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利用土柱切割法获得了饱和流运移土柱在不同运移时间的土壤溶质 (NH+4 )剖面分布曲线 ,并提出溶质运移初始穿透时间 (T初 )和完全穿透时间 (T末 )等概念以描述运移特征。在运移置换液浓度为 0 .0 4 mol/L时 ,T初 、T末 分别为 5、8左右 ,均比运移置换液浓度为0 .0 8mol/L时的 T初 (3.5左右 )和 T末 (6左右 )大 ;而在运移初始穿透时间时 ,运移置换液浓度为 0 .0 4 mol/L时的土壤平均吸持量为 6.38～ 7.2 7cmol/kg,小于运移置换液浓度为 0 .0 8mol/L时的土壤平均吸持量 (8.1 4～ 1 0 .36cmol/kg) ,表明运移置换液浓度增大 ,溶质运移较快 ,土柱吸持的溶质数量平均水平较高。运移相对时间 (出流液的土柱孔隙体积数 )为 1～ 5,溶质峰移动深度随运移相对时间的延长而增大 ,运移置换液浓度为 0 .0 4 mol/L时 ,土娄土的溶质峰移动深度与运移相对时间呈极显著线性正相关。根据化学动力学和过渡态理论 ,应用“S”型方程可定量描述饱和流运移过程土壤溶质吸持反应动力学特征。运移置换液浓度为0 .0 8mol/L时的反应速率常数比运移置换液浓度为 0 .0 4 mol/L时的反应速率常数大 2～ 3倍 ,相应的溶质吸持反应活化自由能变减小 ,表明运移置换液浓度增大 ,运移过程土壤溶质吸持反应速度加快。
The distribution curve of soil solute (NH + 4) profile of saturated soil column at different transport time was obtained by soil column cutting method. The initial penetration time (T initial) and complete penetration time (T End) and other concepts to describe the characteristics of migration. When the concentration of the replacement fluid was 0. 04 mol / L, the initial T and the end T were about 5 and 8 respectively, both higher than that at the beginning of T (about 3.5) when the concentration of the replacement fluid was 0.08 mol / L. And T (6 or so), respectively. However, at initial transport time, the average soil holding capacity at the concentration of0.040 mol / L was 6.38-7.27 cmol / kg, The average soil holding capacity at the concentration of0.080mol / L (8.14 ~ 1.36cmol / kg) showed that the concentration of migration and displacement solution increased, the solute transport was faster, and the solute The average number is higher. The relative migration time (the pore volume of outflowing soil column) is 1 ~ 5, and the depth of solute peak migration increases with the migration time. When the concentration of migration displacement solution is 0. 04 mol / L, The depth of solute peak movement of earthwork is significantly and positively correlated with the migration time. According to the theory of chemical kinetics and transition state, the “S” type equation can be used to quantitatively describe the kinetic characteristics of soil solute sorption reaction during the process of saturated flow transport. The reaction rate constant at the concentration of 0.080 mol / L was two to three times larger than that at the concentration of 0.4 mol / L, and the corresponding solute sorption reaction was activated Can change smaller, indicating that the concentration of migration replacement solution increases, the process of soil solute adsorption reaction speed up.