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| Titel |
H2S interference on CO2 isotopic measurements using a Picarro G1101-i cavity ring-down spectrometer |
| VerfasserIn |
K. Malowany, J. Stix, A. Van Pelt, G. Lucic |
| 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 ; 8, no. 10 ; Nr. 8, no. 10 (2015-10-06), S.4075-4082 |
| Datensatznummer |
250116625
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| Publikation (Nr.) |
 copernicus.org/amt-8-4075-2015.pdf |
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| Zusammenfassung |
| Cavity ring-down spectrometers (CRDSs) have the capacity to make isotopic
measurements of CO2 where concentrations range from atmospheric
(~ 400 ppm) to 6000 ppm. Following field trials, it has come
to light that the spectrographic lines used for CO2 have an
interference with elevated (higher than ambient) amounts of hydrogen sulfide
(H2S), which causes significant depletions in the δ13C
measurement by the CRDSs. In order to deploy this instrument in environments
with elevated H2S concentrations (i.e., active volcanoes), we require a
robust method for eliminating this interference. Controlled experiments
using a Picarro G1101-i optical spectrometer were done to characterize the
H2S interference at varying CO2 and H2S concentrations. The
addition of H2S to a CO2 standard gas reveals an increase in the
12CO2 concentration and a more significant decrease in the
13CO2 concentration, resulting in a depleted δ13C
value. Reacting gas samples containing H2S with copper prior to
analysis can eliminate this effect. Models post-dating the G1101-i carbon
isotope analyzer have maintained the same spectral lines for CO2 and
are likely to have a similar H2S response at elevated H2S
concentrations. It is important for future work with CRDS, particularly in
volcanic regions where H2S is abundant, to be aware of the H2S
interference on the CO2 spectroscopic lines and to remove all H2S
prior to analysis. We suggest employing a scrub composed of copper to remove
H2S from all gas samples that have concentrations in excess of 1 ppb. |
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