HR: 11:35h
AN: B42A-05    [Abstracts]
TI: Stoichiometry of Carbon, Nitrogen, and Phosphorus Regeneration Interactions in the Hyporheic Zones of Arctic Streams Draining Areas of Continuous Permafrost
AU: * Bowden, W B
EM: breck.bowden@uvm.edu
AF: University of Vermont, Rubenstein School of Environment and Natural Resources 304 Aiken Center, Burlington, VT 05401, United States
AU: Greenwald, M J
EM: Morgan.Johnston@uvm.edu
AF: University of Vermont, Rubenstein School of Environment and Natural Resources 304 Aiken Center, Burlington, VT 05401, United States
AU: Gooseff, M N
EM: mgooseff@engr.psu.edu
AF: Pennsylvania State University, Civil & Environmental Engineering Department 212 Sackett Bldg, University Park, PA 16802, United States
AU: McNamara, J P
EM: jmcnamar@boisestate.edu
AF: Boise State University, Department of Geosciences/COAS 1910 University Drive, Boise, ID 83725-1535, United States
AU: Bradford, J
EM: johnb@cgiss.boisestate.edu
AF: Boise State University, CGISS, MG-206 1910 University Drive, Boise, ID 83725, United States
AU: Zarnetske, J P
EM: zarnetsj@geo.oregonstate.edu
AF: Oregon State University, Department of Geosciences 104 Wilkinson Hall, Corvalilis, OR 97331, United States
AU: Brosten, T
EM: TroyBrosten@mail.boisestate.edu
AF: Boise State University, Department of Geosciences/COAS 1910 University Drive, Boise, ID 83725-1535, United States
AB: We used conservative tracer (Rhodamine WT) additions to examine flow paths in two arctic tundra streams with contrasting physical characteristics (high and low gradient, cobble and peat substrate). We installed mini- piezometers in the same streams to examine nutrient patterns longitudinally and with depth. The combination of the flow and nutrient data allowed us to estimate nutrient regeneration rates. In a separate study, we used whole- stream metabolism methods to estimate whole-system photosynthesis and respiration. Comparison to chamber-based metabolism methods showed that most of the whole-system respiration could be attributed to heterotrophic activity in the hyporheic zone. We found that regeneration of C in the hyporheic zone (respiration) was in reasonable stoichiometric agreement with the regeneration of N and P. Increasing temperature and discharge had relatively modest impacts on ecosystem respiration and photosynthesis. We concluded that a substantial portion of the N and P required to support ecosystem photosynthesis in these permafrost-dominated streams can be obtained from hyporheic regeneration. Second, a substantial portion of the excess C (supersaturated CO₂) in these streams may be due to hyporheic respiration rather than terrestrial runoff of CO₂-laden groundwater. Third, the expected changes in future climate in the arctic foothills may have only a limited effect on the instantaneous rates of C, N, and P processing. The larger effect is likely to be on annual processing rates, due to the longer flowing water season.
UR: http://www.mines.edu/~mgooseff/arctic_proj.html
DE: 0408 Benthic processes (4804)
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0469 Nitrogen cycling
DE: 0744 Rivers (0483, 1856)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting