HR: 17:30h
AN: B22D-06    [PDF]
TI: Dissolved Inorganic Carbon Cycling in the Yukon River
AU: * Striegl, R G
EM: rstriegl@usgs.gov
AF: United States Geological Survey, PO Box 25046, MS 413, Denver, CO 80225-0046 United States
AU: Dornblaser, M M
EM: mmdornbl@usgs.gov
AF: United States Geological Survey, 3215 Marine St., Boulder, CO 80303 United States
AU: Chanton, J P
EM: jchanton@mailer.fsu.edu
AF: FLorida State University, Department of Oceanography, Tallahassee, FL 32306-4340 United States
AB: Carbon dynamics of the Yukon River are controlled by complex interactions among inorganic and organic carbon pools, including mineralization of particulate and dissolved organic carbon, hydrologic input of dissolved carbonate species, dissolution of particulate carbonates, and atmospheric interaction of CO2 and CH4. Dissolved inorganic carbon (DIC) undergoes strong seasonality in concentration and source in the Yukon River. DIC and CO2 build up under ice in winter, due to mineralization of organic carbon from the previous year's primary production and input of bicarbonate rich groundwater. Winter DIC in the main stem of the river typically approaches concentrations of 4 millimolar, with CO2 partial pressure exceeding ten times atmospheric, and delta 13C-DIC in the range of -11 to -13 permil. Spring runoff mixes a variety of source waters into the Yukon, with tributary waters from landscapes rich in wetlands contributing DIC as depleted as -18 to -25 permil delta 13C-DIC. However, the net composition of DIC in the Yukon River is dominated by dissolution of particulate inorganic carbonates in runoff and glacial melt water that increase the 13C-DIC of the Yukon River at Stevens Village from about -12.6 permil in late spring to about -5.2permil in late summer. Coincident increase in the apparent age of 14C-DIC was from about 2200 YBP to 4500 YBP. High rates of carbonate dissolution occasionally lead to uptake of atmospheric CO2 by the river during summer. Results of carbon loads modeling, water and carbonate mixing calculations, and calculations of carbon discharge to the Bering Sea by the Yukon River, not completed at the time of abstract submission, will also be presented.
DE: 0400 Biogeosciences
DE: 1600 GLOBAL CHANGE (New category)
DE: 1615 Biogeochemical processes (4805)
DE: 1800 HYDROLOGY
SC: Biogeosciences [B]
MN: 2003 Fall Meeting