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进行的非饱和土壤中多离子运移和交换反应的研究表明,在非饱和非稳态流下,土壤中非反应性溶质Cl~-运移时的锋面趋向滞后于水的湿润锋面。由于交换反应,交换性离子锋面和峰出现的位置则滞后的更多,并与离子的交换能力、浓度和供水强度有关。交换反应主要表现在含水量较为稳定和溶液总浓度较为恒定的区域。在一定浓度范围内,用恒定的2离子 Gapon 交换参数,能够较好地模拟以 Ca~(2+)为主的土壤中 Ca-Mg-Na-K 交换体系中 Ca~(2+)的运移;当某1离子与土壤溶液中总的阳离子的活度比发生较大的变化时,模拟时应考虑 Gapon 交换参数的改变。由本研究确定的供试土壤的 Gapon 交换参数 K_(Mg-Ca),K_(Na-Ca)和 K_(K-Ca)分别为0.9～0.6,2和0.3。本研究利用非水溶的重有机试剂和高速离心技术提取土壤溶液样品,可用小量土样同时获得离子的液相和交换相组成的分布等信息,因而更贴切地反映了土壤溶液和交换反应的实际情况。
The results of multi-ion transport and exchange reactions in unsaturated soils show that the frontal orientation of the non-reactive solute Cl ~ - transport in the soil lags behind the wet front of the water under unsaturated unsteady flow conditions. Due to the exchange reaction, the location of the exchangeable ion front and peak lags more, and is related to ion exchange capacity, concentration, and water supply intensity. Exchange reaction mainly in the water content is more stable and the total concentration of the solution is more constant area. In a certain range of concentration, constant 2-ion Gapon exchange parameters can simulate Ca 2+ transport in Ca 2+ Mg 2+ -based soil When the activity ratio of total cations in a certain ion and soil solution changes greatly, the change of Gapon exchange parameters should be considered in the simulation. The Gapon exchange parameters K_ (Mg-Ca), K_ (Na-Ca) and K_ (K-Ca) determined by this study were 0.9 ~ 0.6, 2 and 0.3 respectively. In this study, soil samples were extracted by heavy organic reagent and high-speed centrifugation. The information of the liquid phase and the composition of the exchange phase can be obtained by using a small amount of soil samples. Therefore, it is more appropriate to reflect the soil solution and exchange reaction The actual situation.