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Halogens and their role in polar boundary-layer ozone depletion

Simpson, W.R.; Von glasow, R.; Riedel, K.; Anderson, P.S.; Ariya, P.; Bottenheim, J.W.; Burrows, J.; Carpenter, L.; Friess, U.; Goodsite, M.E.; Heard, D.E.; Hutterli, M.A.; Jacobi, H.-W.; Kaleschke, L.; Neff, W.; Plane, J.; Platt, U.; Richter, A.; Roscoe, H.K.; Sander, R.; Shepson, P.B.; Sodeau, J.; Steffen, A.; Wagner, T.; Wolff, E.W.. 2007 Halogens and their role in polar boundary-layer ozone depletion. Atmospheric Chemistry and Physics, 7 (16). 4375-4418. 10.5194/acp-7-4375-2007

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Abstract/Summary

During springtime in the polar regions, unique photochemistry converts inert halide salt ions (e.g. Br-) into reactive halogen species (e.g. Br atoms and BrO) that deplete ozone in the boundary layer to near zero levels. Since their discovery in the late 1980s, research on ozone depletion events (ODEs) has made great advances; however many key processes remain poorly understood. In this article we review the history, chemistry, dependence on environmental conditions, and impacts of ODEs. This research has shown the central role of bromine photochemistry, but how salts are transported from the ocean and are oxidized to become reactive halogen species in the air is still not fully understood. Halogens other than bromine (chlorine and iodine) are also activated through incompletely understood mechanisms that are probably coupled to bromine chemistry. The main consequence of halogen activation is chemical destruction of ozone, which removes the primary precursor of atmospheric oxidation, and generation of reactive halogen atoms/oxides that become the primary oxidizing species. The different reactivity of halogens as compared to OH and ozone has broad impacts on atmospheric chemistry, including near complete removal and deposition of mercury, alteration of oxidation fates for organic gases, and export of bromine into the free troposphere. Recent changes in the climate of the Arctic and state of the Arctic sea ice cover are likely to have strong effects on halogen activation and ODEs; however, more research is needed to make meaningful predictions of these changes.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.5194/acp-7-4375-2007
Programmes: BAS Programmes > Other
BAS Programmes > Global Science in the Antarctic Context (2005-2009) > Climate and Chemistry - Forcings and Phasings in the Earth System
ISSN: 1680-7316
Additional Keywords: Boundary layer; Photochemistry;
NORA Subject Terms: Atmospheric Sciences
Date made live: 13 Aug 2010 08:01
URI: http://nora.nerc.ac.uk/id/eprint/10144

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