HR: 1330h
AN: NB33L-11 [Abstracts]
TI: Effects of Discontinuous Permafrost on Dissolved Organic Matter Dynamics and Whole Stream Metabolism in Boreal Forest Catchments of Interior Alaska
AU: * Betts, E F
EM: ftefb@uaf.edu
AF: University of Alaska Fairbanks, Institute of Arctic Biology, Fairbanks, AK 99775 United States
AU: Jones, J B
EM: ffjbj@uaf.edu
AF: University of Alaska Fairbanks, Institute of Arctic Biology, Fairbanks, AK 99775 United States
AU: O'Donnell, J A
EM: ftjao1@uaf.edu
AF: University of Alaska Fairbanks, Institute of Arctic Biology, Fairbanks, AK 99775 United States
AB:
In the boreal forest of Interior Alaska, discontinuous permafrost is an important control on groundwater flowpaths and,
consequently, regulates dissolved organic matter (DOM) and nutrient inputs into streams. Permafrost restricts ground water
to the organic soil horizon, presumably resulting in streams with high DOM and low nutrient concentrations. Conversely, in
catchments with less permafrost, groundwater percolates to the deeper mineral horizons, causing streams to receive higher
nutrient and lower DOM loads. The effect of discontinuous permafrost on carbon and nitrogen dynamics and whole stream
metabolism was examined in the Caribou-Poker Creeks Research Watershed during the summer of 2004. Metabolism was determined
using whole stream measurements of change in dissolved oxygen. Oxygen evasion was quantified with injections of conservative solute and volatile gas tracers. Results support the proposed model of watershed hydrology and biogeochemistry with the
high permafrost catchment having an average DOC concentration of 7.5 mgC/L compared to 3.0 mgC/L in the low permafrost site. In contrast, nitrate concentration was 115 μgN/L in the high permafrost catchment and 175 μgN/L in the low
permafrost catchment. Due to higher concentration of DOM and lower nitrate concentration, we hypothesize that stream
respiration will be higher and GPP lower in higher permafrost streams.
DE: 0400 Biogeosciences
DE: 1615 Biogeochemical processes (4805)
DE: 1806 Chemistry of fresh water
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly