Cryospheric chemistry of mercury in sea ice

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Mercury is a known developmental neurotoxin. Its high concentration in marine mammals in Canadian Arctic Ocean in recent decades has raised major concerns over the health of these animals and the Northerners who consume these animals as part of their traditional diets. Although monitoring data have suggested that a changing sea ice environment may have been playing a major role in mercury bioaccumulation in the Arctic marine ecosystem, interpreting the significance and implication of such observational data is almost impossible at this time due to the lack of understanding of fundamental physicochemical processes occurring in the sea ice environment. This is largely attributable to a general lack of understanding of aqueous and aquatic chemistry at subzero temperatures. To fill in this major knowledge gap in physical and environmental chemistry, experimental studies at laboratory, mesocosm and field scales will be carried out to characterize subzero-temperature physicochemical processes governing the transformation of Hg in the sea ice environment, with a particular focus on reactions occurring at the sea ice surface and in sea ice brine. The thermodynamic data will then be incorporated into chemical equilibrium models such as FREZCHEM and chemical transport model such as GEOS-CHEM to model how mercury bioaccumulation in the Arctic marine ecosystem would respond to the projected climate change and economic development in the Canadian Arctic. As cryospheric chemistry and sea ice are new scientific frontiers, this study is anticipated to result in major discoveries in heterogeneous reaction pathways and mechanisms at subzero temperatures, as well as in technological development related to sampling, analysis and modeling of natural or engineered cold systems.