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田崎, 和江 ; Tazaki, Kazue
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金沢大学理工研究域地球社会基盤学系
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田崎, 和江 ; Tazaki, Kazue
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金沢大学理工研究域地球社会基盤学系<br />Our atmosphere, oceans, sediments and soils, all reflect major or minor influences of the biosphe
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re. In the sediments, erosion of the topsoil, complex mixture of clay minerals and carbon compounds, is one of crisis in the world economy. Clay mineralogist concerned with the sediments and mineral deposits must understand weathering processes plus microorganisms in detail. Bacteria must be important in all transport processes of elements between sediments and water systems. In the atmosphere, fine particles, such as clays, loess and fly ash produced by combusion of fossil fuels are biologically and chemically recycling in our planet. The consequences of a massive increase in the use of coal or other fossil carbon sources give the global atomospheric increase of CO2N2O, acid gases, etc.Modern electron microscopic techniques and the new array of computer surface techniques, ESCA, Auger, SIMS, etc. have made it possible to see Å level structures, and chemistry of the fine particles. Examples of such fine mineralogical particles in the surface environment are described in this paper.
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田崎, 和江 ; 森, 忠洋 ; 野中, 資博 ; 野田, 修司 ; Tazaki, Kazue ; Mori, Tadahiro ; Nonaka, Tsuguhiro ; Noda, Shuji
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金沢大学理工研究域地球社会基盤学系<br />Concrete sewer pipe was heavily corroded by sulfate which was produced by sulfur oxidizing bacter
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ia in the Ohmuta region of Japan. The corroded materials were studied mineralogically to gain a better understanding of the corrosion mechanism. The formation of jarosite KFe3 (SO4) 2 (OH) 6, as a result of reaction between sulfate and hydration products of portland cement, were found in the most corroded part of concrete sewer pipe. The sulfate-generated corrosion is grouped into several zones on the base of differences in the mineral formation of secondary products:Zone A & B; Jarosite formation zone, Zone C; Fe-rich zone,Zone D; gypsum formation zone, Zone E; Fe-rich zone,Zone F; Cracking zone, Zone G; Fresh concrete zone.Zones A-E in the corroded parts include expansion, loss strength and stiffness and disintegration, whereas Zones E and F show cracking and brown rim stained with iron oxides. In Zone G, ettringite crystals are formed under conditions of high pH. Since hydrated cements containing considerable amount of large ettringite crystals show high strength but no expansion.In order to evaluate the relative effects of corrosion of concrete, the rates of K-feldspar dissolution have been analized by EDAX-step scanning. The dissolution process of K-feldspar was observed that Al and K contents were rapidly decreased near rim, within 2μm region, whereas Fe content was increased.The results of these analyses indicate that the effect of K component from K-feldspar dissolution is important factor to form jarosite at pH of 3.5-4.0. The dissolution mechanism of K-feldspar and the addition of Fe component are changed significantly due to the corrosion of concretes.
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田崎, 和江 ; Tazaki, Kazue
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金沢大学理工研究域地球社会基盤学系<br />By using a transmission electron microscope (TEM) equipped with an energy dispersive electron-mic
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roprobe analyzer, genetical relationships between micro-morphology and chemical composition of kaolin minerals were investigated.The TEM observation revealed that the kaolinite specimens, which show a 7Å basal reflection in X-ray diffraction diagram, are commonly mixtures of particles with various morphology such as film, hexagonal plate and long tube (Table 1). The chemical compositions of these kinds of particles are different from one another as shown in Fig. 1 and 2. Triangular plot of SiO2, Al2O3 and ΣFeO of the Kibushi clay (No.7 in Fig.2) shows limited chemistry of each morphology with slight overlap that SiO2 content of the film of indefinite primitive form is less than that of hexagonal plate, whereas, ΣFeO is lower in the latter. However, the chemistry of the Austria kaolin (No.5 in Fig.2) shows the reverse trend in SiO2 content. This reverse trend might suggest the difference in the source material.
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堀坂, 明生 ; 田崎, 和江 ; 野田, 修司 ; Horisaka, Akio ; Tazaki, Kazue ; Noda, Shuji
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金沢大学理工研究域地球社会基盤学系<br />Biomineralization of pyrite has been found inside of diatom cell in sludge (Hedoro) of Lake Nakau
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mi. Direct observations by using SEM equipped with BSI, and EDX revealed formation processes of microbial pyrite. In sludge (0-2.5cm depth) numerous diatoms (Coscinodiscus nitidus) form several framboidal pyrite (5μm diameter) inside cell. The framboidal pyrite are coated by thin film compose of Fe and S that is the almost same composition as pyrite. The BSI image shows slightly weak dense on the surface of film suggesting presence of organics. Chemical composition of normal diatom cell is alomst pure Si. On the other hand, the diatom forming pyrite shows elementary differences between girdle and valve. Chemistory of the girdle shows Fe and S elements indicating substitution of Si. Quantity of Fe and S increases outside to inside of girdle. The formation process of framboidal pyrite inside cell is as follows: The first step is formation of spherical FeS mineral (pyrrhotite), next step is a mixture of pyrite and pyrrhotite by adding S and dehydration. Then the mixture makes a rough framboid. Hexahedron and pentagonal dodecahedron are the characteristic crystal habits of framboidal pyrite in diatom. Some framboidal pyrite coated by thin film of clays with organics. Dozens of framboid aggregate form a ball 50μm in diameter. Formation of framboidal pyrite in diatom should be initially controlled by organics of biofilm.
