Heavy Metal Enrichment Efficiency Of Magnolia Grandiflora In Different Pollution Degree In Yongkang City

The concentration of heavy metal(Mn,Cu,Zn,Pb,Cr,Ni)in leaves,branches,trunk of Magnolia grandiflora L.and rhizosphere soils in Yong Kang city was measured by using the Inductively Coupled Plasma Optical Emission Spectroscopy(ICP-OES)to compare the heavy metal enrichment characteristics between different heavy metal content gradient on the basis of previous study.the enrichment of heavy metal of trees organs in different pollution degree are discussed,provide theoretical basis and data support for the future development and management of urban greening tree species and selection of tree species in different polluted areas.The study results showed that:(1)The results showed that the concentration of heavy metals in different heavy metal content gradient of Magnolia grandiflora L.,the concentration of the same element in different organs,and the concentration of different elements and different soil heavy metal content in the same organ were all different.Heavy metal concentration in Magnolia grandiflora L.followed the order of Mn > Zn > Cr > Cu > Pb > Ni.The heavy metal absorption capacity in above-ground organs followed the order of trunk>leaf>branch.And the heavy metal content in first 3 gradient is higher than the after 3 gradient.(2)Meanwhile,the study showed that the enrichment capacity of Magnolia grandiflora L.in different organs followed the order of trunk>branch>leaf,the trunk showed high enrichment characteristics of Pb(1.256)and Ni(1.188).The sort orders were strikingly different between the order of heavy metal content and concentration coefficient,which illustrated that the enrichment capacity of heavy metals by Magnolia grandiflora L.was not proportionate to the increased content of heavy metals.(3)The heavy metal accumulation in above-ground organs followed the order of trunk>leaf>branch.Trunk accounted for more than 60% and the Pb,Ni element accumulation in the highest proportion,attain average of 88.50%,84.93%.(4)Predict the remediation time of different levels of heavy metal contaminated soil by using Magnolia grandiflora trunk,Cu?Pb?Ni has the shortest remediation time;secondly is Zn and Cr;Mn has the longest remediation time.(5)Comprehensive considering the contents of heavy metals,enrichment coefficient,accumulation and remediation time in Magnolia grandiflora L,suggest that Magnolia grandiflora L.were suitable for remediation of soils contaminated by Cu?Ni?Pb and can be used for mild and moderate heavy metal contaminated soil repair.