HR: 11:05h
AN: B42A-04    [Abstracts]
TI: Biogeochemistry of the Amazon River Basin: the role of aquatic ecosystems in the Amazon functioning
AU: * Victoria, R L
EM: reyna@cena.usp.br
AF: Centro de Energia Nuclear na Agricultura - Universidade de Sao Paulo, Av. Centen rio, 303, Piracicaba, SP 13416-000 Brazil
AU: Ballester, V R
EM: vicky@cena.usp.br
AF: Centro de Energia Nuclear na Agricultura - Universidade de Sao Paulo, Av. Centen rio, 303, Piracicaba, SP 13416-000 Brazil
AU: Krushe, A V
EM: alex@cena.usp.br
AF: Centro de Energia Nuclear na Agricultura - Universidade de Sao Paulo, Av. Centen rio, 303, Piracicaba, SP 13416-000 Brazil
AU: Richey, J E
EM: jrichey@u.washington.edu
AF: School of Oceanography - University of Washington, Box 355351, Seattle, WA 98195 United States
AU: Aufdenkampe, A K
EM: aufdenkampe@stroudcenter.org
AF: Stroud Water Research Center, 970 Spencer Road, Avondale, PA 19311 United States
AU: Kavaguishi, N L
EM: nei@cena.usp.br
AF: Centro de Energia Nuclear na Agricultura - Universidade de Sao Paulo, Av. Centen rio, 303, Piracicaba, SP 13416-000 Brazil
AU: Gomes, B M
EM: bmgomes@unir.br
AF: Universidade Federal de Rondonia, Ji-Parana, Ji-Parana, RO 900000 Brazil
AU: Victoria, D d
EM: dcvictori@cena.usp.br
AF: Centro de Energia Nuclear na Agricultura - Universidade de Sao Paulo, Av. Centen rio, 303, Piracicaba, SP 13416-000 Brazil
AU: Montebello, A A
EM: amonte@cena.usp.br
AF: Centro de Energia Nuclear na Agricultura - Universidade de Sao Paulo, Av. Centen rio, 303, Piracicaba, SP 13416-000 Brazil
AU: Niell, C
EM: cniell@mbl.ecu
AF: The Ecosystem Center, 7 MBL St., Woods Hole, MA 02543 United States
AU: Deegan, L
EM: ldeegan@mbl.edu
AF: The Ecosystem Center, 7 MBL St., Woods Hole, MA 02543 United States
AB: In this study we present the results of an integrated analysis of physical and anthropogenic controls of river biogeochemistry in Amaz“nia. At the meso-scale level, our results show that both soil properties and land use are the main drivers of river biogeochemistry and metabolism, with pasture cover and soil exchange cation capacity explaining 99% (p < 0.01) of the variability observed in surface water ions and nutrients concentrations. In small rivers, forest clearing can increase cations, P and C inputs. P and light are the main PPL limiting factors in forested streams, while in pasture streams N becomes limiting. P export to streams may increase or remain nearly undetectable after forest-to-pasture conversion, depending on soil type. Pasture streams on Oxisols have very low P export, while on Ultisols P export is increased. Conversions of forest to pasture leads to extensive growth of in channel Paspalum resulting in higher DOC concentrations and respiration rates. Pasture streams have higher DOC fluxes when compared to the forest ones. In pasture areas the soil are compacted, there is less infiltration and higher surface run off, leaching soil superficial layers and caring more DOC to the streams. In forest areas infiltration is deeper into the soils and canopy interaction is higher. Mineralogy and soil properties are key factors determining exports of nutrients to streams. Therefore, land use change effects on nutrient export from terrestrial to aquatic ecosystems and the atmosphere must be understood within the context of varying soil properties across the Amazon Basin.
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting