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| Titel |
Climatic and geomorphic controls on the erosion of biomass from subtropical mountain forest |
| VerfasserIn |
R. G. Hilton, A. Galy, N. Hovius, S. J. Kao, M. J. Horng, H. Chen |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250062498
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| Zusammenfassung |
| Erosion of particulate organic carbon (POC) occurs at very high rates in mountain river
catchments, yet the proportion derived recently from atmospheric CO2 in the terrestrial
biosphere (POCbiomass) remains poorly constrained. Here we examine the fluvial transport of
suspended POCbiomass in mountain rivers of Taiwan and investigate the climatic and
geomorphic controls on the rates of transfer. In 11 study catchments we combined previous
geochemical quantification of POC source (accounting for fossil POC from bedrock), with
hydrometric measurements of water discharge (Qw) and suspended sediment load over
2 years. POCbiomassconcentration (mg L-1) was positively correlated with Qw,
with no dilution at high flow. This climatic control on POCbiomass transport was
moderated by catchment geomorphology: the gradient of a linear trend between
POCbiomass concentration and normalised Qw increased as the proportion of steep
hillslopes (> 35Ë ) in the catchment increased. This is likely to reflect enhanced
supply of POCbiomass by erosion processes which act efficiently on the steepest
sections of forest. Across Taiwan, POCbiomass yield was correlated with suspended
sediment yield. This export of POCbiomass imparts an upper bound on the residence
time of carbon in the biosphere, of on average ~800 yr. Over longer time periods,
POCbiomass transferred with large amounts of clastic sediment can contribute to
atmospheric CO2 sequestration through burial in marine sediments. Our results
show that this carbon transfer should be enhanced in a wetter and stormier climate,
and that the rates are moderated on geological timescales by regional tectonics. |
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