[Retention and resuspension of atmospheric particles with two common urban greening trees]

The purification mechanisms of plant leaves with atmospheric particles include adsorption, resuspension, rainwater leaching and absorption. However, few studies focused on the resuspension process of atmospheric particles suspending on the surface of leaves, and the correlation between content of adsorbed particles and content of elements in the leaves. Therefore, two common greening tree species, Platanus acerifolia and Magnolia grandiflora, were selected to analyze the atmospheric particles contents on the leaf surface, the leaf mineral element content, and the resuspension ratios. The results showed that the adsorption capacity of P. acerifolia (4.98 g·m^-2) was higher than that of M. grandiflora (2.65 g·m^-2), which might be connected with rough leaves and dense hairs. The selected 15 elements were all detected by ICP on the leaf surface and in the leaves of two species. In general, the elemental values of the leaf surface were positively related with those in the leaves. However, the two plants showed different selective absorption capacities because positive relation between element adsorption and absorption was only found for Cr, Fe and V for P. ace-rifolia, while such relation was only not found for K, Mn, Si, Ti and Zn for M. grandiflora. The results implied that the absorption was of high selectivity to different elements. Moreover, both increase in wind speed and exposure duration in the wind significantly enhanced resuspension ratios of atmospheric particles. We suggested that resuspension should be taken into account of assessing the relationship between the atmospheric particles deposition and associated plants' function in the future.