HR: 17:30h
AN: H24B-07    [Abstracts]
TI: Organic matter transport from the Peruvian Andes to the Amazon River
AU: * Townsend-Small, A
EM: amy@utmsi.utexas.edu
AF: The University of Texas at Austin, Marine Science Institute 750 Channel View Drive, Port Aransas, TX 78373 United States
AU: Noguera, J L
EM: nogueratj@yahoo.es
AF: Andean Amazon Research Station, Jiron Lima 687, Oxapampa, Pasco Peru
AU: McClain, M E
EM: mcclainm@fiu.edu
AF: Florida International University, Department of Environmental Studies, Miami, FL 33199 United States
AU: Brandes, J A
EM: brandes@utmsi.utexas.edu
AF: Skidaway Institute of Oceanography, 10 Ocean Science Circle, Savannah, GA 31411 United States
AB: The Andes are a major source of sediments, dissolved minerals, and water to the Amazon River. The current study seeks to determine the extent to which the Andes are a source for organic carbon and nitrogen to the Amazon River proper. We have employed a variety of isotopic (stable and radiocarbon) and elemental tracers of carbon and nitrogen cycling. Our results suggest that the organic carbon content of Andean rivers is highly variable with altitude and hence terrestrial ecosystem type and geomorphology. The data indicate that suspended and dissolved organic matter is derived from altered soil pools, with evidence of sorption of N-rich fractions onto fine sediment fractions. Erosion, and therefore age and degree of alteration from plant sources, of terrestrial soils into Andean rivers is tightly coupled to rainfall events ("hot moments"). As noted elsewhere and supported by our data, Andean riverine carbon is quite young and suggests that such exports are unusually susceptible to changes in climate.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 1815 Erosion
DE: 1862 Sediment transport (4558)
SC: Hydrology [H]
MN: Fall Meeting 2005