| Research Abstract |
The purpose of this research is to develop improved measurement methods and prediction models for transport and fate of environmental impact chemicals. The major research accomplishments can be grouped into 6 sections as follows.
1. New method for measuring chemical transport and retardation using minimal amounts of measurement time, chemical and soil : High Performance Liquid Chromatography (HPLC) based soil micro-column methods for measuring the transport and sorption of multiple environmental impact chemicals have been developed.
2. Improved methods for measuring and predicting diffusive transport of water-dissolved chemicals in undisturbed soil : A new method, called the undisturbed half-cell (UHC) method, for measuring the solute diffusion coefficient in undisturbed soil has been developed and verified for different Japanese and European soils.
3. Identification of important transport processes for adsorbing chemicals in undisturbed and macro-porous soils : Small soil particles and o
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rganic macromolecules have been shown to be mobile and able to act as carriers for adsorbed chemicals. Such particle-bound chemical transport can cause enhanced leaching of chemicals and nutrients through the soil.
4. New knowledge on the main chemical adsorption and diffusion processes in unsaturated soil systems : A comprehensive transport-fate model for a volatile organic chemical, covering both water-phase and air-phase chemical diffusion, chemical vapor sorption and hydrophobic chemical sorption, has been developed.
5. Identification of links between chemical fate processes including sorption time-dependency, internal diffusion and biodegradation : Sorption of pesticides and polycyclic aromatic hydrocarbons (PAHs) has been investigated. Improved conceptual models for adsorption-desorption non-singularity (hysteresis) and sorption time-dependency (kinetics), based on internal diffusion concepts, have been proposed.
6. Improved, soil type dependent models to predict the major transport parameters in the soil air phase : New models to predict gas diffusivity and gas permeability in soils, as a function of soil-water content and soil type (including pore size distribution parameters), have been developed and successfully verified against data for more than 50 Japanese and European soils. Less
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