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April 13, 2010; 107 (15)

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Cover image: Pictured are frost flowers on Arctic sea ice. Frost flowers may release significant quantities of molecular bromine into the springtime polar atmosphere. This halogen compound forms bromine oxide, which destroys ozone. Denis P?hler et al. measured high bromine oxide concentrations in the lower Arctic atmosphere above sea ice, suggesting that naturally occurring halogens may play a more integral role in ozone depletion than previously thought. See the article by P?hler et al. on pages 6582–6587, which is part of the Atmospheric Chemistry Special Feature. Photograph courtesy of Denis P?hler.

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