摘要
对 3种可变电荷土壤和 4种恒电荷土壤在不同 pH、不同浓度、不同相伴阴阳离子下混合体系中Cl-和NO-3的吸附进行了测定。结果表明 ,在Cl-和NO-3 共存体系中 ,Cl-比例增大使可变电荷土壤Na+ 吸附量及OH-释放量增加 ,而对恒电荷土壤影响不大。Cl-和NO-3 吸附量随平衡Cl-和NO-3 浓度增加而增大 ,随pH升高而减少。但恒电荷土壤在上述各种条件下对Cl-和NO-3 吸附均相同 ,而可变电荷土壤对Cl-吸附量大于NO-3 的吸附量 ;NO-3 、Cl-的选择系数为 0 5 1～ 0 78,Cl-和NO-3 的相对吸附量分别为 5 6 9%和 43 1%。在不同相伴阳离子下 ,可变电荷土壤平衡溶液Cl-/NO-3 比值均小于 1,且为Na+ >K+ >Ca2 + >Mg2 + >Fe3 + ;而恒电荷土壤Cl-/NO-3比值为 1左右 ,且不受阳离子类型的影响。由此认为 ,Cl-和NO-3 在两类土壤中均以电性吸附为主 ,恒电荷土壤对Cl-和NO-3 的亲合力及吸附机理相同 ;而可变电荷土壤对Cl-的亲合力 >NO-3 。
Adsorption of chloride and nitrate ions by three typical variable charge soils and four typical constant charge soils of China was studied under different pH, concentration and coexisting cations and anions When identical concentration of Cl - or NO - 3 was added to soil, the adsorption of Cl - by variable charge soils was higher than that of NO - 3 The selective coefficient was from 0 51 to 0 78 although the adsorption both Cl - and NO - 3 increased with decreasing pH and with increasing Cl - or NO - 3 concentration The concentration ratio Cl -/NO - 3 in soil suspension was less than 1 0 under different pH and coexisting cations such as Na +, K +, Ca 2+ , Mg 2+ , Fe 3+ These results indicated that the variable charge soils had a higher preference for chloride ions relative to nitrate ions, and this tendency could not be changed by factors such as the pH, the concentration of the anions, the accompanying cations and etc Which suggested that this difference in affinity is caused by the difference in the nature of the interactions between these two ions and variable charge soils. However, the ratio Cl -/NO - 3 in equilibrium soil suspension of constant charge soils was almost near 1.0 under various pH, concentrations and species of coexisting anions and cations, which indicated that the adsorption mechanism and affinity of Cl - and NO - 3 by constant charges soils were not different significantly. Moreover, it was observed that a negative adsorption of Cl - and NO - 3 by constant charge soils in a mixed system containing equal amount of chloride and nitrate ions at low concentration.Which do a competitive adsorption of chloride and nitrate ions and repulsion of negative charge on the surface of soil particles for anion cause.
出处
《植物营养与肥料学报》
CAS
CSCD
北大核心
2002年第1期22-28,共7页
Journal of Plant Nutrition and Fertilizers
基金
国家自然科学基金项目 ( 4 98310 0 5 )
中国博士后科学基金项目资助
