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STUDY ON WATER AND SALT MOVEMENT DURING SOIL FREEZING AND THAWING

土壤冻融过程中水盐运动的研究

基本信息

批准号：
11460113
负责人：
AKAE Takeo
金额：
$ 8.58万
依托单位：
OKAYAMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

1. As a background and a beginning point of this research, an example of water and salt movement during soil freezing and thawing was introduced from Hetao Irrigation District, Inner Mongolia, China. Regional and field level salt movement, relation between salt accumulation in spring and fall irrigation, soil water supply and leaching effect by the fall irrigation, improvement method of the salinized land were discussed.2. Dielectric constant of frozen cemented soil was measured and the water in it was classified into hydrated and structural bound state. The quantity of those water was estimated. Water potential of the structural bound water was also estimated.3. Thermal conductivity of frozen and unfrozen soil was calculated by analyzing the amplitude of temperature oscillation in relation to depth when sinusoidal temperature oscillation was given to the soil surface. The method was applied to determine the soil temperature change in the field, and thermal conductivity of frozen and u … More nfrozen state was estimated by this method.4. A new method to measure unsaturated hydraulic conductivity of a frozen soil was developed. A frozen soil sample was equilibrated under centrifuge force field and water loss was measured by change of the moisture profile in the sample. The hydraulic conductivity was calculated by the water loss divided by the gradient of centrifuge force and time. The measured hydraulic conductivity ranged from 10^<-9> cm/s to 10^<-8> cm/s.5. Soil was frozen and thawed from the bottom of the soil column, and the soil moisture and salt movement was measured. The result was examined against the initial soil moisture and salt concentration. The higher the initial soil moisture, the water and salt movement increased. Heat flux in the soil was estimated by the thermal conductivity and the measured temperature distribution.6. Soil column was frozen and thawed from the top surface, and water and salt movement was measured under conditions of open or closed surface and high or low initial soil moisture. The frozen depth was influenced little by the initial soil moisture, but greater movement of water and salt toward freezing front was observed at high initial soil moisture. At high soil moisture, salt accumulation was proceeded after thawing under opened surface condition. Less

1.以内蒙古河套灌区土壤冻融过程中水盐运移为背景和切入点，介绍了该灌区土壤冻融过程中水盐运移的实例。探讨了区域和田间水平盐分运移规律，春、秋灌积盐关系，秋灌对土壤水分的补给和淋溶作用，盐渍化土地的改良方法.测定了冻结水泥土的介电常数，并将冻结水泥土中的水分为水化态和结构结合态。估计了这些水的数量。并估算了结构结合水的水势.通过分析土壤表面温度正弦振荡时温度振荡幅度随深度的变化关系，计算了冻结和未冻结土壤的导热系数。应用该方法测定了田间土壤温度变化、冻结和未冻结土壤的导热系数 ...更多信息利用该方法对非冻结状态进行了估计.提出了一种测定冻土非饱和导水率的新方法。冻土样品在离心力场下平衡，通过样品中水分剖面的变化来测量水分损失。渗透系数由失水量除以离心力梯度和离心时间计算。测得的水力传导率范围为10 μ <-9>cm/s至10 μ <-8>cm/s。从土柱底部开始冻融土壤，测定土壤水盐运动。并与土壤初始含水量和盐分浓度进行了对比分析。土壤初始含水量越高，水盐运移越快。利用土壤热导率和实测温度分布估算土壤热通量.从土柱顶面开始冻融，测定了在开放和封闭表面、土壤初始含水量高低两种条件下的水盐运动。土壤初始含水量对冻结深度的影响不大，但在较高的初始含水量下，水盐向冻结前沿的运移较大。在土壤含水量较高的条件下，解冻后在敞开的地表条件下，土壤盐分会发生积累。少