1998 Fiscal Year Final Research Report Summary
Study on estimation of soil water status by using microwave remote sensing
| Project/Area Number |
09660259
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Irrigation, drainage and rural engineering/Rural planning
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| Research Institution | Kagawa University |
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Principal Investigator |
ISHIDA Tomoyuki Kagawa University, Department of Agriculture, Associate Professor, 農学部, 助教授 (40184535)
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| Project Period (FY) |
1997 – 1998
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| Keywords | BOUND WATER / DIELECTRIC RELAXATION / COMPLEX PERMITTIVITY / CLAY / INTERFACIAL POLARIZATION |
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| Research Abstract |
The dielectric behavior of moist kaolinite, montmorillonite, allophane and imogolite was examined with a time domain reflectometry method in a wide frequency range of 10^3 - 10^<10> Hz. The peak locates at approximately 10 MHz. It is concluded that the structure of bound water differs between the sheet silicate and amorphous minerals. The interfacial polarization in the diffuse double layer was found only in montmorillonite and kaolinite samples, indicating that the Maxwell-Wagner and surface polarization effects cannot be regarded as a general mechanism responsible for the interfacial polarization of all the clay-water systems.
Dielectric measurements were performed on silica, alumina and silica-alumina gel suspensions. For all the gels, a relaxation peak due to bound water was observed. This peak locates around 1-10 MHz. The silica and alumina gels have a different bound water structure The silica-alumina gels exhibit two different peaks other than the peak of bulk water. It is suggested that both peaks are caused by the orientation of bound water molecules.
Dielectric measurements were performed on montmorillonite, allophane and imogolite suspensions under various pH conditions. Allophane has two peaks, indicating that its peaks are very similar to those of silica-alumina eels. Imogolite has only one peak. The relaxation strength of montmorillonite is greater than that of the other two clays. For all the clays, the relaxation strength depended on the pH.A change in the relaxation strength is explained in terms of the different network structures of the clay particles. It is suggested that bound water influences on the network structure formation.
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Research Products
(6 results)
