now and ice processes in the deposition and fate of mercury in the Arctic.
Lead PI: Matthew Sturm, Cold Regions Research and Enginnering Lab
Atmospheric mercury enters the arctic ecosystem through a set of
complex atmospheric chemical reactions that require sea ice and leads
to provide reactive bromine, low ambient temperatures, and enough
sunlight for photolysis. As a consequence, virtually all atmospheric
mercury entering the arctic ecosystem is initially deposited in the
snow pack, both on land and at sea. Up to one third of this initial
deposit is re-emitted to the atmosphere before the snow melts, but the
remainder ends up in snow melt run-off. The fate of this water-borne
mercury is uncertain and undoubtedly different on land vs. sea ice. Two
key unanswered questions are: How much of the elemental mercury
initially deposited is converted to toxic methylmercury, and where does
this methylmercury ultimately come to rest? Since cryospheric processes
related to snow and ice in large measure determine the answers to these
questions, this project sets out to study these processes. The
processes studied straddle the Arctic Coast, have pan-Arctic
significance, and have a direct impact on human and ecosystem health.