title: Amazon River carbon dioxide outgassing fuelled by wetlands.
abstract: 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.
authors: 1] Laboratoire Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), CNRS, Université Bordeaux 1, Avenue des Facultés, 33405 Talence, France [2] Laboratoire Géosciences et Environnement de Toulouse, Institut de Recherche pour le Développement, Université Paul Sabatier, 14 avenue Edouard Belin, 31400 Toulouse, France.
authors: Gwenaël
authors: G
authors: Abril
authors: Laboratoire Géosciences et Environnement de Toulouse, Institut de Recherche pour le Développement, Université Paul Sabatier, 14 avenue Edouard Belin, 31400 Toulouse, France.
authors: Jean-Michel
authors: JM
authors: Martinez
authors: Laboratoire d'Océanologie et Géosciences, CNRS, Université du Littoral Côte d'Opale, 32 avenue Foch, 62930 Wimereux, France.
authors: L Felipe
authors: LF
authors: Artigas
authors: Laboratoire Géosciences et Environnement de Toulouse, Institut de Recherche pour le Développement, Université Paul Sabatier, 14 avenue Edouard Belin, 31400 Toulouse, France.
authors: Patricia
authors: P
authors: Moreira-Turcq
authors: 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.
authors: Marc F
authors: MF
authors: Benedetti
authors: Laboratório de Ecologia Aquática, Departamento de Biologia, Universidade Federal de Juiz de Fora, Rua José Lourenço Kelmer, MG 36036-900 Juiz de Fora, Brazil.
authors: Luciana
authors: L
authors: Vidal
authors: Laboratoire Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Muséum National d'Histoire Naturelle, CNRS, IRD, UPMC, 61 rue Buffon, 75005, Paris, France.
authors: Tarik
authors: T
authors: Meziane
authors: NIOZ (Royal Netherlands Institute for Sea Research), Department of Marine Organic Biogeochemistry, Texel, 1790 AB Den Burg, The Netherlands.
authors: Jung-Hyun
authors: JH
authors: Kim
authors: Programa de Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista, RJ 24020015 Niterói, Brazil.
authors: Marcelo C
authors: MC
authors: Bernardes
authors: Laboratoire Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), CNRS, Université Bordeaux 1, Avenue des Facultés, 33405 Talence, France.
authors: Nicolas
authors: N
authors: Savoye
authors: Laboratoire Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), CNRS, Université Bordeaux 1, Avenue des Facultés, 33405 Talence, France.
authors: Jonathan
authors: J
authors: Deborde
authors: Instituto de Geociências, Universidade de Brasília, Campus Universitário Darcy Ribeiro, DF 70.910-900 Brasília, Brazil.
authors: Edivaldo Lima
authors: EL
authors: Souza
authors: Institut des Sciences de la Terre d'Orléans, 1A rue de la Férollerie, 45071 Orléans Cedex 2, France.
authors: Patrick
authors: P
authors: Albéric
authors: Laboratório de Oceanografia Química, Universidade Estadual de Santa Cruz, Rodovia Ilhéus-Itabuna, 45662-900 Ilhéus, Bahia, Brazil.
authors: Marcelo F
authors: MF
authors: Landim de Souza
authors: Laboratório de Ecologia Aquática, Departamento de Biologia, Universidade Federal de Juiz de Fora, Rua José Lourenço Kelmer, MG 36036-900 Juiz de Fora, Brazil.
authors: Fabio
authors: F
authors: Roland
mesh_terms: D001272:Atmosphere / Q000737:chemistry; D001938:Brazil; D057486:Carbon Cycle; D002245:Carbon Dioxide / Q000032:analysis*; D060106:Lakes / Q000737:chemistry; D010944:Plants / Q000378:metabolism; D045483:Rivers / Q000737:chemistry*; D014872:Water Movements; D053833:Wetlands
chemical_list: D002245:Carbon Dioxide