Groundwater polluted with gasoline was found out in Kumamoto city in 1991. Benzene and alkylbenzenes, components of gasoline, in the polluted groundwater were determined by the employment of GC/MS. The polluted area was about 50×50 m² in February, 1991, and rapidly extended to 100×200 m² after a half year. The removal of the polluted groundwater was started in December 1991, resulting in the reduction of the concentration of gasoline in the groundwater in July, 1992.
The hydrocarbon ratio in the gasoline was found to be modified in the process of flowing in the groundwater. The dye components in the gasoline, however, were not modified, and identical with those of the sampled gasoline in the polluted well. The above results indicated that a certain gasoline station was the source of groundwater pollution, and the method employed for analysis of the dyes was useful for various types of environmental pollution with gasoline.
The polluted groundwater denoted larger in ratio of benzene and alkylbenzenes than that in gasoline. Moreover, the vertical concentration of benzene and alkylbenzenes in the geo-materials was shown highest at the surface of groundwater. Furthermore, at the beginning of the pollution, the groundwater was mainly contaminated by benzene, i.e. a most soluble component of gasoline. These results suggested that most part of gasoline horizontally translocated on the surface of groundwater, and that some parts of the soluble component of gasoline, benzene and alkylbenzenes, extended in the flow of groundwater.

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Trichloroetylene in water was degraded photocatalytically by using thin-film TiO₂. The photocatalyst of the thin-film TiO₂ was prepared on the surface of quartz tubes by means of sol-gel process. The degradation reaction was studied by using the thin-film TiO₂ prepared under the different condition of the calcination temperatures. The blacklight fluorescent lamp and the low pressure mercury lamp were used for the illumination. Under the illumination of the blacklight fluorescent lamp, the TiO₂ of anatase accelerated the decomposition reaction rates about two times as fast as the TiO₂ of rutile. Under the illumination of the low pressure mercury lamp, the decomposition reaction of trichloroetylene proceeded without the photocatalyst and the addition of the TiO₂ of anatase accelerated the reaction a little further. No product of the degradation reaction was detected except CO₂ and HCl. The life of the thin-film TiO₂ photocatalyst was tested for six months intermittently and it was confirmed that the photocatalytic activity did not change during the experimental period.

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The surface analysis of the membranes used for advanced treatment of human excreta were examined in order to clarify the effects of membrane cleaning. The low desalting reverse osmosis membranes were used ; composit polyamide membranes, spiral wound type, the membrane area : 6.5m², desalting degrees : ca.50% (RO-1) and ca.30% (RO-2). In the treatment experiments the membranes were periodically cleaned with tap water, an alkaline solution, and an acid solution. The membranes after the cleaning with each solution were analyzed by refrection FTIR, EPMA and ESCA. In addition, the exhausted cleaning solutions were analyzed by GPC.
The results obtained by the analyses were summarized as follows : (1) both inorganic and organic fouling materials were removed effectively by the acid cleaning and this corresponded to the recovery of the water flux by the cleaning, (2) the organic fouling materials consisted of high molecular weight components (ca.6000 and ca.20000 daltons) such as polysaccharides and proteins, and (3) the complete removal of proteins was difficult even by the acid cleaning, because a little proteins remained on the membranes after the acid celaning.

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Method for the identification and determination of dibromoacetic acid (DBAA) in a chlorinated seawater have been studied. DBAA in a chlorinated seawater was concentrated by solvent extraction technique using diethyl ether followed by the methyl ester derivatization. The solution obtained was analyzed by GC/MS in electron impact ionization mode. The mass spectrum obtained from a chlorinated seawater was similar to that of a authentic compound of DBAA.
For the routine method of determining DBAA in chlorinated seawater, an electron capture detector gas chromatography preceded by the solvent extraction technique was applied to the analysis of chlorinated seawater samples. Results showed that DBAA was detected in the chlorinated seawater used in plants and a swimming pool. DBAA concentration in chlorinated seawater samples used in plants was proportional to that of bromoform, and the ratio of DBAA to bromoform concentration was calculated about 20%.

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