Reference : Shift in the chemical composition of dissolved organic matter in the Congo River network
Scientific journals : Article
Life sciences : Aquatic sciences & oceanology
http://hdl.handle.net/2268/202087
Shift in the chemical composition of dissolved organic matter in the Congo River network
English
Lambert, Thibault mailto [Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Chemical Oceanography Unit (AGO) >]
Bouillon, S. [> >]
Darchambeau, François mailto [Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Chemical Oceanography Unit (AGO) >]
Massicotte, P. [> >]
Borges, Alberto mailto [Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Chemical Oceanography Unit (AGO) >]
28-Sep-2016
Biogeosciences
European Geosciences Union
13
18
5405-5420
Yes (verified by ORBi)
International
1726-4170
1726-4189
Katlenburg-Lindau
Germany
[en] The processing of terrestrially derived dissolved organic matter (DOM) during downstream transport in fluvial networks is poorly understood. Here, we report a dataset of dissolved organic carbon (DOC) concentrations and DOM composition (stable carbon isotope ratios, absorption and fluorescence properties) acquired along a 1700 km transect in the middle reach of the Congo River Basin. Samples were collected in the mainstem and its tributaries during high water (HW) and falling water (FW) periods. DOC concentrations and DOM composition along the mainstem were found to differ between the two periods, because of a reduced lateral mixing between the central water masses of the Congo River and DOM-rich waters from tributaries and also likely because of a greater photodegradation during FW as water residence time (WRT) increased. Although the Cuvette Centrale wetland (one of the world’s largest flooded forest) continuously releases highly aromatic DOM in streams and rivers of the Congo Basin, the downstream transport of DOM was found to result in an along stream gradient from aromatic to aliphatic compounds. The characterization of DOM through parallel factor analysis (PARAFAC) suggests that this transition results from (1) the losses of aromatic compounds by photodegradation and (2) the production of aliphatic compounds by biological reworking of terrestrial DOM. Finally, this study highlights the critical importance of the river-floodplain connectivity in tropical rivers in controlling DOM biogeochemistry at large spatial scale and suggests that the degree of DOM processing during downstream transport is a function of landscape characteristics and WRT
Freshwater and OCeanic science Unit of reSearch - FOCUS
Researchers ; Professionals ; Students
http://hdl.handle.net/2268/202087
10.5194/bg-13-5405-2016
http://www.biogeosciences.net/13/5405/2016/
FP7 ; 240002 - AFRIVAL - African river basins: catchment-scale carbon fluxes and transformations.

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