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| Titel |
Spatial and temporal patterns of dissolved organic matter optical properties across large rivers in Africa |
| VerfasserIn |
Thibault Lambert, François Darchambeau, Alberto Vieira Borges, Bassirou Alhou, Jean-Daniel Mbega, Cristian Teodoru, Trent Richard Marwick, Steven Bouillon |
| 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 |
250092473
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| Publikation (Nr.) |
 EGU/EGU2014-6823.pdf |
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| Zusammenfassung |
| Tropical rivers have disproportionally high carbon transport and outgassing compared to
temperate and Arctic rivers. Yet the cycling of dissolved organic matter (DOM) within
these systems is still poorly studied with the exception of the Amazon basin. The
chromophoric or colored dissolved organic matter (CDOM) is the fraction of DOM that
absorbs ultraviolet and visible light. As the biochemical nature of DOM (and CDOM)
defines its optical properties, optical measurements are particularly useful to assess
the composition of DOM in freshwater and hence can be applied as proxies for
assessments of DOM sources and its biogeochemical role. However, less is known on how
specific optical characteristics can be applied as proxies and how these proxies
vary from one system to another. In this study we compared concentrations and
stable isotopic signature of dissolved organic carbon with optical properties of
DOM from diverse tropical river systems across the African continent including the
Congo basin, the Zambezi basin, the Ogooué basin and the Niger basin. These major
rivers of the African continent were monitored for long period (from 1-3 years) at
biweekly frequency. This large dataset allowed us to compare the spatial and temporal
patterns of DOM quality along various environmental gradients, including hydrology,
river size, terrestrial vegetation and connectivity to terrestrial inputs.The optical
proxies presented and discussed in this study include absorption coefficients a(λ) at
different wavelength (254, 300, 350 and 440 nm), spectral slopes (S275-295and
S350-400), the spectral slope ratio (SR=S275-295:S350-400) and the a(250):a(365) ratio. |
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