摘要
用红壤、赤红壤和砖红壤3种土壤胶体,测定胶体悬液在不同频率时的电导和直流电导,用以观察频散现象。结果表明,各种胶体的电导频散能力因土壤类型而异,红壤最强,赤红壤次之,砖红壤最弱。呈现明显频散所需要的频率,红壤和赤红壤为10千赫左右,砖红壤约为100千赫。可变电荷土壤的类型对电导频散的影响与土壤胶体所带的电荷总量密切相关。对于同一种胶体,悬液相对电导率(某一频率时的电导率与300赫时的电导率之比)随胶体浓度的增加而变大。红壤悬液在各种电解质存在时的电导频散曲线的形状不同,其中KCl者为一斜上直线,Ca(NO_3)_2,和CaCl_2,者则为上翘的曲线。在1到100千赫之间,频散的顺序为:KCl>Ca(NO_3)_2>CaCl_2。呈现明显频散所需要的频率,对KCl者为1千赫左右,Ca(NO_3)_2者约为10千赫,CaCl_2者高达100千赫左右。在同一频率下,红壤胶体悬液的相对电导率随KCl溶液浓度的增加(10^(-5)—10^(-3)mol/L)而减小。
The electrical conductivity of the clay fraction of three red earths in suspension was measured with alternating current at different frequencies and direct current. The results showed that the magnitude of conductivity dispersion in suspension varied with the types of soil. it was strongest for red earth, stronger for lateritic red earth and weak for latosol. The frequency necessary for inducing a distinct conductivity dispersion was about 10 KHz for red earth and lateritic red earth, and nearly 100 KHz for latosol. The effect of the type of soilon conductivity dispersion was closely related to the sum of positive and negative charges carried by clay particles. For a given clay, the relative conductivity (the ratio of conductivity at a given frequency to that at 300 Hz) in suspension increased with the increase in clay concentration.
The curves of the plot of conductivity dispersion in suspension vs. frequency in various electrolyte solutions were of different shapes. The line was nearly linear when KCl was present and concave when Ca(NO_3)_2 or CaCl_2 was present. Between 1 and 100 KHz, the magnitude of conductivity dispersion was of the order: KCl>Ca(NO_3)_2>CaCl_2. The frequency necessary for inducing a distinct conductivity dispersion was about 1 KHz with KCl and nearly 10 KHz with Ca(NO_3)_2, and up to about 100 KHz with CaCl_2.
At a given frequency, the relative conductivity of the clay fraction of red earth in suspension decreased with the increase in KCl concentration (10^(-5)—10^(-3)mol/L).
出处
《土壤学报》
CAS
CSCD
北大核心
1989年第1期16-22,共7页
Acta Pedologica Sinica
基金
中国科学院自然科学基金
