三种螯合剂对吊竹梅修复铀镉复合污染土壤的影响

为探讨螯合剂对植物修复的影响，采用模拟铀镉复合污染土壤的盆栽试验，研究了3种可降解螯合剂乙二胺二琥珀酸(EDDS)、草酸(OA)和柠檬酸(CA)在不同浓度(0.0、2.5、5.0、7.5 mmol/kg)下对吊竹梅吸收、转运、富集U和Cd的影响。结果表明：吊竹梅生长受螯合剂种类及浓度的影响，高浓度(7.5 mmol/kg)的EDDS对吊竹梅有较大的毒害作用，而低浓度(2.5 mmol/kg)的CA和OA显著促进吊竹梅的生长；螯合剂可促进吊竹梅对U和Cd的吸收和转运，其中，用5.0 mmol/kg CA处理时，吊竹梅单株U含量达到峰值，为205.9 mg/kg，是对照组(即0 mmol/kg处理)的5.68倍，用5.0 mmol/kg EDDS处理时，吊竹梅单株Cd含量达到的峰值为47.03 mg/kg，是对照组的2.65倍；在7.5 mmol/kg CA处理下，吊竹梅的U转运系数最高为0.342，是对照组的2.36倍，而EDDS对Cd的转运效果较佳；从单株U、Cd富集量来看，CA不仅对促进吊竹梅富集U的效果最佳，同时，对Cd也有一定效用，而EDDS仅能促进吊竹梅富集Cd，OA对U和Cd的富集效果均较差；此外，CA、EDDS的添加分别增强了土壤中U和Cd的有效态含量。综合而言，施加适宜浓度的螯合剂能增强吊竹梅对U和Cd污染土壤的修复效率。

Effect of Three Kinds of Chelating Agents on Phytoremediation in U and Cd Contaminated Soil by Zebrina pendula

To explore the effects of chelating agent on the phytoremediation in U and Cd contaminated soil, a pot experiment was performed to study the effects of 3 chelating agents (EDDS, OA and CA) and their additive concentrations (0.0, 2.5, 5.0, 7.5 mmol/kg) on U and Cd extraction, translocation, and accumulation in Zebrina pendula. The results show that the growth of Zebrina pendula is affected by the type and concentration of chelating agents. The addition of 7.5 mmol/kg EDDS inhibits the growth of Zebrina pendula.  The application of 2.5 mmol/kg OA and CA increases the net weight of Zebrina pendula. The chelating agents have a positive effect on the uptake and translocation of U and Cd in Zebrina pendula. Applying 5.0 mmol/kg CA, the U content maximally increases by 5.68 times of control check, with levels of 205.9 mg/kg attained. Applying 5.0 mmol/kg EDDS, the Cd content maximally increases by 2.65 times of control check, with levels of 47.03 mg/kg attained. The maximum value of the U translocation factor is 0.342 when CA concentration is 7.5 mmol/kg, which is 2.36 times of that of control check. EDDS could better improve the translocation factor of Cd. Based on the results of U and Cd bioaccumulation, it is concluded that CA has the greatest effect on the accumulation of U and also has effect on that of Cd, EDDS has effect on the accumulation of Cd, while OA has no effect on the accumulation of U and Cd. The addition of CA and EDDS respectively enhances the available contents of U and Cd in soil. These results suggest that chelating agents could improve the effectiveness of phytoremediation with Zebrina pendula in soil contaminated with U and Cd.