中文摘要：

以三峡库区3种紫色土胶体为研究对象,采用动态光散射方法研究其凝聚过程有效粒径变化规律。结果表明：（1）3种紫色土胶体颗粒在低浓度Mg2＋条件下,凝聚体的有效粒径增长与时间呈线性关系,其增长速度基本保持不变;在较高浓度Mg2＋条件下,其有效粒径增长与时间呈对数关系,先快速增长,再缓慢增长,最后基本不变;（2）酸性紫色土、中性紫色土和石灰性紫色土3种胶体凝聚体临界粒径分别为1.1,1.2,1.4μm,表现为中性紫色土〉石灰性紫色土〉酸性紫色土;（3）酸性紫色土和中性紫色土胶体凝聚临界浓度分别为1.0-2.0,2.0-3.0mmol/L,石灰性紫色土凝聚临界浓度为1.0-2.0mmol/L,但更接近于2.0mmol/L,同样表现为中性紫色土〉石灰性紫色土〉酸性紫色土,与它们表面电位值大小规律一致。

英文摘要：

Based on the three purplish soils colloidal in the Three Gorge Reservoir Region,their effective diameter with time was studied by dynamic light scattering.The result showed that：（1）When the concentration of Mg2＋in the three purplish soils colloidal was lower,the increasing of growth rates of effective diameter was linear correlation function of time.They did not show significant changes in an hour.When the concentration of Mg2＋was higher,the growth rates of effective diameter logarithmically increasing with time.The growth rates of effective diameter increased rapidly at first,and then increased slowly and almost invariability at last.（2）The critical effective diameter of acidic,neutral and calcareous purplish soils aggregates were 1.1,1.2,1.4μm,and the order of that was neutral purplish soilcalcareous purplish soilacidic purplish soil.（3）The critical coagulation concentration of acidic and neutral purplish soils were 1.0~2.0mmol/L,2.0~ 3.0mmol/L,and it was 1.0~2.0mmol/L in the calcareous purplish soil,but much closer to 2.0mmol/L.The order was also neutral purplish soilcalcareous purplish soilacidic purplish soil and there had the similar regularity with the surface potential.