Amazon River carbon dioxide outgassing fuelled by wetlands

Black river (Rio Negro). Amazon jungle. Original file

Gwenaël Abril, Jean-Michel Martinez, L. Felipe Artigas, Patricia Moreira-Turcq, Marc F. Benedetti, Luciana Vidal, Tarik Meziane, Jung-Hyun Kim, Marcelo C. Bernardes, Nicolas Savoye, Jonathan Deborde, Edivaldo Lima Souza, Patrick Albéric, Marcelo F. Landim de Souza & Fabio Roland

River systems connect the terrestrial biosphere, the atmosphere and the ocean in the global carbon cycle. A recent estimate suggests that up to 3 petagrams of carbon per year could be emitted as carbon dioxide (CO2) from global inland waters, offsetting the carbon uptake by terrestrial ecosystems. It is generally assumed that inland waters emit carbon that has been previously fixed upstream by land plant photosynthesis, then transferred to soils, and subsequently transported downstream in run-off. But at the scale of entire drainage basins, the lateral carbon fluxes carried by small rivers upstream do not account for all of the CO2 emitted from inundated areas downstream. Three-quarters of the world’s flooded land consists of temporary wetlands, but the contribution of these productive ecosystems to the inland water carbon budget has been largely overlooked. Here we show that wetlands pump large amounts of atmospheric CO2 into river waters in the floodplains of the central Amazon. Flooded forests and floating vegetation export large amounts of carbon to river waters and the dissolved CO2 can be transported dozens to hundreds of kilometres downstream before being emitted. We estimate that Amazonian wetlands export half of their gross primary production to river waters as dissolved CO2 and organic carbon, compared with only a few per cent of gross primary production exported in upland (not flooded) ecosystems. Moreover, we suggest that wetland carbon export is potentially large enough to account for at least the 0.21 petagrams of carbon emitted per year as CO2 from the central Amazon River and its floodplains. Global carbon budgets should explicitly address temporary or vegetated flooded areas, because these ecosystems combine high aerial primary production with large, fast carbon export, potentially supporting a substantial fraction of CO2 evasion from inland waters.

More information about the article: Nature 505,395–398(16 January 2014)

Authors and affiliations:

Laboratoire Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), CNRS, Université Bordeaux 1, Avenue des Facultés, 33405 Talence, France

Gwenaël Abril,

Nicolas Savoye &

Jonathan Deborde

Laboratoire Géosciences et Environnement de Toulouse, Institut de Recherche pour le Développement, Université Paul Sabatier, 14 avenue Edouard Belin, 31400 Toulouse, France

Gwenaël Abril,

Jean-Michel Martinez &

Patricia Moreira-Turcq

Laboratoire d’Océanologie et Géosciences, CNRS, Université du Littoral Côte d’Opale, 32 avenue Foch, 62930 Wimereux, France

L. Felipe Artigas

Equipe Géochimie des Eaux, Institut de Physique du Globe de Paris, Université Paris Diderot, Sorbonne Paris Cité, 35 rue Hélène Brion, 75205 Paris Cedex 13, France

Marc F. Benedetti

Laboratório de Ecologia Aquática, Departamento de Biologia, Universidade Federal de Juiz de Fora, Rua José Lourenço Kelmer, MG 36036-900 Juiz de Fora, Brazil

Luciana Vidal &

Fabio Roland

Laboratoire Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Muséum National d’Histoire Naturelle, CNRS, IRD, UPMC, 61 rue Buffon, 75005, Paris, France

Tarik Meziane

NIOZ (Royal Netherlands Institute for Sea Research), Department of Marine Organic Biogeochemistry, Texel, 1790 AB Den Burg, The Netherlands

Jung-Hyun Kim

Programa de Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista, RJ 24020015 Niterói, Brazil

Marcelo C. Bernardes

Instituto de Geociências, Universidade de Brasília, Campus Universitário Darcy Ribeiro, DF 70.910-900 Brasília, Brazil

Edivaldo Lima Souza

Institut des Sciences de la Terre d’Orléans, 1A rue de la Férollerie, 45071 Orléans Cedex 2, France

Patrick Albéric

Laboratório de Oceanografia Química, Universidade Estadual de Santa Cruz, Rodovia Ilhéus-Itabuna, 45662-900 Ilhéus, Bahia, Brazil

Marcelo F. Landim de Souza 

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