Lü Zhe, Wei Wei, Zhou Ying, Cheng Shui-Yuan, Wang Xiao-Qi
Key Laboratory of Beijing on Regional Air Pollution Control, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China.
Huan Jing Ke Xue. 2019 Jan 8;40(1):1-10. doi: 10.13227/j.hjkx.201806087.
Beijing authorities issued three red alerts for heavy air pollution at 6 pm on December 7 and 7 am on December 18, 2015, and at 1 pm on December 15, 2016, respectively. To better understand the different causes of the three red alerts and assess the effectiveness of emergency measures dealing with heavy air pollution, the PM concentrations, meteorological conditions, weather conditions, and air mass transmission were analyzed during the red alerts using data from environmental and meteorological monitoring stations in Beijing. All three red alerts were affected by secondary transformation, but the high PM concentrations were mainly affected by meteorological conditions. During the first and second red alerts, the ground in Beijing was controlled by a uniform pressure field and the regional transport was mainly affected by southwestern and southern air masses. During the third red alert, the ground was under the control of a wide range of low pressure and affected by the superposition of southwestern and local air masses. During the third red alert, the PM pollution was the most serious. Its average concentration was the highest (273.6 μg·m), that is, 1.2 times and 1.3 times higher than that of the previous two alerts, respectively. The WRF-CMAQ model was used in combination with the emission reduction of each source to evaluate the effects of the emergency measures related to the third red alert. The results show that the average daily emission reduction of pollutants was 678.4 t, the average concentration of PM decreased by 79.1 μg·m, and the average reduction ratio was 26.9% after the emergency measures were implemented. The increase of coal-fires, traffic, and other sources control the emergency measures, early alert start-up time, and inter-region joint prevention and effectively mitigate the increasing PM concentration.
北京当局分别于2015年12月7日下午6点、12月18日上午7点以及2016年12月15日下午1点发布了三次重空气污染红色预警。为了更好地理解这三次红色预警的不同成因，并评估应对重空气污染应急措施的有效性，利用北京环境和气象监测站的数据，对红色预警期间的细颗粒物（PM）浓度、气象条件、天气状况及气团传输进行了分析。三次红色预警均受到二次转化的影响，但高PM浓度主要受气象条件影响。在第一次和第二次红色预警期间，北京地面受均匀气压场控制，区域传输主要受西南和南部气团影响。在第三次红色预警期间，地面处于大范围低压控制之下，受西南和本地气团叠加影响。第三次红色预警期间，PM污染最为严重。其平均浓度最高（273.6μg·m），分别比前两次预警高出1.2倍和1.3倍。结合各源减排情况，利用WRF-CMAQ模型评估了与第三次红色预警相关的应急措施效果。结果表明，实施应急措施后，污染物日均减排量为678.4吨，PM平均浓度下降了79.1μg·m，平均减排率为26.9%。加强对燃煤、交通等源排放的管控、提前预警启动时间以及区域间联防联控，有效缓解了PM浓度的上升。
