缓释微胶囊EDTA强化玉米提取土壤中铅铜的效应研究

将EDTA转化成具有缓释性能的微胶囊EDTA（Cap-EDTA）作为螯合剂,采用大宝山矿区周边重金属复合污染农田土壤进行重金属连续批浸提及盆栽试验,比较研究Cap-EDTA和未微胶囊化EDTA（Ncap-EDTA）对土壤铅铜活化的动态变化及其对玉米吸收提取铅铜的影响。结果表明：Cap-EDTA处理土壤溶液中初始增溶的铅铜质量分数显著低于Ncap-EDTA处理,且使土壤溶液中的铅铜质量分数长时间持续保持在适度范围内。添加Cap-EDTA的处理显著提高玉米吸收提取铅铜的效率,如实施3 mmol·kg-1的Cap-EDTA使玉米地上部Pb的积累高达1.26 mg·pot-1,是对照处理的1.9倍,是等量Ncap-EDTA处理的1.4倍。因此,在进行污染土壤植物修复的EDTA调控时,采用微胶囊化EDTA,能降低因直接实施EDTA而带来的污染地下水风险,且显著提高玉米修复效率。

Phytoremediation of Pb and Cu contaminated soil with maize and microencapsulated EDTA

Chelate-assisted phytoextraction using agricultural crops has been widely investigated as a remediation technique for soils contaminated with heavy metals with low mobility.Here,we report the use of a controlled-release microencapsulated EDTA（Cap-EDTA） by emulsion solvent evaporation to phytoremediate soil contaminated with Pb and Cu.Incubation experiments were carried out to assess the effect of Cap and non-microencapsulated EDTA（Ncap-EDTA） on the mobility of soil metals.Simultaneously phytoextraction efficiencies of maize after Cap and Ncap-EDTA application were tested in pot experiments.The results showed that EDTA effectively increased the mobility of Pb and Cu in the soil solution and Cap-EDTA treatment provided lower but more constant water-soluble concentrations of Pb and Cu in the soil solution.Maize shoot concentrations of Pb and Cu were lower with Cap-EDTA application than with Ncap-EDTA.However,shoot dry weight was significantly higher with Cap-EDTA application.Consequently,the Pb and Cu phytoextraction potentials of maize significantly increased with Cap-EDTA application compared with the control and Ncap-EDTA application.Addition of Cap-EDTA（3 mmol·kg-1） significantly increased the Pbphytoextractioneffciencyof maize to 1.26 mg pot-1of Pb in one growing season,almost a 1.9-fold increase compared with the control and a 1.4-fold increase compared with corresponding Ncap-EDTA（3 mmol·kg-1） applications.The risk of groundwater contamination may,thus,be alleviated and plant uptake of Pb and Cu may increase after incorporation of Cap-EDTA.It is concluded that Cap-EDTA is a better choice than EDTA for Chelate-assisted phytoextraction.