施用螯合剂对重金属污染土壤中籽粒苋镉吸收转运的影响

Effect of Applying Chelators on Cadmium Uptake and Transfer by Amaranthus hypochondriacus L.in Heavy Metal Contaminated Soil

为探讨籽粒苋及螯合剂辅助植物修复技术在重金属镉污染土壤修复领域应用的可行性,以籽粒苋为富集植物,通过田间试验研究了螯合剂类型(EDDS、NTA、EDTA及柠檬酸)、施用量(0.1%、0.2%)及施用时间(播种后60、75 d)对籽粒苋生物量及其重金属吸收转运以及土壤镉含量的影响。结果表明:施用EDDS、NTA、EDTA及柠檬酸4种螯合剂,籽粒苋根系对镉的吸收相比对照(种植籽粒苋而不施加螯合剂)增加了12.96%~55.37%,籽粒苋地上部分对镉的吸收相比对照(种植籽粒苋而不施加螯合剂)增加了19.77%~49.67%,4种螯合剂促进植株镉吸收能力的大小依次为NTA>EDDS>EDTA>柠檬酸;单独种植籽粒苋及螯合剂辅助处理可显著降低土壤中总镉含量,降低量为0.05~0.26 mg/kg,说明籽粒苋具有富集重金属镉的能力,而螯合剂可以提升籽粒苋对土壤镉的富集效果;随着螯合剂施用量的增加,籽粒苋对土壤重金属镉的移除效果随之提高;籽粒苋播种60 d后施用螯合剂的效果优于播种75 d后的施用效果。综合考虑螯合剂适应性及成本,认为可降解螯合剂NTA是一种较为理想的辅助籽粒苋修复土壤镉污染的螯合剂。

In order to explore the feasibility of planting Amaranthus hypochondriacus L.along with applying chelators in the remediation of cadmium-contaminated soil,a field experiment was conducted with four chelators(EDDS,NTA,EDTA and citric acid)by using Amaranthus hypochondriacus L.as the enrichment plant and single Amaranthus hypochondriacus L.without chelators as control.The effects of the type,application rate(0.1%and 0.2%)and applying time(60 and 70d after sowing)of chelators on the biomass and cadmium uptake and transfer of Amaranthus hypochondriacus L.and soil cadmium content were studied.The results showed that the application of these four chelators promoted the cadmium uptake by Amaranthus hypochondriacus L.;compared with the control group,the cadmium absorption of the roots increased by 12.96%-55.37%,the cadmium absorption of the aboveground parts increased by 19.77%-49.67%.The capacity of these 4 kinds of chelators on promoting cadmium uptake of Amaranthus hypochondriacus L.was NTA>EDDS>EDTA>citric acid.Single Amaranthus hypochondriacus L.and its combined application with chelators both significantly reduced total cadmium content in the soil by 0.05-0.26 mg/kg,which has demonstrated that Amaranthus hypochondriacus L.has the ability to enrich cadmium,while chelators can enhance the enrichment of Amaranthus hypochondriacus L.to cadmium in soil.With the increase of applying rate of the chelators,the removal effect of Amaranthus hypochondriacus L.to soil cadmium rose.Applying chelators 60d after sowing Amaranthus hypochondriacus L.seeds was of a better auxiliary efficacy than that 75 days after sowing.In view of the adaptability and costs of chelators,it is considered that NTA is an ideal chelator for promoting Amaranthus hypochondriacus L.to remedy cadmium-contaminated soil.