HR: 14:55h
AN: B43F-06    [Abstracts]
TI: Increased Permafrost Thaw and Groundwater Contribution to Streamflow Affect DOM, DIC and DIN Export and Chemistry in the Yukon River Basin
AU: * Striegl, R G
EM: rstriegl@usgs.gov
AF: USGS, Box 25046 MS 413, Denver, CO 80225, United States
AU: Walvoord, M A
EM: walvoord@usgs.gov
AF: USGS, Box 25046 MS 413, Denver, CO 80225, United States
AU: Aiken, G R
EM: graiken@usgs.gov
AF: USGS, 3215 Marine Street, Boulder, CO 80303, United States
AU: Wickland, K P
EM: kpwick@usgs.gov
AF: USGS, 3215 Marine Street, Boulder, CO 80303, United States
AB: Climate warming in arctic and subarctic watersheds is affecting hydrology and carbon and nitrogen biogeochemistry in multiple ways and at multiple scales. Permafrost thaw, thermokarst formation, wetland drying, melting of alpine glaciers and perennial snow fields, and vegetation change all have direct impacts on water and carbon budgets, especially at the local scale. We conducted a basin wide assessment of long-term change in the amount and timing of streamflow throughout the Yukon River basin of Northwest Canada and Alaska and related those hydrologic changes to recent within-basin measurements of carbon and nitrogen export and chemistry. Our analysis indicates that ongoing permafrost thaw and subsequent increased infiltration result in increased groundwater contribution to streamflow, which in turn is shifting the amount and chemistry of dissolved inorganic and organic carbon and nitrogen exported to the Bering Sea. Groundwater currently comprises about one fourth of Yukon River water and contributes 5-10 percent of the dissolved organic carbon and nitrogen (DOM) and 35-45 percent of the dissolved inorganic carbon (DIC) and nitrogen (DIN) loads. A general increasing trend in groundwater contribution to streamflow of 0.7-0.9 percent per yr, with no pervasive change in annual water discharge, will result in decreased DOM concentration and export and increased DIC and DIN concentration and export, consistent with recent measured changes in DOM and DIC export during the thaw season. Preliminary results also suggest that the increasing groundwater component has a greater hydrophilic fraction and bioavailability than surface-runoff derived riverine DOM.
UR: http://ak.water.usgs.gov/yukon/
DE: 0428 Carbon cycling (4806)
DE: 0429 Climate dynamics (1620)
DE: 1806 Chemistry of fresh water
DE: 1879 Watershed
SC: Biogeosciences [B]
MN: 2007 Fall Meeting