High Concentrations of Perfluoroalkyl Acids in Arctic Seawater Driven by Early Thawing Sea Ice

• Main Authors: Jack Garnett (6802640), Crispin Halsall (1862722), Anna Vader (8253), Hanna Joerss (649633), Ralf Ebinghaus (1462171), Amber Leeson (6802646), Peter M. Wynn (2389882)
• Format: Other Non-Article Part of Journal/Newspaper
• Language: unknown
• Published: 2021
• Subjects: Ecology; Sociology; Inorganic Chemistry; Environmental Sciences not elsewhere classified; Astronomical and Space Sciences not elsewhere classified; Biological Sciences not elsewhere classified; Chemical Sciences not elsewhere classified; late-season ice pack; sea ice compartments; PFAA; seawater; sea ice layer; marine food web; Arctic marine system; Thawing Sea Ice Poly; PFOA; surface ice floe components drives; North Sea infuenced; sea ice; sea ice column; Arctic; Barents Sea; ice pack; Sea ice
• Online Access: https://doi.org/10.1021/acs.est.1c01676.s001

Poly- and perfluoroalkyl substances are synthetic chemicals that are widely present in the global environment including the Arctic. However, little is known about how these chemicals (particularly perfluoroalkyl acids, PFAA) enter the Arctic marine system and cycle between seawater and sea ice compartments. To evaluate this, we analyzed sea ice, snow, melt ponds, and near-surface seawater at two ice-covered stations located north of the Barents Sea (81 °N) with the aim of investigating PFAA dynamics in the late-season ice pack. Sea ice showed high concentrations of PFAA particularly at the surface with snow-ice (the uppermost sea ice layer strongly influenced by snow) comprising 26–62% of the total PFAA burden. Low salinities (<2.5 ppt) and low δ 18 O H20 values (<1‰ in snow and upper ice layers) in sea ice revealed the strong influence of meteoric water on sea ice, thus indicating a significant atmospheric source of PFAA with subsequent transfer down the sea ice column in meltwater. Importantly, the under-ice seawater (0.5 m depth) displayed some of the highest concentrations notably for the long-chain PFAA (e.g., PFOA 928 ± 617 pg L –1 ), which were ≈3-fold higher than those of deeper water (5 m depth) and ≈2-fold higher than those recently measured in surface waters of the North Sea infuenced by industrial inputs of PFAAs. The evidence provided here suggests that meltwater arising early in the melt season from snow and other surface ice floe components drives the higher PFAA concentrations observed in under-ice seawater, which could in turn influence the timing and extent of PFAA exposure for organisms at the base of the marine food web.