用离子活度法和悬液Wien效应法测定土壤对单价阳离子结合能的比较研究  

COMPARISON BETWEEN ION ACTIVITY METHOD AND SUSPENSION WIEN EFFECT METHOD IN DETERMINING BINDING ENERGY BETWEEN SOILS AND MONOVALENT CATIONS

作　　者：周俊[1,2] 李成保[2] 程程[1,2] 王玉军[2] 周东美[2] 周立祥[1] 

机构地区：[1]南京农业大学资源与环境科学学院,南京210095 [2]中国科学院土壤环境与污染修复重点实验室,中国科学院南京土壤研究所,南京210008

出　　处：《土壤学报》2010年第6期1151-1158,共8页Acta Pedologica Sinica

基　　金：中国科学院知识创新工程项目(ISSASIP0718);国家自然科学基金项目(47871114)资助

摘　　要：选用黑土、黄棕壤、红壤和砖红壤黏粒与蒙脱土作供试样本,用离子活度法与悬液Wien效应法测定不同黏粒对单价阳离子Na+和K+的平均结合自由能。测试结果表明,对于黑土、黄棕壤和蒙脱土而言,用Wien效应法和离子活度法测定的钠离子的平均结合自由能ΔGbi比较一致,离子活度法相对于Wien效应法测定的钠离子平均自由结合能的相对误差在24%至10%之间;对于黑土和黄棕壤而言,用Wien效应法和离子活度法测定的钾离子平均结合自由能ΔGbi十分一致,相对误差在2%以下;对于红壤,相对误差为11.5%。结果还表明,钠玻璃电极应用于本试验条件下,仅当标准溶液与被测悬液的pH之差在0.5以下,才有测定意义;液膜钾电极在本试验条件下可用于测量土壤悬液中K+离子的活度,但在蒙脱土悬液中K+离子活度测量值偏大而不适用;到目前为止,还不能直接应用Wien效应法来测求带有正电荷的可变电荷土壤,如砖红壤,对单价阳离子的结合能。Samples of montmorillonite and clay fractions（2 μm） of black soil,yellow-brown soil,red soil,and latosol were used in the test to determine mean free binding energies（ΔGbi） between monovalent cations Na＋,and K＋ and various clay particles with the ion activity method and the suspension Wien effect method.Results show that the values of ΔGbi determined of Na＋ to black soil,yellow-brown soil and montmorillonite with the two different methods were quite similar,and the relative errors of ΔGbi of Na＋ determined with the ion activity method in relation to those determined with the Wien effect method varied in the range from 24% to 10%;the values of ΔGbi determined of K＋ to black soil,and yellow-brown soil with the two different methods were almost the same,with relative errors lingering below 2%.But the relative errors of ΔGbi determination of red soil were about 11.5%.The results also indicated that the sodium glass electrode is applicable to this experiment only when the difference in pH between the standard solution and the suspension to be tested is less than 0.5;and the liquid-membrane potassium electrode can be used to determine K＋ activity in the soil suspensions in this experiment,but can not in the suspensions of montmorillonite.However,it is still impossible to directly apply the Wien effect method to determination of binding energy of monovalent cations to the variable-charge soils,positive in charge,such as latosol.

关 键 词：离子活度 悬液Wien效应 土壤黏粒 单价阳离子 平均结合自由能 

分 类 号：S153.2[农业科学—土壤学]