|Abstract Title:||Climate Change Effects on Mercury in the Arctic Environment and in Biota|
|Presenter Name:||Melissa McKinney|
|Session:||Special Session - Climate-Driven Perturbations of Arctic Mercury Cycling|
|Day and Session:||Friday 29th July - Session Three|
|Start Time:||13:00 UTC|
Abstract Information :
This presentation summarizes findings from the 2021 AMAP Mercury Assessment on climate change-mercury interactions. Recent evidence indicates climate change is influencing the transport, biogeochemistry, and bioaccumulation of Hg in the Arctic. Modeling results suggest climate influences seasonal and interannual variability of atmospheric Hg deposition. The clearest evidence of current climate change effects is increasing Hg transport from terrestrial catchments, where widespread permafrost thaw, glacier melt, and coastal erosion are promoting Hg export downstream. Thermokarst development and soil erosion are increasing river transport of particulate-bound Hg and altering conditions for aquatic Hg transformations. More severe and frequent wildfires within Arctic and boreal regions may be contributing to the atmospheric pool of Hg. Climate change influences on Hg biogeochemical cycling remain poorly understood. Seasonal evasion and retention of inorganic Hg may be altered by reduced sea-ice cover and higher chloride content in snow from expanded open water areas. Experimental evidence indicates warmer temperatures enhance methylmercury production in sediments and soils. Correlations between marine species? Hg concentrations and climate variables suggest physical changes that alter Hg transport and deposition are impacting biotic Hg concentrations. Terrestrial herbivores may be exposed to higher Hg concentrations if exploiting coastal/marine foods due to ice-over of terrestrial plants. Yet, Hg concentrations in predators may be reduced with shifts from sea ice-based to land-based foraging. How climate change influences Hg in freshwater fishes is not clear, but it may depend on lake-specific alterations in ice duration, turbidity, food web length, energy sources, and growth dilution. Northward range shifts of sub-Arctic species and altered body condition may also affect Hg levels in Arctic biota. Improved geographic coverage of measurements and modeling approaches are needed to better evaluate net effects of climate change and long-term implications for Hg contamination in the Arctic and its biota.