Hexabromocyclododecanes in soils, plants, and sediments from Svalbard, Arctic: Levels, isomer profiles, chiral signatures, and potential sources

This study investigated the occurrence, stereoisomeric behavior, and potential sources of hexabromocyclododecanes (HBCDs) in topsoil and terrestrial vegetation from Svalbard and ocean sediment samples from Kongsfjorden, an open fjord on the west coast of Spitsbergen. The mean levels of total concentrations (Σ3HBCDs) were comparable to those in other remote regions and were lower than those in source regions. Elevated proportions of α-HBCD with an average of 41% in the terrestrial samples and 25% in ocean sediments compared to those in commercial products (10-13% for α-HBCD) were observed, implying isomerization from γ- to α-HBCD in the Arctic environment. In addition, the extensive deviations of enantiomeric fractions (EFs) from the racemic values reflected the effect of biotransformation on HBCD accumulation. Linear correlation analysis, redundancy analysis, and back-trajectory were combined to infer possible HBCD sources, and the results showed the important role of global production and long-range environmental transport (LRET) for the entry of HBCDs into the Arctic at an early stage. To the best of our knowledge, this study represents the first report on the diastereoisomer- and enantiomer-specific profiles of HBCDs in the Arctic terrestrial environment and sheds light on the transport pathways and environmental fate for more effective risk management related to HBCDs in remote regions. Environmental Implication HBCDs have become a global pollution problem due to their persistence, long-range transport ability, and toxicity to wildlife and humans. However, little is known about their occurrence and stereoisomeric behaviors in the Arctic terrestrial environment. This study investigated the isomer profiles and chiral signatures of HBCDs in soils, plants, and sediments from the Svalbard, Arctic. To the best of our knowledge, this study provides the first report on the diastereoisomer- and enantiomer-specific profiles in various Arctic environmental matrices. This work contributes to a better understanding of biogeochemical cycling for more effective risk management related to HBCDs in the Arctic.