Carbon Pathways through Tropical River Systems: From Small Streams to the Oceans (Lessons from the Amazon and Mekong)
Jeffrey
E.
Richey, University of Washington, jrichey@u.washington.edu
(Presenting)
The end member typically used to define the watershed inputs to the plumes of large tropical rivers represents an enigmatic signal. The chemistry at that point is such a large-scale signal, as the aggregated product of multiple sources and processes that it is difficult to understand the dynamics producing it. While the chemistry at small-scale sources is at least periodically studied in such systems, how that source signal propagates through a river network to the ultimate pour-point is very poorly known. In terms of summarizing the watershed outputs to the ocean, that endmember is usually determined at a gauging station located a considerable distance upriver from the actual marine environment, with not only new sources of water coming in below that station, but with complex deltas and islands modifying the actual input to the sea. An emerging reality is that not only will climate change be modifying the flow regimes which influence plumes, but a “new round” of dams in large tropical basins seems likely, with undetermined consequences for plumes and coasts. Recent data from river sampling networks in the Amazon and Mekong River systems examine systematic variations in pCO2 relative to other chemical parameters, including O2, DOC, and FPOC; suggesting an environmental “coherence” across scales. Modeling examines how basin changes might ultimately modify export. In an Earth System construct, large tropical forests and their plumes might be considered as unified ecosystems.
NASA Carbon Cycle & Ecosystems Active Awards Represented by this Poster: