土壤有机矿质复合体的表面电荷特性及对锌的吸附

Surface Charge Characteristics and Zinc Adsorption ofOrgano-mineral Complexes in Soils￣①

供试土样为中国的棕壤、红壤和赤红壤及巴基斯坦的ｇｕｊｒａｎｗａｌａｓｅｒｉｅｓ和ｋｏｔｌｉｓｅｒｉｅｓ．与Ｈ－粘粒比，Ｈ－粘粒复合体有较多的净负电荷和较少的正电荷。在红壤和赤红壤中，Ｈ－粘粒复合体的表面积比Ｈ－粘粒大，但在棕壤，ｇｕｊｒａｎｗａｌａｓｅｒｉｅｓ和ｋｏｔｌｉｓｅｒｉｅｓ中则相反。在ｐＨ近７．０时，因有机质而使负电荷百分数增加的次序为赤红壤＞红壤＞ｇｕｊｒａｎｗａｌａｓｅｒｉｅｓ＞ｋｏｔｌｉｓｅｒｉｅｓ＞棕壤。当ｐＨ＜７时有机质可以提高赤红壤、红壤和ｋｏｔｌｉｓｅｒｉｅｓ对锌的吸附，在各种锌浓度下，有机质均能提高棕壤和ｇｕｊｒａｎｗａｌａｓｅｒｉｅｓ对锌的吸附。与Ｌａｎｇｍｕｉｒ和Ｔｅｍｋｉｎ方程比较，Ｆｒｅｕｎｄｌｉｃｈ方程最适合描述Ｈ－粘粒复合体对锌的吸附行为，但Ｌａｎｇｍｕｉｒ方程最适合于自然粘粒复合体。

Three soils fron China ie. fragiaqualf(brown soil),udult(red soil)and oxisol(laterit-ic red earth)and two from Pakistan i.e. hoplustalf (gujranwala series)and chromustert(kotli se-ries)were studied.Net negative charges of H-clay complexes were found more and positive charges less than those of H-clays. H-clay complexes of udul and oxisol had larger surface area than H-clay,while reverse was true in fragiaqualf,hoplustalf an chromustert.The perecentage of increase in negative charge due to organic matter near pH 7.0 followed the order of oxisol > udult>ho-plustalf>chromustert>fragiaqualf Organic matter increased the adsorption of zinc by oxisol,udult and chromustert at pH<7.0,and by fragiaqualf and hoplustalf at all Zn concentrations. Freundlich equation was found to be best fit in H-clays and H-clay complexes as compared to Langmuir and Temkin equations. Langmuir equation was found to be the best fit in natural clay complexes.