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| Titel |
Composition changes of eroded carbon at different spatial scales in a tropical watershed suggest enrichment of degraded material during transport |
| VerfasserIn |
C. Rumpel, V. Chaplot, P. Ciais, A. Chabbi, B. Bouahom, C. Valentin |
| 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 ; 11, no. 12 ; Nr. 11, no. 12 (2014-06-20), S.3299-3305 |
| Datensatznummer |
250117474
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| Publikation (Nr.) |
 copernicus.org/bg-11-3299-2014.pdf |
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| Zusammenfassung |
| In order to assess whether eroded carbon is a net source or sink of
atmospheric CO2, characterisation of the chemical composition and
residence time of eroded organic matter (EOM) at the landscape level is
needed. This information is crucial to evaluate (1) how fast EOM can be
decomposed by soil microbes during its lateral transport and (2) its impact
at deposition sites. This study considers a continuum of scales to measure
the composition of EOM across a steep hillslope landscape of the Mekong basin
with intense erosion. We sampled suspended sediments eroded during rainfall
events from runoff plots (1 and 2.5 m2) and the outlets of four nested
watersheds (0.6 × 104 to 1 × 107 m2). Here
we show that changes in the chemical composition of EOM (measured by nuclear magnetic resonance
spectroscopy) and in its 13C and 15N isotope composition from plot
scale through to landscape scale provide consistent evidence for enrichment
of more decomposed EOM across distances of 10 km. Between individual soil
units (1 m2) to a small watershed (107 m2), the observed
28% decrease of the C/N ratio, the enrichment of 13C and
15N isotopes as well as O-alkyl C in EOM is of similar magnitude as
changes recorded with depth in soil profiles due to soil organic matter
"vertical" decomposition. Radiocarbon measurements indicated ageing of EOM
from the plot to the watershed scale. Therefore transport of EOM may lead to
enrichment of stabilised soil organic matter compounds, eventually being subject to export
from the watershed. |
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