Study On The Reduction Effect Of The Green Belt On PM_2.5 In The Side Of The River Beach Expressway In Urumqi

As a node city of the Silk Road Economic belt,Urumqi is a city with a low level of drought and rain and frequent sand and dust weather.Fine particulate matter in the air has become the primary pollutant in Urumqi’s atmosphere now.Therefore,how to protect the atmosphere reasonably and promote the sustainable development of oasis city is particularly important.Taking the main urban area of Urumqi and the forest belt of Hetan Expressway as the research background,this paper collected and organizedthe PM2.5 concentration data of Urumqi from January 2018 to December 2018,and selected three monitoring points of the north section,middle section and south section of Hetan expressway,and uses BR-HOL-1210 air quality detector and Kestrel 4500 meteorological instrument to monitor the PM2.5 concentration and meteorological factors hourly.Arcgis,R language and spss 19.0,the spatial difference analysis,multiple regression analysis and single factor analysis of variance were used to analyze the spatial and temporal distribution characteristics of PM2.5 concentration,the differences of PM2.5 in different horizontal gradients,vertical heights and functional areas in the expressway forest belt,the characteristics of PM2.5 reduction rate in the forest belt,and the differences between PM2.5 and meteorological factors coupling relationship in Urumqi.The main conclusions are as follows:(1)The diurnal and seasonal variation of PM2.5 in Urumqi is obviously different;the concentration of PM2.5 increases from southwest to northeast in spatial distribution;CO,NO2,SO2,PM10 are positively correlated with PM2.5,and O3 is negatively correlated with PM2.5;the model based on R software is relatively stable and can be used to predict the change trend of PM2.5 in the future.(2)The highest concentration of PM2.5 in spring and winter appeared at 15:00 at noon,13:00 in summer and 14:00 in autumn.The concentration of PM2.5 in three functional areas is different.On the whole,the concentration of PM2.5 in commercial area and suburban expressway forest belt is the highest at 10～20 m,and the width of residential area can be configured at 50 m to achieve dust retention effect.PM2.5 has the highest concentration at 1.5 m on the vertical height.(3)The reduction rate of PM2.5 in forest belt varies with seasons,and the effect is obvious at 30～50 m in April and October.In July and December,the reduction rate is positive at 50 m.The highest daily reduction rate appeares in the morning and afternoon respectively,which isroughly shown in 11:00-12:00 in the morning and 16:00-18:00 in the afternoon.The reduction rate is as follows business area>residential area>suburban area.(4)The results of regression analysis show that the contribution rate of temperature and humidity to PM2.5 is 27.16%and 16.62%,respectively.Wind speed of 0～3 m/s will accumulate PM2.5.the PM2.5 concentration is significantly reduced when it is greater than 3 m/s and plays a significant role in diffusion.