摘要
研究了草酸对Cd2+、Zn2+单一及复合条件下在陕西塿土、黄绵土、黑垆土、黄褐土、砂土5种土壤中的吸附特征,并探讨了草酸的影响机制。结果表明,除在低Zn2+平衡浓度下,5种土壤中草酸促进了Zn2+的吸附外,总体上在Cd2+、Zn2+单一处理及其复合处理中,草酸降低了土壤对Cd2+、Zn2+的吸附。草酸既没有改变塿土、黑垆土吸附能力最强、砂土吸附能力最弱的结果,也没有改变Cd2+、Zn2+之间的相互拮抗作用。草酸对Cd2+、Zn2+吸附的影响机制主要在于其与Cd2+、Zn2+形成络合物。草酸主要通过降低电性引力的方式减弱土壤对Cd2+的吸附能力,而对于Zn2+,在低平衡浓度下,草酸对Zn2+吸附的促进作用来源于在土壤氧化物矿物表面形成少量的三元表面络合物的桥键合效应,在高平衡浓度下,对Zn2+吸附的抑制作用来源于草酸对土壤有机质化学吸附点位的竞争。对Cd2+、Zn2+吸附起决定作用的依然是土壤本身性质。
The effects of oxalic acid on the Cd2＋, Zn2＋ adsorption at both Cd2＋or Zn2＋ sole treatment and Cd2＋ ＋ Zn2＋ complex treatment in 5 kind of soils, i.e. Lou soil, Loessial soil, Dark loessial soil, Yellow cinnamon soil and Sandy soil, were carried out and the adsorption mechanism were discussed also. The results showed that oxalic acid could decrease Cd2＋ or Zn2＋ adsorption in both Cd2＋ or Zn2＋ sole treatment and Cd2＋ ＋ Zn2＋ complex treatment as a whole, except that oxalic acid promote Zn2＋ adsoption in 5 kind of soils at lower Zn2＋ equilibrium concentration. The adsorption capacity sequence of 5 kinds of soils, that Lou soil and Dark Loessial Soil had a strongest adsorption capacity while the Sandy soil′s adsorption was the least, and inter-antagonism between Cd2＋ and Zn2＋ adsorption in soils were not changed by coexistence of oxalic acid. The affecting mechanism of oxalic acid on the Cd2＋ or Zn2＋ adsorption was its complexing action. Oxalic acid decreases the Cd2＋ adsorption in soils by reducing the electrostatic-attraction of soil, but the effects of oxalic acid on Zn2＋ adsorption was affected by Zn2＋ equilibrium concentration. Oxalic acid could promote the Zn2＋ adsorption in lower Zn2＋ equilibrium concentration by bridge-bonding of ternary-complex-compound formed on the surface of soil oxide mineral, but decrease the Zn2＋ adsorption in higher Zn2＋ equilibrium concentration by competing with the chemical adsorption sites on the surface of soil organic materials. As a results, oxalic acid could affect but not decided Cd2＋ or Zn2＋ adsorption in 5 kinds of soils, the soil properties were the determining factors.
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2011年第11期2265-2270,共6页
Journal of Agro-Environment Science
基金
国家自然科学基金项目(40301021)
关键词
复合吸附
草酸
镉
锌
complex adsorption
oxalic acid
cadmium
zinc
作者简介
孟昭福（1968-），男，辽宁盖州人，博士，教授，博士生导师主要从事土壤污染及修复方面的研究。E—mail：zfmeng1996@263．net
