We determined the monosaccharide composition of dissolved organic matter (DOM) to evaluate the origin of DOM in Lake Kasumigaura. We applied high-performance liquid chromatography coupled with pulsed amperometric detection (HPLC-PAD) for the analysis of monosaccharides. We collected water samples from Lake Kasumigaura in 2004 and prepared samples from culture medium used for growing blue-green algae that are typically found in Lake Kasumigaura. The dissolved total saccharides (DTS) content of the lake water ranged from 1.8 to 3.0 μM. The DTS content of the DOM from lake water ranged from 3 to 6%. The monosaccharide composition in the lake water was uniform all year round. The main monosaccharides were fucose, rhamnose, arabinose, galactose, glucose, mannose, xylose and ribose. The algae released a large amount of DTS during the stationary phase. The concentration and composition of the released DTS differed substantially among the algal species. The released DTS was 43.2 to 126 μM. Glucose was the most predominant among the monosaccharides of the DTS. The DTS content of the algal DOM ranged from 11 to 33% depending on the type of algae. The monosaccharide composition was very different between the lake-water-derived and algal-derived DOMs.

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The Characterization of cement-granulated coal ash was carried out for the purpose of remediation of organically rich sediment by controlling the nutrient balance of ecosystems. The granulated coal ash used in this study is composed of SiO₂, CO₃, Al₂O₃, CaO with quartz and aluminum silicate as the main phases. Moderate dissolutions of phosphate, silicate and calcium were observed. This may be useful for the neutralization of the acidified sediment and effective for controlling the balance of nutrients in coastal seas. Although the growth of the diatom S. costatum was inhibited under the batch culture condition owing to pH increase, such a pH increase would not occur under natural conditions because of magnesium precipitates and carbonate equilibrium.

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The Nagara rivermouth barrage was constructed 5.4km upstream from the rivermouth and has been in operation since July 1995. In this study, an analysis using monitoring data was performed to establish the cause of the high concentration of phytoplankton at St. Ise (1.0km upstream from the barrage). The high concentration of phytoplankton appears under good conditions for reproduction (retention time, water temperature, solar radiation, and nutrients), therefore, self-replication of phytoplankton was one of the factors associated with this phenomenon. In addition, GR (the actual value of chlorophyll a (Chl.a) growth rate calculated from the monitoring data) was compared with GR_max (the maximum value of Chl.a growth rate determined from self-replication of phytoplankton based on its composition) to evaluate the effect of the accumulation of phytoplankton. GR was frequently greater than GR_max and it was verified that accumulation plays an important role in the occurrence of the high concentration of phytoplankton at St. Ise. The reasons for accumulation were thought to be that opposite flow induced by an oncoming wind horizontally and reversely transports the phytoplankton and that the settling velocity of the phytoplankton decreases in the presence of a thermal stratification.

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A questionnaire survey was carried out to analyze the residents' preferences for Teganuma basin. Their preferences were measured quantitatively by conjoint analysis, and the relationships between their preferences and personal attributes were analyzed. The estimated monetary values of river attributes can be applied to the effective planning of wastewater treatment in the basin. The results showed that frequent waterfront users gave high monetary values and recognized the waterfronts as amenity spaces. The marginal willingness to pay (MWTP) values were calculated as 4092, -1824, and 790 yen · y^-1 per capita for decreasing 1mg · l^-1 BOD, 10% water quantity, and 10% life-cycle energy consumption by waste water treatments, respectively. The value for improving river water quality was relatively high and water quantity was also recognized as having a high value. This suggests that a distributed wastewater treatment system ensuring both rivers water quality and quantity can lead to more desirable waterfronts for residents as compared with the conventional sewerage system.

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