Collaborative Research: Fog Drop Reactions of Green Leaf Volatiles as a Source of Secondary Organic Aerosols

绿叶挥发物(GLV)作为水相二次有机气溶胶(SOA)的一种来源具有潜在的重要意义，但其重要性尚不清楚。GLV是一种活性的、含氧的有机化合物，从植物中大量排放出来，既可以在雾滴表面发生反应，也可以在雾滴内部发生反应。这些水溶液反应可以通过光化学产生的氧化剂发生，如羟基自由基、单重态分子氧和有机化合物的激发三重态。GLV也在气相中被氧化，以生成更多的水溶性产品，这些产品也可以参与雾滴反应，形成SOA。推动这项研究的假设是，GLV及其第一代氧化产物的吸收和光氧化可能是雾水中次生有机碳的重要来源。这一假设将通过四个目标来检验：(1)收集路易斯安那州和加利福尼亚州的雾水并对其进行化学表征。(2)测定光照雾水中GLV的光氧化、有机物组成的变化以及SOA的形成。(3)定量测定光照雾水中的光氧化剂及其与GLV的反应活性。(4)综合每个目标的结果，以确定雾中GLV反应的机制，并评估GLV作为SOA水来源的重要性。在项目期间，将指导博士后学者、研究生和本科生，包括通过路易斯安那州立大学-UCD本科生交换研究计划。研究结果将被整合到两所大学的本科生和研究生教学中。而且，由于雾事件会影响路易斯安那州和加利福尼亚州受监管污染物的浓度，特别是PM2.5，这项工作的结果将通知州空气质量政策机构。

Green leaf volatiles (GLVs) are potentially significant but of unknown importance as a source of aqueous-phase secondary organic aerosol (SOA). GLVs are reactive, oxygenated, organic compounds that are emitted from plants in significant quantities and that can react both at the surface of fog drops and within the bulk of the drops. These aqueous reactions can occur via photochemically generated oxidants such as hydroxyl radical, singlet molecular oxygen, and excited triplet states of organic compounds. GLVs are also oxidized in the gas phase to make more water soluble products that could also participate in fog-drop reactions to form SOA. The hypothesis driving this research is that the uptake and photooxidation of GLVs and their first generation oxidation products can be a significant source of secondary organic carbon in fogwater. This hypothesis will be tested through four objectives: (1) Collect and chemically characterize fogwaters from Louisiana and California. (2) Measure GLV photooxidation, changes in organic composition, and the formation of SOA in illuminated fogwaters. (3) Quantify photooxidants in the illuminated fog waters and their reactivity with GLVs. (4) Integrate results from each objective in order to determine the mechanisms for GLV reactions in fogwaters and assess the significance of GLVs as an aqueous source of SOA.A post-doctoral scholar, a graduate student, and undergraduate students will be mentored during the project, including through an LSU-UCD undergraduate exchange research program. The results from the research will be integrated into undergraduate and graduate teaching at both institutions. And, because fog events can affect the concentrations of regulated pollutants, especially PM2.5, in both Louisiana and California, results from this work will inform state air quality policy agencies.