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| Titel |
A novel source of atmospheric H2: abiotic degradation of organic material |
| VerfasserIn |
H. Lee, T. Rahn, H. L. Throop |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 9, no. 11 ; Nr. 9, no. 11 (2012-11-12), S.4411-4419 |
| Datensatznummer |
250007385
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| Publikation (Nr.) |
 copernicus.org/bg-9-4411-2012.pdf |
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| Zusammenfassung |
| Molecular hydrogen (H2) plays an important role in atmospheric
chemistry by competing for reactions with the hydroxyl radical (OH·) and
contributing to the production of H2O in the stratosphere, indirectly
influencing stratospheric ozone concentrations. The dominant pathway for
loss of H2 from the atmosphere is via microbially-mediated soil uptake,
although the magnitude of this loss is still regarded as highly uncertain.
Recent studies have shown that abiotic processes such as photochemically
mediated degradation (photodegradation) of organic material result in direct
emissions of carbon (C) and nitrogen (N)-based trace gases as well as
H2. This H2 production has important implications on source-sink
dynamics of H2 at the soil-atmosphere interface and thus it is
important to quantify its variability over a range of plant types and
materials. Here, we show laboratory observations of H2 production and
its temperature dependence during abiotic degradation of four plant litter
types as well as pure cellulose and high lignin content woody material. A
greater amount of H2 was produced in the absence of solar radiation
than from photodegradation alone, verifying that low temperature thermal
degradation of plant litter is a source of H2. In addition, we measured
a significant release of H2 both in the presence and absence of
O2. Our results suggest that abiotic release of H2 during organic
matter degradation is ubiquitous in arid ecosystems and may also occur in
other terrestrial ecosystems. We propose that because these processes occur
at the soil-atmosphere interface, they provide a previously unrecognized
proximal source of H2 for microbial uptake and confound interpretation
of direct measurements of atmospheric uptake that are important for
constraining the global H2 budget. |
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