中文摘要：

水体中土壤细颗粒凝聚直接影响着泥沙颗粒沉降、搬运和淤积等过程，对物质生物地球化学循环起着十分关键的作用。采用吸管法和正交实验分析了不同环境因素对黄壤和紫色土细颗粒絮凝沉降的影响。结果表明：土壤细颗粒沉降分为快速沉降和慢速沉降两个阶段；在正交设计值范围内，随着电解质浓度升高，黄壤和紫色土平均沉降速度ω均减小；随着温度升高，黄壤的ω基本不变，紫色土的∞由先快速减小逐渐变稳定；pH值对两种土壤细颗粒絮凝沉降影响较大；BaCl，电解质体系土壤的颗粒平均沉速约是NaCl电解质土壤的2倍，而与AICl，电解质土壤的沉降效果相差不大。获得的两种土壤细颗粒最佳絮凝条件为三峡库区水体生态环境安全提供了基础数据。

英文摘要：

The flocculation of soil fine particles in water body directly affect the sediment particle settling, transporting and sil- ting process, which plays a crucial role in biogeocbemical cycles. With the pipette technique and orthogonal experiments, we an- alyzed the influences of different environmental factors on the flocculation and settlement of yellow and purple soils fine particles. The results show that ： the settlement of fine particles was divided into two phases of quick settling and slow settling; the average settling velocities of yellow and purple soils were decreased with the rise of electrolyte concentration in the scope of orthogonal de- sign value ; settling velocity of the yellow soil was constant with the increase of temperature, and the settling velocity of purple soil became stable gradually after rapidly decrease first; sediment flocculation and settlement of fine particles of the two soils were af- fected by pH ; the average settling velocity of particles in BaCl： electrolyte system was about 2 times of NaCI, and the settlement in AICI3 and BaC12 electrolyte system was almost the same. The best condition of flocculation and settlement of fine particles can be a basis for safe ecological environment in Three Gor,,es Reservoir Areas.