Simulation Study Of The Effect Of Particulate Matter By Native Tree Species In Beijing

In order to study the capture process and capture capacity of particulate matter by different types of tree species,the experimental method of indoor simulation was used in the study,under the condition of static wind,constant temperature and constant humidity,24 tree species were selected as the study object,real time monitoring of PMs’ mass concentration method and multilayer membrane filtration were used to measure accumulative capture amount,capture velocity,time limit for capturing particulate matter,capture amount per unit leaf area and purification rate,the influence of three kinds of atmospheric particulatesw by 24 planting was systematically analyzed.The results show that:1)Before and after the experiment,the proportion of different diameter particles in the air were as follows:the proportion of PM1 accounted for 42.5%and 42.5%of PM2 5 before and after the experiment respectively,PM1 accounted for 22.9%and 29.1%of PM10 respectively,PM2 5 accounted for 53.8%and 63.5%of PM10 respectively,it shows the proportion of size small particles increased through the simulation experiment process,this suggests that the vegetation is easier to capture the particles with larger size.2)24 kinds of tree species have capture effect on PM10,PM2 5,and PM1 and the capture processes were similar,the process was that they captured PMs from fast to slowly and could not capture PMs anymore when reaching the maximum of capture amount,its capture velocities changed form fast to slow,finally turned to 0,green vegetation did not capture particulate matter anymore.The values of capture velocities of 24 tree species indicate the capture capacity order:evergreen coniferous arbor>deciduous broadleaved arbor>evergreen broadleaved shrub.3)There exist time limit for capturing PM10,PM2.5 and PM1 by 24 species of green vegetation,and the time limit for cpturing PM1 was longest,PM2.5 was the second,time limit for capturing PM10 was shortest.Time limit for capturing PM1 by 24 tree species is about 35 to 76 hours,about 80%of them in more than 50 hours;Time limit for capturing PM2.5 is about 24 to 46 hours,about 80%are between 30-40 hours;Time limit for capturing PM10 is about 22-35 hours.Time limit for capturing PMs of different kinds of green vegetation is different obviously.4)Green tree species capture PM10 and PM2.5 and PM1 mainly rely on leaf surface,the capture amount of unit leaf surface and the purification rate of 24 tree species indicate that thecapture capacity of coniferous tree species and deciduous broadleaf tree species is better than evergreen broad-leaf shrub tree species,arbor tree species are better than shrub tree species,conifer tree species are better than broad leaved tree species basically.