土壤胶体在不同饱和度土壤介质中的释放与淋溶行为研究

采用饱和与非饱和填充土柱纵向淋溶研究方法，结合对流弥散模型方程（CDE）对穿透曲线的拟合计算，全面考察了土壤介质水饱和度、土壤水pH/离子强度、土壤孔隙水流速和土壤胶体颗粒大小对天然土壤胶体在实际土壤介质中释放、沉积迁移行为的影响。分别获取胶体扩散系数和阻滞因子值，定量说明实验中水化学、水动力学等条件的作用影响力。结果显示，介质不饱和条件不利于胶体的释放和淋溶；高pH和低离子强度条件对土壤胶体释放与迁移有利；淋溶过程的间断干扰，可以促使土壤胶体的增量淋溶释放；淋溶强度及胶体颗粒粒径大小，能够影响胶体穿透时间和穿透浓度峰值大小。

Release and Mobilization of Soil Colloid in the Natural Soil Packed Column with Various Water Saturations

Packed soil columns（saturated/unsaturated） and the CDE （convection dispersion equation） mathematically fitting studies were conducted to explore the influence of a series of physiochemical factors on the release and transport of natural soil colloids in subsurface. The main factors investigated in this study included the water saturation, pore-water pH/ionic strength, leaching interruption and colloid size. Experimental and modeling results suggested that the water saturation had strong negative effects on the release and transport of soil colloid in porous media which could be attributed to the high AWI（Air-water-interface ） interaction between colloid and soil grain surfaces. High pH and low ionic strength could enhance the colloid release from the soil collector and lead to a less amount of retention in soil. The early break- through of colloids compared to the conservative tracer was observed and the extent of the early breakthrough was found to increase with the increase of colloid size and leaching intensity. It was also demonstrated that the flow interruption could affect the release of colloid significantly by breaking the equilibrium between the deposited colloids and the ones in the bulk solution in soil pore structure.