Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Hydrol. Earth Syst. Sci., 13, 2349-2358, 2009
http://www.hydrol-earth-syst-sci.net/13/2349/2009/
doi:10.5194/hess-13-2349-2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
 
10 Dec 2009
Spatial variation in soil active-layer geochemistry across hydrologic margins in polar desert ecosystems
J. E. Barrett1, M. N. Gooseff2, and C. Takacs-Vesbach3 1Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
2Department of Civil & Environmental Engineering, Pennsylvania State University, University Park, PA 16802, USA
3Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
Abstract. Polar deserts are characterized by severe spatial-temporal limitations of liquid water. In soil active layers of the Antarctic Dry Valleys, liquid water is infrequently available over most of the arid terrestrial landscape. However, soils on the margins of glacial melt-water streams and lakes are visibly wet during the brief Austral summer when temperatures permit the existence of liquid water. We examined the role of these hydrologic margins as preferential zones for the transformation and transport of nutrient elements and solutes in an environment where geochemical weathering and biological activity is strictly limited by the dearth of liquid water. We report on hydropedological investigations of aquatic-terrestrial transition zones adjacent to 11 stream and lake systems in the Antarctic Dry Valleys. Our results show that wetted zones extended 1–11 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 appear to be influenced by both the hydrology and microbial-mediated biogeochemical processes. Salt concentrations are enriched near the distal boundary of the wetted fronts due to evapo-concentration of pore water in lake margin soils, while organic matter, ammonium and phosphate concentrations are highest in stream channel sediments where potential for biological activity is greatest. Thus, in the Antarctic Dry Valleys, intermittently wet soils on the margins of streams and lakes are important zones of both geochemical cycling and biological activity.

Citation: Barrett, J. E., Gooseff, M. N., and Takacs-Vesbach, C.: Spatial variation in soil active-layer geochemistry across hydrologic margins in polar desert ecosystems, Hydrol. Earth Syst. Sci., 13, 2349-2358, doi:10.5194/hess-13-2349-2009, 2009.
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