| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1999: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1998: ¥900,000 (Direct Cost: ¥900,000)
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| Research Abstract |
This study is to investigate the movement and the form of residual mercury in environmental surface soils. Soil samples were collected from sites of 123 areas mainly on Chiba Prefecture. The results show the total mercury concentrations in the studied soils were ranged from 78.6 ppm at the top to 0.002 ppm. As the results, background concentration in geochemical soils, which was derived from crust mother rock, was about 0.03 ppm and background concentration in environment urban soils was 0.15 ppm. The soils from the sites of university, hospital and old military building trace in urban areas, which have been treated with mercury-containing chemicals for many years, contained over 1 ppm mercury, indicating the neither leaching, nor volatilization of mercury played a significant role. It was afraid that the urban soils were strongly influenced by the anthropogenic contamination. Binding forms of residual mercury in surface soils of urban environment were studied by means of a pyrolysis method. The results show mainly that mercury chloride, organism-bound Hg, and mercuric sulfide occurring in the studied soils could be identified by their thermal release behavior. Metallic mercury did not detected from surface soils in all samples. Leaching experiments with acid rain water did not extracted mercury species. The results obtained from this research were found that the residual mercury in soils was chemically stable in urban environment. Mercury evaporation from soils as a function of temperature is the only loss route of residual mercury in surface soils of urban environment.
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