中文摘要：

土壤胶体的凝聚或分散紧密地联系着许多环境问题，并受胶体表面电荷性质的调控。以黄壤为实验材料，利用动态光散射技术研究pH作用下该可变电荷胶体颗粒的凝聚动力学。结果发现：土壤胶体的凝聚与否强烈依赖于pH。不同浓度HNO3和KOH诱发的土壤胶体凝聚均表现出慢速和快速凝聚特征，在快速凝聚中，HNO3作用较KOH作用的黄壤胶体平均凝聚速率更高、变化更快，表明表面电荷中和诱发的凝聚远大于压缩双电层诱发的凝聚。通过快速平均凝聚速率变化的反转点对应的pH，估计电荷零点（Zero point of charge，ZPC），提供了一个实验测定ZPC的新方法。

英文摘要：

Aggregation/Dispersion behavior of soil colloids is closely related to numerous environmental factors and regulated by surface charges of the colloids. Dynamics of the aggregation of variable charge colloids in yellow earths different in pH was studied with the dynamic light scattering technique. Results show that stability of the aggregation of soil colloids was strongly dependent upon pH. The aggregation of colloids induced by HNO3 or KOH, different in concentration would exhibit the characteristics of fast diffusion limited cluster aggregation （DLCA） or slow reaction limited cluster aggre- gation （RLCA）. In the former, the aggregation induced by HNO3 was faster in average velocity and in variation than that by KOH, which suggests that the aggregation induced by neutralization of surface charge was faster than that by compression of double electron layers. The use of the pH corresponding to the turning point where average aggregation velocity changes pH in DLCA to estimate zero point of charge （ZPC） provides a new method for measuring ZPC in experiment.