Heavy Metal Pollution of Dust,Topsoil and Roadside Tree Near by Main City Roadways

To effectively control heavy metal pollution of city roadways induced by motors, the pollution index method was adopted to analyze and evaluate the characteristics of heavy metal pollution of roadway dust and topsoil near by roadside trees, and grasp the status of heavy metal pollution of city roadways.The capability for the leaves of a roadside tree to capture heavy metals and the diversity of the capabilities of different trees were discussed.The results show that the heavy metal concentration of roadway dust in downtown Tokyo increases with the traffic,and it is higher in dust than in topsoil.There is the trend,i.e.,Pb pollution,representing car pollution,declines in Tokyo,but its concentration is higher and Pb pollution will exist for a long time.Moreover,Pt pollution has been brought about due to the use of Pt in the exhaust-purified system of motor vehicles.The heavy metal concentration is always higher in the leaves of roadside trees than in those of homologous trees in a contrast spot,and there is a great difference in the heavy concentration of inhomogeneous trees and Rhododendron oomurasak can accumulate more heavy metal.As a result,to plant trees that can accumulate more heavy metals can restrain the diffusion of heavy metal pollution of city roadways.