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

本研究主要研究环境舱内的二次有机气溶胶(SOA)，即从气相中凝聚出来的极小颗粒，以及气体和颗粒沉积对舱壁的影响。模拟研究一般使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，SOA的模型预测和大气测量之间存在差异。对历史实验室实验的重新分析表明，之前报告的SOA产量可能被低估了。这项研究的信息对于理解气溶胶引起的健康效应和对全球气溶胶辐射强迫的贡献是至关重要的。拟议的工作包括：(1)测量单个有机物种在舱壁上的沉积速率，并将这些速率与该物种的分子性质相关联；(2)室内实验，对大量重要的生物和人为挥发性有机化合物进行实验，其中水蒸气向颗粒和壁面的竞争被调节；以及(3)开发一个室内蒸汽动力学的综合模型，使之能够从单个物种的数据中定量评估蒸汽壁沉积和外推对大气“无壁”条件的影响。

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.