Basic study on pollutant movement in an unsaturated zone considering stagnant.

为了评价污染物在非饱和带的运动，对各种土壤进行了示踪试验。本研究强调由于土壤的非均质性，多孔区存在滞流区。结果表明，多孔带中滞流区对污染物的运移有一定的影响。饱和条件下，活动性区与停滞区之比估计为10^<-1>量级，而非饱和条件下，活动性区与停滞区之比估计为10^<-3> ~ 10^<-2>量级。由于采用解析解的数值模拟较好地拟合了非饱和区溶质运动，因此考虑停滞区概念的四参数模型是足够合理的。实验结果也考虑了非均质性。即使在10^<-2> m到10^< -1> m的实验空间尺度上，也能识别出异质性。未扰动土壤的异质性大于扰动土壤的异质性。结论是：1。评价非饱和带污染物的运动应考虑停滞区的存在。考虑停滞效应的对流色散方程可以很好地评价非饱和区污染物的运动。由于在实验室实验尺度上已经认识到了异质性，所以在未来的分析中，除了停滞效应之外，还需要考虑异质性的模型。

To evaluate pollutant movement in an unsaturated zone, tracer tests were carried out for various soils. This research emphasizes the existence of stagnant region in porous zone due to heterogeneity of soils.Results show that there is effect of stagnant region in porous zones on pollutant movement. Ratio of the mobile region to the stagnant region was estimated as magnitude 10^<-1> for saturated condition, while that was from 10^<-3> to 10^<-2> for the unsaturated condition. Since solute movement in unsaturated zone was well fitted by the numerical simulation using tlte analytical solution, the four parameter model due to the concept of stagnant region is enough reasonable.The heterogeneity was also considered for the experimental results. Even for the spatial scale of the experiments, 10^<-2> to l0^<-1> m, the heterogeneity was recognized. Heterogeneity of undisturbed soil was larger than that of disturbed one.The conclusion is :1. We should consider the existence of stagnant region for evaluation of pollutant movement in unsaturated zone.2. The Convection Dispersion Equation considering stagnant effect works well for the evaluation of pollutants movement in unsaturated zone.3. Since heterogeneity was recognized for laboratory experimental scale, the model considering heterogeneity in addition to stagnant effect is necessary for analyses in the future.