行道树国槐不同形态重金属富集效能研究

Study on Enrichment Efficiency of Heavy Metals in Different Formations in Roadside Trees of Sophora japonica L.

[目的]揭示不同形态重金属在行道树国槐各器官的富集特征。[方法]采用改进BCR连续提取法对北京市蓝靛厂北路旁的土壤和国槐的叶片、树枝、树皮、树干与树根中Cr、Ni、Mn、Cu、Zn、Cd和Pb等7种重金属元素进行提取,并用ICP-MS测定各形态重金属浓度。[结果]结果表明:树皮中7种重金属元素浓度最高,重金属元素在树根向树干、树干向树枝和树枝向树叶的迁移均以酸溶态为主。树皮和树干为重金属元素的主要贮存器官;重金属元素在叶片中以相对活跃的酸溶态存在。国槐对不同形态重金属的富集效能大小依次为:可氧化态>可还原态>酸溶态>残渣态;国槐对7种重金属的平面富集效能和空间富集效能分别达到372.90mg·m^-2和45.48mg·m^-3。[结论]国槐各器官的重金属浓度存在显著差异;重金属元素在国槐体内的运输以酸溶态为主;重金属元素以相对稳定形态贮存在树皮和树干;国槐对可氧化态重金属的有效净化效率高于其他形态。

[Objective]To characterize the enrichment accumulation profiles of heavy metals in different organs of Sophora japonica L.[Method] From the soil and different organs of the road side tree of Sophora japonica L.along Landianchang North Road,Beijing City,seven kinds of heavy metals including Cr,Mn,Ni,Cu,Zn,Cd,and Pb were extracted by the modified BCR method.The concentrations of heavy metals in samples were determined by the Inductively Coupled Plasma Mass Spectroscopy (ICP-MS).[Results] The bark part has the highest concentration of heavy metals.Heavy metal elements were transferred from trunk to bark,from bark to branch,and then from branch to leaf,mainly in acid soluble species.The bark and trunk are the main storage organs for heavy metals.Heavy metal elements existed in leaves in a more active acid soluble species.The enrichment efficiency for different heavy metal elements of Sophora japonica L.followed the order of oxidizable>reducible>acid soluble>residual forms.The plane and space enrichment efficiency of the Sophora japonica L.were 372.90 mg·m^-2 and 45.48mg·m^-3,respectively.[Conclusion] There were significant differences for the heavy metals accumulation between different organs.Heavy metal elements were transported from the root to leaves mainly in an acid soluble form.Heavy metal elements were stored in the bark and trunk in relatively stable forms.Sophora japonica L.showed the greatest purification efficiency for oxides form of heavy mental elements rather than other forms.