Continental Scale Biogeochemical Cycles in the Amazon: A Riverine Perspective

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This project will test the working hypothesis that "the distributions of the respective chemical species follow a predictable annual pattern, with interannual variability falling within a characteristic 'envelope' driven by discharge effects on the sequences of (a) tributary inputs, which can be described by a regional chromatography model (b) in situ carbon oxidation, which is maintained through a dynamic equilibrium, and (c) mainstemvarzea linkages, which are a function of basin structural features. Specific research objectives include: Objective 1. The Regional Chromatograph: (1) Developing a regional-scale research paradigm (2) Examining the chemical basis for a regional chromatographic model. (3) Developing the capability to model water, chemical, and sediment routing at subbasin scales, and (4) Developing a sampling network for tributary basin and upriver sampling. Objective 2: Mainstem Dynamics: (1) Determining interannual variability by continuing the Marchantaria monthly time series for routine parameters and augmenting these with more detailed chemical characterizations and maintaining data input from the DNAEE hydrologic data base. (2) Examining the "dynamic equibrium" concept through analyses of the patterns of biogenic gases, bacterial carbon dynamics, temporal variability inorganic composition, and selected N and P forms. (3) Modeling mainstem routing and mainstem-floodplain exchange through the extension of a 2-dimensional hydrodynamic model, incorporating remote sensing data on water and sediment exchange. The research is pertinent to resolution of major ecological questions at the continental scale within the preview of global change. Past work has been productive, and collaborative arrangements with Brazilian scientists are excellent.