HR: 1330h
AN: H43B-02    [Abstracts]
TI: Nutrient Cycling in Riparian Soils and Sediments Bordering Cold Desert Streams and Lakes
AU: * Barrett, J E
EM: John.E.Barrett@Dartmouth.edu
AF: Dartmouth College, 6182 Steele Hall, Hanover, NH 03755 United States
AU: Gooseff, M N
EM: mgooseff@mines.edu
AF: Colorado School of Mines, 1516 Illinois Street, Golden, CO 80401 United States
AU: Northcott, M
EM: cinnamon__bear@hotmail.com
AF: Colorado School of Mines, 1516 Illinois Street, Golden, CO 80401 United States
AU: Bobb, M
EM: bobbm@unm.edu
AF: University of New Mexico, 133 Castetter Hall, ALbuquerque, NM 87131 United States
AU: Zeglin, L
EM: lzeglin@unm.edu
AF: University of New Mexico, 133 Castetter Hall, ALbuquerque, NM 87131 United States
AU: Bate, D B
EM: Douglas. Bradley.Bate@Dartmouth.edu
AF: Dartmouth College, 6182 Steele Hall, Hanover, NH 03755 United States
AU: Takacs-Vesbach, C
EM: cvesbach@unm.edu
AF: University of New Mexico, 133 Castetter Hall, ALbuquerque, NM 87131 United States
AB: Riparian zone processes are critical to whole watershed biogeochemistry, because hydrology links the material and energy budgets of aquatic and terrestrial ecosystems. In temperate watersheds, these riparian zones have been identified as biogeochemical "hot-spots" because of the increased microbial activity and biogeochemical exchanges between terrestrial and aquatic ecosystems. In the Antarctic Dry Valleys, riparian zones are crucial landscape features because of the scarcity of liquid water in this polar desert. Dry valley hydrological margins may therefore provide a model system for understanding physical and hydrological influences on microbial ecology and biogeochemistry. We report on our first season of field work investigating aquatic-terrestrial transition zones on the margins of 11 stream and lake systems in the dry valleys. Wetted zones extended 2-10 m from the edges of lotic and lentic systems. While capillary demand and surface evaporation drive a one-way flux of water through these zones, the scale of these transition zones is determined by the topography and physical characteristics of the surrounding soils. Nutrient concentrations and fluxes are influenced by both the hydrology and microbially mediated biogeochemical processes (e.g. denitrification). For example, nutrient concentrations are enriched near the distal boundary of the wetted fronts due to evapo-concentration of pore water in lake margin soils. Stream margin soils, in contrast, have low nutrient concentrations and appear to be flushed more regularly because of dynamic hydrologic boundary conditions. These trends in nutrient availability across aquatic-terrestrial transition zones structure distinct environments for microbial communities. Continuing work is addressing the functioning of the microbial communities and their role in controlling transformation and mobility of nitrogen in these wetted zones.
DE: 0400 Biogeosciences
DE: 1818 Evapotranspiration
DE: 1831 Groundwater quality
DE: 1866 Soil moisture
SC: Hydrology [H]
MN: 2005 Joint Assembly