我国几种地带性土壤无机胶体的表面电荷特性

研究了用返滴定法测定我国七个不同地带土壤无机胶体的表面电荷特性。结果表明 :( 1 )返滴定法测定的供试土壤无机胶体可变电荷量随纬度升高而逐渐上升。这主要与供试土壤粘土矿物、铁铝氧化物组成及含量有关。一般来说 ,土壤层状硅酸盐粘土含量越多 ,永久负电荷量和其可变负电荷量越大 ;铁铝氧化物含量越高 ,可变负电荷量越低。( 2 )七个地带性土壤无机胶体的Qv pH曲线上在pH5左右有一峰值 ,这可能与供试土壤胶体中铁铝氧化物的ZPC及供试土样层状硅酸盐的边面Si OH基吸附H 及Al OH基离解H 有关

SURFACE CHARGE CHARACTERISTICS OF SOIL COLLOIDS IN CHINA

Surface charge characteristics of inorganic colloids in soils distributed in different latitudes of China were studied by back-titration method. Results showed that:(1) From south to north,variable surface charge increases with the latitude,which is mainly related to content and composition of soil clay minerals and Fe and Al oxides in the soils. Generally speaking,the higher the content of silicate salt clay in the soil,the higher the permanent negative charge and variable negative charge. The higher the contents of Fe and Al oxides,the lower variable negative charge. (2) There exits a peak around pH5 on every Q v-pH curve of inorganic soil colloids from 7 different zonal soils. Maybe it is a result of H absorption by Si-OH and H dissociation from Al-OH on the lateral of layer silicates at different pH values. It is possibly related with ZPC of Fe and Al oxides.