中文摘要：

采用联合测定法和光散射技术分别研究了有机质对土壤颗粒表面电荷性质和水体中胶体颗粒凝聚过程的影响。结果表明：添加有机质能显著改变土壤表面电荷性质,使得土壤颗粒表面电荷数量降低6.8%,比表面积增加12.3%,使颗粒表面电荷密度减小,表面电位降低;进一步理论计算表明添加有机质降低了胶体颗粒间的静电排斥力,使得净引力增大,胶体颗粒更易发生凝聚。通过动态光散射分析水体中土壤胶体颗粒的凝聚特征,发现有机质去除前后的临界聚沉浓度（CCC）分别为91.6 mmol/L和139.3mmol/L,去除有机质土壤显著大于未去除有机质的土壤,相应浓度下的临界电位值计算结果均为-150mV左右,与颗粒间出现净引力的临界浓度值基本一致。有机质对水体中胶体颗粒凝聚特性的影响主要是通过改变颗粒表面性质使得颗粒间的相互作用发生变化而引起。

英文摘要：

Based on the method of combined determination and light scattering,we studied the effect of organic matter on the surface charge properties of soil colloidal particles and condensation process of colloidal particles in water bodies.The results showed that the addition of organic matter significantly changed the surface charge properties of soils,because of the total charge number increased about 6.8%,the specific surface area decreased about 12.3%,and organic matter addition decreased the surface charge density of the particles and the surface potential.Further theoretical calculations showed that the addition of organic substance reduced the electrostatic repulsion between colloidal particles,which made the net gravity increase and aggregation of soil colloids become easier.The aggregation characteristics of soli colloids in the water bodies were studied by the method of light scattering,the results showed that the critical coagulation concentration（CCC）was 91.6mmol/L before removing organic matter,and it was 139.3mmol/L after organic matter was removed,and the difference betweent these two values was significant.The critical surface potentials for colloidal particle dispersive or aggregate were both about-150 mV at the corresponding concentrations.And the above concentrations were the critical concentrations that net gravitational attraction appeared between particles.The effect of organic matter on the aggregation characteristics of colloidal particles in water bodies was mainly through changing surface properties and the corresponding interactions of particles.