摘要
研究了我国典型３种可变电荷土壤和４种恒电荷土壤在陪伴阳离子分别为Ｋ十、Ｎａ十、Ｃａ２＋时和１ｍｍｏｌＬ－１ＫＣ１、Ｋ２ＳＯ４支持电解质中ＮＯ３－的吸附。结果表明，ＮＯ３－吸附量随ｐＨ的增加而减小。在添加相同浓度ＮＯ３－时，３种可变电荷土壤对ＮＯ３－的吸附量顺序为Ｃａ（ＮＯ３）２＞ ＫＮＯ３＞ＮａＮＯ３＞ＫＮＯ３十ＫＣＩ＞ＫＮＯ３＋Ｋ２ＳＯ４；在初始ＮＯ３－浓度０．５－５ｍｍｏｌＬ－１的范围内，吸附量随浓度变化的关系符合Ｌａｎｇｍｕｉｒ等温吸附式．由此求出与ＮＯ３－吸附结合能有关的常数（Ｋ）在不同共存离子存在下数值较小且差异不大，因此认为不同陪伴阳离子和不同伴随阴离子对ＮＯ３－吸附的电性机理影响不大，只是改变了土壤表面的正电荷数量从而使吸附量发生变化。４种恒电荷土壤对ＮＯ３－的吸附量通常很小，其中在Ｃａ（ＮＯ３）２介质中较在其他介质中稍大，最大吸附量仅为１．５～ｍｍｏｌ ｋｇ－１左右，约为可变电荷土壤的１／１０，且在浓度较低时常观察到负吸附。
The adsorption of nitrate ions by three variable charge soils and four constant charge soils of China were measured under different pH, co-existing CI- or SO3- and accompanying K+, Na + or Ca2+. The results showed that the amount of NO3- adsorbed by soils decreased with increasing pH. For variable charge soils, the amount of adsorbed NO3- in different electrolytes decreased in the order Ca(NO3)2 > KNO3 > NaNO3 > KNO3 + KCI > KNO3 + K2SO4. Within the range of 0.5 to 5 mmol L-l of NO3- added, the adsorption can be described by the Langmuir equation satisfactorily, and the adsorption energy parameter (K) as calculated from the equation was similar in magnitude when different anions and cations co-existed. This implies that the adsorption of NO3- is mainly determined by electric force, which can not be changed by such factors as the type and the concentration of co-existing cations and anions. These factors can only influence the adsorption of nitrate through changing the surface properties, mainly the quantity of positive charge of the soil. However, the adsorption of nitrate by constant charge soils was a little higher in Ca(NO3)2 Solution than that in other electrolytes. The maximum amount of adsorption by these soils was only 1.5 mmol kg-1, corresponding to about one tenth of the adsorbed NO3- by variable Charge soils. For these constant charge soils, a negative adsorption of NO3- was usually observed at low concentrations.
出处
《土壤学报》
CAS
CSCD
北大核心
2001年第2期204-211,共8页
Acta Pedologica Sinica
基金
国家自然科学基金(49831005)
中国科学院重点项目(KZ952-J1-204)
中国博士后科学基金资助项目