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田崎, 和江 ; 荒谷, 美智 ; 矢野 , 倉実 ; 海保, 邦夫 ; 野田, 修司 ; Tazaki, Kazue ; Aratani, Michi ; Yanokura, Minoru ; Kaiho, Kunio ; Noda, Shuji
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金沢大学理工研究域地球社会基盤学系<br />Spherical heating-shocked mica clays are found in Cretaceous-Tertiary (K-T) boundary sediments in
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the eastern district of Hokkaido, northernmost Japan. The K-T boundary sediments contain relatively high Ir concentrations suggesting an asteroid struck the Earth and caused mass extinctions at the end of the Cretaceous. Foraminifera are totally absent in the grayish black clay. Mineralogical investigations of the claystone have been carried out by the use of X-ray powder diffraction, high resolution electron microscope, energy dispersive spectrometer and heavy-iron Rutherford scattering. Singularity of clay minerals of a continuous stratigraphic section spanning the K-T boundary reveals that the spherical interstratified clay in < 2μm fraction are largely decomposed. The spherical clay shows characteristic stacking disorder of 14Å, 10Å, 7Å phase, which is suggested to be heating eventsin the K-T boundary.
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田崎, 和江 ; Tazaki, Kazue
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金沢大学理工研究域地球社会基盤学系<br />Imogolite was studied by the scanning electron microscope. Imogolite which examined was separated
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from Kurayoshi pumice beds. The samples were dried successively in the sealed vessel at critical point of CO2. This drying method exceeds in preservation of natural surface of imogolite than that of air-drying.The form of imogolite was observed as fibres-like threads. The threads were curled and entangled forming nets which were piled up one above the other. The diameter of these threads ranged from 0.03 to 0.06 μm.
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田崎, 和江 ; 田崎, 耕市 ; 小松, 正幸 ; Tazaki, Kazue ; Tazaki, Koichi ; Komatsu, Masayuki
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金沢大学理工研究域地球社会基盤学系<br />Various volcanoclastic and sedimentary rocks were dredged from southern part of the Mariana Trenc
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h by 17th cruise of R/V D. Mendeleev. Clay mineralogical investigation of seventeen samples made clear the presence of abundant montmorillonite and a trace of chlorite. Phillipsite is the most abundant zeolite. Clinoptilolite and chabazite are also recognized.Occurrences of montmorillonite and phillipsite from deep sea sediments of the Pacific Ocean have been well established.
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田崎, 和江 ; 野中, 資博 ; 森, 忠洋 ; 野田, 修司 ; Tazaki, Kazue ; Nonaka, Tsuguhiro ; Mori, Tadahiro ; Noda, Shuji
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金沢大学理工研究域地球社会基盤学系<br />Mortar bars are exposed to H2S gas (25-300ppm) for 10 months at 12-30C°. Sulfate-generated deteri
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orations in the mortar bars include expansion, cracking and disintegration. The heavily corroded mortar bar produced gypsum, calcite and secondary ettringite with a trace amount of barite. The secondary ettringite shows the same chemistry as the primary ettringite, but the morphology is quite different from the primary one. Ettringite crystals with sharp point, 10-20μm long, are primary formed during the hydration of mortar bar, whereas small lath-shaped crystals, about 3μm long as observed by SEM are high concentration of hydroxyl ions. Gypsum, calcite and the secondary ettringite are formed step by step under acidic condition. The iron oxides layer is presented significantly between corroded and un-corroded zones which is the same process of deterioration on portland cement concrete.
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田崎, 和江 ; Fyfe, W. S. ; Tazaki, Kazue
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金沢大学理工研究域地球社会基盤学系<br />Alkali-feldspar in an alkaline rock shows evidence for the formation of iron rich primitive clay
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precursors in the earliest weathering stage. High-resolution TEM with EDAX, electron diffraction patterns and lattice images clearly show the decomposion of Alkali-feldspar and growth of primitive sheet structure mineral. The primitive clay precursors consist of Si and Fe with small amount of K and Al. These precursors with 14-20 A spacing show diffuse rings electron diffraction pattern due to low crystallinity and random orientation. The diameter of precursors is 150-200 A.
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