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。作为这项研究的背景和起点，来自中国内蒙古的Hetao灌溉区引入了土壤冷冻和融化过程中水和盐运动的例子。讨论了区域和田间盐的运动，春季和秋季灌溉中的盐积累，土壤供水和通过秋季灌溉的提升效应，盐土地的改进方法进行了讨论。2。测量冷冻水泥土的介电常数，并将其中的水分类为水合和结构结合的状态。估计这些水的数量。还估计结构结合水的水潜力3。通过分析正弦温度振荡的温度振荡放大器，将冷冻和未冻结的土壤的导热率与深度相关的放大器计算。应用该方法来确定田间的土壤温度变化，并通过该方法估算了冷冻和U的热导率。4。开发了一种测量冷冻土壤不饱和水解电导率的新方法。在离心力场下，冷冻的土壤样品是等效的，通过样品中的水分特征的变化来测量水分流失。水解电导率是由水损失除了离心力和时间的梯度来计算的。测得的水解电导率范围从10^<-9> cm/s到10^<-8> cm/s.5。将土壤冷冻并从土壤柱的底部解冻，并测量土壤水分和盐的运动。对最初的土壤水分和盐浓度进行了检查。初始土壤水分越高，水和盐的运动增加。通过热导率和测得的温度分布估算土壤中的热通量。6。将土壤柱从顶表面冷冻并融化，并在开放或封闭的表面以及高或低初始土壤水分的条件下测量水和盐的运动。最初的土壤水分对冷冻深度的影响很小，但是在高初始土壤水分处观察到水和盐向冰冻的前进。在高土水分处，在打开的表面状况下解冻后，进行盐的积累。较少的