Research On Capture Air Particulate Ability Of Main Trees In Beijing

In recent years, air pollution has become the main environmental problems in our county, which has damage effect on the health of lives. Many large cities in our country, how to control and manage the fog and haze has been become environmental issues by scientists, government officials and public concerning. The plants not only play a significant role in the adsorption of pollutants and airborne particulates by increasing the land surface roughness, as well as reducing the wind speed and the adsorptive action of the branches, leaves and stalks, especially absorbing PM2.5. So that the trees can reduce the concentration of air particulate and improve the air quality.In this paper, our based on the resuspension particle method and distributed measurement evaluation; Secondly the aerosol regenerator, canopy analyzer, scanning electron microscopy and the Atomic Force Microscopy(AFM). Finally we analysised the adsorption particular matter ability of main tree in Beijing at different season and study sites. According to the research results, the adsorption particular matter ability of Beijing forest was measured. Preliminary results show:1)the needle-leaved tree species adsorbed more airborne particulates than that of the broad-leaved tree species for the same leaf area in test tree species, including TSP, PM10 and PM2.5. In needle-leaved tree species, Cedrus deodara.Platycladus orientalis and Pinus tabuliformis exhibits the highest adsorption capacity; Populus tomentosa,Koelreuteria panicidata, Ginkgo biloba, Quercus mongolica and Robinia pseudoacacia exhibits the lowest adsorption capacity; the PM10 account for the most particulate matter in leaves, the proportion is 58.74%～92.82%.But the proportion of PM2.5 is owing to different trees, and is 16.90%～63.75%.2) Through Studying on the particulates-absorbing capacities of the leaves of six common tree species in Beijing. During the period of observation, we found that the needle-leaved tree species adsorbing capacity of TSP and PM10 showed an U-shaped trend over time, the lowest in August, September and October:But that for broad-leaved tree species was (?)-shaped over time, the highest in July and August. Compared with the PM2.5 absorption, no regularity was found. Through observation of leaf surface topography by AFM, the greater the leaves roughness was, the stronger the adsorptive capacities of leaves was.3) At different study sites, same tree species leaves were significantly different in stagnating TSP. Per unit leaf area, the tree species leaves situated around the 5th Ring Road had higher ability to adsorption TSP than the tree species leaves at Botanical Garden, while their abilities to adsorption PM? showed no significant difference; At same time, significantly adaptive changes were found in leaf structure. Comparing to the light pollution, the heavy pollution shrank plant leaf outer epidermal cells, roughed leaf skin textures and increased stomatal frequency and villous length. In spite of the significant changes on plant leaves exposing to the heavy pollution, these plants could still maintain normal and healthy growth.4) According to Beijing seventh forest resource survey data, the total adsorption TSP amount of Beijing forest is 451.28 million kg/a, PM10 is 274.13 million kg/a, PM2.5 is 107.60 million kg/a, PM1.0 is 15.99 million kg/a. When calculating adsorptive amount for dust in different forest ages, the results show that mature forest is highest and young forest is lowest in confer-leaves trees, but in broad-leaves the Mid-maturation forest is highest. In the last, based on the results of this paper and the characteristics in Beijing, the optimization and forestation advice is put forward.