Seismic anisotropy is a powerful tool for detecting the geometry and style of deformation in the Earth's interior, as it primarily reflects the deformation-induced preferred orientation of anisotropic crystals. Although seismic anisotropy in the oceanic upper mantle is generally parallel to the plate motion, the propagation direction of the fast shear-wave is oriented subparallel to the trench axis in several subduction zones. In this study, the distribution of seismic anisotropy in the mantle wedge is inferred from deformation mechanism: a lattice-preferred orientation and seismic anisotropy are generated by deformation via dislocation creep, but not by diffusion creep or frictional sliding. Based on the thermal structure beneath northeast Japan, deformation throughout most of the mantle wedge is inferred to be controlled by diffusion creep, and the region of dislocation creep is limited to a thin layer of 10-20 km thickness within a region of relatively high stress and low temperature located above the subducting plate and beneath the island arc crust. The variation of the seismic anisotropy in subduction systems is probably due to the change of active slip-system in olivine as a consequence of chemical and physical properties in the mantle wedge.
Water pollutions with toxic anionic species become the matter of the world wide concern. The cause of the water pollution is related to the mobility of elements on earth surface environment. Because the most important transfer media of elements on earth surface is water, the water solubility of elements is essential factor to determine the mobility. The important physico-chemical processes governing the water solubility are dissolution and formation of minerals and adsorption and desorption of elements to mineral surfaces. The fact that the abundance of dissolved trace elements in natural waters is usually lower that what might be expected based on the solubility products of associated minerals is primarily attributed to adsorption of the trace elements onto mineral surfaces. In order to predict the behavior of toxic anionic species on earth surface, it is essential to understand adsorption processes of anionic species on mineral surfaces quantitatively. In present paper, I introduce the studies that focus on the adsorption processes of arsenate on minerals by means of field observation and theoretical consideration.
Smectite-based film “Claist®” was developed. Layered smectite crystals are orderly densely stacked and added organic polymer acts as a binder. Purified bentonite, and synthetic smectite were used because of their good film formability. The film has superior heat-resistance and gas barrier performance. Transparent films were also successfully made from synthetic smectite and transparent organic polymer. The films are hopeful for electric devices including display, hydrogen gas tight sheet, solar cell back sheet, gasket and packing, functional wallpaper, and so on.