基于臭氧监测仪OMI对流层NO₂柱浓度产品研究了京津冀城市群2005年-2014年NO₂时空变化及影响因素:(1)10年柱浓度年均增长率为3.35%,且年度波动较大。忽略2008年国家奥运会的环境治理所引起的变化,2005年-2011年NO₂呈逐渐升高趋势;2012年-2014年呈逐渐降低趋势,以2014年下降最为显著。(2)呈西北低东南高的趋势。燕山-太行山山系以北的承德和张家口市浓度较低,山系以南主要有北京-天津-唐山与石家庄-邢台-邯郸两个污染中心。(3)京津冀北部三面环山不利于NO₂的扩散,夏季丰富的降水对NO₂具有显著湿沉降作用。(4)通过相关性分析、文献及国家政策印证等方法,发现地区产业及能源结构很大程度上决定了地区的污染来源。北京市10年来第三产业一直处于主导且稳步提高,煤炭消耗量低,但汽车保有量增加了1.5倍,主要来源为机动车尾气排放;天津市第二产业比第三产业比重略高,煤炭消耗量是北京的两倍之余,但汽车保有量仅是北京市的一半,由此可知工业排放和机动车是共同来源;河北省第二产业比重很高,燃煤量占京津冀地区的80.6%,河北省工业排放是NO₂的主要来源,但近几年随着机动车保有量的剧增,其尾气排放分担率不可小觑。

Using satellite-derived NO₂ column data from Ozone Monitoring Instrument (OMH), we analyzed the characteristics and factors affecting the spatio-temporal distribution of tropospheric NO₂ column density in Beijing-Tianjin-Hebei Region from 2005 to 2014. Results demonstrated that (1) tropospheric NO₂ column density considerably fluctuated on the temporal scale and increased at an annual rate of 3.35%, with the highest column density in 2011; NO₂ level increased during 2005 to 2011, ignoring changes in 2008, and decreased from 2012 to 2014.(2) The spatial distribution of tropospheric NO₂ column density significantly changed, with the lowest distribution found in the northwest part and the highest in the southeast part. Tropospheric NO₂ column density was low in Zhangjiakou and Chengde in north Beijing-Tianjin-Hebei Region but high in Beijing-Tianjin-Tangshan and Shijiazhuang-Xingtai-Handan.(3) Beijing-Tianjin-Hebei is surrounded on three sides by mountains in north and is not conducive to NO₂ distribution. Precipitation exhibited a highly negative correlation with NO₂ concentration because of atmospheric wet deposition. (4) Pollution sources were highly determined by industrial and energy structures. The tertiary industry is dominant and increases steadily in Beijing, where coal consumption is low, but car ownership increases 1.5 times; as such, the main source of NO₂ in Beijing is motor vehicle exhaust emissions. The second industry of Tianjin is slightly higher than the third industry; in this area, coal consumption is twice higher than that in Beijing but car ownership is only half of that in Beijing; thus, industrial emissions and motor vehicles are a common source of NO₂ in Tianjin. A high proportion of secondary industry is found in Hebei, where coal accounted for 80.6% of that in the Beijing-Tianjin-Hebei Region; hence, Hebei industrial emissions are the main source of NO₂, although vehicle emissions have increased with increased vehicle ownership in the recent years.