HR: 17:40h
AN: U44A-06 INVITED     [Abstracts]
TI: Source and Flux of DOC in the Kolyma River Watershed of North-East Siberia
AU: * Finlay, J
EM: jfinlay@umn.edu
AF: Department of Ecology, Evolution and Behavior, University of Minnesota, 1987 Upper Buford Cicle 100 Ecology Building, St. Paul, MN 55108 United States
AU: Neff, J
EM: neffjc@colorado.edu
AF: Geological Sciences Deptartment and Environmental Studies Program, University of Colorado at Boulder, Benson Earth Sciences Building, 2200 Colorado Avenue, Boulder, CO 80309 United States
AU: Davydov, S P
EM: sazimov@cher.sakha.ru
AF: Northeast Science Station, Pacific Institute of Geography , Far East Branch, Russian Academy of Sciences, P.0. Box 18, Cherskii, Republic of Sakha, Cherskii, 678830 Russian Federation
AU: Davydova, A I
EM: sazimov@cher.sakha.ru
AF: Northeast Science Station, Pacific Institute of Geography , Far East Branch, Russian Academy of Sciences, P.0. Box 18, Cherskii, Republic of Sakha, Cherskii, 678830 Russian Federation
AU: Zimov, S A
EM: sazimov@cher.sakha.ru
AF: Northeast Science Station, Pacific Institute of Geography , Far East Branch, Russian Academy of Sciences, P.0. Box 18, Cherskii, Republic of Sakha, Cherskii, 678830 Russian Federation
AB: Predicting responses of high latitude carbon cycles to warming and hydrologic changes requires detailed understanding of controls of riverine carbon sources and fluxes. The Kolyma River of north-east Siberia is a large watershed with continuous permafrost and increasing summer temperatures. Results of high resolution investigation of DOC dynamics from the river and surrounding sub watersheds show that DOC flux is dominated by the brief spring runoff period. Relationships of DOC concentration and discharge are dramatically different during the thaw than all other periods. Consideration of high concentrations of DOC during peak water flux conditions yields greater estimates of DOC flux than all previous estimates for the watershed, suggesting that undersampling of DOC during spring could underestimate fluxes substantially. Analyses of C14 and other indicators of river DOC composition show modern organic C during springtime, with increasingly ancient material transported as soil thaw depths increases. Upland watersheds with large stores of organic carbon deposited during the Pleistocene appear to the source of old carbon in rivers. The current flux of ancient carbon from the Kolyma River is small since river discharge is low during summer. Changes to the regional temperature or hydrologic regimes, however, could influence the flux of currently stored DOC and nutrients to rivers.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1621 Cryospheric change (0776)
DE: 1630 Impacts of global change (1225)
DE: 1635 Oceans (1616, 3305, 4215, 4513)
DE: 1655 Water cycles (1836)
SC: Union [U]
MN: Fall Meeting 2005