Influence Of Different Types Of Greenbelts On Atmospheric Particulate Matter In Lin'an Area Of Hangzhou

In order to explore the regulation effect of urban green space on particulate matter,this study takes the landscape ecological forest(broad-leaved forest,bamboo forest,coniferous forest)in Lin'an area of Hangzhou as the research object.From July 2017 to August 2018,the concentration of particles inside and outside the green space is simultaneously observed horizontally.In this paper,the effects of weather conditions on the concentration of particulate matter in green space and the temporal variation of particulate matter concentration were studied.The relationship between plant allocation index and green space on particulate matter reduction rate was compared.The research results are as follows:(1)The seasonal concentration changes of the three test plots under selected weather conditions were: winter > autumn > spring > summer.From the extreme analysis,the maximum value in the year-round test appeared in winter,and the minimum value in the year-round test appeared in summer.(2)The diurnal variation of atmospheric particulate matter concentration in the three seasons of the three plots basically showed the characteristics of “middle low,early and late high”.The daily variation curves of the three plots in each season are basically consistent with the characteristics of "Winter > Autumn > Spring > Summer",but only in the evening,the atmospheric particulate matter concentration in autumn appears more than in winter.(3)Among the three plots,the concentration of the three types of particulate matter on cloudy days was greater than that of rainy days and sunny days.The concentration of the three particulate matter in the rainy days was among the three,with the smallest on sunny days.The difference between the different ones is because the test date is different,and the second is the gap in the ability of the three forest areas to reduce atmospheric particulate matter.(4)Correlation between atmospheric particulate matter concentration and meteorological factors: The concentration of atmospheric particulate matter is negatively correlated with temperature and wind speed.That is,the higher the temperature,the higher the wind speed and the lower the concentration of atmospheric particulate matter;the concentration of atmospheric particulate matter is positively correlated with humidity and air pressure,ie,humidity.The higher the pressure,the higher the atmospheric particulate concentration.In the case of different particle diameters,the coefficient of determination of wind speed is the largest,and the wind speed is the most critical factor affecting the concentration of atmospheric particulate matter.The coefficient of determination of temperature and humidity is second,and the pressure is the smallest.(5)The three particle concentration reduction coefficients of the three plots are basically the smallest in summer,followed by spring,autumn,and winter.In spring,broad-leaved forest <coniferous forest < bamboo forest;in summer,broad-leaved forest < bamboo forest <coniferous forest;in autumn,broadleaved forest <coniferous forest < bamboo forest;in winter,coniferous forest <bamboo forest < broadleaf forest.Broad-leaved forests have the best reduction effect in spring,summer and autumn,but in winter they have the worst reduction effect.(6)By analyzing the diurnal variation law of the reduction coefficient of different greenland plant configuration methods,we found that the reduction efficiency of coniferous forest at night was the worst among the three plots.The depletion efficiency of broad-leaved forest is the best among the three in most of the spring,summer and autumn,but it is the worst in the winter afternoon.