Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants|
|Research Institution||Hiroshima University|
YAMAUCHI Toshiko Hiroshima University, Associate Professor, 工学部, 助教授 (80034396)
MOLDRUP Per University of Aalborg, Associate Professor, 土木工学科, 助教授
ROLSTON D.E. Univ. of California,Davis, 環境工学科, 教授
ITO Sotaro Hiroshima University, Professor, 工学部, 教授 (90034404)
ROLSTON Dennis e University of California, Davis, Professor
寺西 靖治 広島大学, 工学部, 教授 (10032020)
|Project Period (FY)
1994 – 1995
Completed(Fiscal Year 1995)
|Budget Amount *help
¥5,800,000 (Direct Cost : ¥5,800,000)
Fiscal Year 1995 : ¥2,800,000 (Direct Cost : ¥2,800,000)
Fiscal Year 1994 : ¥3,000,000 (Direct Cost : ¥3,000,000)
|Keywords||VOCs / Pesticide / Adsorption / desorption / Diffusion in soils / Micro-column method / Solute transport model / Retardation factor / Biodegradation / 土壌吸脱着 / 土壌内の拡散・分散 / 遅延特性 / 土壌処理|
The project focused on the following four main areas concerning the fate of chemicals in polluted soils.
1) Pesticide adsorption/desorption and biodegradation :
Pesticide (Asulam and Simazine) adsorption and desorption on two soil types (decomposed granite, DG,and a natural loam soil) was investigated. Linear and Freundlich adsorption isotherms best described the data of DG and loam, respectively. The hysteresis in adsorption/desorption was significant in the case of the loam soil. Soil texture and organic matter content strongly affected both pesticide adsorption and desorption. Slight biodegrdation of pesticides in the soil solution phase was observed.
2) Retardation of Volatile Organic Chemicals (VOCs) in soils :
Retardation of VO2S (1,1,1-trichloroethane and toluene) in two soil types (DG and a clayy soil) was determind using a newly developed soil micro-column method based on gas chromatography. Only small effects of column dimensions were observed, suggesting the new method to be adv
antageous to measure VOC fate in polluted soils. The VOC retardation increased with decreasing temperature, and the effect of temperature on retardation was most significant in the low soil-water content range.
3) VOC diffusion and biodegradation in soils :
Competitive adsorption of two compounds (water and VOC) under diffusion conditions in soils was measured. The VOC adsorption in dry soils did not follow Henry's law, and only small decreases in the soil-water content caused adsorption to increase with one or several orders of magnitude.
Biodegradation of VOCs strongly depended upon which chemicals were pesent.Aerobic TCE (tetra、chloroethylene) degradation occurred only in the presence of toluene. Competitive inhibition between toluene and TCE degradation and toxicity of TCE at high concentrations were observed.
4) Modeling solute transport in soils :
A new, more realistic model for VOC adsorption in dry soils, based on the measured VOC adsorption data, was presented. Also, more accurate modelling methods for predicting solute transport, retardation, and biodegradation was developed and validated against both analytical solutions and measured data. Less