HR: 1340h
AN: B23D-1604    [Abstracts]
TI: Using radiocarbon to detect the loss of old soil carbon in hydrologic fluxes from permafrost
AU: * Von Kiparski, G
EM: kiparski@ucr.edu
AF: Unviersity of California, Riverside, Department of Environmental Sciences, Riverside, CA 92521, United States
AU: Sickman, J
EM: jsickman@ucr.edu
AF: Unviersity 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: Unviersity of California, Riverside, Department of Environmental Sciences, Riverside, CA 92521, United States
AU: Crummer, G
EM: gcrummer@ucr.edu
AF: University of Florida, Department of Botany, Gainesville, FL 32611, United States
AB: Transfers of C to the atmosphere from melting permafrost have been hypothesized to be a positive feedback to climate change. However, sustained and significant transfers must come from old C, which forms the bulk of the soil pool, and may be detectable in the Δ¹⁴C isotopic signature of hydrologic C losses. At the Eight Mile Lake watershed (Healy, Alaska) we have made regular measurements of the Δ¹⁴C of DOC and DIC in surface inflow to the lake and in waters draining a severely thawed tussock tundra subcatchment. Δ¹⁴C- DIC values typically ranged from +40 to +70 permil and suggest that the DIC pool at both locations is in near isotopic-equilibrium with the atmosphere. In surface inflow, Δ¹⁴C-DOC values ranged from +20 to +60 permil, while in drainage from severely thawed permafrost values ranged from -20 to +20 permil. At both sites, Δ¹⁴C-DOC was lowest at the onset of snowmelt in the spring (ca. April-May) and gradually increased until freezing occurred in September. Negative Δ¹⁴C-DOC values in waters draining thermokarst features demonstrate a substantial amount of older, temperature stablized carbon is mobilized in the spring when DOC concentrations are at maximum (40 to 50 mg L^-1).
DE: 0428 Carbon cycling (4806)
DE: 0702 Permafrost (0475)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting