Divergent biophysical controls of aquatic CO2 and CH4 in the World's two largest rivers.
Carbon emissions to the atmosphere from inland waters are globally significant and mainly occur at tropical latitudes. However, processes controlling the intensity of CO2 and CH4 emissions from tropical inland waters remain poorly understood. Here, we report a data-set of concurrent measurements of the partial pressure of CO2 (pCO2) and dissolved CH4 concentrations in the Amazon (n = 136) and the Congo (n = 280) Rivers. The pCO2 values in the Amazon mainstem were significantly higher than in the Congo, contrasting with CH4 concentrations that were higher in the Congo than in the Amazon. Large-scale patterns in pCO2 across different lowland tropical basins can be apprehended with a relatively simple statistical model related to the extent of wetlands within the basin, showing that, in addition to non-flooded vegetation, wetlands also contribute to CO2 in river channels. On the other hand, dynamics of dissolved CH4 in river channels are less straightforward to predict, and are related to the way hydrology modulates the connectivity between wetlands and river channels.
Université de Liège, Unité d'Océanographie Chimique, Institut de Physique (B5), B-4000, Belgium.
Alberto V
AV
Borges
Laboratoire Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), CNRS, Université Bordeaux 1, Avenue des Facultés, 33405 Talence, France.|Programa de Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista s/n, 24020015, Niterói, RJ, Brazil.
Gwenaël
G
Abril
Université de Liège, Unité d'Océanographie Chimique, Institut de Physique (B5), B-4000, Belgium.
François
F
Darchambeau
Katholieke Universiteit Leuven, Department of Earth and Environmental Sciences, Celestijnenlaan 200E, B-3001 Leuven, Belgium.
Cristian R
CR
Teodoru
Laboratoire Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), CNRS, Université Bordeaux 1, Avenue des Facultés, 33405 Talence, France.
Jonathan
J
Deborde
Laboratório de Ciências Ambientais, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense - UENF, Av. Alberto Lâmego, Parque Califórnia, CEP 28013602, Campos dos Goytacazes, RJ, Brazil.
Luciana O
LO
Vidal
Université de Liège, Unité d'Océanographie Chimique, Institut de Physique (B5), B-4000, Belgium.
Thibault
T
Lambert
Katholieke Universiteit Leuven, Department of Earth and Environmental Sciences, Celestijnenlaan 200E, B-3001 Leuven, Belgium.
Steven
S
Bouillon