|Abstract Title:||Sources and Changes of Arctic Atmospheric Mercury|
|Presenter Name:||Ashu Dastoor|
|Company/Institution:||Air Quality Research Division, Environment and Climate Change Canada, Dorval, Quebec, Canada.|
|Session:||Special Session - Climate-Driven Perturbations of Arctic Mercury Cycling|
|Co-Authors:||Ashu Dastoor,Simon Wilson,Oleg Travnikov,Andrei Ryjkov,Hlne Angot,Jesper Christensen,Frits Steenhuisen,Marilena Muntean|
Abstract Information :
This presentation summarizes findings from the 2021 AMAP Mercury Assessment on the state of knowledge of the global anthropogenic sources of mercury (Hg) emissions, and examines the recent changes (and their drivers) and source attribution of Hg transport and deposition to the Arctic using models. Global anthropogenic Hg emissions for 2015 were ~2220 Mg, ~20% higher than 2010. The model simulations suggest that changes in meteorology are having a profound impact on contemporary atmospheric Hg in the Arctic. Reversal of North Atlantic Oscillation phase from strongly negative in 2010 to positive in 2015 led to lower temperature and more sea ice in the Canadian Arctic, Greenland and surrounding ocean in 2015. These changes enhanced production of bromine species and Hg(0) oxidation and lowered Hg(0) evasion in 2015, which led to increased Hg(II) and reduced Hg(0) modeled air concentrations in these regions in-line with High Arctic observations. Combined meteorology and anthropogenic emission changes led to overall elevated modeled Arctic air Hg(0) levels between 2010 and 2015 contrary to observed declines at most monitoring sites, likely due to uncertainties in anthropogenic emission speciation, wildfire emissions and model representations of air-surface Hg fluxes. Global anthropogenic, legacy and geogenic Hg emissions were, respectively, responsible for 32%, 64% (wildfires: 6-10%) and 4% of the annual Arctic Hg deposition. The relative contributions to annual Arctic Hg deposition of anthropogenic origin from global source regions were: East Asia (32%), Commonwealth of Independent States (12%), Africa (12%), Europe (8%), Southeast Asia (8%), South Asia (7%), South America (7%), Central America (6%), North America (3%), Arctic (3%), Middle East (2%), and Australia and New Zealand (0.1%). Modeling reveals significant spatiotemporal variations in anthropogenic Arctic Hg deposition, driven by regional differences in Hg transport, surface uptake and precipitation, and inter-seasonal differences in atmospheric circulation and deposition pathways.