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| Titel |
Extreme 13C depletion of CCl2F2 in firn air samples from NEEM, Greenland |
| VerfasserIn |
A. Zuiderweg, R. Holzinger, P. Martinerie, R. Schneider, J. Kaiser, E. Witrant, D. Etheridge, V. Petrenko, T. Blunier, T. Röckmann |
| 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. 2 ; Nr. 13, no. 2 (2013-01-17), S.599-609 |
| Datensatznummer |
250017590
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| Publikation (Nr.) |
 copernicus.org/acp-13-599-2013.pdf |
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| Zusammenfassung |
| A series of 12 high volume air samples collected from the S2 firn core
during the North Greenland Eemian Ice Drilling (NEEM) 2009 campaign have
been measured for mixing ratio and stable carbon isotope composition of the
chlorofluorocarbon CFC-12 (CCl2F2). While the mixing ratio
measurements compare favorably to other firn air studies, the isotope
results show extreme 13C depletion at the deepest measurable depth (65 m),
to values lower than δ13C = −80‰ vs.
VPDB (the international stable carbon isotope scale), compared to present
day surface tropospheric measurements near −40‰. Firn
air modeling was used to interpret these measurements. Reconstructed
atmospheric time series indicate even larger depletions (to −120‰) near 1950 AD, with subsequent rapid enrichment of
the atmospheric reservoir of the compound to the present day value.
Mass-balance calculations show that this change is likely to have been
caused by a large change in the isotopic composition of anthropogenic CFC-12
emissions, probably due to technological advances in the CFC production
process over the last 80 yr, though direct evidence is lacking. |
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