中国华东地区PM_(2.5)浓度时空变化及与景观格局关联研究

The Spatial-temporal Change of PM_(2.5) Concentration and Its Relationship with Landscape Pattern in East China

大气PM_(2.5)是影响空气质量的首要污染物之一,如何有效监测和治理大气PM_(2.5)浓度对我国生态环境质量的可持续发展具有重要意义。基于卫星光谱波段表观反射率、气象、土地利用等辅助参数,以我国华东地区长江三角洲-福建连续区域(长三角-闽)为研究区,构建了随机森林(RF)模型来估算2016、2018和2020年长三角—闽区域的近地面PM_(2.5)浓度,并基于3期土地分类数据,分析长三角-闽区域PM_(2.5)浓度空间分布和景观格局的相关性。结果表明:①2016、2018和2020年长三角-闽区域由RF模型估算的PM_(2.5)浓度与地面实测值之间的R2分别为0.91、0.89和0.90;RMSE分别为9.07、10.19和8.03μg/m^(3)。②2016~2020年间各年份长三角—闽区域的PM_(2.5)年均浓度呈现逐年降低的趋势,且空间分布总体呈“江苏>上海>浙江>福建”的格局。③合理管控耕地、建筑用地和水体的景观所占比例,降低其景观优势度和边缘密度有利于缓解PM_(2.5)年均浓度;适当提高林地景观的占比、边缘密度和形状复杂度,均有利于降低PM_(2.5)浓度,且当其形成较大斑块,越有助于改善空气质量。研究结果可为区域大气污染防治和景观格局规划管理提供科学依据和决策参考。

Atmospheric PM_(2.5) is one of the primary pollutants affecting air quality.Therefore,how to effectively monitor and manage PM_(2.5) concentrations is of great significance to the sustainable development of ecological quality in China.Based on a series of auxiliary parameters,i.e.,Top-of-Atmospheric reflectance(derived from remote sensing imageries),meteorology,and land use,a Random Forest(RF)model was developed to esti⁃mate ground-level PM_(2.5) concentrations in the contiguous Yangtze River Delta-Fujian(YRD-FJ)region locat⁃ed in East China in 2016,2018 and 2020.The correlation between the spatial distribution of PM_(2.5) concentra⁃tions and landscape patterns in YRD-FJ region using 3-period land classification data was carried out.The re⁃sults show that(1)the R2 between the PM_(2.5) concentrations estimated by the RF model and the ground-level measured values in YRD-FJ region in 2016,2018,and 2020 are 0.91,0.89,and 0.90,respectively;the RMSE are 9.07、10.19 and 8.03μg/m3,respectively.(2)The annual average PM_(2.5) concentrations in YRD-FJ region showed a trend of year-on-year decrease from 2016 to 2020,and its spatial distribution was generally in the pattern of"Jiangsu>Shanghai>Zhejiang>Fujian".(3)Reasonable control of the landscape proportion of cropland,built-up land and water bodies,and reduction of their landscape dominance and edge density are conducive to alleviating the annual average PM_(2.5) concentrations.Additionally,appropriate increase in forest oc⁃cupancy,edge density,and shape complexity are beneficial to reducing PM_(2.5) concentrations.Our results could provide the scientific basis and decision-making reference for the control of regional air pollution and landscape pattern planning.