The “Parade Blue”: effects of short-term emission control on aerosol chemistry

Abstract

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.

Nitrate-driven urban haze pollution during summertime over the North China Plain

“…For observations in Beijing, the total PM 1 mass was simultaneously measured using a PM-714 monitor (Kimoto Electric Co., Ltd., Japan) based on the β-ray absorption method (Li et al, 2016). Meteorological conditions, including temperature, RH, wind speed, and wind direction, were reported by an automatic meteorological observation instrument (Mi-los520, VAISALA Inc., Finland).…”

Severe air pollution events not avoided by reduced anthropogenic activities during COVID-19 outbreak

“…The answer is true. China has succeeded in various emission reduction campaigns such as during the 2014 Asia-Pacific Economic Cooperation (APEC) meeting and the 2015 China Victory Day Parade Wang et al, 2017;Xue et al, 2018;Li et al, 2016). In order to reduce anthropogenic emission, factories, industrial plants, construction sites, and gas stations was temporarily closed in and around Beijing, vehicles were kept off the roads, and 6-days mandatory holidays were brought to state-owned enterprises, local government offices and educational institutions (Sun et al, 2016;Wang et al, 2016;Li et al, 2017d;Huang et al, 2015).…”

Response of major air pollutants to COVID-19 lockdowns in China

“…Yan et al (2012) found that near-surface SO 2 concentrations in the PRD region during the Asian Games were lower than in the same period in previous years using OMI data. Huang et al (2015) found that the tropospheric NO 2 concentration in North China Plain during APEC in 2014 was 47% lower than that in the same period of the previous 3 years; Li et al (2016) found that the total PM 1 mass was reduced by 52–57% during the 2015 China Victory Day Parade (V-day Parade) by excluding the effects of meteorological parameters. Compared with those events, the COVID-19 lockdown exerts much more evident influences on the society in terms of both persistence and strength.…”