本文用平衡水汽压法研究了紫色土对气态水的吸附特征以及被吸附气态水的热力学函数.结果表明,紫色土对气态水的吸附属多分子吸附,在一定温定、湿度条件下,土壤具有一定吸附限量。最大平衡吸附量为中性紫色土>钙质紫色土>酸性紫色土,并与土壤物理性粘粒、粘粒、有机质、粘粒团聚度、阳离子代换量(CEC)密切相关.其中,以物理性粘粒含量及其团聚度和阳离子代换量影响最大.土壤吸附气态水是一个放热过程,被吸附气态水的相对偏摩尔焓(△(?))、自由能(△(?))和熵(△(?))比纯水低。当土壤含水量为6.00%时,相对偏摩尔焓、自由能和熵的大小顺序为中性紫色土<钙质紫色土<酸性紫色土。偏摩尔熵和焓受有机质的影响最大,物理性粘粒和CEC 对相对偏摩尔自由能(△(?))的作用较大。 In this paper, the equilibrium vapor pressure method was used to study the adsorption characteristics of purple soil to gaseous water and the thermodynamic functions of the adsorbed gaseous water. The results show that adsorption of purple soil to gaseous water belongs to multi-molecular adsorption. Under certain temperature and humidity conditions, Has a certain adsorption limit. The maximum amount of equilibrium adsorption is neutral purple soil> calcareous purple soil> acidic purple soil, which is closely related to soil physical clay, clay, organic matter, clay agglomeration and cation exchange capacity (CEC) Physical clay content and its reunion degree and cation exchange capacity have the greatest influence on the adsorption of gaseous water on the soil, which is an exothermic process, relative partial molar enthalpy (△ (?)), Free energy (△ (?)) ) And entropy (△ (?)) Than pure water. When the soil water content is 6.00%, the relative partial molar enthalpy, free energy and entropy order are neutral purple soil