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| Titel |
A sublimation technique for high-precision measurements of δ¹³CO2 and mixing ratios of CO2 and N2O from air trapped in ice cores |
| VerfasserIn |
J. Schmitt, R. Schneider, H. Fischer |
| 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. 7 ; Nr. 4, no. 7 (2011-07-19), S.1445-1461 |
| Datensatznummer |
250002055
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| Publikation (Nr.) |
 copernicus.org/amt-4-1445-2011.pdf |
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| Zusammenfassung |
| In order to provide high precision stable carbon isotope ratios (δ13CO2
or δ13C of CO2) from small bubbly,
partially and fully clathrated ice core samples we developed a new method
based on sublimation coupled to gas chromatography-isotope ratio mass
spectrometry (GC-IRMS). In a first step the trapped air is quantitatively
released from ~30 g of ice and CO2 together with N2O are
separated from the bulk air components and stored in a miniature glass tube.
In an off-line step, the extracted sample is introduced into a helium
carrier flow using a minimised tube cracker device. Prior to measurement,
N2O and organic sample contaminants are gas chromatographically
separated from CO2. Pulses of a CO2/N2O mixture are admitted
to the tube cracker and follow the path of the sample through the system.
This allows an identical treatment and comparison of sample and standard
peaks. The ability of the method to reproduce δ13C from bubble
and clathrate ice is verified on different ice cores. We achieve
reproducibilities for bubble ice between 0.05 ‰ and 0.07 ‰ and for clathrate
ice between 0.05 ‰ and 0.09 ‰ (dependent on the ice core used). A comparison
of our data with measurements on bubble ice from the same ice core but using
a mechanical extraction device shows no significant systematic offset. In
addition to δ13C, the CO2 and N2O mixing ratios can
be volumetrically derived with a precision of 2 ppmv and 8 ppbv,
respectively. |
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