The total areas of the existing natural and reclaimed tidal flat in Ago Bay were estimated by multispectrum aerial picture analysis. Approximately 70% of the tidal flat and shallow areas have already been lost because of land reclamation and dyke construction. The sediment quality and characteristics of macrobenthos in the natural tidal flats (estuary, in front of and behind the dykes) were investigated in this study. The macrobenthos in the natural tidal flat in front of and behind the dyke was poor in organic matter, because these sediments were relatively oligotrophic in front of the dyke and hypertrophic behind the dyke. Thus it is considered that the reclamation by constructing the dykes was one of the major causes of the deterioration of the benthic ecosystem and decrease in the biological productivity of Ago Bay.

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A sensitive, selective and rapid analytical method was developed for the determination of 4, 6-dinitro-o-cresol (DNOC) and 2, 6-dinitro-p-cresol (DNPC) in environmental water samples by liquid chromatography/tandem mass spectrometry (LC/MS/MS). Trace amounts of DNOC and DNPC in water samples adjusted to pH3 were collected on an Autoprep PS-Liq@ cartridge (PS-Liq cartridge) at flow rate of a 50ml · min^-1 and then eluted with 5ml of acetonitrile. The targets were separated with a reversed-phase column (ODS-3, 2.1 mm x 150mm, and 5μm) and measured by mass spectrometry operated in the electrospray ionization (ESI)-negative mode. The method detection limit (MDL) was 0.24ng · l^-1 for DNOC and 0.49ng · l^-1 for DNPC. The method was then applied to the environmental water samples from Osaka Prefecture. The concentrations of DNOC were 2.1∼74ng · l^-1 and those of DNPC were n.d.∼43ng · l^-1.

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Human activities have a tremendous effect influence on the environment of enclosed coastal seas. Increased population and economic growth have caused increased pollution loads to those areas, leading to the degradation of water quality. Enclosed coastal seas are characterized by various factors and, accordingly, those factors should be properly considered in environmental management Those factors are classified to three categories: natural, socioeconomic and aquatic environmental factors. In this study, 25 enclosed coastal seas in Japan, in which 13 showed degradation and 12 showed improvements, have been subjected to discriminant analyses to determine the linear discriminant function of 12 factors. Twelve of the 13 degraded seas were correctly discriminated using the function of 92 % success, and eleven of the 12 improved seas were correctly discriminated with 92% success. We tested the performance of the discriminant function for using 24 enclosed coastal seas and the result ware correctly discriminated with 92% success. The linear discriminant function thus obtained was used to estimate the relative importance of the factors embedded in the function and to provide sound guidance for future environmental management.

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In the 1970s, high economic growth enabled the industrialization of Japan. This led to the alteration and destruction of the natural environment. Furthermore, it caused large changes in the social structure. Urban areas were expanded because of the increasing population and industrialization in cities. On the other hand, rural areas became depopulated with an ageing society and there was a subsequent decline in agricultural and forestry industries. Moreover, Japan is located in the northernmost region of the Asian monsoon zone, and tends to suffer from serious floods due to the heavy rain during the rainy season and frequent typhoons. Volcanic activity has damaged river basins and influenced the water environment of enclosed coastal seas. The various human activities and natural disasters also damaged river basins and generated pollutants. It is thought that these phenomena have had a large impact on the water environment of the Ariake Sea. As a result, approximately 4% water quality in the Ariake Sea was deteriorated by the desolation of river basins. Approximately 75% of the water quality (COD values) of the Ariake Sea was deteriorated by the impact of the change in social conditions. In addition, approximately 25% of the water quality of the Ariake Sea was deteriorated by natural disaster.

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