Development of integrated numerical method for predicting soil and groundwater pollution based on atmosphere linked model

1.研究目的三氯乙烯（TCE）等氯代烃的致癌性使其污染地下水造成严重的环境问题。污染物或扩散物质的泄漏行为可以用多孔介质中的输运过程来处理，包括不饱和带挥发性气体的运移和含水层中的液相对流弥散两部分。该研究的目的是模拟土壤和地下水中的污染迁移，并根据Takano博士的污染迁移方案和土壤与低层大气耦合模型（SALSA：土壤与大气连接模拟算法）将其应用于实际的现场。研究分为四个步骤：1)考虑大气中动量、热量和质量输运过程的土壤污染迁移建模；2)地表边界条件的引入；3)土壤和含水层污染迁移模型的耦合；4)参数敏感性分析和现场应用。2)研究结果Sato， Wada教授和Asaeda教授使用浅非饱和层VOC迁移模型进行了数值模拟。结果表明，土壤湿度和温度对污染物的迁移起着重要作用，降雨增强了污染物的向下运移。高野博士通过在近畿大学（Kinki University）一座建筑物的屋顶上进行气象和水文观测，调查了蒸散速率和排水水质。Sato教授、Asaeda教授和Sasaki先生通过室内实验，在均匀填充的玻璃微珠中建立了饱和多孔介质中VOC输运的基本数学模型。Sato教授、Asaeda教授、Wada教授和Sasaki先生建立了一种新的含水层运移模型，用于预测饱和和非饱和多孔介质中污染物的运移行为，并将其应用于现场调查。

1.Objective of the studyGroundwater pollution by chlorinated hydrocarbons, such as trichloroethylene (TCE) causes a serious environmental problem because of their carcinogenic characteristics. Behaviors of leaked pollutant or diffusive material can be dealt with transport processes in porous media, consisting of two parts, volatile gases migration in unsaturated zone and liquids phase convective dispersion in aquifer. The objective of the study is to model the pollution migration in soil and groundwater and to apply it to practical field sites based on a pollution migration scheme, by Dr. Takano and a coupled soil and lower atmosphere linked model (SALSA : Soil Atmosphere Linking Simulation Algorithm). The investigation is carried out by next four steps, i)modeling of pollution migration in soil accounting for transport processes on momentum, heat and mass in atmosphere, ii)introduction of the boundary conditions at a surface, iii)coupling of the pollution migration model in soil and aquifer, iv)parameter sensitivity analysis and application for field site.2)Results of the studyProf. Sato, Prof. Wada and Prof. Asaeda carried out numerical simulations using the VOC migration model in shallow unsaturated layer. The results gave that soil moisture and temperature play significant role in the migration, and rainfall enhances the downward transport of pollutant. Dr. Takano investigated the evapotranspiration rate and drainage water quality through meteorological and hydrological observations on the rooftop of a building at Kinki University. Prof. Sato, Prof. Asaeda and Mr. Sasaki made a basic mathematical model of VOC transport in saturated porous media by laboratory experiments in uniformly packed glass beads. A new migration model in aquifer has been developed to predict pollutant behavior in saturated and unsaturated porous media, and application for investigated field site by Prof. Sato, Prof. Asaeda, Prof. Wada and Mr. Sasaki.