Coupling of Carbon, Biogeochemical, and Hydrological Cycles: A Fluvial Perspective
Jeffrey
E.
Richey, University of Washington, jrichey@u.washington.edu
(Presenting)
Reynaldo
Luiz
Victória, Centro de Energia Nuclear na Agricultura, reyna@cena.usp.br
While it is often stated that, at regional scales, river basins are natural integrators of surficial processes, the mechanics of how to interpret such information is far from understood (indeed, the “truth” of the statement has rarely, if ever, even been validated). The chemical composition of river water is sensitive to both underground and surficial processes acting over a wide range of characteristic temporal and spatial scales. Chemical signatures of riverine materials can, in theory, be used to identify different drainage basin source regions, reaches or stages and can be tied to landscape-related processes such as chemical weathering and nutrient retention by local vegetation. Fluxes of measured constituents can be compared over any segment of the water flowpath to establish local mass balances and budgets. Such comparisons are particularly useful in establishing the magnitudes of unknown sources (e.g. photosynthesis or groundwater inputs) or sinks (e.g. respiration or gas exchange) of bioactive materials within critical sections of the water network. In this talk we utilize a coupled hydrologic and geochemical model to evaluate an extensive field data set to see if we can establish a systematic basin perspective that can deconvolve chemical hydrographs at the mouths of Amazon tributaries, in terms of their antecedent causes.