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Global Inorganic Source of Atmospheric Bromine

Enami, S. and Vecitis, C. D. and Cheng, J. and Hoffmann, M. R. and Colussi, A. J. (2007) Global Inorganic Source of Atmospheric Bromine. Journal of Physical Chemistry A, 111 (36). pp. 8749-8752. ISSN 1089-5639.

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A few bromine molecules per trillion (ppt) causes the complete destruction of ozone in the lower troposphere during polar spring and about half of the losses associated with the “ozone hole” in the stratosphere. Recent field and aerial measurements of the proxy BrO in the free troposphere suggest an even more pervasive global role for bromine. Models, which quantify ozone trends by assuming atmospheric inorganic bromine (Br_y) stems exclusively from long-lived bromoalkane gases, significantly underpredict BrO measurements. This discrepancy effectively implies a ubiquitous tropospheric background level of ∼4 ppt Br_y of unknown origin. Here, we report that I^- efficiently catalyzes the oxidation of Br^- and Cl^- in aqueous nanodroplets exposed to ozone, the everpresent atmospheric oxidizer, under conditions resembling those encountered in marine aerosols. Br^- and Cl^-, which are rather unreactive toward O_3 and were previously deemed unlikely direct precursors of atmospheric halogens, are readily converted into IBr_2^- and ICl_2^- en route to Br_2(g) and Cl_2(g) in the presence of I^-. Fine sea salt aerosol particles, which are predictably and demonstrably enriched in I^- and Br^-, are thus expected to globally release photoactive halogen compounds into the atmosphere, even in the absence of sunlight.

Item Type:Article
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URLURL TypeDescription Information
Enami, S.0000-0002-2790-7361
Hoffmann, M. R.0000-0001-6495-1946
Colussi, A. J.0000-0002-3400-4101
Additional Information:© 2007 American Chemical Society. Received: June 22, 2007; In Final Form: July 20, 2007. This project was financially supported by the National Science Foundation (ATM-0534990). S.E. is grateful to Prof. M. Kawasaki (Kyoto University), Prof. Y. Matsumi (Nagoya University). and the JSPS Research Fellowship for Young Scientists.
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Japan Society for the Promotion of Science (JSPS)UNSPECIFIED
Issue or Number:36
Record Number:CaltechAUTHORS:20150623-154752216
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Official Citation:Global Inorganic Source of Atmospheric Bromine S. Enami, C. D. Vecitis, J. Cheng, M. R. Hoffmann, and A. J. Colussi The Journal of Physical Chemistry A 2007 111 (36), 8749-8752 DOI: 10.1021/jp074903r
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58465
Deposited By: George Porter
Deposited On:29 Jul 2015 00:05
Last Modified:03 Mar 2020 13:01

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