During springtime every year, a unique set of chemical reactions occur in the Arctic troposphere, resulting in the occurrence of bromine explosion events (BEEs), ozone depletion events (ODEs) and mercury depletion events (MDEs). These events have major implications for biogeochemical processes across the OSA. For instance, MDEs are suspected to play a major role in mercury deposition in the Arctic Ocean where it bioaccumulates and biomagnifies in marine mammals. The key process in these events is the photochemical activation of seawater bromide to atomic bromine. Although this bromine activation process is believed to be enhanced at the surface of sea ice and/or snow, the mechanism remains unknown. Furthermore, this process may also be accelerated by chlorine and iodine related species. In this subproject, the effect that the composition of condensed phases has on tropospheric bromine chemistry will be studied by combining the real-time BrO concentration in the troposphere and time series of chloride, bromide, iodide and iodate concentrations in the cryosphere. During the ice camp, first-year sea ice cores, underlying seawater and snow (including snow overlying ice and snow on tundra) will be sampled during and after BEEs. Chloride, bromide and inorganic iodine concentrations of bulk sea ice and snow will be analyzed at different depths. Near real-time tropospheric BrO concentrations over the experimental site will be retrieved from the satellite data.

Fieldwork site: Field camp, Cambridge Bay, Nunavut, Canada

Project Lead: W.Xu 

PI: Dr. F.Wang

Project Participants: Wen Xu (CEOS); Dr. Feiyue Wang (CEOS)

Fieldwork summary/photo blog

Link to project summary report