交换性阳离子和胡敏酸对粘土絮凝——分散的作用

选用Ｎａ、Ｃａ＾＋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：粘粒悬浮液中Ｎａ或Ｃａ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Ｃａ浓度较高时，有机质推动对粘粒的分散作用。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Ｃ

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

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.