Secondary organic aerosol reduced by mixture of atmospheric vapours
Secondary organic aerosol reduced by mixture of atmospheric vapours
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DOI：
10.1038/s41586-018-0871-y
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发表时间：
2019-01-31
期刊：
影响因子：
64.8
通讯作者：
Kiendler-Scharr, Astrid
中科院分区：
文献类型：
--
作者：
McFiggans, Gordon;Mentel, Thomas F.;Kiendler-Scharr, Astrid
二次有机气溶胶有助于大气颗粒物的负担，对空气质量和气候的影响。植物排放的萜类等生物源挥发性有机物是重要的二次有机气溶胶前体物，异戊二烯是全球生物源挥发性有机物排放的主要来源。然而，与其他萜类化合物相比，异戊二烯氧化产生的颗粒质量通常是适度的。在这里，我们表明，异戊二烯，一氧化碳和甲烷可以各自抑制瞬时质量和来自单萜类化合物的混合物中的大气蒸气的总质量产率。我们发现，异戊二烯“清除”羟基自由基，防止它们与单萜反应，和由此产生的异戊二烯过氧自由基的高度氧化的单萜产品。这些影响降低了低挥发性产物的产率，否则这些产物将形成二次有机气溶胶。全球模式计算表明，氧化剂和产物清除可以有效地在真实的大气中运行。因此，产生适量气溶胶的高反应性化合物（如异戊二烯）不一定是二次有机颗粒质量的净生产者，它们在大气蒸气混合物中的氧化可以抑制二次有机气溶胶的颗粒数量和质量。我们建议，在大气中的二次有机气溶胶的形成机制，需要考虑更现实，占氧化前体分子的产品之间的机械相互作用（被认为是必要的臭氧生产建模时）。
Secondary organic aerosol contributes to the atmospheric particle burden with implications for air quality and climate. Biogenic volatile organic compounds such as terpenoids emitted from plants are important secondary organic aerosol precursors with isoprene dominating the emissions of biogenic volatile organic compounds globally. However, the particle mass from isoprene oxidation is generally modest compared to that of other terpenoids. Here we show that isoprene, carbon monoxide and methane can each suppress the instantaneous mass and the overall mass yield derived from monoterpenes in mixtures of atmospheric vapours. We find that isoprene 'scavenges' hydroxyl radicals, preventing their reaction with monoterpenes, and the resulting isoprene peroxy radicals scavenge highly oxygenated monoterpene products. These effects reduce the yield of low-volatility products that would otherwise form secondary organic aerosol. Global model calculations indicate that oxidant and product scavenging can operate effectively in the real atmosphere. Thus highly reactive compounds (such as isoprene) that produce a modest amount of aerosol are not necessarily net producers of secondary organic particle mass and their oxidation in mixtures of atmospheric vapours can suppress both particle number and mass of secondary organic aerosol. We suggest that formation mechanisms of secondary organic aerosol in the atmosphere need to be considered more realistically, accounting for mechanistic interactions between the products of oxidizing precursor molecules (as is recognized to be necessary when modelling ozone production).