Dynamics and Biogeochemistry of River Corridors and Wetlands (Proceedings of symposium S4 held during the Seventh IAHS Scientific Assembly at Foz do Iguaçu, Brazil, April 2005). IAHS Publ. 294, 2005, 69-77

Seasonal links between the Amazon corridor and its flood plain: the case of the várzea of Curuaí

M. P. BONNET1, G. BARROUX1, P. SEYLER1, G. PECLY2, P. MOREIRA-TURCQ3, C. LAGANE1, G. COCHONNEAU4, J. VIERS1, F. SEYLER1 & J. L. GUYOT5

1 IRD UR 154, Laboratoire des Mécanismes de Transfert en Géologie, F-31400 Toulouse, France

bonnet@lmtg.obs-mip.fr

2 COPPE/UFRJ, Laboratório de Traçadores, 21945-970 Rio de Janeiro, Brazil

3 IRD-LMTG -Departamento de Geoquímica, Universidade Federal Fluminense, Morro do Valonguinho s/n, 24020-007 Niterói, RJ, Brazil

4 IRD LMTG Maison de la télédétection, F-3400 Montpellier, France

5 IRD-LMTG, Casilla 18-1209, Lima 18, Peru

Abstract Due the large extent (about 600 000 km2) of the Amazonian flood plain it is expected to greatly influence the Amazon River dynamics, in terms of suspended solids and chemical fluxes. However, up to now, fluxes and exchanges between the main stream and its flood plain are poorly known and it is still difficult to precisely quantify to what extent the flood plain may play a significant role. For several years, in the framework of the HyBAm (Hydrology and Geochemistry of the Amazonian Basin, IRD-CNPq) research programme, in situ hydrological and geochemical conditions have been investigated in a flood plain located in the lowest part of the river course. This data set enabled development of a model describing fluxes exchanged between the flooded area and the Amazon River. The model—in a relatively simple form—was in good agreement with the data. The results show that the flood plain is a source of water and of redox sensitive elements, such as arsenic, for the Amazon River.

Key words Amazon River; flood plain; modelling