To obtain fundamental information on the nature and properties of sediments in dammed lakes, we investigated various properties of sediment from dammed Lake Ono using soil scientific methods. Furthermore, the Lake Ono sediment was characterized by comparing its various properties with those of yellow soil. 1) Lake Ono is a eutrophic lake which phosphorus is a limiting factor. 2) The pH, exchangeable base content, and degree of base saturation of the sediment were much higher than those of the soil. 3) The clay content of the sediment was 2 times higher than that of the soil. The texture of the sediment was Heavy clay (HC), while that of the soil was Clay loam (CL). There were no large differences on organic carbon and total nitrogen contents, and the C/N ratio between the sediment and the soil. 5) The “combine”-form humus content of the sediment was higher than that of the soil. The reverse was true for the “free”-form humus content. 6) The X-ray diffraction patterns of the clay fraction of the sediment were almost the same as those of the clay fraction of the soil. 7) The elemental composition and ¹³C-NMR spectrum of the fulvic acid isolated from the sediment were similar to those of the soil. On the basis of the present findings and previous information on the properties of soil distributed in catchment areas, it was assumed that the Lake Ono sediment is strongly affected by soil particles and Ca in its catchment areas, which flow into the lake.

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To synthesize a high-performance phosphorus adsorbent suitable for wastewater treatment, ferrous sulfate was mixed with volcanic ash soil, brown forest soil or red soil and then heated. We inspected the phosphorus adsorption ability and the various characteristics of soils heated with ferrous sulfate, and examined the phosphorus adsorption mechanism. The results are as follows. The phosphorus adsorption ability, active iron (Feo), active aluminum (Alo), free iron (Fed) and free aluminum (Ald) levels of the three soil types increased markedly. The specific surface area of the three soil types decreased markedly upon heating with ferrous sulfate. The silicon level extracted using oxalate extration solution (Sio) increased in the volcanic ash soil heated with ferrous sulfate where as in brown forest soil and red soil the silicon level decreased markedly upon heating with ferrous sulfate. We showed that the phosphorus adsorption abilities of the three soil types with and without ferrous sulfate positively correlated with Feo, Alo, Fed and Ald levels; while they were not correlated with specific surface area and Sio.

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Chlorinated ethylenes (tetrachloroethylene (PCE), trichloroethylene (TCE), cis-1,2-dichloroethylene (cis-DCE), and 1,1-dichloroethylene (1,1-DCE)), which are soil and groundwater contaminants, were degraded by chemically reacting with hydrogen peroxide, tungstate, and ammonium salt at 25°C. The degradation reaction progressed in a neutral to slightly basic environment of pH 6-9. The degradability of the ethylenes was in the order of 1,1-DCE > TCE > cis-DCE > PCE; and this showed degradation characteristics different from those of conventional oxidizing agents (such as potassium permanganate). Furthermore, treatment by this reaction was applied to groundwater sample from a contaminated site, and all chlorinated ethylenes in the water sample were degraded except for PCE.

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