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).

ResultsThe 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.