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本文研究了冻融和干湿交替过程对土壤大孔隙及由其导致的优先水流形成的作用，以及表面活性剂直链烷基苯磺酸盐（LAS）在水稻和大豆土壤中的优先迁移。结果表明，冻融和干湿交替均可使土壤产生大孔隙和优先水流，而且前者的作用比后者强，LAS在1．5m水稻土体和大豆土体的优先穿透时间均为23天，而优先穿透淋洗水量却相差甚大，前者为69mm，后者仅为9mm。优先迁移过程不受土壤吸附／解吸过程的制约。受土壤吸附／解吸过程制约的平衡穿透淋洗水量，水稻系统和大豆系统分别185mm和178mm，两者很为接近。在水稻和大豆土壤，LAS的优先穿透时间比平衡穿透时间分别提前了21天和35天。优先穿透峰浓度在大豆系统可达平衡穿透峰浓度的20％～30％，在水稻系统则高达30％～86％。在没有大孔隙的填充土柱中，观察不到这种优先迁移的现象。
In this paper, the effects of freeze-thaw and wet-dry alternation processes on the macropores of the soil and the preferential flow induced by them were studied, and the preferential migration of the surfactant linear alkyl benzene sulfonate (LAS) in rice and soybean soils was studied. The results showed that both the freeze-thaw and wet-dry alternations could lead to macropores and preferential flow in soil, and the effect of the former was stronger than that of the latter. The preferential penetration time of LAS in 1.5m paddy soil and soybean soil was 23 days , While the first penetration of rinsing water is very different, the former is 69mm, the latter is only 9mm. Preferential migration is not subject to adsorption / desorption of soil. Balanced by the process of soil adsorption / desorption, the amount of penetrating rinsing water was 185mm and 178mm for the rice system and the soybean system, respectively, and the two were very close. In rice and soybean soils, the LAS preferential penetration time was 21 and 35 days earlier than the equilibrium breakthrough time, respectively. The peak penetrating peak concentration of soybeans reached 20% ~ 30% of the peaked equilibrium concentration in the soybean system and 30% ~ 86% in the rice system. In filled columns without macropores, this preferential migration is not observed.