土地盐碱化过程中的冻融作用机制——以吉林省西部平原为例

Mechanism of Freeze thaw Action in Land Salinization Process ——As an sample in West Jilin Province

冻融作用是土地盐碱化独特的形成机制 ,它与因地面强烈蒸发而引起的现代积盐过程有所区别 ,对冻融区域春季积盐具有明显的控制作用。在冻融过程中 ,土壤剖面结构发生变异 ,形成冻结层、似冻结层和非冻结层。土壤冻结和融化形成了特殊的水盐运动规律 ,冻结过程中随着水分向冻层聚集 ,冻层以下土层及地下水中的盐分向冻层积累 ,整个冻层的土壤含盐量明显增加 ;在融化过程中 ,随着地表蒸发逐渐强烈 ,使冬季逐渐累积于冻结层中的盐分 ,转而向地表强烈聚集 ,其强烈程度近乎“爆发式”。没化通之前 ,冻层象一块连续不断的大隔水层 ,隔断了冻层之上土壤水分与冻层之下潜水的联系 ,此时土壤盐碱化的发生与地下水位没有直接联系 ,而是受冻层以上冻融滞水的直接影响。所以用潜水临界深度来解释春季“爆发式”

As a particular mechanism of land salinization, freeze thaw action is differing from salification process by violent evaporation, it has distinct control action on springtime salification, but it has not been much accounted adequately.In the process of freezing and thawing, soil profile constitution is divided into three layers: frozen layer, semi frozen layer and unfrozen layer, special travel of water and salt was made. In the process of soil freezing, soil water and salt move towards frozen layer from the underlayers, salinity in the frozen layer increased evidently. In the process of soil thawing, the salinity of frozen layer assembles in the upper soil layer along with violent vaporizing in springtime. Its intensity level of salification like “eruption” this time, the land salinization has no relation with ground water table, because frozen layer by way of waterproof layer insulate unconfined water. So it is unauthentic that the critical depth of unconfined water controlled that “eruption” salification in springtime.