Abstract:

Diffusion coefficient of chloride ion in four type textural soils at various water contentunder different temperature were measured by the diffusion-cell method using36Cl labelledNaCl solution, The results showed that the diffusion coefficient(D)in the soil increased butthe activation energy decreased with increasing soil water content, which indicated that theforce to be overcome during the diffusion was lower at higher soil water content. The D valuedecreased with increasing soil water tension(S).The relation could be descilbed by the pow-er equation in the form of D=sS-b, The D value increased with increasing temperature, andincreasing temperature 10℃ from 5℃ to 45℃ caused the D value increased by 10%～30%with average of nearly 20%. The relationship between D value and soil water content as wellas temperature could be described by the nonlinear regression equation. Moreover,it wasfound that the D value increased with increasing clay content of soil under same water ten-sion,in general,the correlation between D and clay content was significantly positlve.

Key words: chloride ion, diffusion coefficient, activation energy of diffusion, soil water content, temperature

摘要：

采用￣（３６）Ｃｌ标记扩散池法，测定了４种不同质地土壤在有效水含量范围内不同温度下Ｃｌ￣－的扩散系数。结果表明，Ｃｌ￣－扩散系数（Ｄ）随土壤水分增加近线性增大，与Ｃｌ￣－扩散的活化能随水分增加而降低，土壤水分高时，Ｃｌ￣－扩散与所需克服的能障较低相一致。Ｄ值随土壤水吸力（Ｓ）增大而减小，符合幂函数Ｄ－ａＳ－ｂ关系。５～４５℃下每升温１０℃，Ｃｌ￣－扩散系数增加量为１０％～３０％，平均为２０％左右。土壤水含量和温度与Ｃｌ￣－扩散系数的定量关系可用非线性多元方程描述。试验还发现，同一水吸力下，Ｃｌ￣－扩散系数随土壤质地变粘而增大，与土壤粘粒含量呈显著正相关。

关键词: 氯离子, 扩散系数, 扩散活化能, 土壤含水量, 温度