交换性阳离子和胡敏酸对粘土絮凝-分散的作用

THE ROLE OF EXCHANGABLE CATION (Na +, Ca 2+ ) AND HUMIC ACID IN THE FLOCCULATION AND DISPERSION OF CLAYS

选用Ｎａ＋、Ｃａ２＋和胡敏酸（ＨＡ）研究不同价态的交换性阳离子、土壤有机质对纯矿物和土壤粘粒絮凝－分散的作用。结果表明：粘粒悬浮液中Ｎａ＋或Ｃａ２＋浓度较低时，土壤有机质均能提高纯矿物和土壤粘粒的分散程度，表现为粘粒悬浮液的临界絮凝浓度（ＣＦＣ）随ＨＡ添加量的增加而提高。当Ｎａ＋或Ｃａ２＋浓度较高时，有机质失去对粘粒的分散作用。用Ｈ２Ｏ２去除土壤有机质后，土壤粘粒分散程度明显下降，ＣＦＣ减小，有机质含量较高的黄棕壤ＣＦＣ下降程度大于有机质含量较低的红壤。与Ｃａ２＋作用下相比，Ｎａ＋作用下ＨＡ对粘土矿物的分散度较大，１∶１型高岭矿或以１∶１型矿物为主的红壤的粘粒悬浮液的ＣＦＣ受ＨＡ的影响大于２∶１型蒙脱矿或以２∶１型矿物为主的黄棕壤。

Roles of exchangable cation and humic acid (HA) for the flocculation and dispersion of soil clays and clay minerals were studied. The results showed that HA promote the dispersion of both soils clays and clay minerals in the lower concentration of Na + or Ca 2+ in the suspensions. The critical flocculation concentration (CFC) of clay suspension increased with the addition of humic acid (HA). However, the role of HA for dispersion of clays was limited while the suspension with a higher concentration of Na + or Ca 2+ . The reason was that the higher electrolyte concentration led to the flocculation of HA. On the other hand, CFC was decreased obviously with the removal of soil organic matters by H 2O 2. The CFC of clay suspension of yellow brown soil with higher content of organic matter (OM) droped more dramatically than that of red soil, which has lower OM content. The dispersion of Na clays by Na HA was more effectively than that of Ca clays by Ca HA.