The macroscopic behaviors of soil ground such as compression and deformation consist of the integrated microscopic behaviors of soil particles and pores such as movement and entrapment. Resultant compression and deformation of soil ground are mlutiple behaviors, because of the wide variation for soil particle shape, size and type, a charge and chemical action of clay particles and the heterogeneity for structure of pore size distribution. The conventional consolidation tests were carried out to investigate the consolidation characteristics for sand-clay mixed soils, and their pore size distributions and microstructures were examined by using mercury-intrusion porosimetry (MIP) and scanning electron microscope (SEM). As a result, it was found that small intra-aggregate pores were not compressed until all macro pores have been collapsed due to the consolidation proceeding, and the largest interaggregate pores were the first affected.

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Complexation reactions of environmentally important oxyanions such as nitrate (NO_3), sulfate (SO_4), phosphate (PO_4), and arsenate (AsO_4) on brucite (Mg(OH)_2) surfaces were investigated to understand the role of brucite in immobilization of hazardous oxyanions at hyperalkaline environment. The impacts by surface complexation reactions on solid state properties of brucite were also evaluated. Synthetic brucite was used for the adsorption and post-adsorption experiments as a starting material. In the adsorption experiments, the synthesized brucite was reacted with various oxyanion solutions with concentration up to 100μmol/L for 12 hours at 25 degrees Celsius. The obtained adsorption isotherms showed that brucite had the selectivity for oxyanions during adsorption with the affinity sequence being NO_3<SO_4≪PO_4<AsO_4. To distinguish the adsorption mode (inner-sphere complexes or outer-sphere complexes) of these oxyanions, zeta potential measurements were performed. For the brucite with NO_3 and SO_4, there is little change in the zeta potential in the pH range 10.5 to 10.7. However, the zeta potential of brucite with adsorbed PO_4 decreased at pH 10.6 when the adsorbed amounts increased. The zeta potential of brucite with adsorbed AsO_4 also decreased with increasing amounts adsorbed. This shows that PO_4 and AsO_4 were attached to the brucite surfaces by a strong interaction additional to the electrostatic balance. Isoelectric point (pH_<IEP>) of the brucite was also determined by zeta potential measurements. The pH_<IEP> of brucite with NO_3 and SO_4 was close to 13.0. On the other hand, pH_<IEP> of the brucite with PO_4 was approximately 10.7 and that of the brucite with AsO_4 was close to 10.2. These results indicate that NO_3 and SO_4 presented as diffuse ions on the brucite surfaces. In contrast, PO_4 and AsO_4 formed inner-sphere complexes by a ligand-substitution reaction on the brucite surfaces. It took notice of influences on the solubility of brucite caused by the formation of inner-sphere complexes. The saturation indexes (SI) of brucite with PO_4 and AsO_4 have a range from 0.24 through 0.39, and were lower than that of sample without the oxyanions. The decreasing in SI indicates that the solubility of brucite is decreasing by the inner-sphere complexes with PO_4 and AsO_4. Therefore, it implies that the adsorption reactions of PO_4 or AsO_4 induced the notable decreasing in the solubility of brucite itself. It is revealed that the formation of inner-sphere complexes on the brucite surfaces contributes to the stabilization of brucite as well as the decreasing mobility of these oxyanions. Consequently, the adsorption mode of anions on brucite should be determined by chemical properties inherent in the elements; oxyanions with low ionic potential have a tendency to form inner-sphere complexes with brucite surfaces.

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Three kinds of zeolites with different crystal structures with the composition of Li_2O・Al_2O_3・2SiO_2・xH_2O were used as a precursor of β-eucryptite. The difference in the zeolite structures resulted in the difference in thermal-transformation processes to β-eucryptite from the zeolites. Li-A (BW) zeolite gave rise to the following thermal-transformation without the formation of a intermediated amorphous phase: Li-A (BW)→anhydrous ABW→γ-eucryptite→β-eucryptite. In Li-exchanged zeolite A, the zeolite structure decomposed at 720℃, and simultaneously formed mainly β-eucryptite, along with a small amount of γ-eycryptite. Li-exchanged Linde F zeolite became an amorphous material at 300℃, and then generates γ-eucryptite and β-eucryptite from the amorphous phase at 720℃. In all of Li type zeolites, a single phase of β-eucryptite was finally obtained by heating above 1000℃.

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Acid precipitation is caused mainly by the oxidation of atmospheric SO_2, NO_2 and C0_2. Aerosol particles containing these oxides, fly ash and mineral dust are cycling on a global scale. NO_2 concentration, rainwater and air dust in the atmosphere have been investigated by electron microscopy. Rainwater sampled (May 29^<th> 2008) from the solitary island of Hekura-jima (Wajima, Ishikawa Prefecture), located in the Sea of Japan, was strongly acidic (pH 4.8) and high in electrical conductivity (EC). This is despite the fact that Hekura-jima has no industry or cars and as such, is believed to be less polluted than other areas in the same prefecture. NO_2 concentrations measured at Hekura-jima (May 28-29^<th> 2008) and at the uninhabited island of Ohshima, in the city of Wajima, Ishikawa Prefecture, (July 22-23rd 2008) indicated quite low values. The acid rain, sulfur materials and mineral dust were found deposited on the surfaces of black pine trees located to the northwestern side of Hekura-jima, suggesting that these atmospheric pollutants originate from surrounding countries rather than from local sources. Scanning electron micrographs of aerosol dust sampled from Hekura-jima on May 27-29^<th>, 2008, showed evidence of atmospheric pollutants of fly ash, sulfuric mineral dust of gypsum and pollen from pine trees. On this basis, it can be assumed that air pollution occurred frequently not only in industrial areas but also in certain solitary and uninhabited islands of Japan. White and green microbial mats were observed on tuff rock located at the uninhabited Ohshima Island suggesting that acidic rainwater that had seeped into the rock was subsequently exuded from cracks within the rocks. X-ray powder diffraction (XRD) and X-ray fluorescence (XRF) analysis of the green microbial mats collected from Ohshima Island showed mainly amorphous Al-Si materials. Optical and transmission electron micrographs of the green microbial mats showed various living microorganisms of diatoms and filamentous cyanobacteria within the granular particles. The living microbes clearly demonstrated a blue fluorescence under UV irradiation. Spherical materials were found inside the filamentous cyanobacterial cells, and chlorophyll was found inside the cocci cells of the microbes. On the other hand, opaque spherical materials of fly ash coexisted with microbes within the diatom cells. An energy dispersive X-ray (EDX) analysis of the fly ash indicated that the main components were Al and Si. In addition, it was found that the granular materials were also composed of Al and Si. The abundant diatoms and filamentous microbes associated with the submicrometer Al-Si chemical compositions of the particles suggested an environmental co-ecosystem comprised of green microbial mats and Al-Si bio-clay mineralization. Environmental interactions between the aerosol particles, rainwater, tuff rock, and microorganisms at the uninhabited Ohshima Island showed a particular natural circulatory system. The diatoms, cyanobacteria and silicate bacteria were found to trap and feed on the mineral dust of Al-Si particles and fly ash collected from the ecosystem of the green microbial mats. The amorphous granular particles of mineral dust and fly ash have a correlation with microorganisms in which they act as carriers of atmospheric pollutants. These particles also play an important role in the environmental purification ability.

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