金属离子浓度对泥沙淤积干重度影响试验研究

天然河流水体中的金属离子对淤积物干重度有很大影响。通过静水沉降试验初步研究了天然河水中常见金属离子Na+，Ca2+和Al3+对泥沙淤积干重度的影响。试验结果表明① 金属离子对泥沙淤积干重度的影响机理均相同，但是高价离子对泥沙淤积干重度影响大；② 离子对泥沙淤积干重度的影响可分为3个阶段，第1阶段干重度减小，第2阶段干重度增加并达到最大值，第3阶段干重度减小最后趋于不变；③ 在不同离子浓度范围内，泥沙浓度对干重度的影响不同；④ 离子浓度、泥沙浓度相同时，中值粒径越大干重度越大，且中值粒径大的泥沙干重度达到最大值所需离子少。

Experimental Study on Influence of Concentration of Cations on Dry Specific Weight of Sediment

Water quality has much influence on the dry sperific weight of sediment in natural river, the primary influence is from the metal cations in water. This paper studies the influence of Na+,Ca2+,and Al3+, which are familiar in natural river, on the dry specific weight of sediment by the experimentation of sediment settling in water. The results of the experimentation show some conclusions as follows. ① The influence mechanism of the metal cations on the dry specific weight of sediment is similar, but the influence of high valence ions is bigger. ② The influence of the concentration of  cations on the dry specific weight of sediment is biggest, and the change of dry specific weight may be divided into three phases with the concentration of cations increase: first phase is that the dry specific weight is reduced; the second phase, the dry specific weight is increased and reached the maximal value; the third phase, the dry specific weight is reduced once again and, finally, is remained constantly. ③ when the concentration of cations is equal, the influence of sediment concentration on dry specific weight  has different changes with the concentration of cations increase. ④ As the concentration of Ca2+ and the sediment concentration are the same, the bigger the median size of sand, the heavier its dry specific weight, and the number of cations of larger median size, which is needed to reach the maximal value of dry specific weight, is less than that ofsmaller median size.