Human development activities should be incorporated as integral components of Earth's ecosystems.The land use/land cover change with rapid urbanization,especially the growth and spread of impervious surface,was changing the structures,degrading the functions of the urban ecological systems and posing threats to air quality.The ISC had been recognized as a geographical indicator to reflect the intensity of human development activities.The ISC in the BTH,which were interpreted from Landsat imagery,rose from 0.7％ to 1.5％ during 2000 to 2014.The mean of the PM2.5 concentration had soared from 45.7 to 77.3tg/m3.We stratified the BTH by differences in the PM2.5 concentration between 2000 and 2014 into slight (0～9.9μg/m3),moderate (10～29.9μg/m3),heavy (30～49.9μg/m3),hazardous (50～ 77μg/m3),the area for slight,moderate,heavy,hazardous was 42374,90700.5,60635.1,and 20279.0km2,respectively.The result revealed that the hazardous zone (Beijing-Langfang-Tianjin-Tangshan along the highway G1 and BeijingBaoding-Shijiazhuang-Xingtai-Handan along the highway G4) were accompanied by the ISC growth rate of 208.3％.Meanwhile,the spatial distribution of PM2.5 aggravation was consistent with the impervious surface expansion in the BTH region,such as the growth rate of the ISC in the southeast (160％) was greater than that in the northwest (50％),and the increase of the PM2.5 concentration in the southeast (45.5μ.g/m3) was also greater than that in the northwest (17.0μ.g/m3).Moreover,at the county level,we had found that larger county,in term of the ISC,have higher PM2.5 concentration.176counties within BTH region were stratified by ISC into unstressed (0～4.9％),lightly stressed (5％～9.9％),stressed (10％～14.9％),impacted (15％～24.9％),degraded (＞25％),and the corresponding mean of the PM2.5 are (42.7±10.5),(79.9± 11.9),(95.6±15.4),(99.1±10.8),(115.3±9.2)μ.g/m3,respectively.The unstressed counties had 0～5％ imperviousness and typically had good air quality,and the counties have 5％～25％ imperviousness and showed clear signs of degradation.The degraded counties have ＞25％ imperviousness and averaged (115.3±9.2)μg/m3 of the PM2.5 concentration,reaching three times that of the unstressed counties.The proportion and spatial distribution of impervious surface should be considered in the National New-type Urbanization development of China,making the cities surrounded by enough greenbelt and water areas and controlling the county with ISC ＜25％ on the basis of the existing impervious surface spatial distribution to form a remedy for the PM2.5 pollution.%基于2000年、2003年、2006年、2009年、2014年的遥感影像提取不透水表面数据以及相应年份的PM2.5质量浓度估算值.以不透水表面覆盖率(ISC)为城市化指标来分析城市化对PM2.5质量浓度的影响,分别从城市、县区尺度探讨城市扩张对PM2.5污染时空分布及演变的影响机制,定量研究二者相互关系;以京津冀地区为例,其ISC从2000年的0 7％增长到2014年的1.5％,而PM2.5浓度从45.7μg/m3飙升到77.3μg/m3.根据2000与2014年的PM2.5浓度差值,把京津冀地区划分为轻度(0～9.9μg/m3)、中度(10～29.9μg/m3)、重度(30～49.9μg/m3)、严重(50～77μg/m3)污染区域,相应的不透水表面增长率分别为43.3％、110.5％、165.5％和208.3％.严重污染区域位于北京-廊坊-天津-唐山(沿高速公路G1)和北京-保定-石家庄-邢台-邯郸(沿高速公路G4),伴随着较高的不透水面增长率(208.3％).同时,在2000～2014年期间,京津冀地区ISC空间分布与PM.2.5污染空间分布高度一致,以太行山和燕山山脉为界的东南地区的不透水表面增长率为160.0％,显著高于西北地区的增长率50％,同时东南地区的PM2.5浓度增长值45.5μg/m3也显著高于西北地区的17.0 μg/m3.此外,把京津冀地区174个乡镇按照其ISC划分为5个级别:松散型(0～4.9％)、轻度紧凑型(5％～9.9％)、紧凑型(10％～14.9％)、密集型(15％～24.9％)、高度密集型(＞25％),乡镇数量分别为42、35、52、34、11,对应的PM2.5浓度均值分别为(42.7±10.5)、(79.9±11.9)、(95.6±15.4)、(99.1±10.8)、(115.3±9.2) μ.g/m3.其中松散型乡镇的空气质量较好,而严重雾霾笼罩在高度密集型的乡镇中.结果表明当乡镇ISC为5％和25％时,对区域PM2.5质量浓度带来剧烈的增长.当ISC ＞5％时,PM2.5浓度发生了激烈增长,其比＜5％的乡镇高了87.2％.当ISC ＞25％时,其PM2.5浓度飙升到(115.3±9.2) μg/m3,大约是＜5％乡镇的3倍.结论表明,在城市化进程中,不透水表面扩张对PM2.5污染的加剧带来严重影响,不透水表面扩张应该成为城市空气污染一个不可忽视的影响因素之一.
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