摘要：通过5个有代表性站点2008年7月10日—8月31日的NO2浓度的地面实测数据,分析了北京城市区域NO2浓度的时空特征,讨论了奥运会期间相关政策措施对不同污染源的控制效果。结果表明:NO2化学性质活跃、寿命短、反应速率快,其自身独特的化学性质制约了NO2在时空上的积累,因此在低层大气中浓度分布很不均匀,其随测点地理位置不同有较大的差异,有显著地时空分布特征,受不同性质不同形式的排放源排放条件的影响,局地变化性强。相关的空气质量保障措施的实施与控制力度大小对NO2排放产生不同程度的影响:奥运会举行期间,一系列空气污染管理决策和措施的实施行之有效,源控制效果较好。各站点间NO2浓度变化在空间上具有相对独立性。在1d的时间轴上,各测站NO2浓度变化均表现为相似的双峰型日变化,即NO2平均日变化各站点同时刻呈现城市区域尺度的同步性空间结构特征,各测站间NO2浓度变化的差异主要表现为两方面:局地排放源影响效应,反映不同测点局地污染影响特征差异;城市热岛效应,反应城郊热力差异。
关键词：氮氧化物；时空分布；污染源
Abstract：Based on the observational data of near surface NO2 concentrations of five representative ground stations from July 10 to August 31，2008， the temporal and spatial characteristics of NO2 were analyzed and the control effects of Olympic-related policies and measures from variation emission sources were also discussed. The results showed that the NO2 characteristics， such as the relatively active chemical properties， short life and fast reaction rate， constrainted on its temporal and spatial accumulation. On account of this， for one thing, the distribution of NO2 concentration between different stations were relative independence. The day-to-day variability in NO2 was very uneven and local. The implementation of air-protection measures and the degree of supervision strength had a certain extent influence on the emission of NO2. During the period of the Beijing Olympic Games， the measures were effective and the emission sources were better controlled. For another， the hour-to-hour variability of all the five stations in NO2 presented similar characteristics of bimodal diurnal variation and urban regional scale “synchronization” of spatial structure. The differences of NO2between the stations were mainly expressed in two aspects：the impact of local effects of emission sources， which reflecting closely on the situ pollutant distribution and variation； and the urban heat island effect， which reflecting the uneven peri-urban thermal distribution of different stations.
Keywords：nitrogen oxide； atmospheric photochemical pollution； emission source
