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| Titel |
Effects of freezing on soil temperature, freezing front propagation and moisture redistribution in peat: laboratory investigations |
| VerfasserIn |
R. M. Nagare, R. A. Schincariol, W. L. Quinton, M. Hayashi |
| 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 ; 16, no. 2 ; Nr. 16, no. 2 (2012-02-15), S.501-515 |
| Datensatznummer |
250013179
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| Publikation (Nr.) |
 copernicus.org/hess-16-501-2012.pdf |
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| Zusammenfassung |
| There are not many studies that report water movement in freezing peat.
Soil column studies under controlled laboratory settings can help
isolate and understand the effects of different factors controlling freezing
of the active layer in organic covered permafrost terrain. In this study,
four peat Mesocosms were subjected to temperature gradients by
bringing the Mesocosm tops in contact with sub-zero air temperature while
maintaining a continuously frozen layer at the bottom (proxy permafrost).
Soil water movement towards the freezing front (from warmer to colder
regions) was inferred from soil freezing curves, liquid water content time
series and from the total water content of frozen core samples collected at
the end of freezing cycle. A substantial amount of water, enough to raise
the upper surface of frozen saturated soil within 15 cm of the soil surface
at the end of freezing period appeared to have moved upwards during
freezing. Diffusion under moisture gradients and effects of temperature on
soil matric potential, at least in the initial period, appear to drive such
movement as seen from analysis of freezing curves. Freezing front (separation front between soil zones
containing and free of ice) propagation is controlled by latent heat for a
long time during freezing. A simple conceptual model describing freezing of
an organic active layer initially resembling a variable moisture landscape
is proposed based upon the results of this study. The results of this study
will help in understanding, and ultimately forecasting, the hydrologic
response of wetland-dominated terrain underlain by discontinuous permafrost. |
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