陕西几种土壤粘粒的表面固有特征

Surface intrinsic characteristics of soil clays in Shaanxi

表面络合模式中的恒定容量模式 (CCM)、三层模式 (TL M)均不同程度适应于描述土壤粘粒表面的固有特征。 TL M图解法的单外推法既可求出表面酸度常数 ,同时也可求出介质阳离子的络合常数 ;供试土壤粘粒的表面固有酸度常数 p Kinta2 在 5 .1 1～ 6 .4 4 ,且呈现土娄土 >黄绵土 >黑垆土 >黄褐土。同一土壤粘粒在不同介质中的固有酸度常数也有明显的差异 ,p Kinta2 (Ca2 + ) <p Kinta2 (K+ ) <p Kinta2 (Na+ )。供试介质阳离子表面络合常数的大小为Kint Ca2 + >Kint Na+ ,Kint K+ 。

Constant capacitance model and Triple layer model can successfully described surface characteristics to some extent.The surface intrinsic constants were obtained by the graphical methods.Single extrapolation of the graphical methods in triple layer model can not only obtain the intrinsic acidity constants but also cationic complexation constant.The intrinsic constants of different soil clay were related to mineral type,organic matter and oxide content.The tested soil colliods was between 5.11 to 6.44,and showed the trend of old manured loessal soil >yellow cinamon soil>dark cultivated loessal soil>yellow loessal soil,the sequence of cation surface complexation constants is K int Ca 2+ > K int Na + ? K int K + .