In order to clarify the effect of daily cover soil on moisture movement in a solid waste landfill, water permeation experiments were carried out using large two-dimensional lysimeters in which inclined cover soil layers were constructed, and the effects were examined by unsaturated water flow analysis.
It was proven that the moisture movement was uneven horizontally because of the existence of inclined cover soil layers, and rainwater permeation through these layers to the landfill waste was impeded. It was demonstrated that the unevenness of horizontal permeation decreased as the slope of a cover soil layer became gentler. This suggests that uneven permeation could be mitigated by the proper positioning of inclined soil layers in the landfill waste layers.

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Fukuoka Prefecture operates a program for the certification of recycled-material products in order to identify which ones are eco-friendly and distribute them to the public. This study aims to estimate the effects of such a program in terms of the amount of reduction for final waste disposal and carbon dioxide emissions. It was confirmed that the certified products reduced the amount of final waste by as much as the total amount of waste disposed of in Fukuoka Prefecture in the year 2005, while only a minor amount of reduction in CO₂ emissions was found as a result of these products. The products have been divided into three categories : (1) products that are effective in the reduction of waste disposal ; (2) products that are effective in reducing CO₂ emissions ; and (3) products that are neither effective in reducing waste disposal or CO₂ emission amounts. As of yet, none of recycled-material products much effective in both waste disposal and CO₂ emission reductions have been developed or given certification. All the products had more or less positive effects in both types of reduction, which implies that the policies being promoted in this materials recycling program do not conflict with those related to the issue of global warming.

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Chemical treatment with liquid chelating agent is a common method to restrain leaching of heavy metals from melting furnace fly ash. However, the long-term stability of the metal chelate compounds in the treated fly ash could be a potential problem.
In this research, persistence of the metal chelate compounds in the samples excavated from an eight-year-old landfill site was evaluated by the n-butyl acetate extraction method. Concentration of metals in leachate by JLT-13 leaching test and in effluent of the landfill was measured. The research result shows that the persistence ratio of the lead chelate compound was very low. The extraction ratio of excavated samples from the landfill was equal to or less than 10% of the extraction ratio of the samples right after the treatment. Therefore, it is possible that the lead chelate compound was degraded after being buried in the landfill. However, lead concentrations in both the leachate by JLT-13 and in effluent water from the landfill were very low, with the maximum value of 0.031mg/L. The results from the pH-dependence test indicate that lead was transformed into some chemical compounds. These chemical compounds are very hard to dissolve, even in a strong alkali solution.

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With the aim of establishing a convenient and accurate method for monitoring floating marine debris that is not easily degradable, we investigated the various articles of waste in the litter that accumulates on the beaches of Tottori. This is an area where litter from every Asian Pacific region is supposed to drift ashore. Surveys were carried out a total of eight times between the years 2005 and 2008 on a 500m strip for each different beach. The surveys showed that the different types of articles were unevenly distributed, and both the kinds and numbers varied greatly. Unfortunately, the total amount of any particular item found in the accumulated litter was not proportional to the total amount of what was washed ashore. It became necessary, therefore, to monitor limited items periodically, while removing them. In selecting items, attention was paid to their individual characteristics, such as if they were prone to sinking, if they were stable in water, or if they were region-specific items. We classified the articles into four major groups : consumer goods, fishery-related items, agricultural and medical implements. The consumer goods were further divided into : articles for indoor use, outdoor use, or both indoor and outdoor. In this grouping, drink bottles were classified as indoor and outdoor use, for example, according to their volume and not their composition. As the source for this kind of litter is common to every region, periodical monitoring of the items that appear often for each group is a practical method for surveying.

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