Study On The Source Approtionment And Physicochemical Characteristics Of Foliar Dust And Surface Dust In Different Urban Areas

We have taken Nanjing as a case study and chosen five different urban areas with typical plots of trees, including foliar dusts and surface dusts in same areas. The particulate size of foliar dusts and surface dusts were determined with a Laser Particle Sizer, the total concentrations of heavy metals in dusts were determined with ICP-AES, on which the potential risk of heavy metals was evaluated, and then the correlation of various heavy metals was analyzed and the sources of the dusts were discussed. Since two dusts have connections but also differences with each other, the dust pollution status of different unban areas can be indicated by the research of them and that can provide consultations on the management of dust.The main conclusions of this study can be summed up as follows:(1)The grain size distribution of foliar dusts and surface dusts obeyed the normal distribution with single-apices. The size of two dusts mainly concentrated in[10-50]μm, the particulate size of foliar dusts was finer than surface dusts. Potential ecological risk of dusts in commercial area and industrial area were severe because of the high percentage of fine particulates.(2)The monthly and spatial variance of heavy metals in foliar dusts and surface dusts showed that the contents of Cr, Cu, Pb, Zn abided similar regularity, the contents of them were highest in May or September, and lowest in July; The contents of heavy metals in commercial and industrial areas were highest, and the contents of Cu were highest in industrial area, while the contents of Pb and Zn were highest in commercial area, the dusts pollution in traffic hub area and street multi-layer greening area were milder than other areas, the foliar dust pollution in educational and residential area was conspicuous, which should pay attention on it. Potential ecological risk assessment showed that ecological risk of foliar dusts was more serious than surface dusts,the dusts pollution of commercial and industrial areas in Nanjing were at alarming risk, have all reached the moderate risk level.(3) Pearson correlation analysis found that foliar dusts and surface dusts had relatively high correlation by the analysis ofCr, Cd, Pb, Zn, Cu, Mn and Ni, in which Cr, Pb, Zn, Cu had highest correlation, all those indicated foliar dusts and surface dusts had similar sources.(4) The source apportionment of foliar dust and surface dust illustrated that Coal-fired in industry,the traffic dust and the city building materials dust were main sources of the foliar dust, the contribution rate of these three kinds of dust sources has achieved 56.183%; The traffic pollution, waste incineration and industry dust were main sources of the surface dust, the contribution rate of these three kinds of dust sources has achieved76.715%.