HR: 0800h
AN: OS51B-0562    [Abstracts]
TI: Export Fluxes of Dissolved Organic Carbon From the Yukon River
AU: * Guo, L
EM: guol@iarc.uaf.edu
AF: University of Alaska Fairbanks, International Arctic Research Center, Fairbanks, AK 99775 United States
AU: * Guo, L
EM: guol@iarc.uaf.edu
AF: University of Southern Mississippi, Department of Marine Science, Stennis Space Center, MS 39529 United States
AU: Cai, Y
EM: ycai@iarc.uaf.edu
AF: University of Alaska Fairbanks, International Arctic Research Center, Fairbanks, AK 99775 United States
AU: Belzile, C
EM: Claude_Belzile@uqar.qc.ca
AF: University of Alaska Fairbanks, International Arctic Research Center, Fairbanks, AK 99775 United States
AU: Macdonald, R
EM: MacdonaldRob@pac.dfo-mpo.gc.ca
AF: Institute of Ocean Science, 9860 West Saanich, Sidney, BC V8L 4B2 Canada
AB: Quantitative determination of export fluxes of carbon species through Arctic rivers is required to constrain the carbon budget in the Arctic Ocean and to understand the biogeochemical consequence of climate change in Northern drainage basins. In order to quantify the annual riverine export flux from the Yukon River, monthly or bimonthly water samples were collected at Pilot Station from July 2004 to July 2005 and analyzed for concentrations of dissolved organic carbon (DOC), particulate organic carbon (POC) and dissolved inorganic carbon (DIC). Concentration of DOC varied from 182 to 1683 uM (average 441 uM), with the highest concentration during river ice opening and the lowest in April under the ice. In contrast, DIC concentration increased from ice opening in May (1178 uM) to winter frozen season (2128 uM), with an average of 1588 uM. In addition to the DOC maximum during ice opening, an elevated DOC concentration was observed during the early stage of river ice formation, suggesting the rejection of DOC from ice during its formation. There was a positive correlation of DOC with freshwater flow rate whereas DIC correlated negatively with flow, indicating a hydrological control on both components but different source terms and transport mechanisms. Integrated annual export flux during 2004/2005 was 2.78x10¹² g-C/y for DOC and 4.53x10¹² g-C/y for DIC. Within the annual fluxes, only 5% of DOC and 17% of DIC were exported during the winter period when the river was frozen over. Long-term observations of DOC and DIC together with their molecular and isotopic signatures are needed to understand how the Yukon River Basin responds to a changing climate.
DE: 1804 Catchment
DE: 1806 Chemistry of fresh water
DE: 4805 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4912)
DE: 4806 Carbon cycling (0428)
DE: 9315 Arctic region (0718, 4207)
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005