Spatial variation in soil active-layer geochemistry across hydrologic margins in polar desert ecosystems

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 vi...

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Bibliographic Details
Published in:Hydrology and Earth System Sciences
Main Authors: Barrett, John E., Gooseff, Michael N., Takacs-Vesbach, Cristina D.
Other Authors: Biological Sciences
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2009
Subjects:
Online Access:http://hdl.handle.net/10919/48618
http://www.hydrol-earth-syst-sci.net/13/2349/2009/hess-13-2349-2009.html
https://doi.org/10.5194/hess-13-2349-2009
Description
Summary: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. National Science Foundation 0338174 McMurdo Dry Valleys Long Term Ecological Research program