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| Titel |
Photochemical chlorine and bromine activation from artificial saline snow |
| VerfasserIn |
S. N. Wren, D. J. Donaldson, J. P. D. Abbatt |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 19 ; Nr. 13, no. 19 (2013-10-07), S.9789-9800 |
| Datensatznummer |
250085731
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| Publikation (Nr.) |
 copernicus.org/acp-13-9789-2013.pdf |
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| Zusammenfassung |
| The activation of reactive halogen species – particularly Cl2 – from sea
ice and snow surfaces is not well understood. In this study, we used a
photochemical snow reactor coupled to a chemical ionization mass spectrometer
to investigate the production of Br2, BrCl and Cl2 from
NaCl/NaBr-doped artificial snow samples. At temperatures above the NaCl-water
eutectic, illumination of samples (λ > 310 nm) in the presence
of gas phase O3 led to the accelerated release of Br2, BrCl and the
release of Cl2 in a process that was significantly enhanced by acidity,
high surface area and additional gas phase Br2. Cl2 production was only
observed when both light and ozone were present. The total halogen release
depended on [ozone] and pre-freezing [NaCl]. Our observations support a
"halogen explosion" mechanism occurring within the snowpack, which is
initiated by heterogeneous oxidation and propagated by Br2 or BrCl
photolysis and by recycling of HOBr and HOCl into the snowpack. Our study
implicates this important role of active chemistry occurring within the
interstitial air of aged (i.e. acidic) snow for halogen activation at polar
sunrise. |
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