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| Titel |
Isotopic signatures of production and uptake of H2 by soil |
| VerfasserIn |
Q. Chen, M. E. Popa, A. M. Batenburg, T. Röckmann |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 22 ; Nr. 15, no. 22 (2015-11-24), S.13003-13021 |
| Datensatznummer |
250120180
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| Publikation (Nr.) |
 copernicus.org/acp-15-13003-2015.pdf |
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| Zusammenfassung |
| Molecular hydrogen (H2) is the second most abundant reduced
trace gas (after methane) in the atmosphere, but its biogeochemical cycle is
not well understood. Our study focuses on the soil production and uptake of
H2 and the associated isotope effects. Air samples from a grass field
and a forest site in the Netherlands were collected using soil chambers. The
results show that uptake and emission of H2 occurred simultaneously at
all sampling sites, with strongest emission at the grassland sites where
clover (N2 fixing legume) was present. The H2 mole fraction and
deuterium content were measured in the laboratory to determine the isotopic
fractionation factor during H2 soil uptake (αsoil) and the
isotopic signature of H2 that is simultaneously emitted from the soil
(δDsoil). By considering all net-uptake experiments, an overall
fractionation factor for deposition of αsoil = kHD / kHH = 0.945 ± 0.004
(95 % CI) was obtained. The difference in
mean αsoil between the forest soil 0.937 ± 0.008 and the
grassland 0.951 ± 0.026 is not statistically significant. For two
experiments, the removal of soil cover increased the deposition velocity
(vd) and αsoil simultaneously, but a general positive
correlation between vd and αsoil was not found in this
study. When the data are evaluated with a model of simultaneous production
and uptake, the isotopic composition of H2 that is emitted at the
grassland site is calculated as δDsoil = (−530 ± 40) ‰.
This is less deuterium depleted than what is
expected from isotope equilibrium between H2O and H2. |
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