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| Titel |
A high volume sampling system for isotope determination of volatile halocarbons and hydrocarbons |
| VerfasserIn |
E. Bahlmann, I. Weinberg, R. Seifert, C. Tubbesing, W. Michaelis |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 4, no. 10 ; Nr. 4, no. 10 (2011-10-04), S.2073-2086 |
| Datensatznummer |
250002109
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| Publikation (Nr.) |
 copernicus.org/amt-4-2073-2011.pdf |
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| Zusammenfassung |
The isotopic composition of volatile organic compounds (VOCs) can provide
valuable information on their sources and fate not deducible from mixing
ratios alone. In particular the reported carbon stable isotope ratios of
chloromethane and bromomethane from different sources cover a
δ13C-range of almost 100‰ making isotope ratios a very promising tool
for studying the biogeochemistry of these compounds. So far, the
determination of the isotopic composition of C1 and C2 halocarbons others
than chloromethane is hampered by their low mixing ratios.
In order to determine the carbon isotopic composition of C1 and C2
halocarbons with mixing ratios as low as 1 pptv (i) a field suitable
cryogenic high volume sampling system and (ii) a chromatographic set up for
processing these samples have been developed and validated. The sampling
system was tested at two different sampling sites, an urban and a coastal
location in Northern Germany. The average δ13C-values for
bromomethane at the urban site were −42.9 ± 1.1‰ and agreed well with
previously published results. But at the coastal site bromomethane was
substantially enriched in 13C by almost 10‰. Less pronounced
differences were observed for chlorodifluoromethane, 1,1,1-trichloroethane
and chloromethane. We suggest that these differences are related to the
turnover of these compounds in ocean surface waters. Furthermore we report
first carbon isotope ratios for iodomethane (−40.4‰ to −79.8‰), bromoform
(−13.8‰ to 22.9‰), and other halocarbons. |
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