北京9.3阅兵前后天津市大气污染变化特征分析

Characteristic of air pollutants in Tianjin before,during and after the Beijing Military Parade in 2015

2015年8月23日—9月4日京津冀地区对部分污染源实行了临时性的减排管控措施,为保障9月3日北京大阅兵的空气质量起到了重要作用。天津作为协同减排的重要城市,阅兵期间空气质量变化一直备受关注。为评估这次减排管控措施对空气质量的改善效果,于2015年8月10日—9月15日,选择天津市气象局院内观测场,利用自动在线观测仪器对大气污染物NO_x、SO_2、CO、O_3及PM_(2.5)进行了连续观测,以天津所采取的临时减排措施为时间节点,对人为管控前后污染物的浓度水平、源贡献及日变化特征进行了比对分析,并结合气团输送特征讨论了气象条件在各时段的贡献。结果显示:在减排期间(2015年8月23日—9月4日),NO、NO_2、SO_2、CO、O_3及PM_(2.5)浓度较减排前(2015年8月10日—22日)分别降低了12.3%、34.1%、41.8%、21.1%、39.0%及63.1%,燃煤、工业及扬尘源控制效果显著;减排后(2015年9月5日—15日)较减排期,NO、NO_2、SO_2、CO及PM_(2.5)浓度分别升高了77.2%、46.1%、13.3%、12.5%和11.5%,空气质量主要受机动车源的影响。NO_2、SO_2、CO及PM_(2.5)在各时段的日变化基本呈早晚双峰型,NO呈早单峰型,O_3呈午后单峰型,减排措施有效降低了峰值和浓度水平,污染物排放至大气后,近地面气象要素也会有所影响。由气团的输送特征可知,有利的气象条件也是减排期间良好空气质量的重要因素,减排后CO、SO_2和PM_(2.5)无显著回升主要得益于清洁气团的频繁出现。

To reduce air pollutant concentrations during September 3 of 2015 military parade in Beijing,some temporary emission control measures were implemented from 23^（th） August to 4^（th） September in Beijing-Tianjin-Hebei Region,which played an important role in guaranteeing good air quality during September 3 military parade in Beijing.As an important city in cooperative emission reduction,the variation of air quality in Tianjin has widely been known.Atmospheric concentrations of NO_x,SO_2,CO,O_3 and PM_（2.5） were simultaneously observed with Automatic observing instruments from 10^（th） August to 15 thSeptember of 2015 to assess the effects of the emission control measures in the observation field in Tianjin Meteorological Bureau.The daily variation,source contribution and diurnal variation during different periods were given through comparison and analyses,and some discussion of the relationship between concentration variation of pollutants and the characteristics of air mass trans-port was also progressed according to the time node when the emission reduction measures were taken in Tianjin.The results showed that the concentrations of NO,NO_2,SO_2,CO,O_3 and PM_（2.5） during the emission control period （23^（th） August-4^（th） September,2015） reduced by 12.3%,34.1%,41.8%,21.1%,39.0% and 63.1%compared to the pre-emission control period （10^（th）-22^（th） August,2015）,which indicated the significant reduction from industrial,coal-combustion and dust.the concentrations of NO,NO_2,SO_2,CO and PM_（2.5） increased by77.2%,46.1%,13.3%,12.5% and 11.5% after emission control period （5^（th）-15^（th） September,2015） compared with emission control period,while air quality is mainly affected by vehicle exhaust emission.The diurnal variation of pollutants showed that the average diurnal variation of NO_2,SO_2,CO and PM_（2.5） were similar with peaking in early morning and evening,while the peak of NO appeared at early morning,the peak of O_3 appeared at noon.Our results demonstrated that great improvements of air quality were achieved during the emission control period due to the emission control measures.During three periods,the peak and concentration were mainly reducted by emission control measures,while pollutants fumed to the air,meteorological parameters might have an impact on them.According to the characteristics of air mass transport,the favorable meteorological conditions were also play an important role during the emission control period,and clean air mass occurred frequently during the the post-emission control period,which resulted in less significant rebound of CO,SO_2 and PM_（2.5）.