AGS-PRF: Synthesizing Laboratory and Field Measurements of Biogenic Volatile Organic Compounds

本研究的目的是调查异戊二烯(C5H8)及其氧化产物在大气中的主要化学和物理损失途径，并评估它们在二次有机气溶胶(SOA)形成中的作用。AGS的一名博士后研究员将在加州理工大学新建的雾霾实验室进行实验室研究，以探索在各种条件下形成SOA的潜在机制。将研究的三个主要机理是：(1)异戊二烯衍生的环氧二醇(IEPOX)在原始环境中在不同数量的NOx存在下形成的气相OH氧化，(2)异戊二烯衍生的有机化合物(过氧化氢、IEPOX、乙醇醛等)的反应吸收和水溶液光化学。在气溶胶液态水中，以及(3)水蒸气与异戊二烯臭氧分解稳定的Criegee中间体反应生成的过氧化氢。2013年夏天，在美国国家科学基金会(NSF)赞助的现场活动-南方氧化物和气溶胶研究(SOAS)期间，使用最先进的化学电离质谱仪(CIMS)测量了作为SOA重要前体的多功能有机化合物。实验室研究的结果将被用来评估可能的SOA形成机制，这可能解释在SOAS现场活动期间收集的观测数据。异戊二烯是由森林和植物排放的，是大气中排放最高的有机化合物之一。异戊二烯氧化的产物形成臭氧和二次有机气溶胶，对人类健康有害，并扰乱地球气候。这项研究将产生对模拟异戊二烯氧化产物对气候变化的影响至关重要的信息。这项研究得到了AGS博士后研究奖学金计划的支持。

This objective of this research is to investigate the major chemical and physical loss pathways for isoprene (C5H8) and its oxidation products in the atmosphere and assess their role in the formation of secondary organic aerosol (SOA). An AGS Postdoctoral Research Fellow will conduct laboratory studies in Caltech's newly built smog chambers to explore potential mechanisms for SOA formation under various conditions. The three primary mechanisms that will be investigated are: (1) the gas-phase OH-oxidation of isoprene-derived epoxydiols (IEPOX), that are formed in pristine environments, in the presence of varying amounts of NOx, (2) the reactive uptake and aqueous photochemistry of isoprene-derived organic compounds (hydroperoxide (ISOPOOH), IEPOX, glycolaldehyde, etc.) in aerosol liquid water, and (3) the formation of hydroperoxides from the water vapor reaction with stabilized Criegee intermediates from the ozonolysis of isoprene.Multifunctional organic compounds that are important precursors to SOA were measured during an NSF sponsored field campaign in the summer of 2013, the Southern Oxidant and Aerosol Study (SOAS), using a state-of-the-art chemical ionization mass spectrometer (CIMS). Results from the laboratory studies will be used to assess possible mechanisms for SOA formation that might explain the observational data collected during the SOAS field campaign.Isoprene is emitted by forests and plants and is among the most highly emitted organic compounds in the atmosphere. The products of isoprene oxidation form ozone and secondary organic aerosols, which are harmful to human health and perturb the Earth's climate. This research will produce information that is critical to modeling the influence of isoprene oxidation products on climate change.This research is supported under the AGS Postdoctoral Research Fellowship program.