[en] The Oubangui is a major tributary of the Congo River. We describe the biogeochemistry of contrasting tributaries within its central catchment, with watershed vegetation ranging from wooded savannahs to humid rainforest. Compared to a 2-year monitoring record on the mainstem Oubangui, these tributaries show a wide range of biogeochemical signatures, from highly diluted blackwaters (low turbidity, pH, conductivity, and total alkalinity) in rainforests to those more typical for savannah systems. Spectral analyses of chromophoric dissolved organic matter showed wide temporal variations in the Oubangui compared to spatio-temporal variations in the tributaries, and confirm that different pools of dissolved organic carbon are mobilized during different hydrological stages. d13C of dissolved inorganic carbon ranged between -28.1 per mil and -25.8 per mil, and was strongly correlated to both partial pressure of CO2 and to the estimated contribution of carbonate weathering to total alkalinity, suggesting an important control of the weathering regime on CO2 fluxes. All tributaries were oversaturated in dissolved greenhouse gases (CH4, N2O, CO2), with highest levels in rivers draining rainforest. The high diversity observed underscores the importance of sampling that covers the variability in subcatchment characteristics, to improve our understanding of biogeochemical cycling in the Congo Basin.
Disciplines :
Earth sciences & physical geography
Author, co-author :
Bouillon, Steven
Yambélé, Athanase
Gillikin, David P.
Teodoru, Cristian
Darchambeau, François ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Lambert, Thibault
Borges, Alberto ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Language :
English
Title :
Contrasting biogeochemical characteristics of the Oubangui River and tributaries (Congo River basin)
Publication date :
2014
Journal title :
Scientific Reports
eISSN :
2045-2322
Publisher :
Nature Publishing Group, London, United Kingdom
Volume :
4
Issue :
5402
Pages :
1-10
Peer reviewed :
Peer Reviewed verified by ORBi
European Projects :
FP7 - 240002 - AFRIVAL - African river basins: catchment-scale carbon fluxes and transformations.
Name of the research project :
AFRIVAL: ‘‘African river basins: catchment-scale carbon fluxes and transformations’’
Funders :
CER - Conseil Européen de la Recherche [BE] CE - Commission Européenne [BE]
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