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| Titel |
DMS and MSA measurements in the Antarctic Boundary Layer: impact of BrO on MSA production |
| VerfasserIn |
K. A. Read, A. C. Lewis, S. Bauguitte, A. M. Rankin, R. A. Salmon, E. W. Wolff, A. Saiz-Lopez, W. J. Bloss, D. E. Heard, J. D. Lee, J. M. C. Plane |
| 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 ; 8, no. 11 ; Nr. 8, no. 11 (2008-06-17), S.2985-2997 |
| Datensatznummer |
250006187
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| Publikation (Nr.) |
 copernicus.org/acp-8-2985-2008.pdf |
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| Zusammenfassung |
| In situ measurements of dimethyl sulphide (DMS) and methane sulphonic acid
(MSA) were made at Halley Station, Antarctica (75°35' S, 26°19' W)
during February 2004–February 2005 as part of the CHABLIS (Chemistry of the
Antarctic Boundary Layer and the Interface with Snow) project. DMS was
present in the atmosphere at Halley all year (average 38.1±43 pptV)
with a maximum monthly average value of 113.6±52 pptV in February
2004 coinciding temporally with a minimum in sea extent. Whilst seasonal
variability and interannual variability can be attributed to a number of
factors, short term variability appeared strongly dependent on air mass
origin and trajectory pressure height. The MSA and derived non-sea salt
sulphate (nss-SO42−) measurements showed no correlation with those
of DMS (regression R2=0.039, and R2=0.001 respectively)
in-line with the complexity of DMS fluxes, alternative oxidation routes,
transport of air masses and variable spatial coverage of both sea-ice and
phytoplankton. MSA was generally low throughout the year, with an annual
average of 42 ng m−3 (9.8±13.2 pptV), however MSA:
nss-SO42− ratios were high implying a dominance of the addition
oxidation route for DMS. Including BrO measurements into MSA production
calculations demonstrated the significance of BrO on DMS oxidation within
this region of the atmosphere in austral summer. Assuming an 80% yield
of DMSO from the reaction of DMS+BrO, an atmospheric concentration of BrO
equal to 3 pptV increased the calculated MSA production from DMS by a factor
of 9 above that obtained when considering only reaction with the hydroxyl
radical. These findings have significant atmospheric implications, but may
also impact on the interpretation of ice cores which previously relied on
the understanding of MSA and nss-SO42− chemistry to provide
information on environmental conditions such as sea ice extent and the
origins of sulphur within the ice. |
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