 |
| Titel |
Supercooled interfacial water in fine-grained soils probed by dielectric spectroscopy |
| VerfasserIn |
A. Lorek, N. Wagner |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1994-0416
|
| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 7, no. 6 ; Nr. 7, no. 6 (2013-12-06), S.1839-1855 |
| Datensatznummer |
250085186
|
| Publikation (Nr.) |
 copernicus.org/tc-7-1839-2013.pdf |
|
|
|
|
|
| Zusammenfassung |
| Water substantially affects nearly all physical,
chemical and biological processes on the Earth. Recent Mars
observations as well as laboratory investigations suggest that water
is a key factor of current physical and chemical processes on
the Martian surface, e.g. rheological phenomena. Therefore it is of
particular interest to get information about the liquid-like state
of water on Martian analogue soils for temperatures below
0 °C. To this end, a parallel plate capacitor has been developed
to obtain isothermal dielectric spectra of fine-grained soils in the
frequency range from 10 Hz to 1.1 MHz at Martian-like temperatures down to −70 °C. Two Martian analogue
soils have been investigated: a Ca-bentonite (specific surface of
237 m2 g−1, up to 9.4% w / w gravimetric water
content) and JSC Mars 1, a volcanic ash (specific surface of
146 m2 g−1, up to 7.4% w / w). Three soil-specific
relaxation processes are observed in the investigated
frequency–temperature range: two weak high-frequency processes
(bound or hydrated water as well as ice) and a strong low-frequency
process due to counter-ion relaxation and the Maxwell–Wagner
effect. To characterize the dielectric relaxation behaviour,
a generalized fractional dielectric relaxation model was applied
assuming three active relaxation processes with relaxation time of
the ith process modelled with an Eyring equation. The real part of
effective complex soil permittivity at 350 kHz was used to
determine ice and liquid-like water content by means of the Birchak
or CRIM equation. There are evidence that bentonite down to
−70 °C has a liquid-like water content of 1.17 monolayers
and JSC Mars 1 a liquid-like water content of 1.96 monolayers. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|