An evaluation framework for policy scenarios related to wood resource flow under long-term social change in Japan was developed. Then, change of wood resource flow and life-cycle CO₂ emissions reduction effects in residential, paper and wood energy sectors until 2050 were evaluated for various policy scenarios such as housing service life extension, wooden house increase or decrease, enhancement of recycled paper usage and bio-ethanol production. In the case of housing service life extension and bio-ethanol production policy scenarios, CO₂ emissions reduction effects were estimated to increase in both the residential and wood energy sectors and the amount of CO₂ emissions reduction from no policy scenario in 2050 reached nearly 4% of domestic CO₂ emissions in 1990.

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Carbonization and gasification processes are being developed in Japan to convert sewage sludge into fuel. It is necessary to tailor these technologies in terms of thermal recovery, local conditions, costs, and hazardous materials. Therefore, we investigated the effect of the pyrolysis temperature on the composition and heating value of char, tar, and gas, and the rate equation for the production of hydrocarbon gas. We were able to recover about 70% of the low heating value of dry sludge cake as char at 573K. By contrast, at over 773K, both the yield and low heating value of char were decreased, and the recovery from char was inefficient. At 1173K, we were able to recover only about 36% of the low heating value of dry sludge cake as gas. The production of H₂ and CO was increased with steam, and we were able to recover about 50% as gas.

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The health hazard caused by asbestos has become a serious social issue, and thoroughness in prevention measures of scattering asbestos becomes an important problem. Complete removal or careful asbestos containment procedures will be necessary, if sprayed asbestos are found. Asbestos containment is performed in order to reduce or eliminate the risks of asbestos exposure on human health. In asbestos containment, it is very important to confirm the spraying condition. In this study, it proposes the method of confirming the spraying condition by using the wide-band ultrasonic wave.

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Accurate prediction for gas transport parameters, soil-gas diffusivity and air conductivity, is important to quantify methane emission from wetland. However, only limited measurements of gas transport parameters are available for peat soils. In this study, undisturbed soil cores were collected from a peat soil profile at the Bibai wetland, Hokkaido. Simultaneous measurements of volume shrinkage, soil-water retention curve, and gas transport parameters were carried out. The peat samples showed remarkable shrinkage following drainage, and the soil-gas diffusivity and air conductivity were greatly affected by pore structure change due to shrinkage. Examining pore structure indexes and water drainage from inner- and outer-pores in peat soil, changes in gas transport parameters can be classified into three stages with increasing in pF.

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Our investigations in an estuarine tidal flat system of Nanakita River showed that the sediment organic content fluctuated continuously in stations where macrobenthos biota had been maintained stably for a few decades. This suggests dynamic equilibrium of sediment organic content in those stations. The cycle period and range of the variations in sediment organic content and its physical mechanisms differed distinctly between non-cohesive and cohesive sediments. At stations where sediment resuspension and wash-outs of sediment organic matter at spring tides did not occur regularly, the sediments were cohesive, hence stably maintaining higher sediment organic contents compared with stations with non-cohesive sediments. Based on these results, we proposed conceptual models for processes maintaining the dynamic equilibrium of sediment organic content and the relationship between frequency of sediment resuspension and long-term averages of sediment organic content. It is expected that the conceptual application of dynamic equilibrium of sediment properties enhances restorations of tidal flat ecosystems.

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This study was performed to understand the actual conditions of self pollution at the downstream of a dam and discusse its mechanism. When periphyton communities at the downstream of a dam were compared with communities at the upstream of a dam, the differences were especially remarkable during a summer time. At the upstream site, the communities were formed which were dominated cyanobacteria and a little biomass. At the downstream site, the diatom predominated communities were formed and the biomass were significantly much than the periphyton at the upstream site. In addition, at the downstream site, the phenomenon that a part of periphyton community detached and floated in the water were observed. These results suggested that the organic matter produced by periphyton were accumulated on the reverbed and loaded to the stream water. It was guessed that the self pollution at the downstream site were occurred because of not only a decline of flood frequency but also a decline of a grazing pressure by the fish.

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The hybrid-type vibration isolation wall using gas cushions is a new technology to isolate against the propagation of environmental ground vibrations. This type vibration isolation wall is one of the vibration isolation methods by constructing the open trench-type wall of the triple structure composed of gas cushions, soil cement walls and steel sheet piles in the ground. This vibration isolation wall can be expected to have same effect with open trenches that is considered to be the most effective means.
Firstly, the authors described in this paper that the new applicable construction method when the ground construction conditions are not severe. Then, the vibration isolation performance of this hybrid-type wall is examined by field measurements with a vibration exciter and the railroad traffic vibration. Also, the vibration isolation mechanism is confirmed by the two dimensional FEM analysis.

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The purposes of this study were examine the effect of spread and press wood chip from plant waste on weed control, investigation of the mechanism of weed control and suggestion of effective method for weed control. We made 16 experimental sites from combinations factors that removing surface soil conclude root of weed or not removing before spread wood chip, thickness of wood chip layer (4 levels), spraying sand to surface of wood chip layer or not and investigated growth of weed, soil environment, the characteristics of wood chip decomposition. It was thought that weed had been controlled by not only cut off light but also heat from fermentation of wood chip, decreasing oxygen. The most effective method for weed control was suggested that not removing surface soil, over 200mm of wood chip thickness and spraying sand to surface of wood chip layer.

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One of the major environmental issues we face today is global warming, and specifically, an urban heat island phenomenon. The Japan Highway Public Corporation has made many attempts to mitigate this problem by creating environmentally-friendly parking and service areas. For the first time in Japan, a water-retentive pavement consisting of a ground granulated blast-furnace slag with embedded water supply equipment was implemented in the Hasuda service area of the Tohoku Expressway. The result is a pavement surface temperature that is consistently at least 10 degrees lower than it would be with ordinary pavement. The cooling effects vary according to water supply methods and the ratio of retained water.

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