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| Titel |
First measurements of continuous δ¹⁸O-CO2 with a Fourier Transform InfraRed spectrometer in Heidelberg, Germany |
| VerfasserIn |
Sanam Noreen Vardag, Samuel Hammer, David Griffith, Ingeborg Levin |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250095574
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| Publikation (Nr.) |
 EGU/EGU2014-11034.pdf |
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| Zusammenfassung |
| Continuous in-situ measurements of δ13C and δ18O in atmospheric CO2 open the door to
differentiating between different CO2 source and sink components with high temporal
resolution. Until now only few instruments have been able to provide a continuous
measurement of the oxygen isotope ratio in CO2. The Fourier Transform InfraRed (FTIR)
spectrometer measures both the 13C/12C and 18O/16O ratios of CO2, but the precision and
accuracy of the δ18O-CO2 measurements have not yet been evaluated. Here we
present a first analysis of δ18O-CO2 measurements with an FTIR trace gas and
isotope analyser in Heidelberg. We find that the spectrometer resolves 18O in CO2
with a reproducibility of better than δ18O= ± 0.3 oas determined from target gas
measurements over a period of ten months. An Allan variance test shows that the δ18O
repeatability reaches 0.1 ofor hourly means. The compatibility of the spectroscopic
measurements was determined by comparing FTIR measurements of δ18O of ambient air
to the mass-spectrometric measurements on flask samples episodically collected
over two diurnal cycles (events). A compatibility of better than ± 0.1 ofor δ18O
was found during these comparisons. Even though the FTIR precision does not
reach that of isotope ratio mass spectrometry, a number of interesting scientific
applications seem possible. In particular, investigation of processes that govern the δ18O
variability of atmospheric CO2 on the regional scale seem very promising. Two
episodes of recent ambient air measurements in Heidelberg, one in winter and one in
summer, illustrate how high resolution regional δ18O and δ13C records may provide
a better understanding of the regional scale processes leading atmospheric CO2
variability. However, quantitative analysis requires comprehensive knowledge on the
isotopic signature of different CO2 sources and sinks as well as the influencing water
reservoirs, which may largely govern the δ18O-CO2 variability during summer. |
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