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| Titel |
Spatial variation in soil active-layer geochemistry across hydrologic margins in polar desert ecosystems |
| VerfasserIn |
J. E. Barrett, M. N. Gooseff, C. Takacs-Vesbach |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 13, no. 12 ; Nr. 13, no. 12 (2009-12-10), S.2349-2358 |
| Datensatznummer |
250012069
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| Publikation (Nr.) |
 copernicus.org/hess-13-2349-2009.pdf |
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| Zusammenfassung |
| 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. |
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