冻融条件下苏打盐渍土的水盐变化规律研究

Variation laws of water and salt in soda-saline soil under freeze-thaw condition

冻融作用是导致我国北方半干旱地区土地盐渍化的主要原因之一。以吉林西部大安市为研究区域,通过野外调查和样品采集,开展了盐渍土的室内试验,研究了冻融过程中土壤水盐的运移规律。研究结果表明:该地区土壤中的水盐在冻融过程中经历了两次迁移过程,不同阶段具有各自的特点。冻结过程中,未冻层的水不断向冻层迁移并随之冻结,盐分亦随水分迁移;融化过程中,未融化的冰层阻碍水盐下渗,上层滞水向表层运移并蒸发,使表层盐分急剧增加。在水盐运移过程中,电导率与总盐的变化具有良好的相关关系。室内模拟试验为进一步阐明该区盐渍土的形成机理与影响因素提供了科学依据。

Freeze-thaw action is one of the main causes that leading to soil salinization in semi-arid areas of northern China.Taking Da＇an city in western Jilin Province as the research area,we carried out laboratory experiment of saline soil and researched the migration law of water and salt during freezing and thawing through field survey and sample collection.The results showed that migration of water and salt in soil experiences two different stages in the process of freezing and thawing.In freezing process,water in the unfrozen layers continuously migrated to the frozen layer and was subsequently frozen,salt also migrated with water;in thaw process,frozen layers blocked the infiltration of water and salt,and the perched water migrated to the surface and then continuously evaporated,leading to a rapid increase of salinity in surface.Throughout the whole process,the variation of conductivity and total dissolved salt had an obvious relationship.The laboratory simulation test provided scientific truths for further clarifying the formation mechanism and influence factors of the saline soil.