4. Changes in Arctic mercury levels – processes affecting mercury transformations and biotic uptake Introduction
22 February 2022
the succession of vegetation communities after glacier retreat A major consequence of climate warming in the Arctic is acting as an active “pump” drawing down Hg(0) from the and Subarctic has been the thawing and degradation of atmosphere and increasing the amount of Hg sequestered in permafrost (Jorgenson et al., 2001, 2006; Lantz and Kokelj, areas affected by glacier retreat in a form available. [...] From Bowman et al., 2016; Kim et al., 2017), Southern Ocean the Canada Basin eastwards to the Canadian Arctic Archipelago, (Cossa et al., 2011; Gionfriddo et al., 2016); Mediterranean Sea the depth of the MeHg enrichment layer shoals up to ~100 m (Cossa et al., 2009, 2012, 2017; Heimbürger et al., 2010), Baltic and the peak MeHg concentration slightly decreases. [...] of the studies have attributed the subsurface MeHg to in situ Hg methylation in the water column associated with 184.108.40.206 Snow and sea ice organic matter remineralization (Sunderland et al., 2009; Cossa et al., 2011; Wang et al., 2012b; Heimbürger et al., 2015), Snow, which covers large parts of the Arctic landscape and yet the biotic or abiotic processes that are responsible for the sea icescape,. [...] Th e two main routes of sea-ice drift in the Arctic are via the Transpolar could lead to oxygen depletion in the bottom of the ice column Drift that circulates from the eastern to central Arctic and and denitrifi cation processes that favor anoxic environments the Beaufort Gyre which circulates clockwise in the western could then be important in the lower parts of the ice (Rysgaard Arctic. [...] bioavailability of Hg “includes the availability of inorganic Hg Despite the critical role of phytoplankton as the dominant forms to microbial populations responsible for Hg methylation energy source for food webs in the ocean, few measurements of and the availability of MeHg in prey items to predators within MeHg have been made of Arctic phytoplankton.