【摘要】 准确模拟土壤水汽吸附曲线对于研究土壤与水分子之间的相互作用机理及预测土壤中挥发性有机气体的运移有重要意义。选择了中国不同地区七种典型土壤,评价了GuggenheimAnderson-deBoer(GAB)模型对水汽吸附和解吸曲线的模拟效果,并就水汽吸附行为的影响因素、水分子与土壤颗粒的相互作用机制进行了讨论。结果表明,对于七种供试土壤的水汽吸附和解吸曲线,GAB模型均方根误差小于0.000 7,决定系数大于0.995。相比土壤水汽解吸附过程,水汽吸附过程土壤的单层吸附水含量较低,而纯液态和单层吸附的水分子自由焓差较高。水汽吸附与解吸附过程中土壤单层水含量和滞后指数与有机碳含量呈极显著的正相关关系,而与黏粒含量的相关性受矿物类型的影响。更多还原

【Abstract】 【Objective】The isotherm of soil water vapor adsorption is one of the basic hydraulic characteristics of soil. Simulating the isotherm accurately is of great significance to studying mechanism of the interaction between soil and water molecules and predicting migration of volatile organic gases in soil.【Method】In this study, seven typical soils of different regions of China were collected for determination of water vapor sorption isotherms with vapor sorption analyzer, separately, in lab. During the process, the water activity of the sample was controlled with the range of 0.1～0.9, and temperature was at 25 °C. Then the GAB(Guggenheim-Anderson-de Boer) model was used to evaluate effect of the simulation of water vapor sorption isotherms, and its performance was evaluated by root mean square error and determination coefficient. Factors influencing factors of water vapor adsorption behavior and mechanism of the interaction between water molecules and soil particles were discussed. 【Results】For simulation of water vapor adsorption and desorption curves of the seven types of soils investigated, the root mean square error of the GAB model was lower than 0.000 7, while the determination coefficient was higher than 0.995. Compared with the soil water vapor desorption process, the monolayer water adsorption during the water vapor adsorption process was quite lower, but the molecules free enthalpy of pure liquid water and single-layer adsorbed water was rather high. Monolayer water content during the adsorption and desorption processes and hysteresis index were ultra-significantly and positively related to the organic carbon content. Monolayer water content was higher during the desorption process(M0 = 0.002 8～0.031 4) than during the adsorption process(M0 = 0.001 2～0.023 0) in the seven types of soils. The relation of monolayer water content with clay content was affected by type of soil mineral. And no significant relationships were observed between soil physico-chemical properties(such as organic carbon content, clay content and so on) and other GAB model parameters(for instance, C, K) during the adsorption and desorption process. 【Conclusion】The GAB model is proved to be able to accurately describe water vapor adsorption and desorption processes in the investigated soils. Soil water vapor sorption capacity is highly affected by soil organic carbon content,clay content and type of soil mineral. Hysteresis occurred in all the investigated soils, and varies with soil physico-chemical properties.更多还原