季节性冻融对盐荒地水盐运移的影响及调控

Effects of seasonal freeze thawing on water and salt movement in saline lands

季节性冻融是干旱区土壤盐碱化形成的主要驱动因子，但冻融过程中土壤水盐耦合关系及热量调控机理仍不清楚。通过分析2009年11月～2010年5月新疆玛纳斯河流域典型盐荒地季节性冻融过程中土壤剖面160cm以内的水分、盐分和温度动态变化，探讨了不同土层冻融过程中水热盐的耦合关系。结果表明：土壤最大冻结深度为150cm左右，表土层（0～40cm）温度与气温关系密切；土壤剖面水分呈现“C”型垂直分布，表土层和底土层（100～160cm）含水量较大，而心土层（40～100em）含水量不足10％，土层平均含水率在冻融前期增加了12．91％，而在初蒸期减少了10．01％；土壤剖面盐分在冻结期和初蒸期表聚作用明显，心土层和底土层含盐量稳定，土壤剖面含盐量表现为“积盐-脱盐-再积盐”的变化过程。水热盐之间具有高度协同性，心土层和底土层表现为水盐相随、而表土层为水去盐留的耦合特征，热量传输是调控水盐运移的关键因素。

The main driving factor of soil relationship of freezing and thawing in soil salinization in the arid is seasonal freezing and thawing but the coupling water, salt and heat regulation mechanism are still unclear. In this paper the typical saline soil was selected, and collected the data from Manas River Basin, Xinjiang, China, to analyze the dynamic changes of water, salt and temperature at 160 cm soil profile from November 2009 to May 2010, fur- ther to investigate the hydrothermal and salt coupling effect between the different soil layers in freezing and thaw- ing processes. Results showed as follows ： the most soil freezing depth is 150 cm and its temperature is closely re- lated to the temperature of the surface soil （0-40 cm）; moisture contents showed the ＂C＂ distribution pattern, the topsoil and subsoil （ 100-160 cm） have a high moisture and the inner soil layer＇ s （40-100 cm） have water con- tents less than I0%, in the freeze-thaw period, there was an average soil water content increased up to 12.91% and the beginning of the steamed period decreased to 10.01%. While the salinity was significantly gathered at the surface of the soil profile in the freezing period and beginning of steaming period, the inner soil and subsoil salt contents were stable, the whole process for soil salt contents appeared as salt accumulation - desalination - salt accumulation in the process of changes. The study found through hydrothermal and salt analysis that the heat transfer is a key factor in regulating water and salt transport with high degree of energy between the salt and water, furthermore, salt and water performance in the inner soil and subsoil goes side by side and the surface soil water removes by leaving the salt on it. In connection with the mechanism for seasonal water and salt transport in the study area, the research found a comprehensive set of methods to deal with the problems which caused by seasonal freezing and thawing of soil salinization.