Halogens and their role in polar boundary-layer ozone depletion

• Main Authors: Simpson, W. R., von Glasow, R., Riedel, K., Anderson, P., Ariya, P., Bottenheim, J., Burrows, J., Carpenter, L. J., Friess, U., Goodsite, M. E., Heard, D., Hutterli, M., Jacobi, H.-W., Kaleschke, L., Neff, B., Plane, J., Platt, U., Richter, A., Roscoe, H., Sander, R., Shepson, P., Sodeau, J., Steffen, A., Wagner, T., Wolff, E.
• Other Authors: Geophysical Institute and Department of Chemistry, University of Alaska Fairbanks (UAF), School of Environmental Sciences Norwich, University of East Anglia Norwich (UEA), National Institute of Water and Atmospheric Research Wellington (NIWA), British Antarctic Survey (BAS), Natural Environment Research Council (NERC), McGill University = Université McGill Montréal, Canada, Environment and Climate Change Canada, Institute of Environmental Physics Bremen (IUP), University of Bremen, Dept. of Chemistry, Institute of Environmental Physics Heidelberg (IUP), Universität Heidelberg Heidelberg = Heidelberg University, University of Southern Denmark (SDU), School of Chemistry Leeds, University of Leeds, Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung = Alfred Wegener Institute for Polar and Marine Research = Institut Alfred-Wegener pour la recherche polaire et marine (AWI), Helmholtz-Gemeinschaft = Helmholtz Association, Center for Marine and Atmospheric Research, Institute of Oceanography, NOAA Earth System Research Laboratory (ESRL), National Oceanic and Atmospheric Administration (NOAA), Atmospheric Chemistry Department MPIC, Max Planck Institute for Chemistry (MPIC), Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Purdue Climate Change Research Center, Purdue University West Lafayette, Department of Chemistry
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2007
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Arctic; Sea ice
• Online Access: https://hal.science/hal-00296318; https://hal.science/hal-00296318/document; https://hal.science/hal-00296318/file/acp-7-4375-2007.pdf

International audience 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.