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| Titel |
Soil redistribution and weathering controlling the fate of geochemical and physical carbon stabilization mechanisms in soils of an eroding landscape |
| VerfasserIn |
S. Doetterl, J.-T. Cornelis, J. Six, S. Bodé, S. Opfergelt, P. Boeckx, K. Van Oost |
| 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 ; 12, no. 5 ; Nr. 12, no. 5 (2015-03-04), S.1357-1371 |
| Datensatznummer |
250117841
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| Publikation (Nr.) |
 copernicus.org/bg-12-1357-2015.pdf |
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| Zusammenfassung |
| The role of eroding landscapes in organic carbon stabilization operating as
C sinks or sources has been frequently discussed, but the underlying
mechanisms are not fully understood. Our analysis aims to clarify the
effects of soil redistribution on physical and biogeochemical soil organic
carbon (SOC) stabilization mechanisms along a hillslope transect. The
observed mineralogical differences seem partly responsible for the
effectiveness of geochemical and physical SOC stabilization mechanisms as
the mineral environment along the transect is highly variable and dynamic.
The abundance of primary and secondary minerals and the weathering status of
the investigated soils differ drastically along this transect. Extractable
iron and aluminum components are generally abundant in aggregates, but show no
strong correlation to SOC, indicating their importance for aggregate
stability but not for SOC retention. We further show that pyrophosphate
extractable soil components, especially manganese, play a role in
stabilizing SOC within non-aggregated mineral fractions. The abundance of
microbial residues and measured 14C ages for aggregated and
non-aggregated SOC fractions demonstrate the importance of the combined
effect of geochemical and physical protection to stabilize SOC after burial
at the depositional site. Mineral alteration and the breakdown of aggregates
limit the protection of C by minerals and within aggregates temporally. The
14C ages of buried soil indicate that C in aggregated fractions seems to
be preserved more efficiently while C in non-aggregated fractions is
released, allowing a re-sequestration of younger C with this fraction. Old
14C ages and at the same time high contents of microbial residues in
aggregates suggest either that microorganisms feed on old carbon to build up
microbial biomass or that these environments consisting of considerable
amounts of old C are proper habitats for microorganisms and preserve their
residues. Due to continuous soil weathering and, hence, weakening of
protection mechanisms, a potential C sink through soil burial is finally
temporally limited. |
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