HR: 0800h
AN: OS51B-0561    [Abstracts]
TI: Fluxes of Colloidal Organic Carbon to the Arctic Ocean From North American Rivers
AU: * Cai, Y
EM: ycai@iarc.uaf.edu
AF: International Arctic Research Center, University of Alaska Fairbanks, 930 Koyukuk Drive, Fairbanks, AK 99775-7335 United States
AU: Guo, L
EM: guol@iarc.uaf.edu
AF: International Arctic Research Center, University of Alaska Fairbanks, 930 Koyukuk Drive, Fairbanks, AK 99775-7335 United States
AB: Colloidal organic carbon (COC) is a major component in the carbon biogeochemical cycle. The Arctic Ocean receives a disproportionally large input of global terrestrial organic carbon, but the riverine input of COC to the Arctic Ocean is still poorly quantified. Water samples were collected during Summer 2005 from the Mackenzie River, Sagavanirktok River, Kuparuk River, and the Yukon River Basin, including Yukon River, Tanana River and Chena River. Using cross-flow ultrafiltration, the concentration of COC (1kD to 0.45um) and its percentage in bulk dissolved organic carbon (DOC) were quantified with the application of an ultrafiltration permeation model. Riverine export fluxes of COC by these rivers were also estimated based on freshwater discharge and corresponding COC concentrations. COC concentrations derived from the ultrafiltration permeation model ranged from 0.54 to 14.3 mg-C/L, while the percentages of COC in the bulk DOC remained somewhat constant, ranging from 62 to 77% with an average of 68ñ5%. These COC percentages are higher than those found in tropical/subtropical rivers, indicating the importance of COC in the Arctic rivers. The annual export flux of COC was 2.30E+12 g-C/y for the Yukon River, 1.23x10¹² g-C/y for the Mackenzie River, 1.51x10⁹ g-C/y for the Sagavanirktok River, and 3.89x10⁹ g-C/y for the Kuparuk River. Within the COC export flux from the Yukon River Basin, ~65% was from the Yukon River, ~3% was from the Tanana River, and 32% was from the Koyukuk River and other tributaries. The total COC discharged by rivers into the Arctic Ocean was estimated as 12.2-17.7x10¹² g-C/y, given a DOC flux of 18-26x10¹² g-C/y to the Arctic Ocean and an average COC percentage of 68%.
DE: 4207 Arctic and Antarctic oceanography (9310, 9315)
DE: 4806 Carbon cycling (0428)
DE: 4809 Colloids
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005