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| Titel |
Control of the extraction procedures on the response of DOC concentration and composition to soil temperature increase |
| VerfasserIn |
Thibault Lambert, Anne-Catherine Pierson-Wickmann, Gérard Gruau, Anne Jaffrezic, Laurent Jeanneau, Armelle Racape |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250094728
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| Publikation (Nr.) |
 EGU/EGU2014-10159.pdf |
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| Zusammenfassung |
| Dissolved organic carbon (DOC) leached from soils is a crucial component of the terrestrial
C cycling and a major source for DOC export at the landscape scale by stream and river
waters. In the context of global warming, it is necessary to understand how changes in soil
temperature will impact the DOC dynamic in soils, but this remains a matter of debate. We
conducted a series of experiments in order to study both biological and physical processes
involved in soil DOC production and mobilisation at different temperatures. Two
experiments of DOC extraction were conducted at different temperatures: (i) soil solution
percolation through a soil column and (ii) soil solution agitation in jars, which are both
commonly used in the literature. The organo-mineral horizon of a wetland soil was
incubated during 14 days at temperature ranging from 4 to 30 °C. Along with DOC
concentrations, changes in DOC composition were assessed by monitoring the
natural stable carbon isotopic composition of (δ13C) and the specific ultra violet
absorbance (SUVA) of DOC. The results showed strong differences between the
two extraction procedures in term of DOC response to temperature rise, both in
concentration and composition. DOC released by percolation through soil column
displayed a strong concentration increase with increasing temperature. Whatever the
temperature, a low SUVA and relatively high δ13C values indicated a release of
molecules with lower aromaticity and lower molecular weight the two first days than
after. On the contrary, DOC extracted by agitation in jars showed minor changes in
both concentrations and composition along the incubation. The difference observed
between soil leaching and batch incubation can mainly be explained by the extraction
procedures. Indeed, the percolation procedure favors transfer from the micro-porosity
to the macro-porosity pool between two successive leaching, whereas agitation
procedure releases DOC produced and accumulated in the whole soil. Furthermore,
agitation extraction leads to the disruption of soil micro-aggregates, resulting in
the mobilisation of organic carbon that was not previously in the dissolved phase
and forcing the mobilisation of the immobile DOC pool (micro-porosity), whereas
percolation only mobilised the mobile DOC pool located in the soil macro-porosity. |
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