Study On The Relationship Between Vegetation Coverage And PM_2.5 Concentration In The Downtown Area Of Nanchang City

With the acceleration of urbanization and industrialization in China,atmospheric environmental problems,especially the increasingly frequent haze,have aroused wide public concern.PM2.5 is believed to be the main cause of smog.Quantitative analysis of the influence of vegetation landscape on PM2.5 concentration distribution is a key and difficult point in current landscape science research.Studies have shown that PM2.5concentration distribution is mainly affected by meteorological conditions,but the landscape,especially is have a significant effect on the vegetation landscape,how to draw lessons from landscape ecology pattern and process of interaction between research idea,on the space coupling vegetation patterns and distribution of PM2.5,reveal the relationship between different scales vegetation and PM2.5 remain to be further research.In order to minimize the interference of meteorological conditions on the results of the study,manifest the distribution of the vegetation landscape of PM2.5,first of all,this study is based on the hypothesis that the same seasonal weather conditions are basically identical,in downtown nanchang city as research area,using nanchang in 2017 eight countries real-time air quality monitoring stations of PM2.5 measured data and the regression model for land use and form virtual sample,spatial interpolation of four seasons and high precision simulation downtown nanchang PM2.5 concentration spatial distribution of each season.Secondly,Landsat8 OLI images of typical months in four seasons were used to estimate the vegetation coverage of the study area based on the normalized vegetation index?NDVI?using binary pixel model to represent the spatial distribution of vegetation landscape.Finally,random sampling was used to construct buffer zones of different sizes with sample points as the center,and the relationship between them was analyzed at different scales,so as to discuss the influence of vegetation landscape on PM2.5.The results show that:1)selecting appropriate influencing factors as variables,LUR model was established to simulatePM_2.5.5 concentration in nanchang city.The model passed the accuracy test,and this method was feasible.2)ThePM_2.5.5 concentration distribution in the central urban area of nanchang city decreases significantly from the urban center to the urban periphery,with an obvious time distribution law of"high in winter and spring,low in summer and autumn".3)The spatial distribution of vegetation coverage in the study area is obviously different,and the four seasons of spring,summer,autumn and winter all show a low vegetation coverage in the urban center area and high coverage around the city are presented.The average FVC of the four seasons in the study area in spring,summer,autumn and winter of2017 was 0.52,0.57,0.55 and 0.49,respectively,showing a trend of increasing first and then decreasing.There was a certain difference in FVC of the four seasons,but it was not very obvious.4)PM2.5 and FVC concentration show a significant negative correlation in the 300m,500m,1000m,and 1500m buffer space selected in this study.The influence of vegetation coverage on PM2.5 concentration in different scales in the same season and in different seasons is different.there exists a significant negative correlation between vegetation coverage and PM_2.5.5 concentration in the adopted spatial scale.The influence of vegetation coverage on PM_2.5.5 concentration varies from season to season.Moreover,in the same season,the influence of vegetation coverage on PM_2.5.5 concentration changes at different scales;5)the influence of vegetation coverage on PM2.5 concentration is complicated,and there are certain differences between different seasons.In general,the fitting degree of PM2.5concentration and vegetation coverage curve regression model is better than that of linear regression model,indicating that vegetation coverage and PM2.5 concentration are not simple linear relations.6)In different PM2.5 concentration levels,the influence of vegetation coverage on PM2.5concentration is different.The higher the PM2.5 concentration is,the more obvious the influence of vegetation coverage on its concentration is.This study can provide a certain idea for coupling urban vegetation landscape with PM2.5 concentration,and also provide a certain reference for optimizing urban vegetation pattern and alleviating air pollution through quantitative analysis.This study has important reference value for quantitative analysis of the influence of vegetation landscape on PM2.5 concentration distribution and how to alleviate atmospheric environment by optimizing urban vegetation pattern.