Rainforest-like Atmospheric Chemistry in a Polluted Megacity
Rainforest-like Atmospheric Chemistry in a Polluted Megacity
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DOI：
10.5194/acp-2020-35
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发表时间：
2020-02
影响因子：
6.3
通讯作者：
M. Newland;D. Bryant;R. Dunmore;T. Bannan;W. Acton;B. Langford;J. Hopkins;F. Squires;William J.
中科院分区：
文献类型：
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作者：
M. Newland;D. Bryant;R. Dunmore;T. Bannan;W. Acton;B. Langford;J. Hopkins;F. Squires;William J.
抽象的。挥发性有机化合物（VOC）排放到大气中对二次污染物（如臭氧和二次有机气溶胶（SOA））产生的影响由一氧化氮（NO）浓度介导。受污染的城市大气通常被认为是高NO环境，而偏远地区，如热带雨林，人为影响最小，被认为是低NO。减少城市空气污染的政策通常是假设化学是由高NO制度控制。然而，我们从北京中心的观察表明，这种简单的政权分离是有缺陷的。尽管是在世界上最大的特大城市之一，我们观察到显着的气体和气溶胶相氧化产物的形成与低NO雨林状制度在下午。这是由于令人惊讶的低浓度的NO，加上高浓度的VOC和大气氧化剂羟基（OH）。箱模型计算表明，在上午高NO化学占主导地位（95%），但在下午低NO化学起着更大的作用（30%）。随着全球越来越重视减少空气污染，用于制定城市空气质量政策的建模工具需要充分代表高和低NO制度，如果他们有效用。
Abstract. The impact of volatile organic compound (VOC) emissions to the atmosphere on the production of secondary pollutants, such as ozone and secondary organic aerosol (SOA), is mediated by the concentration of nitric oxide (NO). Polluted urban atmospheres are typically considered to be high-NO environments, while remote regions such as rainforests, with minimal anthropogenic influences, are considered to be low-NO . Policy to reduce urban air pollution is typically developed assuming that the chemistry is controlled by the high-NO regime. However, our observations from central Beijing show that this simplistic separation of regimes is flawed. Despite being in one of the largest megacities in the world, we observe significant formation of gas and aerosol phase oxidation products associated with the low-NO rainforest-like regime during the afternoon. This is caused by a surprisingly low concentration of NO, coupled with high concentrations of VOCs and of the atmospheric oxidant hydroxyl (OH). Box model calculations suggest that during the morning high-NO chemistry predominates (95 %) but in the afternoon low-NO chemistry plays a greater role (30 %). With increasing global emphasis on reducing air pollution, the modelling tools used to develop urban air quality policy need to adequately represent both high- and low-NO regimes if they are to have utility.