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| Titel |
Deuterium content of H2 measured on air samples from the CARIBIC project |
| VerfasserIn |
A. M. Batenburg, T. Schuck, C. A. M. Brenninkmeijer, T. Röckmann |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250025895
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| Zusammenfassung |
| H2 is present in the atmosphere at levels of ~500 ppb; its largest sources are the oxidation of
methane and other hydrocarbons and combustion processes. In the coming decades, H2
levels are expected to rise due to use of hydrogen as an energy carrier. This may
affect methane lifetimes and stratospheric ozone depletion. Unfortunately, large
uncertainties still exist in the global H2budget. The different sources and sinks of H2 have
very distinct isotopic signatures and fractionation coefficients, respectively. For
this reason, measurements of isotopic composition are a promising tool to gain
insight into H2 source and sink processes and to constrain the terms in the global
budget.
The CARIBIC project uses an automated instrument container on board of a commercial
passenger aircraft to carry out in situ measurements of trace gases and aerosols and to collect
air samples. The use of a commercial airliner results in samples mostly from the Upper
Troposphere-Lower Stratosphere (UTLS) region. Although the UTLS region is considered to
be an interesting part of the atmosphere, relatively few measurements have been made there
before. The CARIBIC samples are routinely analyzed for various gases, including four
important greenhouse gases.
In addition, air samples of 15 CARIBIC flights have now been analyzed for molecular
hydrogen concentration (H2) and H2 deuterium content (δD-H2) in the isotope laboratory of
the Institute of Marine and Atmospheric Research Utrecht (IMAU). A GC-IRMS system
(similar to Rhee et al. [2004]) is used to determine the concentration and deuterium content of
atmospheric H2 precisely and routinely. This poster will present a selection of the first
results.
For some flights, samples close to the takeoff and landing region show strong
contamination signatures (high H2 concentrations and low δD-H2 values). With the exclusion
of these samples, δD values correlate negatively with methane concentration, as
observed previously by Rahn et al. [2003] and Röckmann et al. [2003]. Samples
from the stratosphere tend to have lower methane concentrations and higher δD-H2
values.
References
Rhee, T.S., J. Mak, T. Röckmann, and C.A.M. Brenninkmeijer (2004), Continuous-flow
isotope analysis of the deuterium/hydrogen ratio in atmospheric hydrogen, Rapid Commun.
Mass Spectrom., 18, 299-306
Rahn, T., J.M. Eiler, K.A. Boering, P.O. Wennberg, M.C. McCarthy, S. Tyler,
S. Schauffler, S. Donnelly, and E. Atlas (2003), Extreme deuterium enrichment
in stratospheric hydrogen and the global atmospheric budget of H2, Nature, 424,
918-921
Röckmann, T., T.S. Rhee, and A. Engel (2003), Heavy hydrogen in the stratosphere,
Atmos. Chem. Phys., 3, 2015-2023
http://www.caribic-atmospheric.com |
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