Technologies for the effective use of coal ash generated from coal power plants as construction materials have been making great progress due to growing interest in achieving a sustainable materials-cycling society. However, among the different kinds of coal, which is the raw material of coal ash, there are those that elute hazardous substances in excess of the environmental soil quality standards. To control the elution of such hazardous substances, coal ash is solidified. There are few examples which have investigated change in the amount of hazardous substance elution, or intensity over a long period of time with respect to coal ash solidified with cement. Thus, the authors have been continuously measuring the strength of embankments made from solidified coal ash and the elution quantities of hazardous substances. Such measurements show that, in some cases, the strength of solidified coal ash decreases in the long term. It is also found that solidification can lower the levels of some hazardous substances to below the environmental standard value. However, it is also found that even with solidification, elution quantities of some of hazardous substances can exceed the standard value over time.

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The serious nuclear disaster in the Fukushima Daiichi nuclear energy plant of the Tokyo Electricity Power Company was occurred by the tsunami which was caused by the Great East Japan Earthquake on March 11, 2011. The radioactive materials emitted by the disaster were widely diffused in and around Fukushima prefecture including the Pacific Ocean by wind, rain and a flow of river. It can’t be always said that there is no risk of the condensation of radioactive materials in human’s body by ecological chain if fish take in radiation in the ocean contaminated by the radioactive materials. However the effective decontamination methods of the radioactive materials are not developed and the decontamination is less-advanced. The establishment of a new decontamination method is urgent need and indispensable in light of disadvantageous effect on ecological system. Thus, in this study, it is aimed to establish a new decontamination technology of radioactive materials deposited on seabed or lake bed. In particular, the new adsorption material which can adsorb radioactive materials is developed and the new method which can move them from the bottom sediment is proposed. The results obtained from various tests with or without the water circulation and the adsorption material indicate that the water circulation is effective and that the adsorption material has a great deal of potential in the decontamination of radioactive materials. It is expected that the proposed method and the developed adsorption material are efficient to remove radioactive materials from seabed or lake bed when they are expansively applied to the real decontamination.

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Large amounts of radioactive materials were spread over a wide range by the accident of Fukushima Daiichi nuclear power plant occurred on March 11, 2011. Currently, the decontamination of radioactive materials discharged by this accident is urgently needed. However, the efficient and effective decontamination technology is not established. The current state is that the completion of final decontamination is nowhere in sight because the disposal volume is enormous. It is necessary to achieve the extraction of the cesium that firmly fixed to the clay mineral in soil and the volume reduction of the disposal materials so as to base our prediction on the decontamination. The authors focus attention on the fact that the cesium is solubility and exists as a monovalent cation in the solution. Through the fact, the method that the cesium ion in soil migrates to the cathode plate connected with the negative side if a DC power supply due to electrophoresis and is captured by the adsorbent placed between the soil and the cathode plate is proposed. First, in this study, the test with a small chamber was conducted to examine the extraction characteristic of cesium and the adsorption property of an adsorbent material. Secondly, the adsorption property of the adsorbent material for cesium through the electrophoresis adsorption test was investigated by more practically test with a large-scale chamber which is extended from the test with a small chamber. From the test with a small chamber, it is turned out that there is not most changes in extraction characteristics even if the passage of time is changed, and that the used adsorbent has a very high adsorption ability. From the test with a large-scale chamber, it is found that the adsorption effect of the large-scale test is inferior to the small one due to the decrease of energizing performance.

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This paper presents a case history of behavior during a series of pumping tests in an alternated multi- aquifer-aquitard system in Tianjin, China. The groundwater system at the test site is composed of a phreatic aquifer and three confined aquifers. Three groups of singe well pumping tests were conducted in aquifers to obtain the hydrogeological parameters of aquifers and to investigate the hydraulic connection between aquifers. Test results show that there is hydraulic connection between aquifers. Moreover, analytical method is employed to analyze hydrogeological parameters. The analytical solution using Dupuit equation was performed for phreatic aquifer and Hatush-Jacob and Cooper-Jacob method was conducted for confined aquifers.

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Excavated soils and rocks generated from construction works in Japan sometimes contain heavy metals derived from nature. Without proper treatment, these soils will generate hazardous leachate and cause environmental contamination. Sorption layer method is a newly developed technology which has a potential to be an economical countermeasure. It utilizes a permeable soil layer with sorption capacity lying beneath piled soil and rock in embankments to retain the chemicals of concern dissolved in the leachate, thus making the effluent meeting the environmental standard. In this study, the performance of sorption layer by mixing decomposed granite soil with Ca/Mg composite immobilizing agent is discussed. The mechanical, hydraulic and sorption performances of soil-immobilizing agent mixture affected by different mixing ratio and curing period is evaluated. Experimental results showed that curing increase the unconfined compressive strength of the mixture. Higher immobilizing agnet content exhibited higher sorption capacity.

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Desertification is a kind of land degradation phenomena which can be caused by natural or artificial environmental problems. Especially, Asia is considered to be highly vulnerable to desertification than other area. Authors have been trying to develop the measures of anti-desertification which is sustainable and with highly added value. In order to accomplish this purpose, licorice (Glycyrrhiza uralensis Fisch.), a kind of medical herb grows natively in Chinese and Mongolian arid region, was experimentally planted in Mongolian arid area. It is one of the most demanded medicinal herbs in Japanese pharmaceutical industry, but numbers of native licorice in these regions are decreasing due to several causes. Authors developed Greening Soil Material (GSM) as one of the effective methods to plant licorice where once was habitat of licorice. It is pipe-shaped with more than 10 times higher water and nutrient holding capacity compared to the deserted ground. The experimental research using GSM has been conducted in Southern Mongolia.###From the results of past experimental study, important factors for survive and healthy growth of licorice in arid area were revealed: volume, water content, and calcium content in GSMs. In order to suggest the suitable conditions for survive of licorice in its non-habitat area, this paper presents the relationship between survival ratio of licorice and volume of GSMs, water content of GSMs, and calcium content of GSMs and quantifies these relationships

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Dredged soils from navigation channel or anchorage area have been used in reclamation of artificial intertidal flats in Japan. Immediately after the reclamation, because the dredged clay filled in the intertidal flat has not consolidated, a safety assessment system is strongly required to avoid depression of foot into an extremely soft soil at a place where sand capping is significantly thin. In addition, temporal variation of the dredged soils filled in the intertidal flats has not been clarified yet. In this study, a follow up research at an artificial intertidal flat in Tokuyama-Kudamatsu Port, Yamaguchi, Japan, was periodically conducted for several years since its completion of reclamation in 2008. Shear wave velocity obtained by MASW in the extremely soft sediments was only 25 m/s. Gradual increase with elapsed time in shear strength of dredged soil layer was mostly caused by chemical bonding (thixotropy effect) rather than densification (consolidation). Because MASW can describe both the thickness of sand capping and softness of the dredged soils, this technology is useful to assess the safety of artificial intertidal flats.

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