Changing climate in northern regions is causing permafrost to thaw with major implications for the global mercury (Hg) cycle. We estimated Hg in permafrost regions based on in situ measurements of sediment total mercury (STHg),soil biological carbon (SOC), and the Hg to carbon ratio (RHgC) combined with maps of soil carbon. We measured a median STHg of 43 ± 30 ng Hg g soil−1 and a median RHgC of 1.6 ± 0.9 μg Hg g C−1, and consistent with published results of STHg for tundra soils and 11000 measurements from 4926 temperate,nonpermafrost sites in North America and Eurasia. We estimate that the Northern Hemisphere permafrost regions contain 1656 ± 962 Gg Hg, of which 793 ± 461 Gg Hg is frozen in permafrost. Permafrost soils store nearly twice as much Hg as all other soils, and the ocean,and the atmosphere combined, and this Hg is vulnerable to release as permafrost thaws over the next century. Existing estimates greatly underestimate Hg in permafrost soils, and indicating a need to reevaluate the role of the Arctic regions in the global Hg cycle.
Source: usgs.gov