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| Titel |
Oxygen isotopic signature of CO2 from combustion processes |
| VerfasserIn |
M. Schumacher, R. A. Werner, H. A. J. Meijer, H. G. Jansen, W. A. Brand, H. Geilmann, R. E. M. Neubert |
| 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 ; 11, no. 4 ; Nr. 11, no. 4 (2011-02-16), S.1473-1490 |
| Datensatznummer |
250009359
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| Publikation (Nr.) |
 copernicus.org/acp-11-1473-2011.pdf |
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| Zusammenfassung |
For a comprehensive understanding of the global carbon cycle precise
knowledge of all processes is necessary. Stable isotope (13C and
18O) abundances provide information for the qualification and the
quantification of the diverse source and sink processes. This study focuses
on the δ18O signature of CO2 from combustion processes,
which are widely present both naturally (wild fires), and human induced
(fossil fuel combustion, biomass burning) in the carbon cycle. All these
combustion processes use atmospheric oxygen, of which the isotopic signature
is assumed to be constant with time throughout the whole atmosphere. The
combustion is generally presumed to take place at high temperatures, thus
minimizing isotopic fractionation. Therefore it is generally supposed that
the 18O signature of the produced CO2 is equal to that of the
atmospheric oxygen. This study, however, reveals that the situation is much
more complicated and that important fractionation effects do occur. From
laboratory studies fractionation effects on the order of up to 26%permil; became
obvious in the derived CO2 from combustion of different kinds of
material, a clear differentiation of about 7‰ was also found in car exhausts
which were sampled directly under ambient atmospheric conditions.
We investigated a wide range of materials (both different raw materials and
similar materials with different inherent 18O signature), sample
geometries (e.g. texture and surface-volume ratios) and combustion
circumstances. We found that the main factor influencing the specific
isotopic signatures of the combustion-derived CO2 and of the
concomitantly released oxygen-containing side products, is the case-specific
rate of combustion. This points firmly into the direction of (diffusive)
transport of oxygen to the reaction zone as the cause of the isotope
fractionation. The original total 18O signature of the material
appeared to have little influence, however, a contribution of specific
bio-chemical compounds to individual combustion products released from the
involved material became obvious. |
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