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| Titel |
Sulfur isotopic analysis of carbonyl sulfide and its application for biogeochemical cycles |
| VerfasserIn |
Shohei Hattori, Kazuki Kamezaki, Takahiro Ogawa, Sakae Toyoda, Yoko Katayama, Naohiro Yoshida |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250123082
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| Publikation (Nr.) |
 EGU/EGU2016-2270.pdf |
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| Zusammenfassung |
| Carbonyl sulfide (OCS or COS) is the most abundant gas containing sulfur in the
atmosphere, with an average mixing ratio of 500 p.p.t.v. in the troposphere. OCS is
suggested as a sulfur source of the stratospheric sulfate aerosols (SSA) which plays an
important role in Earth’s radiation budget and ozone depletion. Therefore, OCS budget
should be validated for prediction of climate change, but the global OCS budget is
imbalance.
Recently we developed a promising new analytical method for measuring the stable sulfur
isotopic compositions of OCS using nanomole level samples: the direct isotopic analytical
technique of on-line gas chromatography-isotope ratio mass spectrometry (GC-IRMS) using
fragmentation ions S+ (Hattori et al., 2015). The first measurement of the δ34S value for
atmospheric OCS coupled with isotopic fractionation for OCS sink reactions in the
stratosphere (Hattori et al., 2011; Schmidt et al., 2012; Hattori et al., 2012) explains the
reported δ34S value for background stratospheric sulfate, suggesting that OCS is a potentially
important source for background (nonepisodic or nonvolcanic) stratospheric sulfate
aerosols.
This new method measuring δ34S values of OCS can be used to investigate
OCS sources and sinks in the troposphere to better understand its cycle. It is known
that some microorganisms in soil can degrade OCS, but the mechanism and the
contribution to the OCS in the air are still uncertain. In order to determine sulfur
isotopic enrichment factor of OCS during degradation via microorganisms, incubation
experiments were conducted using strains belonging to the genera Mycobacterium,
Williamsia and Cupriavidus, isolated from natural soil environments (Kato et al.,
2008). As a result, sulfur isotope ratios of OCS were increased during degradation of
OCS, indicating that reaction for OC32S is faster than that for OC33S and OC34S.
OCS degradation via microorganisms is not mass-independent fractionation (MIF)
process, suggesting that this reaction does not contribute to the MIF signatures
observed in sulfate aerosol samples and/or Archaean rock records. At the presentation,
we report the comparison of 34ɛ values determined using some strains and the
atmospheric implications for the OCS degradation in the present atmosphere are
discussed.
Hattori, S., Danielache, S. O., Johnson, M. S., Schmidt, J. A., Kjaergaard, H. G.,
Toyoda, S., Ueno, Y., Yoshida, N. Ultraviolet absorption cross sections of carbonyl
sulfide isotopologues OC32S, OC33S, OC34S and O13CS: isotopic fractionation in
photolysis and atmospheric implications, Atmos. Chem. Phys., 11, 10293-10303,
2011.
Schmidt, J. A., Johnson, M. S., Jung, Y., Danielache, S. O., Hattori, S., Yoshida, N.,
Predictions of the sulfur and carbon kinetic isotope effects in the OH + OCS reaction, Chem.
Phys. Lett., 531, 64-69, 2012.
Hattori, S., Schmidt J. A., Mahler D., Danielache, S. O., Johnson M. S., Yoshida N.
Isotope Effect in the Carbonyl Sulfide Reaction with O(3P), J. Phys. Chem. A, 116,
3521-3526, 2012.
Hattori, S., Toyoda, A., Toyoda, S., Ishino S., Ueno, Y., Yoshida, N.: Determination of the
Sulfur Isotope Ratio in Carbonyl Sulfide using Gas Chromatography/Isotope Ratio Mass
Spectrometry on Fragment Ions 32S+, 33S+, and 34S+, Anal. Chem., 87, 477-484,
2015.
Kato, H., Saito, M., Nagahata, Y., Katayama, Y.: Degradation of ambient carbonyl sulfide
by Mycobacterium spp. in soil. Microbiol., 154(1), 249-255, 2008. |
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