Assessment Of Foliar Dust Particle Retention And Toxic Metal Accumulation Ability Of Fifteen Roadside Tree Species: Relationship And Mechanism

The resuspension of urban road dust particles with high concentration of toxic metals becomes one of the main sources of particulate matter that affects air quality and the health of human beings. To address this problem, foliar dust capture ability and toxic metal accumulation capacity are evaluated through 15 tree and shrub species collected from three main roads in Nanjing. The element analysis results show that traffic, industry and the combustion of chemical fuel are important sources of road dust and its bound Cu, Zn, Cr and Pb. Among the plants, Cedrus deodara has the highest dust retention ability of 75.4 mu g cm(-2) d(,)(-1) followed by Nerium indicum and Acer paltnatum, while Platamus orientalis exhibits the lowest dust capture ability of 9.19 mu g cm(-2) d(-1), which is related to the microstructure feature of the plant leaf. Leaf particles in different size fraction differ among the species, but fine particles (PM < 2.5 mu m) predominate in most cases. Nerium indicum, Cerasus yedoensis and Salix babylonica are the three species that accumulate the highest amounts of Cu, Zn, Cr and Pb. Moreover, a significant positive correlation between foliar toxic metal and dust retention amounts (especially fine particles) was found, indicating foliar uptake of toxic metals after deposition of dust particles on the leaf surface. Taken together, plant leaves can simultaneously capture road dust and its bound toxic metals. Moreover, Nerium indicum could be used as an urban landscape barrier for road dust and toxic metals.