An overall understanding of the processes controlling the biogeochemistry of the Amazon River mainstem requires consideration of a series of scales. This project addresses primarily those processes operating at the fast- to intermediate dynamic control of the linkages between the mainstem and floodplain. Based on a series of research cruises the research team will: 1) Use a rating-curve approach to define material hydrographs at the primary sampling stations. 2) Predict fluxes for the respective elements. 3) Calculate the residence time of water on the floodplain, with inundation patterns determined by Landsat imagery. 4) Use the routing model to provide boundary conditions to a two- dimensional hydrodynamic model. 5) Use this model to drive a sediment transport/exchange model, calibrated with data from field sites validated with field data and with turbidity patterns visible on Landsat MSS images. 6) Use a series of isotope tracers of organic mater to identify sources responsible for exchange. 7) Examine potential DOC adsorption mechanisms. 8) Refine the within river respiration rate estimates. 9) Identify what class of compounds may be the substrates by measuring changes in biomarkers. 10) Evaluate the overall potential of these compounds using the hydrodynamic model as a driver. The research team is an excellent one with a long history of productive collaboration. Facilities at the grantee institution are excellent, and accommodations at the Brazilian operations center. Relations with Brazilian scientific partners are long- standing and excellent.
