京津冀与长三角区域大气NO2污染特征

基于地面监测及遥感反演数据,研究了京津冀与长三角区域大气NO2污染特征,并进行了对比分析.从2005～2011年的平均近地面质量浓度和垂直柱浓度来看,京津冀与长三角中心城市大气NO2基本处于同一污染水平;其区域背景站的NO2浓度也差异不大,且与两大区域过渡地带的合肥市大致相同.区域NO2高浓度中心夏季较为分散,秋冬季高浓度范围明显扩大,冬季全部连为一片.近年来随着中心城区污染企业的外迁,北京、上海等城市核心区NO2近地面污染有所缓解,但区域背景站NO2近地面浓度和垂直柱浓度都有所升高,京津冀与长三角NO2整体污染水平形势依旧严峻.从区域分布看,北京、上海等城市NO2浓度较高,NO2柱浓度高出区域背景的50%左右,大约是欧亚大陆背景水平的3倍;近地面NO2浓度地域差异更大,北京、上海等中心城市NO2近地面质量浓度是城市清洁区的2倍,是区域背景的10倍以上,达欧亚大陆背景站瓦里关的上千倍.北京奥运及上海世博等大型活动之前及期间大气污染集中整治效果较为明显,但活动结束后,城市大气NO2污染都出现反弹.结果表明,区域空气质量的持续改善需要区域内各省市常抓不懈的联防联控,仅靠短期内运动式的污染治理难以从根本上解决大气环境问题.

Characteristics of Atmospheric NO2 in the Beijing-Tianjin-Hebei Region and the Yangtze River Delta Analyzed by Satellite and Ground Observations

The interannual variability of NO₂ levels in two major Chinese economic regions, the Beijing-Tianjin-Hebei (BTH) economic circle and the Yangtze River Delta (YRD), were studied using multiple years of OMI-retrieved NO₂ columns and ground measurements. The NO₂ columns were comparable in the two regions, which were~50% higher than the BTH and YRD regional background and two times higher than the Asia-Europe continental background. Satellite data showed that the high NO₂ regions scattered around Beijing and Shanghai in summer, and the coverage of high NO₂ regions increased in spring and merged in winter, affecting the entire eastern China. Ground level NO₂ concentrations in the urban centers of Beijing and Shanghai were also comparable, which were~10 times greater than the regional background and 1000 times higher than the Asia-Europe continental background. As industries gradually migrated out of the urban centers, the NO₂ concentrations in Beijing and Shanghai decreased, but the regional background NO₂ concentration in BTH and YRD increased. It reflected in part the impact of NO_x emission reductions related to fossil fuel combustion as a result of air quality control measures in BTH and YRD. NO₂ levels during the Beijing 2008 Olympic Games and the Shanghai World Expo 2010 decreased temporarily, but bounced back quickly afterwards, indicating that sustainable air quality improvement can only be achieved through long-term regional efforts.