2017年厦门金砖会晤期间气象因素与管控措施对空气质量的影响

The influence of meteorological factors and control measures on air quality during the 2017 Xiamen BRICS summit

2017年厦门金砖会晤期间采取了大气污染临时管控措施,使AQI小时值和日均值均达到了双优的预期目标.本文根据管控措施实施的前、中、后阶段,厦门及周边城市大气污染物浓度的变化,对气象因素和人为因素的影响分别进行分析.结果发现,气态污染物对临时管控措施的敏感性最强,SO_2和NO_2的降幅(39.9%和25.6%)明显高于PM_(2.5)和PM_(10)的降幅(5.5%和4.8%),台风外围带来的大风和降水可显著改变大气污染物的周期性变化规律.大气PM_(2.5)组成及SO_2/NO_2、SO【math395z】/NO【math396z】、OC/EC和WSOC/OC等比值变化显示机动车(尤其是柴油货车)是本地区大气污染物的重要来源.控制变量分析显示,厦门金砖会晤期间气象因素对颗粒物和NO_2削减的贡献更大(20.3%),而临时管控措施对SO_2的削减效果更明显(23.2%),且有一半以上(51%～64%)的大气污染物来自外来源输送.

The hourly and daily means of AQI were both below 50 （perfect level） during the 2017 Xiamen BRICS Summit due to the temporary air pollution control measures. In this study, the influence of meteorological factors and control measures on the air pollutants were discussed based on their variations during the pre-control, under-control and after-control periods. The results showed that gaseous pollutants were more sensitive to the control measures than that of particulate matters. The drops of SO2 and NO2 during the under-control period were 39.9% and 25.6%, respectively which were much higher than those of PM2.5 （5.5%） and PM10 （4.8%）. The high winds and rainfall caused by Typhoon Mawar could significantly reduce the air pollutant levels and their periodicities. The daily variations of major components in PM2.5 and the ratios of SOJNO2, SO24-/NO~, OC/EC and WSOC/OC indicated that the vehicle exhaust especially heavy duty diesel truck was the major source of air pollutants in Xiamen, Zhangzhou and Quanzhou cities. Around 20.3% drop of NO2 during the BRICS Summit was attributed to the meteorological factors while 23.2% drop of SO2 was due to the influence of temporary control measures. More than half （51% ~ 64% ） of the air pollutants in Xiamen was from regional transport during the under-control period.