentrations have increased over the past decade. These findings underscore the need for continued monitoring of Arctic terrestrial wildlife, particularly in the context of environmental change and remobilisation of legacy contaminants.