| With the intensification of processes of industrialization and urbanization, and the application of vehicle transportation gradually increased, especially in developing countries, the rapid development of the environmental protection and economic are not in synch, air pollution caused by fine particulate such as common haze aroused people’s attention gradually.In addition to beautify the city, through the effect of humidification and cooling, increasing environmental negative ion, reducing noise to control the city climate, plants can also absorb or intercept pollutants in the air through leaf stomata or the lenticelle of branches, and even some water soluble pollutants could be dissolved in water film on the surface of the wet plant, in order to purify the air in cities, plants can also lower the temperature of the environment through shading and transpiration to slow down some atmospheric chemical reaction and reduce the formation of the secondary particles indirectly.This study uses three types of research and data analysis methods to analys and evaluate the typical configuration modes of urban forest’impact on PM2.5.1, The PM2.5 concentration, temperature, relative humidity (RH), wind speed, and wind direction at five locations on the North Fifth-ring Road and Beijing-Xizang Highway were continuously monitored. The correlation between the concentration of PM2.5 and environmental factors was analyzed using a regression analysis method. The results showed:(1) the variation trends were different between locations with greenbelts and the location without a greenbelt. For the location without a greenbelt, the concentrations of PM2.5 decreased as the distances to the road increased. For locations with greenbelts, concentrations of PM2.5 at different distances showed both increasing and decreasing trends; (2) the concentrations of PM2.5 at roadside had a significant influence on the concentrations of PM2.5 inside the greenbelts. The influences of air temperatures and RH were also significant. However, no significant relationship was identified between the concentrations of PM2.5 and wind speeds inside the greenbelts, and (3) the width of greenbelt had some effects on the concentrations of PM2.5 inside the greenbelt.2, The concentration of PM2.5, air temperature, relative humidity (RH), wind speed at three kinds of configuration mode of urban forest were continuously monitored. The correlation between the concentration of PM2.5 and environmental factors was analyzed using a regression analysis method. The results showed:(1) Diurnal changes of PM2.sconcentrations in urban forest edge presented certain regularity; (2) Urban forest has certain reduction effect on PM2.5.Three kinds of configuration mode of urban forest’ effect on PM2.5 reductions are very different, The PM2.5 concentration of in the forest affected by forest structure and meteorological factors, is not always lower than PM2.5 concentrations of the forest edge; (3) The concentrations of PM2.5 at forest edge had a significant influence on the concentrations of PM2.5 inside the forest. The influences of air temperatures, RH and wind speed were also significant; (4) Changes in forest structure have greater impact on urban forest’ PM2.5 reduction. Such as the leaf area index increasing, young forest PM2.s’reduction ability enhancement.3, Continuous monitoring and simulation analysis using Envi-met in a test stand of Beijing Forestry University. The results showed:(1) PM2.5concentration of the experimental forest changes significantly over time. PM2.5 concentration in growing period was lower than the fall and winter; (2) Mode simulation, the PM2.5 concentration in the forest depends largely on PM2.5 source, the more complex the source of PM2.5, the deeper the impact on the forest; (3) Model simulation results influenced by meteorological factors. Initial parameter requires temperature, relative humidity, wind speed, wind direction, and PM2.5 concentration of start time. |
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