Abstract
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 δ18OH20 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.
Highlights
Poly- and perfluoroalkyl substances (PFASs) consist of a large group of synthetic chemicals that are used in a wide variety of industrial and consumer applications.[1]
Perfluoroalkyl acids (PFAAs), including the perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs), are a major group of PFASs, which have a ubiquitous presence in the global environment
Sea ice is a heterogeneous matrix of ice formed from seawater, which over time may have been influenced by atmospheric inputs through precipitation such as snow
Summary
Poly- and perfluoroalkyl substances (PFASs) consist of a large group of synthetic chemicals that are used in a wide variety of industrial and consumer applications.[1] Perfluoroalkyl acids (PFAAs), including the perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs), are a major group of PFASs, which have a ubiquitous presence in the global environment. Understanding the fate and behavior of PFAAs in the environment is important in relation to remote ecosystems such as the Arctic that are reported to be currently experiencing other environmental stressors.[3]. PFAAs have been observed in the remote Greenland Sea[4] and Chukchi/Beaufort Sea regions of the western Arctic[5] with their presence having been linked to transport through ocean currents originating from industrial regions. Little is known about the relative importance of these two pathways with even less information about the fate and behavior of PFAS in sea ice and their subsequent fate during seasonal thaw
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