Rui Shen, Ralf Ebinghaus, Daniel Giddings Vassão, Norman Ratcliffe, Thomas Larsen

Per- and polyfluoroalkyl substances (PFASs) are persistent anthropogenic pollutants with a widespread and significant impact on global marine ecosystems, particularly in the Arctic. Our study is centered in Iceland, an area where the merging of boreal and Arctic marine currents creates a complex ecological landscape. This setting is increasingly being influenced by the warming climate, adding another layer of complexity to the existing challenges posed by pollution. Focusing on two congeneric seabird species breeding in Iceland, the common guillemot (Uria aalge, UA), primarily a boreal species, and Brünnich's guillemot (Uria lomvia, UL), a true Arctic species, our research aims to monitor and understand the bioaccumulative behavior of PFASs. These seabirds, differing in ecological niches and migratory behaviors, serve as ideal sentinels for assessing the impacts of PFASs.
We collected blood plasma samples from both species (UA: n=67, UL: n=45) during their breeding season in June 2018 across Iceland. The analysis included PFASs measurement and stable isotopes of carbon (δ13C) and nitrogen (δ15N), offering insights into the seabirds' exposure levels and foraging behaviors, respectively. This dual-method approach provides a comprehensive assessment of how foraging patterns and past seasonal diet influence their PFASs exposure, shedding light on the ecological implications of these pollutants in the Arctic.
Our findings reveal the presence of C9-13 PFCAs and PFOS in all plasma samples, with a notable interspecies variation in exposure levels. Principal component analysis (PCA) indicates a bioaccumulative pattern predominantly driven by PFCAs homologues, highlighting PFOS persistence. UA generally showed higher exposure levels compared to UL (PFCAs: 10^1.7 ng/g DM, 10^1.5 ng/g DM; PFOS: 10^2.0 ng/g DM, 10^1.8 ng/g DM; total burden: 10^2.2 ng/g DM, 10^2.0 ng/g DM, respectively). Stable Isotope Analysis (SIA) indicated distinct foraging areas for UA, particularly in southern colonies with enriched δ13C values and δ15N enrichment, suggesting diverse food web structures influenced by Atlantic waters. In contrast, northern colonies showed uniformity in marine carbon intake and preference for less δ15N enriched sources. In addition, our findings suggest that PFAS exposure in these seabirds reflects chronic exposure to consistent dietary sources over time.
Despite limitations such as the absence of an isoscape around Iceland, our study underscores the vulnerability of Arctic seabirds to PFAS exposure and the persistence of these pollutants in Arctic ecosystems. The integration of SIA proves invaluable in deciphering foraging behavior and pollutant exposure. These findings contribute significantly to understanding pollution impact on Arctic wildlife, emphasizing the need for continued research in this domain.