AGS-PRF: Experimentally Determined Volatility of Secondary Organic Aerosol Formed Through Aqueous Oxidation

二次有机气溶胶是由森林、化石燃料燃烧和火灾排放的有机气体氧化产生的小颗粒。复杂的化学过程在气候模型中没有得到很好的描述，是气候评估中巨大不确定性的来源，因此产生了可持续发展协定。特别是，云滴中的水对有机气体的氧化被认为是重要的，但表示产生这些粒子的过程及其性质的研究有限。拟议的工作将通过在实验室测量这些含水的SOA颗粒的挥发性来测量和量化它们的持久性，将它们纳入气候模型将使更可靠的评估成为可能。为了限制水基SOA(AQSOA)的产生机制，本研究将对AQSOA化合物的挥发度进行实验量化，以确定在蒸发和清除过程中幸存下来影响全球气候的低挥发性组分。我们的目标是探索前体分子性质与AQSOA挥发性之间的基本关系。实验室研究将从(1)甲基乙二醛、丙酮酸和甲基乙烯基酮氧化、(2)降水样品中的氧化产物和(3)干有机气溶胶氧化来阐明AQSOA-挥发性关系。氧化将在间歇反应器中由过氧化氢光解产生的羟基自由基进行，混合物将用振动孔板气溶胶发生器雾化，然后在流动管中蒸发，最后由光学颗粒计数器检测。极性分辨的挥发性分布将使用洗脱和离子色谱进行测量。研究结果将阐明AQSOA的基本挥发性，以了解它们如何影响过去、现在和未来的气候。

Secondary organic aerosols (SOA) are small particles produced by the oxidation of organic gases emitted by forests, fossil fuel combustion and fires. Complex chemical processes that are not well represented in climate models and are a source of large uncertainties in climate assessments produce sOAs. In particular the oxidation of organic gases by water in cloud drops is recognized to be important but there are limited studies to represent the processes that produce the particles and their properties. The proposed work will measure and quantify the persistence of these aqueous SOA particles by measuring their volatility in the laboratory and their inclusion in climate models will enable more robust assessments. In order to constrain aqueous SOA (aqSOA) production mechanism this research would experimentally quantify the volatility of aqSOA compounds that determine the low volatility fraction that survive evaporation and scavenging to effect global climate. The goal is to probe the fundamental relationship between the precursor molecular properties and aqSOA volatility. The laboratory studies will elucidate aqSOA-volatility relationships from (1) methylglyoxal, pyruvic acid, and methyl-vinyl ketone oxidation, (2) oxidation products in precipitation samples and (3) dried organic aerosol oxidation. The oxidation will be performed by hydroxyl radicals produced from hydrogen peroxide photolysis in a batch reactor, the mixtures will be aerosolized with a vibration orifice aerosol generator then evaporated in a flow tube and finally detected by an optical particle counter. Polarity-resolved volatility distributions will be measured using elution and ion chromatography. The results will elucidate the fundamental volatility properties of aqSOA to understand how they effect past, present and future climate.