Li Haiyan, Zhang Qiang, Duan Fengkui, Zheng Bo, He Kebin
State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Tsinghua University, Beijing 100084, China.
Faraday Discuss. 2016 Jul 18;189:317-35. doi: 10.1039/c6fd00004e.
The strict control on emissions implemented in Beijing, China, during the 2015 China Victory Day Parade (V-day Parade) to commemorate the 70(th) Anniversary of Victory in World War II, provided a good opportunity to investigate the relationship between emission sources and aerosol chemistry in a heavily polluted megacity. From August 11 to September 3, 2015, an Aerosol Chemical Speciation Monitor was deployed in urban Beijing, together with other collocated instruments, for the real-time measurement of submicron aerosol characteristics. The average PM1 mass concentration was 11.3 (±6.7) μg m(-3) during the V-day Parade, 63.5% lower than that before the V-day Parade. Differently to the relatively smaller decrease of organics (53%), secondary inorganic aerosols (sulfate, nitrate and ammonium) showed significant reductions of 65-78% during the V-day Parade. According to the positive matrix factorization results, primary organic aerosol (POA) from traffic and cooking emissions decreased by 41.5% during the parade, whereas secondary organic aerosol (SOA) presented a much greater reduction (59%). The net effectiveness of emission control measures was investigated further under comparable weather conditions before and during the parade. By excluding the effects of meteorological parameters, the total PM1 mass was reduced by 52-57% because of the emission controls. Although the mass concentrations of aerosol species were reduced substantially, the PM1 bulk composition was similar before and during the control period as a consequence of synergetic control of various precursors. The emission restrictions also suppressed the secondary formation processes of sulfate and nitrate, indicated by the substantially reduced SOR and NOR (molar ratios of sulfate or nitrate to the sums of the sulfate and SO2 or nitrate and NO2) during the event. The study also explored the influence of emission controls on the evolution of organic aerosol using the mass ratios of SOA/POA and oxygen-to-carbon ratios. The results showed that for northwesterly airflows, emission restrictions during the V-day Parade also reduced the oxidation degree of organic aerosol.
2015年中国为纪念二战胜利70周年举行抗战胜利日阅兵期间，中国北京实施了严格的排放控制措施，这为研究重污染特大城市排放源与气溶胶化学之间的关系提供了一个绝佳机会。2015年8月11日至9月3日，一台气溶胶化学形态监测仪与其他配套仪器一同部署在北京城区，用于实时测量亚微米气溶胶特征。抗战胜利日阅兵期间，PM1平均质量浓度为11.3（±6.7）μg m⁻³，比阅兵前低63.5%。与有机物相对较小的降幅（53%）不同，二次无机气溶胶（硫酸盐、硝酸盐和铵盐）在抗战胜利日阅兵期间显著下降了65 - 78%。根据正矩阵因子分解结果，来自交通和烹饪排放的一次有机气溶胶（POA）在阅兵期间下降了41.5%，而二次有机气溶胶（SOA）的降幅则大得多（59%）。在阅兵前和阅兵期间类似天气条件下，进一步研究了排放控制措施的净效果。通过排除气象参数的影响，由于排放控制，PM1总质量减少了52 - 57%。尽管气溶胶物种的质量浓度大幅降低，但由于对各种前体物的协同控制，控制期间前后PM1的总体组成相似。排放限制还抑制了硫酸盐和硝酸盐的二次形成过程，这在活动期间SOR和NOR（硫酸盐或硝酸盐与硫酸盐和SO2或硝酸盐和NO2总和的摩尔比）大幅降低中得到体现。该研究还利用SOA/POA质量比和氧碳比探讨了排放控制对有机气溶胶演变的影响。结果表明，对于西北气流，抗战胜利日阅兵期间的排放限制也降低了有机气溶胶的氧化程度。
