三种螯合剂对土壤重金属Cd和Zn形态变化的研究

Effects of Three Chelate on the Form Distribution of Cd and Zn in Soil

螯合诱导植物修复技术目前在重金属污染土壤治理领域中具有广阔的发展前景;而土壤中重金属的生物有效性一直是这项技术中的关键。在实验室条件下,利用土壤培养和BCR(the Community Bureau of Reference)连续提取方法,研究了外源重金属Cd、Zn在土壤中的形态转化以及EDTA-Na2、DTPA和酒石酸三种螯合剂的添加对土壤中Cd、Zn形态的影响。结果表明:原土中的Zn主要以可还原态为主,残渣态和可氧化态次之。原土中的Cd含量较少,主要以残渣态主。外源Cd、Zn进入到土壤后,重金属各个形态含量明显增加,主要集中在酸可提取态中。EDTA-Na2、DTPA和酒石酸添加后,土壤中Cd、Zn的酸可提取态明显提高,可还原态和可氧化态含量降低,残渣态没有明显变化。三种螯合剂的添加浓度和Cd、Zn的有效态有着明显的线性相关性,其中DTPA的相关性最高。EDTA-Na2在1.25 mmol.kg-1的时候对Cd和Zn活化效果最好;比对照组分别提高了34.16%和23.24%,说明EDTA-Na2在1.25 mmol.kg-1的施加浓度下,对修复重金属污染土壤中的Cd和Zn具有较大潜力。

In the field of the contamination of environment with heavy metals,chelate-induced phytoremediation had a broad development prospect,and bioavailability of heavy metals in soil was always the key to this technology.In the laboratory conditions,the pot experiment and BCR extraction technique were undertaken to study the distribution of form transformations of soluble heavy metals which added into soil and the effect of EDTA-Na2,DTPA and Tartaric Acid on the form of Cd and Zn in soil.The results show that Zn in the original soil mainly existed in reducible state primarily,residual and oxidizable secondly,while original Cd content was less,almost existed in residual.After soluble heavy metals of Cd and Zn into soil,heavy metal content of each form had increased obviously,while the content of Cd and Zn mainly existed in acid soluble With the addition of EDTA-Na2,DTPA and Tartaric Acid,the acid soluble of Cd,Zn had improved significantly,at the same time,the reducible and oxidizable levels were low,the residual did not changed obviously.Three kinds of chelate concentration had significant correlation with the acid soluble of Cd and Zn,while the DTPA had the highest correlation.When the additional concentration of EDTA-Na2 was 1.25 mmol.kg-1,activation ability of EDTA-Na2 respectively reached the maximum value,but also increased more 34.16% and 23.24% than the blank groups.It showed that with the additional concentration of 1.25 mmol.kg-1,EDTA-Na2 had a great potential for Cd and Zn remendiation of heavy metal pollution.