Role of clay in water flow and solute transport in soils

粘土在土壤中水流和溶质运输中的作用

基本信息

批准号：
15510003
负责人：
TORIDE Nobuo
金额：
$ 2.11万
依托单位：
Mie University (2004-2005)Saga University (2003)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Water flow and solute transport in soils were intensively monitored in a laboratory soil column to investigate the role of clay in flow and transport in a soil. Following three major results were obtained in this study. (1) Response of hydraulic conductivity of clay to Na-Ca mixed solution were quite different between high-swelling Bentonite and Hydrodynamic dispersion coefficients for undisturbed and disturbed Japanese volcanic ash soils, Andisols, in a field and low-swelling Ariake clay. The saturated hydraulic conductivities for various solution conditions were determined based on consolidation experiments. (2) Solute dispersivities were determined based on solute concentration for a Japanese valcanish ash soil, Andisol. The dispersivity increased as the pore-water velocity increased for a saturated disturbed soil whereas it decreased for lower water contents because of the aggregated structure. The dispersivity for the saturated undisturbed field Andisols was more than ten times greater than for the disturbed soil, and increased with the observation depth. On the other hand, the dispersivity for the unsaturated undisturbed soil became close to that for the disturbed soil. Flow and transport in the saturated undisturbed soils become heterogeneous because of macro-pores such as root channels, while these macro-pores become empty as the water content decreases. (3) Water content and electrical conductivity measurements with Time domain reflectometry (TDR) were intensively investigated for clayey soils in laboratory and field condition. Specific calibrations were proposed for accurate estimation of water contents and soil solution concentrations.

在实验室土柱中对土壤中的水流和溶质迁移进行了集中监测，以研究粘土在土壤中流动和迁移中的作用。本研究获得以下三个主要结果。 (1) 未扰动和扰动的日本火山灰土壤 Andisols 和低膨胀有明粘土的高膨胀膨润土和水动力分散系数之间的粘土导水率对 Na-Ca 混合溶液的响应有很大差异。根据固结实验确定了各种溶液条件下的饱和水力传导率。 (2) 溶质分散度是根据日本火山灰土壤 Andisol 的溶质浓度确定的。对于饱和的扰动土壤，分散性随着孔隙水速度的增加而增加，而由于聚集结构的原因，分散性随着含水量的降低而降低。饱和未扰动场Andisols的色散率比扰动土壤的色散率大10倍以上，并且随着观测深度的增加而增加。另一方面，非饱和未扰动土壤的分散性变得接近扰动土壤的分散性。由于根通道等大孔隙，饱和原状土壤中的流动和运输变得不均匀，而随着含水量的降低，这些大孔隙变空。 (3) 在实验室和现场条件下对粘土的时域反射计 (TDR) 的含水量和电导率测量进行了深入研究。提出了具体的校准以准确估计含水量和土壤溶液浓度。