Quantifying the Effect of Vapor Wall Deposition on Chamber-Derived Yields of Secondary Organic Aerosol

本研究的重点是研究二次有机气溶胶（SOA），从气相凝聚的非常小的颗粒，在环境室和气体和颗粒沉积到室壁上的影响。模拟研究通常利用来自环境室的基本数据来预测大气中的环境气溶胶浓度。目前，在模式预测和SOA的大气测量之间存在差异。历史室实验的再分析表明，先前报告的SOA产量可能被低估了。这项研究的信息对于了解气溶胶引起的健康影响和对全球气溶胶辐射强迫的贡献至关重要。建议的工作包括：(1)测量单个有机物种在聚四氟乙烯壁上的壁面沉积速率以及这些速率与物种分子特性的相关性；(2)采用多种重要的生物源性和人为挥发性有机化合物的室内实验，调节蒸汽向颗粒和壁面输送之间的竞争；(3)建立了一个综合的气室蒸汽动力学模型，该模型可以从单个物种的数据中定量评估气壁沉积的影响，并外推大气“无壁”条件。

This research is focused on the study of secondary organic aerosol (SOA), very small particles condensed from the gas phase, in environmental chambers and the effects of gas and particle deposition onto the chamber walls. Modeling studies generally utilize fundamental data from environmental chambers in predicting ambient aerosol concentrations in the atmosphere. Currently a discrepancy exists between model predictions and atmospheric measurements of SOA. The reanalysis of historical chamber experiments indicates that prior reported SOA yields may have been underpredicted. The information from this research is critical for understanding aerosol-induced health effects and contributions to global aerosol radiative forcing.The proposed work includes: (1) Measurements of the wall deposition rates of individual organic species on the Teflon walls of a chamber and correlation of those rates to molecular properties of the species; (2) Chamber experiments with a wide range of important biogenic and anthropogenic volatile organic compounds in which the competition between vapor transport to particles and the walls is modulated; and (3) Development of a comprehensive model of chamber vapor dynamics that allows quantitative assessment from data on individual species of the impact of vapor wall deposition and extrapolation to atmospheric "wall-less" conditions.