Sediment and carbon fluxes along a longitudinal gradient in the lower Tana River (Kenya)
Tamooh, F.; Meysman, F.; Borges, A.V.; Marwick, T.R.; van den Meersche, K.; Dehairs, F.; Merckx, R.; Bouillon, S. (2014). Sediment and carbon fluxes along a longitudinal gradient in the lower Tana River (Kenya). J. Geophys. Res. Biogeosciences 119(7): 1340-1353. http://dx.doi.org/10.1002/2013JG002358
In: Journal of Geophysical Research. American Geophysical Union: Richmond. ISSN 0148-0227; e-ISSN 2156-2202, meer
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| Auteurs | | Top |
- Tamooh, F.
- Meysman, F., meer
- Borges, A.V.
- Marwick, T.R.
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- van den Meersche, K., meer
- Dehairs, F., meer
- Merckx, R.
- Bouillon, S.
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| Abstract |
We estimated annual fluxes of suspended matter and different carbon (C) pools at three sitesalong the lower Tana River (Kenya), based on monthly sampling between January 2009 and December2011. Concentrations of total suspended matter (TSM), particulate organic carbon (POC), dissolved organiccarbon (DOC), and dissolved inorganic carbon (DIC) were monitored, as was the stable isotope compositionof the carbon pools. Both TSM and POC concentrations showed strong seasonality, varying over severalorders of magnitude, while DOC and DIC concentrations showed no seasonal variations. A strong shift in theorigin of POC was observed, which was dominated by C3-derived C during dry conditions (low d13CPOCbetween ?28‰and ?25‰), but had significant C4 contributions during high-flow events (d13CPOC up to?19.5‰). Between Garissa and the most downstream sampling point, a clear decrease in suspended matterand organic C fluxes was observed, being most pronounced during high-discharge conditions: on anannual basis, fluxes of TSM, POC, and DIC decreased by 34% to 65% for the 3 year study period. Our resultssuggest that floodplains along the lower Tana River could play an important role in regulating the transportof suspended matter and organic C. A comparison of current flux estimates with data collected prior tothe construction of several hydropower dams reveals that the sediment loading is reduced during lowdischarge conditions. |
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