土壤冻结、消融期水盐动态的初步研究

季节性冻土对土壤盐碱化的影响,主要是发生在半湿润、半干旱和干旱区的温带至亚寒带地区,它包括了我国三北(西北、华北及东北)多数平原区。在三北平原地区,一般季节性冻土平均最大冻结深度为0.5-4.0米,冻土存在历时长达4-8个月之久。

PRELIMINARY STUDY ON THE DYNAMICAL REGIME OF WATER AND SALT DURING THE FREEZING AND THAWING PERIOD OF SOIL

Data of observation indicated that the genesis and evolution of the seasonal frozen soil was the main factor to restrain the movement of water and salt in winter and spring which constituted the peculiar pattern of water and salt movement in soil. During the soil freezing period, soil salt was accumulated in the frozen soil layer with the freezing of the soil. While in spring with the thawing of frozen soil layer, a part of thawing water and salt infiltrated into the ground water, another part of the water was evaporated and salt was accumulated in the surface soil. Therefore the accumulation of salt in the surface soil in spring is actually the result of redistribution of salts in frozen soil layer accumulated in winter. According to the results of the study on relationship between the accumulation of salt in frozen soil layer and the ground water table at the begining of frozen period and experiments, it is proved that if the ground water table is controlled bellow 1.5-2.0 m before frozen period, the accumulation of salt is decreased significantly in the process of soil freezing, the accumulation of salt in the surface soil in spring then can be prevented.