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| Titel |
The age of river-transported carbon: new data from African catchments and a global perspective. |
| VerfasserIn |
Trent R. Marwick, Fredrick Tamooh, Cristian Teodoru, Alberto V. Borges, François Darchambeau, 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 |
250087465
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| Publikation (Nr.) |
 EGU/EGU2014-1515.pdf |
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| Zusammenfassung |
| The role played by river networks in regional and global carbon (C) budgets is receiving
increasing attention. Despite the potential of radiocarbon measurements (Δ14C) to elucidate
sources and cycling of different riverine C pools, there remain large regions from which
little or no data are available. Also, there have been no comprehensive attempts to
synthesize the available information and examine global patterns in the 14C content of
these organic and inorganic riverine C pools. Here, we present new 14C data on
dissolved (n = 25) and particulate (n = 67) organic C from six river basins in tropical
and subtropical Africa, and also compile >1000 literature 14C data and ancillary
parameters from rivers globally. Across the African basins, the new riverine data span
a Δ14C range of -126oto 155o(average Δ14C of 67 ± 51 o) and -869 oto
93o(average 14C of -60 ± 158o) for DOC and POC, respectively. These C radioisotope
signatures represent radiocarbon ages of approximately 1000 BP to modern (post-1950)
for DOC and approximately 16000 BP to modern for POC. Our data show that,
excluding freshwaters strongly perturbed by anthropogenic practices, the DOC fraction
exported by African rivers is always dominated by modern carbon. Globally, a
consistent pattern emerges of older C in systems carrying high loads of organically poor
sediments. In contrast to oceanic environments, riverine DOC is typically (>90%) more
recent in origin than POC. While our analysis does not allow to directly assess the
(controversial) importance of ancient C supporting bacterial respiration in river
systems, the distribution of Δ14C data for dissolved inorganic C (DIC) favors the
hypothesis that, in most cases, more recent organic C is preferentially mineralized. |
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