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首页> 外文期刊>Atmospheric chemistry and physics >Aerosol composition, oxidation properties, and sources in Beijing: results from the 2014 Asia-Pacific Economic Cooperation summit study
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Aerosol composition, oxidation properties, and sources in Beijing: results from the 2014 Asia-Pacific Economic Cooperation summit study

机译：北京的气溶胶成分，氧化性质和来源：2014年亚太经济合作组织峰会研究的结果

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The mitigation of air pollution in megacities remains a great challenge because of the complex sources and formation mechanisms of aerosol particles. The 2014 Asia-Pacific Economic Cooperation (APEC) summit in Beijing serves as a unique experiment to study the impacts of emission controls on aerosol composition, size distributions, and oxidation properties. Herein, a high-resolution time-of-flight aerosol mass spectrometer was deployed in urban Beijing for real-time measurements of size-resolved non-refractory submicron aerosol (NR-PM1) species from 14 October to 12 November 2014, along with a range of collocated measurements. The average (+/-sigma) PM1 was 41.6 (+/- 38.9) mu g m(-3) during APEC, which was decreased by 53% compared with that before APEC. The aerosol composition showed substantial changes owing to emission controls during APEC. Secondary inorganic aerosol (SIA: sulfate + nitrate + ammonium) showed significant reductions of 62-69 %, whereas organics presented much smaller decreases (35 %). The results from the positive matrix factorization of organic aerosol (OA) indicated that highly oxidized secondary organic aerosol (SOA) showed decreases similar to those of SIA during APEC. However, primary organic aerosol (POA) from cooking, traffic, and biomass-burning sources were comparable to those before APEC, indicating the presence of strong local source emissions. The oxidation properties showed corresponding changes in response to OA composition. The average oxygen-to-carbon level during APEC was 0.36 (+/- 0.10), which is lower than the 0.43 (+/- 0.13) measured before APEC, demonstrating a decrease in the OA oxidation degree. The changes in size distributions of primary and secondary species varied during APEC. SIA and SOA showed significant reductions in large accumulation modes with peak diameters shifting from similar to 650 to 400 nm during APEC, whereas those of POA remained relatively unchanged. The changes in aerosol composition, size distributions, and oxidation degrees during the aging processes were further illustrated in a case study of a severe haze episode. Our results elucidated a complex response of aerosol chemistry to emission controls, which has significant implications that emission controls over regional scales can substantially reduce secondary particulates. However, stricter emission controls for local source emissions are needed for further mitigating air pollution in the megacity of Beijing.
机译：由于气溶胶颗粒的来源和形成机制复杂，减轻大城市中的空气污染仍然是一个巨大的挑战。 2014年在北京举行的亚太经济合作组织（APEC）峰会是一项独特的实验，旨在研究排放控制对气溶胶成分，尺寸分布和氧化特性的影响。在此，2014年10月14日至11月12日，在北京市区部署了高分辨率的飞行时间气溶胶质谱仪，用于实时测量尺寸分辨的非难溶性亚微米气溶胶（NR-PM1）物种。并置测量的范围。 APEC期间的平均PM1为41.6（+/- 38.9）g g（-3），与APEC之前相比降低了53％。由于APEC期间的排放控制，气溶胶成分显示出实质性变化。次生无机气溶胶（SIA：硫酸盐+硝酸盐+铵）显示出62-69％的显着减少，而有机物的减少则小得多（35％）。有机气溶胶（OA）的正矩阵分解结果表明，在APEC期间，高度氧化的次级有机气溶胶（SOA）的下降与SIA相似。但是，来自烹饪，交通和生物质燃烧源的主要有机气溶胶（POA）与APEC之前的水平相当，表明存在大量的本地源排放。氧化性质显示出响应于OA组成的相应变化。 APEC期间的平均氧气碳含量为0.36（+/- 0.10），低于APEC之前测得的0.43（+/- 0.13），这表明OA氧化度降低了。 APEC期间主要和次要物种的大小分布变化。在APEC期间，SIA和SOA在大型累积模式下显示出显着减少，峰直径从相似的650 nm变为400 nm，而POA的相对直径则保持相对不变。在严重雾霾事件的案例研究中，进一步说明了老化过程中气溶胶成分，尺寸分布和氧化度的变化。我们的结果阐明了气溶胶化学对排放控制的复杂反应，这对区域范围内的排放控制可以显着减少次生颗粒产生了重大影响。但是，需要采取更严格的本地排放源排放控制措施，以进一步减轻北京这个特大城市的空气污染。

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