基于GIS的北京市林地覆被与PM_(2.5)分布关联性分析

Analysis of the Correlations between PM_(2.5) Distributions and Forest Cover Based on GIS

土地利用方式直接和间接地影响着城市的颗粒物污染程度,了解土地利用与颗粒物污染的关联规律,对改善环境空气质量具有重要的意义。选择颗粒物污染问题突出的北京市为研究对象,以空气质量地面监测站的PM_(2.5)质量浓度数据和卫星遥感解译数据为基础,借助地理信息系统和数理统计方法,对不同土地利用方式特别是林地覆被与细颗粒物分布的关联性进行分析。研究结果表明,(1)北京市的PM_(2.5)质量浓度分布在空间上呈由西北至东南逐级递增的趋势,东南部(107.0μg·m^(-3))>西南部(96.2μg·m^(-3))>城六区(95.3μg·m^(-3))>东北部(79.6μg·m^(-3))>西北部(79.0μg·m^(-3)),季节分布表现为冬季(122.0μg·m^(-3))>春季(81.2μg·m^(-3))>秋季(76.8μg·m^(-3))>夏季(72.9μg·m^(-3)),不同土地利用方式PM_(2.5)质量浓度表现为耕地(96.9μg·m^(-3))>建成区(95.7μg·m^(-3))>未利用土地(91.5μg·m^(-3))>水域(82.8μg·m^(-3))>草地(80.9μg·m^(-3))>林地(79.1μg·m^(-3))。(2)以各监测站点为中心建立不同半径缓冲区,随着缓冲区半径的不断增加林地覆被率与PM_(2.5)质量浓度的负相关性不断增强。当缓冲区半径达到1 000 m时,各个月份林地覆被率与PM_(2.5)质量浓度均在α=0.05水平上呈显著负相关。(3)以各监测站点为中心的3 000 m半径缓冲区内落叶阔叶林、常绿针叶林、落叶阔叶灌木林、常绿阔叶灌木林、乔木园地面积与PM_(2.5)质量浓度均呈负相关关系。研究结果表明,实行未利用土地、耕地以及部分建成区的土地利用方式向林地、草地转化是北京市防控颗粒物污染的可行方略。

Land use has direct or indirect effects on particulate matter pollution.To understand the regularity of particulate pollution in response to land use has important significances in the maintenance and improvement of environmental quality.Beijing,which has highlighted particulate pollution problems,was chosen as the object of the study.Based on PM2.5 air quality data from ground monitoring stations and multiphase satellite remote sensing data,GIS and mathematical statistical methods were used to analyze the correlations between PM_（2.5） distributions and different land use patterns,especially forest cover.The research results showed that：（1）In descending order of spatial scale,the degree of PM_（2.5） mass concentration was from southwest to northeast of Beijing,and northwest region（107.0 μg·m-（-3））southwest region（96.2 μg·m-（-3））six central districts（95.3 μg·m-（-3））northeast region（79.6μg·m-（-3））northwest region（79.0 μg·m-（-3））.In descending order of season,PM_（2.5） mass concentration were winter（122.0 μg·m-（-3））spring（81.2 μg·m-（-3））autumn（76.8 μg·m-（-3））summer（72.9 μg·m-（-3））.From different land use patterns,PM_（2.5） mass concentration were plow land（96.9 μg·m-（-3））urban built-up area（95.7μg·m-（-3））unused land（91.5 μg·m-（-3））water area（82.8 μg·m-（-3））grassland（80.9μg·m-（-3））forest land（79.1 μg·m-（-3））.（2） When different radii of buffer centered on each monitoring station were set up,it suggested that the negative correlation between PM_（2.5） mass concentration and forest cover in buffers increased with the growing radius.When the radius reached 1 000 m,the negative correlation became significant at the 0.05 level.（3） In the buffers with a 3 000 m radius centered on each monitoring station,the area of deciduous broad-leaved forest,evergreen coniferous forest,deciduous broad-leaved shrub,evergreen broad-leaved shrub and fruit orchards had a negative correlation with PM_（2.5） mass concentration.It is a feasible strategy to prevent and control the pollution of particulate matter in Beijing by transforming the unused land,plow land and parts of the urban built-up area into forest land and grassland.