TY  - JOUR
A1  - Lorek, Andreas
A1  - Wagner, Norbert
T1  - Supercooled interfacial water in fine-grained soils probed by dielectric spectroscopy
JF  - Cryosphere
N2  - 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.
KW  - Wasser
KW  - Eis
KW  - Impedanzspektroskopie
KW  - Boden
KW  - initerfacial water, liquid-like water, Mars, dielectric spectroscopy, ice, permittivity, JSC Mars 1, Bentonite, Birchak, CRIM, plate capacitor, monolayer, Hamaker constant, soil
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170425-31490
UR  - https://e-pub.uni-weimar.de/opus4/frontdoor/index/index/docId/3184
SP  - 1839
EP  - 1855
ER  - 
TY  - JOUR
A1  - Lorek, Andreas
A1  - Wagner, Norman
T1  - Supercooled interfacial water in fine grained soils probed by dielectric spectroscopy
JF  - Cryosphere
N2  - 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.
KW  - Grundwasser
KW  - Eis
KW  - Impedanzspektroskopie
KW  - Boden
KW  - dielectric spectroscopy
KW  - planetary research
KW  - Soil
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170516-31840
UR  - http://www.the-cryosphere.net/7/1839/2013/tc-7-1839-2013.html
SP  - 1839
EP  - 1855
ER  -