Near surface oxidation of elemental mercury leads to mercury exposure in the Arctic Ocean biota

• Published in: Nature Communications
• Main Authors: Seung Hyeon Lim, Younggwang Kim, Laura C. Motta, Eun Jin Yang, Tae Siek Rhee, Jong Kuk Hong, Seunghee Han, Sae Yun Kwon
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Portfolio 2024
• Subjects: Science; Q; Arctic cod; Arctic Ocean; Beaufort Sea; Bering Strait; Chukchi; Chukchi Sea; Zooplankton
• Online Access: https://doi.org/10.1038/s41467-024-51852-2; https://doaj.org/article/7d31d668177240f78d9909da8f59f31d

Abstract Atmospheric mercury (Hg(0), Hg(II)) and riverine exported Hg (Hg(II)) are proposed as important Hg sources to the Arctic Ocean. As plankton cannot passively uptake Hg(0), gaseous Hg(0) has to be oxidized to be bioavailable. Here, we measured Hg isotope ratios in zooplankton, Arctic cod, total gaseous Hg, sediment, seawater, and snowpack from the Bering Strait, the Chukchi Sea, and the Beaufort Sea. The Δ200Hg, used to differentiate between Hg(0) and Hg(II), shows, on average, 70% of Hg(0) in all biota and differs with seawater Δ200Hg (Hg(II)). Since Δ200Hg anomalies occur via tropospheric Hg(0) oxidation, we propose that near-surface Hg(0) oxidation via terrestrial vegetation, coastally evaded halogens, and sea salt aerosols, which preserve Δ200Hg of Hg(0) upon oxidation, supply bioavailable Hg(II) pools in seawater. Our study highlights sources and pathways in which Hg(0) poses potential ecological risks to the Arctic Ocean biota.