The Temporal And Spatial Characteristics Of PM₁₀ And PM_2.5 In Different Blocks Of Xi’an And Its Relationship With Green Space Pattern

Green space can alleviate the air pollution problems caused by urbanization,and also increase the landscape effect of the city,enhance the communication between people and the sense of happiness.This research is based on the particulate matter concentration data of 9 air quality monitoring station in different blocks of xi’an from March 2017 to February 2020,and block-scale remote sensing data,quantitative analysis of the relationship between air pollution fine particulate matter and urban green space landscape pattern and its temporal and spatial distribution characteristics in Xi’an.And then combined with the research conclusions to propose green space planning and promotion strategies at the urban block scale.Research indicates:（1）From March 2017 to February 2020,the concentration of PM₁₀and PM_2.5in Xi’an city decreased year by year,and the decline was the most obvious from March 2019 to February 2020.Both of them realized a first decline and then an increase on the 3-year monthly mean curve.The small"U"pattern that drops again,and presents the seasonal characteristics of winter,spring,autumn,and summer;the concentrations of PM10 and PM2.5 at 9 different sites in the study area are about 6.7%-9.7%,6.4%of the urban average.Floating between-6.8%.The concentration of air pollution sites shows the characteristics of regional internal pollution spatially,mainly showing the spatial characteristics of"high-high"and"low-low"gatherings,high in the north and low in the south.（2）PM₁₀and PM_2.5are significantly correlated with green percent of Landscape（G-PLAND）and road percent of Landscape（R-PLAND）,but have no correlation with construction percent of Landscape（B-PLAND）.When G-PLAND increases by 10%,PM₁₀and PM_2.5concentrations decrease by 11.29%and 3.18%respectively;when R-PLAND increases by 10%,PM₁₀and PM_2.5concentrations increase by 5.39%and 6.03%,respectively.It shows that the larger the green patch area rate and the smaller the traffic land area rate,the lower the concentration of PM₁₀and PM_2.5.The sedimentation effect of green land on PM₁₀is stronger than PM_2.5,and road car exhaust is more likely to produce PM_2.5.（3）There is a significant negative correlation between PM₁₀concentration and Green Largest patch index（G-LPI）,indicating that the stronger the Green Largest patch index,the stronger the reduction effect of PM₁₀.The PM₁₀concentration has a significant positive correlation with the Green Landscape Division index（G-DIVISION）,and has a significant negative correlation with the green edge density index（G-ED）only in winter,indicating that the smaller the Green Landscape Division index and the higher green edge density index,the lower the PM₁₀concentration.PM₁₀show positive correlations with Building Aggregation Index（B-AI）in winter.It shows that the more the patches of construction land accumulate,the higher the PM₁₀concentration.（4）Aiming at the research conclusions of block-scale green space combined with air pollution and green space,the new urban block construction improvement strategy is proposed.The new urban area starts from the two perspectives of spatial layout and green space system.The old urban area is analyzed from four perspectives:encouraging the micro-reconstruction of public spaces,encouraging the opening of the subsidiary green space,connecting the grid of public activities in the living circle,and optimizing the layout of urban construction,so as to shape the sustainable development of ecological blocks.