中性紫色土和砖红壤表面电荷性质的比较研究

采用恒流置换法测定了中性紫色土、砖红壤表面电荷总量、表面电位、表面电荷密度及表面电场强度,并讨论了电解质浓度、类型、pH以及环境温度对两种土壤电性参数影响的差异。结果表明:(1)在2:1型电解质体系(Mg(NO3)2)中,中性紫色土和砖红壤的表面电位分别约为-0.18V和-0.10 V。中性紫色和砖红壤表面电荷密度分别为-0.55 C m-2和-0.038C m-2;表面电场强度分别为-4.41E+08J m-1 C-1和-5.40E+07J m-1 C-1。紫色土的表面电荷密度、表面电场强度的值都比砖红壤高出约一个数量级。(2)两种土壤表面电荷密度随电解质浓度增加呈增加趋势,砖红壤的增加幅度要远大于中性紫色土;而表面电位随电解质浓度的增加有所降低,同样砖红壤的减小幅度要远大于中性紫色土。(3)pH对中性紫色土表面电荷性质的改变不是特别明显,而对砖红壤的表面电位和表面电荷密度都有很大程度的增加。

Surface Charge Properties of Neutral Purplish Soil and Latosol

All the physical and chemical properties of soil are ascribed to surface charge of soil particles.Many processes taking place in the soil system are influenced by surface charge.Therefore,parameters of its electrochemical properties,especially the surface potential and the surface charge density,are of the most important.By using kinetic method,surface charge properties of neutral purplish soil and latosol were studied in this paper.The total charge volume,surface potential,surface charge density and electric field strength on surface of soil were determined.The effects of electrolyte concentration,cation variety,temperature and pH on the surface charge properties were also studied.The experimental results showed that:(1) in 2:1 type electrolyte system,the surface potential of the neutral purple soil and Latosol was-0.18 V and-0.10 V,the surface charge density was-0.55 C m-2 and-0.038 C m-2,the electric field strength was-4.41E 08J m-1 C-1 and-5.40E 07J m-1 C-1.The surface potential,the surface charge density and the electric field strength in neutral purple soil were much higher than that in Latosol.(2) with the increasing of electrolyte concentration,the charge quantity and the surface charge density increased a little,and those in the Latosol increased higher than that in the neutral purple soil.But the surface potential decreased and thethose decreased lower in Latosol.(3)The effect of pH on the surface charge properties in neutral purple soil was not obvious,but the surface potential and the surface charge density were increasing with the pH in Latosol.