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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 - Centro de Energia Nuclear na Agricultura (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.

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