CD-06 Abstract

Carbon and Moisture Fluxes along the LBA Transects: Data Assimilation and Modeling

Jeffrey E. Richey, University of Washington (US-PI)
Reynaldo Luiz Victoria, CENA/USP (SA-PI)

Our research addresses the overall role rivers and periodically inundated environments play in the biogeochemical cycles of the Amazon Basin. Recent evidence suggests that outgassing of CO2 is of comparable magnitude to the lower estimates of carbon sequestration by forests. We have two primary objectives:

Objective 1. Complete research on the question of landuse change and its consequences for water chemistry in the Ji-Paraná River Basin

Objective 2. Expand research on the fluxes of gases between wetlands and the atmosphere, by testing the working hypothesis that “CO2 evasion returns as much carbon to the atmosphere as is sequestered in upland forests on an interannual basis.  Export of organic material from upland and riparian forests to fluvial environments is the primary source of carbon that is eventually respired in rivers and evaded as CO2.”

We are addressing our objectives by (1) Conducting fieldwork in characteristic sub-basins to complete water chemistry and to obtain an extensive suite of pCO2 distribution measurements over the hydrologic regime, and to use proven geochemical techniques (gas flux measurements, isotopic tracers, remineralization rates) to quantify the rates of the lateral transfer and cycling of water and bioactive organic matter from the land, through riparian environments and to the river system. (2) Using a terrestrial source/river transport and reaction model to synthesize and extrapolate the site-specific CO2 evasion rate measurements to a basin-wide estimate of CO2 evasion rate. The work will be executed across a series of environments (primarily Manaus, Ji-Parana, Bananal, Acre, Caxiuana, Mato Grosso, and hopefully Tefe). This will be done by setting up specific student-based collaborations at each site, coordinated through CENA. The overall research here is relevant to a series of the LBA-ECO Science questions.  The work considers explicitly the effects of changing land use, the relation of surface water chemistry to regional flow patterns, and the role of the extensive wetlands and temporarily inundated or saturated areas in Amazônia.