江汉平原过渡带黏性层状土弥散试验与模拟研究

为研究江汉平原—大别山区过渡带黏性层状土中溶质迁移的规律，以保守性阴离子Br-为示踪剂，通过等温吸附试验、一维弥散试验、HYDRUS-1D软件模拟反演手段，研究了Br-在黏性层状土中的吸附参数、迁移规律，模拟反演其弥散参数。结果表明：（1）Freundlich模型和Langmuir模型均能较好的拟合吸附试验结果，随着土壤中黏粒比例的增大，土壤对Br-的饱和吸附量有所增加；（2）层状土中土壤质地与结构均会影响穿透曲线的形状，但一维饱和土柱中的弥散过程主要取决于含水介质系统中黏性颗粒的占比，黏粒的增加会对溶质运移产生阻碍作用；（3）通过HYDRUS-1D软件构建模型反演弥散参数，R2均大于0.991，拟合效果较好，分析发现层状土中无论土壤组成类型还是层厚及排序的影响，其本质都是改变了土壤的平均孔隙流速从而影响弥散作用，平均孔隙流速越小其弥散系数越小；（4）试验中粉质黏土弥散系数约为0.005～0.048 cm2/d，远远小于下部砂土弥散系数0.524～7.477 cm2/d，差值达到了至少两个数量级，表明研究区内厚层黏土为控制地层，会较大程度阻碍地下水中溶质运移，上部含水层中的污染物或有机...

A study of dispersion experiment and simulation of the cohesive layered soil in the transition zone of the Jianghan Plain

In order to study the law of solute migration in the cohesive stratified soil in the transitional zone of the Jianghan Plain-Dabie Mountain area, the conservative anion Br? is taken as a tracer agent in the isothermal adsorption experiment. One-dimensional dispersion experiment and HYDRUS-1D software simulation inversion method are used, and the adsorption parameter, migration law and migration inversion dispersion parameter of Br? in the cohesive stratified soil are examined. The results indicate that (1) both the Freundlich model and Langmuir model can well fit the adsorption experiment results, along with the increase of proportion of clay particle in the soil, and the saturation adsorption amount of the soil to Br- increases. (2) Both the soil texture and structure in the stratified soil can influence the shape of the breakthrough curve, but the dispersion process in one-dimensional saturation earth pillar mainly depends on the proportion of clay particles in the water-bearing media system, and the increase of clay particles will produce resistance for solute transport. (3) The invert dispersion parameter through the HYDRUS-1D software construction model, R2 is always larger than 0.991, and the fitting effect is good. The analysis results show that no matter soil component type or layer thickness and ordering in the stratified soil, the essence to influence dispersion function is by changing the average hole flow velocity of the soil, and the dispersion coefficient becomes smaller as the average hole flow velocity is smaller. (4) The silty clay dispersion coefficient in the experiment ranges from 0.005 to 0.048 cm2/d, far less than the sand dispersion coefficient 0.524 to 7.477 cm2/d in the under part, the difference value reaches two order of magnitudes, indicating that the thick layer clay soil is a control layer and will greatly resist solute transport of groundwater. The pollutant or organic matter in the upside water-bearing stratum is very hard to penetrate this layer and migrate downward, and this layer has very good sewage removal performance. The results are of great application value for groundwater environmental protection and water quality control in the transition zone of the Jianghan Plain.