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| Titel |
Novel instrumentation for direct measurements of site-specific isotopic nitrogen and isotopic oxygen in ambient nitrous oxide |
| VerfasserIn |
F. Dong, D. Baer, T. Owano, M. Gupta, R. Provencal |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250070682
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| Zusammenfassung |
| The stable isotope composition of atmosphere trace gases provides information of their origin
and fate that cannot be determined from their mole fraction measurements alone. Biological
source and loss processes, like bacterial production of N2O, are typically accompanied by
isotopic selectivity associated with the kinetics of bond formation and destruction. Due to the
relatively low N2O concentration in ambient air, of the three major biologically mediated
greenhouse gases (CO2, CH4 and N2O), the understanding of N2O isotopic budget lags
behind the other gases.
We report on the development of novel instrumentation for real-time measurements of
site-specific isotopic nitrogen and of isotopic oxygen (δ15Na, δ15Nb, δ15N, δ18O) and mole
fraction [N2O] of nitrous oxide over a wide range of mixing ratios. This novel
technology, which employs cavity enhanced absorption and a mid-infrared tunable
quantum cascade laser and does not require any cryogenic components, has been
developed for in situ simultaneous measurements of the mole fractions of main
isotopomers – 14N14N16O, 15N14N16O, 14N15N16O and 14N14N18O, which leads to the
nitrogen-isotope ratio (δ15N) and the 15N site-specific enrichment. A precision of better
than 1 per mil may be achieved in ambient air (with 320 ppb N2O) in less than
100 seconds measurement time. For higher mole fractions, which may be obtained
using preconcentration, better precision (approaching 0.1 per mil) may be achieved.
Further details on the operation and performance of the instrument will be presented. |
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