Photochemical Aging of Asian Particulate Matter: Formation of Oxygenated Polycyclic Aromatic Hydrocarbons

该项目正在研究长距离运输的多环芳烃(PAH)化合物上发生的反应。多环芳烃由许多类型的燃烧排放，来源包括汽车、发电厂和野火。当这些化合物与臭氧和大气中的羟基发生反应时，它们可能会变得更加有毒。随着多环芳烃的老化和长途运输，它们可能会对人类健康造成越来越大的风险。本研究的具体目标包括：1)预测高相对分子质量多环芳烃的光化学氧化可能形成哪些含氧性多环芳烃；2)利用实验室光化学反应器研究和新的分析方法，测量亚洲颗粒物上含氧性多环芳烃的形成；美国实验室将使用的方法包括二维气相色谱-飞行时间质谱仪(GCxGC/ToF-MS)来分析多环芳烃、opah组分和羟基-多环芳烃(OH-PAH)组分，以及气相色谱-高分辨率质谱仪(GC/HRMS)来确认化合物的身份。此前从中国、日本和韩国获得的样本将被分析，以代表亚洲运输的颗粒物特征。此前从华盛顿和俄勒冈州获得的样本将被评估是否受到亚洲运输的影响。混合单粒子拉格朗日积分轨迹(HYSPLIT)4.0模式将被用来计算采样气团的四天前后轨迹。气象数据以及CO、O3、NO、SO2和气溶胶散射的浓度将被用来帮助解释关于PAH的潜在来源的数据。这一结果将有助于更好地了解亚洲颗粒物的光化学老化以及跨太平洋大气输送到美国西海岸过程中含氧多环芳烃的潜在形成。

This project is investigating the reactions that occur on polycyclic aromatic hydrocarbon (PAH) compounds that are transported over long distances. PAHs are emitted by many types of combustion, from sources such as automobiles, power plants, and wildfires. When these compounds undergo reactions with ozone and the hydroxyl radical in the atmosphere, they may become more toxic. As PAHs age and are transported over long distances, they may cause an increasing risk to human health.The specific goals of this research include: 1) predicting which oxygenated PAH are likely to form from the photochemical oxidation of higher molecular weight PAHs; 2) measuring the formation of oxygenated PAH products on Asian particulate matter using laboratory photochemical reactor studies and new analytical methods; and 3) measuring the oxygenated PAH composition of size fractionated particulate matter collected from Asia and the Pacific Northwestern U.S. Laboratory methods that will be used include 2D gas chromatography with time-of-flight mass spectrometry (GCxGC/ToF-MS) for analysis of the PAH, the OPAH fraction, and the hydroxy-PAH (OH-PAH) fraction, and gas chromatography with high resolution mass spectrometry (GC/HRMS) to confirm compound identities. Previously acquired samples from China, Japan, and Korea will be analyzed to represent particulate matter characteristic of Asian transport. Previously acquired samples from Washington and Oregon will be assessed for influence from Asian transport. A hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) 4.0 model will be used to calculate four-day forward and back trajectories for air masses sampled. Meteorological data and the concentrations of CO, O3, NO, SO2, and aerosol scattering will be used to aid in the interpretation of the data with respect to potential sources of PAH. The results will lead to a better understanding of the photochemical aging of Asian particulate matter and the potential formation of oxygenated PAH during trans-Pacific atmospheric transport to the U.S. West Coast.