Comparison of the Effects of Different Enhancing Agents on Uptake and Transfer of Cd and Pb by Sedum hybridum in the Contami-nated Soil
At present,enhancing heavy metal accumulation in hyperaccumulator has been a hot topic.One of the most promising technologies to increase the efficiency of phytoremediation is the use of enhancing agents.The key of the technology is to choose suitable agents and the combi-ning-hyperaccummulator.In this study,the effects of six different enhancing agents on the remediation of cadmium(Cd)and lead(Pb)con-taminated soil by Sedum hybridum in pot experiments were investigated.The enhancing agents were as follows:rhamonolipid(Rha),ethylenedi-amine dissuccinic acid(EDDS),polyacrylic acid(PAA),polyacrylic acid grafted with humic acid(PAA-HA),plant growth regulator:diethyl-aminoethyl-3,4-dichlorophrylether(DCPTA)and diethylaminoethyl-3,4-dichlorophrylether grafted with Choline Chloride(DCPTA-ChCl).Effects of enhancing agents on Cd and Pb speciation in soil were also studied.The results showed that all these six kinds of agents promoted Cd uptake by Sedum hybridum root.DCPTA,DCPTA-ChCl,PAA and PAA-HA promoted Cd uptake by the shoot parts of Sedum hybridum com-pared to the control.However,Rha and EDDS decreased root Cd translocation into the shoot parts of Sedum hybridum.PAA-HA was more effec-tive at contributing to Pb uptake by Sedum hybridum root,and the corresponding absorption improvement rate is 51.7%.Cd and Pb enrichment factor(BCF)of Sedum hybridum were in the range of 3.96-4.83 and 0.11-0.19,respectively.Cd and Pb translocation factor(TF)of Sedum hybridum were in the range of 2.19-3.05 and 0.19-0.39,respectively.Sedum hybridum was further validated as a Cd hyperaccumulating plant species.The results suggest that PAA and plant growth regulator DCPTA has also been demonstrated to promote plant growth,enhancing Cd and Pb uptake by Sedum germanica.The above findings may be essential for understanding the characteristics of heavy metals hyperaccumulation in plants and selection of excellent candidates of enhancing agents for phytoremediation of heavy metal from contaminated soils.
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