Spatial Characteristics Of PM_10,2.5 In Urban Lake Wetland And Neighboring Green Spaces Under Multiple Ecological Pressure

As a composite underlying surface of water and green space,urban lake wetland and surrounding built environmental green space can effectively improve the overall microenvironment effect and have significant environmental regulation function and ecological benefits in reducing airborne particulate matter.However,in the process of urbanization,the continuous influence of multiple pressures such as traffic pollution,heat island effect and built environment restricts the play of ecological service functions of urban water bodies and green Spaces.In this study,6 urban lake wetlands with area gradient（Xiaonan Lake,Hanzi Lake,Xibei Lake,Yue Lake,Sha Lake and Nan Lake）and their surrounding 500m built environment in the main urban area of Wuhan are selected as the research object,which is divided into a 30×30m grid.This study extract and measure meteorological factors such as the proportion of impermeable underlying surface（PLAND＿I）,land surface temperature（LST）,traffic density（TD）,building density（BD）and building height（BH）,as well as air particulate matter(PM_10,2.5)concentration and wind speed at all seasons by remote sensing and quantitative measurement.The spatial relationship models of urban ecological environment pressure,air PM_10,2.5 concentration,and pressure-air PM_10,2.5 are established based on geostatistics method,and the key scales of"pressure-response"are analyzed.At the same time,combined with the principal component analysis,the influence law of multiple pressures on the PM_10,2.5 of urban lake wetland built environment green space under different spatial scales is explored.It provides scientific basis for improving urban ecological environment under high density human settlement environment and maximizing ecological effect of lake wetland.The main research results are as follows:（1）Spatial correlation of"pressure-air PM_10,2.5"in urban lake wetland regional unitThere are significant differences in the response of air PM concentration in lake wetland built environment green space of different areas to multiple pressures.The overall performance is that with the increase of lake wetland area,lake wetland and built environment green space synergic ability to reduce air PM particles gradually increases,and the combined ecological effect of water and green gradually turns negative due to multiple pressures.However,this result has seasonal differences.In the season of high PM particulate concentration in spring and winter,the synergism of water and green can significantly reduce PM particulate in the air.The specific results are as follows:in spring,in small lake wetland（<10ha）,there are significant positive correlation variables of"pressure-response"in Xiaonan Lake unit,including BH-PM_2.5,BH-PM₁₀,BD-PM_2.5,PLAND＿I-PM_2.5,LST-PM_2.5,LST-PM₁₀;There are significant negative correlation variables for"pressure-response"of units in the medium lake wetland area（10-20ha）,and the variable pairs that showed significant negative correlation are BH-PM_2.5,BD-PM_2.5 and PLAND＿I-PM_2.5.In large scale lake wetland（>50ha）,there are significant positive correlation variables of"pressure-response"in Yue Lake units,including TD-PM_2.5,BH-PM_2.5,BD-PM_2.5,PLAND＿I-PM_2.5,PLAND＿I-PM₁₀ and LST-PM_2.5.The variable pairs of"pressure-response"in the regional units of the large lake wetland（>300ha）are significantly negatively correlated,and the variable pairs showing significant negative correlation included BH-PM_2.5,BD-PM₁₀ and PLAND＿I-PM₁₀.In summer,the significant positive correlation variable pairs of"pressure-response"in Xiaonan Lake regional unit include BH-PM_2.5,BD-PM_2.5,PLAND＿I-PM_2.5,LST-PM_2.5,While TD-PM_2.5,TD-PM₁₀,BH-PM₁₀,BD-PM₁₀,PLAND＿I-PM₁₀,LST-PM₁₀ are negatively correlated;The"pressure-response"variable pairs are significantly negatively correlated with each other,and the variable pairs are BH-PM₁₀,BD-PM₁₀ and LST-PM₁₀.The"pressure-response"variable pairs of Sha Lake and Yue Lake units are significantly positively correlated,and the variable pairs of Yue Lake units are significantly positively correlated with TD-PM_2.5,TD-PM₁₀ and PLAND＿I-PM_2.5.The variable pairs of Sha lake showed significant positive correlation are TD-PM_2.5,BH-PM_2.5,BH-PM₁₀,BD-PM_2.5,BD-PM₁₀,PLAND＿I-PM₁₀,PLAND＿I-PM_2.5,LST-PM₁₀,LST-PM_2.5;The variable pairs in Nan Lake showed significant positive correlation,including BH-PM_2.5 and PLAND＿I-PM_2.5,while BH-PM₁₀ and BD-PM₁₀ showed negative correlation.In autumn,there are significant positive correlation variables of"pressure-response"in Xiaonan Lake and Hanzi Lake units,including BH-PM_2.5,PLAND＿I-PM₁₀ and PLAND＿I-PM_2.5.In Xibei Lake,there are significant negative correlation variables,including TD-PM_2.5,BH-PM_2.5,BD-PM₁₀,PLAND＿I-PM_2.5,PLAND＿I-PM₁₀ and LST-PM₁₀.The"pressure-response"variable pairs of Yue Lake,Sha Lake and Nan Lake are significantly positively correlated,among which the variable pairs of Yue Lake showing significant positive correlation include TD-PM_2.5,BH-PM_2.5,BD-PM₁₀,PLAND＿I-PM_2.5,PLAND＿I-PM₁₀,LST-PM₁₀ and LST-PM_2.5.The variable pairs that showed significant positive correlation with Sha lake included TD-PM₁₀,BH-PM₁₀ and PLAND＿I-PM₁₀.The variable pairs in Nan Lake that show significant positive correlation include TD-PM_2.5,TD-PM₁₀,BH-PM_2.5,BH-PM₁₀,BD-PM₁₀,BD-PM_2.5,PLAND＿I-PM_2.5 and LST-PM_2.5.In winter,the significant positive correlation variable pairs of"pressure-response"in Xiaonan Lake regional unit include TD-PM_2.5,BH-PM_2.5,BD-PM_2.5,PLAND＿I-PM_2.5,LST-PM₁₀,but TD-PM₁₀,BH-PM₁₀,BD-PM₁₀,PLAND＿I-PM₁₀ and LST-PM₁₀ are negatively correlated.Significant negative correlation variables of"pressure-response"in Hanzi Lake are obvious,including TD-PM_2.5,TD-PM₁₀ and LST-PM₁₀;In the Xibei Lake,there are significant positive correlation variables,including TD-PM_2.5,BH-PM₁₀,BH-PM_2.5 and LST-PM_2.5.The variable pairs of"pressure-response"are significantly negatively correlated with each other in the regional units of large-scale lake wetland,and the variable pairs of the Yue Lake are significantly negatively correlated with TD-PM₁₀,BH-PM₁₀,PLAND＿I-PM₁₀ and LST-PM_2.5.The variable pairs of Sha Lake showed significant negative correlation,including BH-PM_2.5,BD-PM_2.5,PLAND＿I-PM_2.5;The variable pairs in Nan Lake showed significant negative correlation,including BH-PM_2.5,BH-PM₁₀,BD-PM₁₀ and PLAND＿I-PM₁₀.（2）Spatial scale range of"pressure-air PM_10,2.5"in urban lake wetland regional unitBased on the variation model,the spatial characteristics of urban ecological environmental pressure,the spatial distribution of air PM₁₀,_2.5,and the spatial response relationship between pressure and PM₁₀,_2.5 are constructed,and the key spatial scales of air PM₁₀,_2.5 spatial distribution and pressure response of units in the lake wetland area are obtained,which are generally shown as follows:The ranking of significant spatial scale variability is small and medium lake wetland（<20ha）<Yue Lake Park（67.6ha）<large lake wetland（>300ha）,and the seasonal regularity of significant spatial scale variability is winter<spring<autumn<summer.The specific results are as follows:In spring,the significant spatial scale variation of small and medium area lake wetlands are concentrated in 60-240m,150-330m and 210-420m,while that of Yue Lake（67.6ha）is 90m,420m and690m.The significant spatial scale variation of large area lake wetland（>300ha）are 150-450m,540-720m and 1200m.In summer,the significant spatial scale variation of small and medium area lake wetlands are concentrated in 60-240m,300m and 420-540m,while that of Yue Lake is 90m,420m and 840m.The significant spatial scale variation of large-scale lake wetlands are 150-450m,750-1200m and 1200-1500m.In autumn,the significant spatial scale variation of small and medium area lake wetland concentrated on 60-180m,300m and 480-510m,while that of Yue Lake is 210m,600m and 840m.The significant spatial scale variation of large area lake wetland are 300-600m,600-1200m and 990-1500m.In winter,the significant spatial scale variation of small area and medium area lakes wetland are concentrated in 60-300m,240-420m and 390-510m,while that of lunar lake is 210m,510m and 810m.The significant spatial scale variations of large lake wetlands are 150-450m,300-600m and 900-1200m.（3）Principal component interpretation of spatial characteristics of"pressure-air PM_10,2.5 concentration"at different spatial scalesBased on the principal component interpretation of the spatial characteristics of"pressure-air PM_10,2.5"at different spatial scales,the small-scale spatial range shows that LST,TD and PLAND＿I have a strong influence on PM_2.5,BH,TD and PLAND＿I have a strong influence on PM₁₀.In the mesoscale spatial range,LST,TD,BH,PLAND＿I and BD have a strong influence on PM_2.5,and TD and BH have a dominant influence on PM₁₀.TD,PLAND＿I,LST and BH have strong influence on PM_10,2.5.Specifically,BH in Xibei Lake in spring shows a strong positive correlation with PM₁₀ only at the small scale（90m）.In summer,LST in Hanzi Lake is positively correlated with PM_2.5 only at the small scale（60m）and TD is positively correlated with PM_2.5 only at the medium scale（300m）.In summer,TD in Yue Lake is positively correlated with PM_10,2.5 only at small scale（90m）,and BH is positively correlated with PM_10,2.5 only at large scale（840m）.In summer,PLAND＿I and TD in Sha Lake are only positively correlated with PM_10,2.5 at small scale（150m）and large scale（1200m）respectively.In autumn,the positive correlation between BH and PM_2.5 in Hanzi Lake only appears at medium scale（300m）.In autumn,TD and BH in Yue Lake are positively correlated with PM_2.5 only at mesoscale（600m）and large scale（840m）,PLAND＿I and TD in Nan Lake are positively correlated with PM_2.5 only at the mesoscale（1200m）.In winter,the positive correlation between LST and PM₁₀ in Xiaonan Lake only appeared at large scale（510m）,the strong positive correlation between Wanzihu BH and PM₁₀ only occurs at large scale（390m）,PLAND＿I in Xibei Lake is positively correlated with PM_2.5 only at small scale（180m）,while LST and BD are positively correlated with PM_2.5 only at mesoscale（270m）.