From February to May, unique chemical reactions occur in the Arctic that release halogen atoms (especially bromine and chlorine atoms) from snow, ice, and aerosol particle surfaces.  These halogen atoms deplete ozone to near zero levels in ozone depletion events, oxidize and deposit mercury, and change oxidative fates and pathways.  Heterogeneous chemistry of salts held on snow, ice, and aerosol particle surfaces is considered to be a key process in producing reactive halogen events.  In this talk, we describe observations of the vertical and horizontal distribution of bromine monoxide, a tracer of reactive halogen production, in the Arctic.  The vertical distribution assists in understanding the competition between heterogenous reactions on the snowpack and reactions on lofted aerosol particles.  We find that atmospheric stability is a key control on the ability of halogens to be lofted away from snowpack surfaces.  The horizontal distribution of bromine monoxide allows us to probe the role of various snow/ice types on halogen activation, and we find that multiple types of surfaces are capable of sustaining halogen activation.  Observations of the horizontal gradients in bromine monoxide assist in constraining the length scale of halogen activated airmasses.  Overall, these observations help us to understand the fundamental chemical mechanism of reactive halogen chemistry and thereby assist in prediction of how rapidly changing arctic environmental conditions (e.g. summer sea ice loss) may affect arctic atmospheric chemistry.

Vertical and horizontal gradients in bromine monoxide assist in understanding arctic halogen activation mechanisms

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.