Study On The Spatiotemporal Characteristics And Influencing Factors Of PM2.5 And PM10 In Nanchang People’s Park

With the rapid development of urbanization and the acceleration of industrialization,the concentration of air particulate matter in cities has risen sharply,and air particulate matter has seriously endangered human health and led to a decline in the quality of urban citizen’living environment.Urban park is an important part of urban green infrastructure,which plays an important role in improving air quality,controlling noise,blocking pathogen transmission and satisfying spiritual needs,which are closely related to human life.In this paper,Nanchang People’s Park is taken as the research object.Through the field observation of PM2.5,PM10 concentrations and meteorological factors in the four quarters from 2021 to 2022,the variation characteristics and influencing factors of PM2.5 and PM10 are discussed from three aspects: spatial distribution characteristics,vegetation structure types and vertical height differences.The main research results are as follows :(1)In the overall spatial distribution of the park,the concentrations of PM2.5 and PM10 showed extremely significant positive correlations with the observation points and relative humidity,and extremely significant negative correlations with wind speed and air temperature.According to the calculation and analysis of Moran’s index,the spatial distribution of PM2.5,PM10,air temperature and relative humidity showed positive correlation and agglomeration.According to the calculation and analysis of the local Moran index,the spatial distribution area of PM2.5 concentration and PM10 concentration are similar,It shows the polarization of high concentration and low concentration,which is high in the north and low in the south.Air temperature and relative humidity have opposite spatial distributions;wind speed has a small number of outliers.Using kriging interpolation method to predict and analyze the spatial distribution of the observed data of PM2.5,PM10 concentration and meteorological factors.The spatial distribution of PM2.5 and PM10 concentrations was consistent with that of relative humidity.The areas with lower concentrations had more overlaps with those with higher air temperature.The wind speed showed a trend of outward diffusion from the highest value in the northern center.(2)The variation characteristics of PM2.5 and PM10 concentrations in green space with different vegetation structures were generally high in the morning,low at noon,and slightly rising in the evening.The seasonal variation trend was winter > autumn > spring > summer.From the perspective of different vegetation structure types,the concentrations of PM2.5and PM10 in the hard pavement square and waterfront green space at the control points in the four seasons were higher.The single structure of grass and arbor was higher than other vegetation structure types.The concentrations of PM2.5 and PM10 in the compound vegetation structure types of arbor + shrub + grass,arbor + shrub and arbor + grass were lower.Correlation with meteorological factors.in the four seasons,PM2.5 and PM10 have extremely significant negative correlation with air temperature,and have extremely significant positive correlation with relative humidity.In spring,autumn and winter,they have extremely significant positive correlation with air pressure.In summer,they have extremely significant positive correlation with air pressure.Only in spring,they have extremely significant positive correlation with wind speed.(3)The distribution law of PM2.5 and PM10 concentrations at the vertical level.The daily changes of PM2.5 and PM10 concentrations at three heights of 50 cm,100cm,and150 cm show a trend of high in the morning,low at noon,and rising in the evening.Compared with the other three seasons,Seasonal change is winter>autumn>spring>summer.At the height of 50 ～ 150 cm,the variation of PM2.5 and PM10 concentration is small,but the lower the height,the greater the concentration of PM2.5 and PM10.In spring and winter,PM2.5 and PM10 concentrations at 50 cm,100cm,and 150 cm have extremely significant negative correlations with air temperature,but showed extremely significant positive correlations with air pressure.There is a very significant positive correlation,Except for the PM2.5 and PM10 concentrations at 50 cm height in spring,which has a significant positive correlation with relative humidity,other heights in spring and winter have a very significant positive correlation with relative humidity.In summer,the concentrations of PM2.5 and PM10 at 50 cm,100 cm and 150 cm were significantly negatively correlated with air temperature and extremely significantly positively correlated with relative humidity.Except that PM10 at 100 cm was significantly positively correlated with air pressure,other heights were extremely significantly positively correlated with air pressure.In autumn,PM2.5 and PM10 concentrations were significantly negatively correlated with air temperature at 50 cm,100cm and 150 cm,and extremely significantly positively correlated with relative humidity and air pressure.Except for the PM2.5 and PM10 concentrations at 100 cm in winter,which were significantly correlated with wind speed,other seasons and heights showed no significant correlation with wind speed.