螯合剂处理下钻叶紫苑对土壤重金属的吸收富集效应

Effects of chelators on the uptake and accumulation of heavy metals by Aster subulatus Michx.

【目的】探究不同螯合剂[乙二胺二琥珀酸(EDDS)、氨三乙酸(NTA)和乙二醇二乙醚二胺四乙酸(EGTA)]对钻叶紫苑镉(Cd)、铅(Pb)、锌(Zn)和铜(Cu)等重金属吸收累积的影响,为螯合剂和钻叶紫苑在环境修复中的应用提供参考依据。【方法】采用大棚内盆栽种植钻叶紫苑试验方法,以不添加螯合剂作对照(CK),探究在3种螯合剂(EDDS、NTA和EGTA)不同浓度(1.0、2.0和3.0 mmol/kg)的作用下,钻叶紫苑中Cd、Pb、Zn和Cu的含量变化。【结果】1.0 mmol/kg NTA和1.0 mmol/kg EGTA处理能显著促进钻叶紫苑的生长(P<0.05,下同),其干重分别较CK增加21.4%和25.8%;1.0 mmol/kg EDDS及2.0和3.0 mmol/kg EGTA处理能有效促进Cd在钻叶紫苑中吸收累积,且Cd在钻叶紫苑中的富集系数和转移系数均有显著提升,以1.0 mmol/kg EDDS处理的富集系数(0.08)和3.0 mmol/kg EGTA处理的转移系数(4.06)最大;1.0 mmol/kg NTA及2.0和3.0 mmol/kg EGTA处理能有效促进钻叶紫苑对Pb的吸收累积,且Pb在钻叶紫苑中的富集系数和转移系数较CK均有显著提升,以3.0 mmol/kg EGTA处理的富集系数和转移系数最大,分别为CK的1.48和1.35倍;2.0和3.0 mmol/kg EDDS、1.0和2.0 mmol/kg NTA及3.0 mmol/kg EGTA处理能有效促进钻叶紫苑对Zn的吸收累积,且Zn在钻叶紫苑中的富集系数和转移系数较CK均有显著提升,以2.0 mmol/kg EDDS处理的富集系数最大,为CK的1.37倍,2.0 mmol/kg NTA处理的转移系数最大,为CK的1.49倍;3.0 mmol/kg EDDS、3.0 mmol/kg NTA和1.0~3.0 mmol/kg EGTA处理能有效促进钻叶紫苑对Cu的吸收累积,以2.0和3.0 mmol/kg EGTA处理的富集系数(均为0.66)和3.0 mmol/kg EDDS处理的转移系数(1.46)最大。【结论】3种螯合剂在合适剂量条件下均可促进钻叶紫苑对Cd、Pb、Zn和Cu的富集与转运(除EDDS对钻叶紫苑吸收富集Pb的影响作用不明显外),因此,以适宜浓度的螯合剂EDDS、NTA和EGTA作为诱导活化剂,可强化钻叶紫苑吸收富集重金属Cd、Pb、Zn和Cu。

【Objective】The experimental objective was to investigate the effects of chelators[ethylene diamine disuccinate(EDDS),nitrilotriacetic acid(NTA)and glycol-bis-(2-aminoethylether)-N,N,N ′,N ′-tetraacetic acid(ETGA)]on the uptake and accumulation of cadmium(Cd),lead(Pb),zinc(Zn)and copper(Cu)with Aster subulatus Michx.,and to provide reference for the application of chelators and A. subulatus Michx. in environmental repairation.【Method】Through pot experiments in greenhouse,to evaluate the effects of application of EDDS(1.0,2.0 and 3.0 mmol/kg),NTA(1.0,2.0 and 3.0 mmol/kg)and ETGA(1.0,2.0 and 3.0 mmol/kg)on contents of heavy metals(Cd,Pb,Zn and Cu)in A. subulatus Michx.,and without the addition of chelating agent as control(CK).【Result】The results indicated that 1.0 mmol/kg NTA and 1.0 mmol/kg EGTA promoted significantly the growth of A. subulatus Michx.(P<0.05,the same blow),and the dry weight increased by 21.4% and 25.8% than those of control,respectively. 1.0 mmol/kg EDDS,2.0 and 3.0 mmol/kg EGTA could effectively promote the absorption and accumulation of Cd in A. subulatus Michx. and increase bioconcentration factor(BCF)and transfer coefficients(IF),and the highest BCF and IF of Cd in A. subulatus Michx. were 0.08 and 4.06,with applying respectively 1.0 mmol/kg EDDS and 3.0 mmol/kg EGTA;1.0 mmol/kg NTA,2.0 and 3.0 mmol/kg EGTA could effectively promote the absorption and accumulation of Pb in A. subulatus Michx.,and the BCF and IF of Pb in A.subulatus Michx. were improved significantly compared with CK,and the highest BCF and IF were respectively 1.48 and1.35 times as those of CK with applying 3.0 mmol/kg EGTA. 2.0 and 3.0 mmol/kg EDDS,1.0 and 2.0 mmol/kg NTA,and3.0 mmol/kg EGTA could effectively promote the absorption and accumulation of Zn in A. subulatus Michx.,and the BCF and IF of Zn were improved significantly compared to CK,and the highest BCF was as 1.37 times as those of CK,with applying 2.0 mmol/kg EDDS. The IF under 2.0 mmol/kg NTA treatment was the largest,which was as 1.49 times as CK.3.0 mmol/kg EDDS,3.0 mmol/kg NTA,and 1.0-3.0 mmol/kg EGTA could effectively promote the absorption and accumulation of Cu in A. subulatus Michx.,and the highest BCF of Cu were both 0.66 with applying 2.0 and 3.0 mmol/kg EGTA,and the highest IF was 1.46 with applying 3.0 mmol/kg EDDS.【Conclusion】Three chelators EDDS,NTAE and GTA in a suitable dose can promote the absorption and accumulation of Cd,Pb,Zn and Cu in A. subulatus Michx(the effects of EDDS on Pb accumulation are not obvious). Therefore,the suitable dose of the three chelators as inductive activators can enhance absorption and accumulation of heavy metals Cd,Pb,Zn and Cu in A. subulatus Michx.