Analysis Of The Deposition Velocitysize Distribution And Source Apportionment Of Particulate Matter On The Leaves Of Typical Greening Tree Species In Shanghai

Here we studied the composition of particulate matter on typical plant’s leaf surfaces and characteristics of dry deposition velocity in Shanghai.Four tree species（Cinnamomum camphora,Platanus acerifolia,Sabina chinensis,and Metasequoia glyptostroboidesd）,air and dust in typical polluted areas were sampled throughout the year of 2016-2017.The pollution characteristics of atmospheric particulates and dust under the background of industrial and traffic pollution areas in Shanghai were determined,and ion and source analytical components of particulate matter were analyzed.The mass spectrometric characteristics of the leaves from different tree species were observed by MATLAB and SPAMS.The adsorption characteristics of typical tree species to different components were investigated by paired sample t test and linear regression.The main conclusions are as follows:（1）There is a significant difference between the components of atmospheric particulates and dust of the typical polluted areas in Shanghai（p<0.05）,but the characteristic spectra of the two are similar,both of them exists obvious OC fragments in the average spectrum,mineral ion peak such as Al⁺（m/z=27）,Si O₃^-（m/z=-76）;The characteristic peak of levodextran;CN^-（m/z=-26）,CNO^-（m/z=-42）;Water soluble ion peak like K⁺（m/z=39）,Na⁺（m/z=23）,O^-（m/z=-16）,OH^-（m/z=-17）;Ion peak produced such as NO₂^-（m/z=-46）,HSO₄^-（m/z=-97）.The highest intensity of the signal is the characteristic peak of water soluble ion.（2）The main components of the remaining particles in the air,natural dust and plant leaves in typical polluted areas of Shanghai are CN^-、NO₃^-、NO₂^-、SO₄^-、Cl^-,etc al.Different types of ion particles exists big difference,but the chemical in the same region of the air,dust and dust on plant leaves has stability（3）There is great fluctuation among the dust catching ability of,the comprehensive strength followed with S.chinensis,C.camphora,P.acerifolia,and M.glyptostroboidesd.The ability of four species in autumn is higher than the rest of the three quarter.In addition,due to changes in climate,surrounding atmospheric,pollution concentration and particle composition of different sampling sites do great influence on the dust retention ability of the same tree species.（4）All of the four tree species has obvious adsorption characteristics to Fe⁺,which mainly come from dust.The chemical compositions of dust adsorption and natural precipitated particles in the same period on blade surface of C.camphora and M.glyptostroboidesd are relatively similar,which shows that they mainly affected by local atmospheric environment,but there are significant differences in the proportion of six kinds and four kinds of ions of absorbing dust on blade surface of S.chinensis and P.acerifolia and the natural precipitated particles in the same period,the characteristic of specialistic adsorption to specific chemical compositions of atmospheric particulates is more obvious in the process of dusting.（5）The chemical composition of particles has a limited effect on the dry sedimentation rate of the plant leaf surface.The particulate matter sedimentation rate affected by chemical composition mostly including HM particulate matter,NA particulate matter and K particulate matter,fluctuates with interspecific difference.DUST particulate matter almost has no effect to the rate.It is obviously that particulates enriched by heavy metal or normal metal elements have the most significant effects on the four species of this study.This suggests that the surface of the common greening trees has obvious adsorption characteristics to particles enriched in metal components during the process of settlement.