HR: 1340h
AN: B23D-1603    [Abstracts]
TI: The role of lakes in carbon transfers from permafrost to the atmosphere
AU: * Sickman, J O
EM: jsickman@ucr.edu
AF: University of California, Riverside, Department of Environmental Sciences, Riverside, CA 92521, United States
AU: Von Kiparski, G
EM: kiparski@ucr.edu
AF: University of California, Riverside, Department of Environmental Sciences, Riverside, CA 92521, United States
AU: Schuur, T
EM: tschuur@ufl.edu
AF: University of Florida, Department of Botany, Gainesville, FL 32611, United States
AU: Vogel, J
EM: jvogel@ufl.edu
AF: University of Florida, Department of Botany, Gainesville, FL 32611, United States
AU: Lucero, D
EM: dlucero@ucr.edu
AF: University of California, Riverside, Department of Environmental Sciences, Riverside, CA 92521, United States
AU: Vicars, W
EM: wcvicars@ufl.edu
AF: University of California, Riverside, Department of Environmental Sciences, Riverside, CA 92521, United States
AB: In interior Alaska, permafrost thawing is increasing hydrologic losses of soil carbon. At the Eight Mile Lake watershed (outside Denali National Park), dissolved organic carbon (DOC) in soil lysimeters and surface runoff, ranged from 15 to 30 mg L^-1 in areas with minimally thawed tussock tundra. In drainages with moderately and severely thawed permafrost, DOC concentrations ranged from 25 to 55 mg L^-1. Dissolved CO₂ concentrations in surface runoff and soil water ranged from 3 to 25 mg L^-1 C-CO₂ and increased with depth of the water table. As inflowing waters transited through Eight Mile Lake they re-equilibrated with respect to CO₂ (lake water C-CO₂ < 1 mg L^-1) and DOC concentrations decreased by 10-20 mg L^-1. On an areal basis, hydrologic yield of carbon (DOC+DIC) measured at the lake inlet was 5.6 g m^-2, whereas at the outlet, yield decreased to 2.4 g m^-2. Heterotrophic bioavailability of organic matter in the lake ranged from 9-14% over 28-day incubations. In contrast, short-term (2-7 day) exposures to ambient sunlight and mineral sediments resulted in losses of 16-22% of DOC in waters collected from inflow streams and soil lysimeters. These experiments indicate that abiotic processes may dominate as the carbon loss mechanism in Eight Mile Lake. Our results suggest that in-lake processing of DOC and DIC may strongly influence regional carbon balances in interior Alaska.
DE: 0428 Carbon cycling (4806)
DE: 0702 Permafrost (0475)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting