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

这个项目正在研究发生在长距离运输的多环芳烃（PAH）化合物上的反应。多环芳烃是由多种燃烧产生的，如汽车、发电厂和野火。当这些化合物与大气中的臭氧和羟基自由基发生反应时，它们可能会变得更有毒。随着多环芳烃的老化和长距离运输，它们可能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)预测高分子量多环芳烃光化学氧化可能形成哪些含氧多环芳烃；2)利用实验室光化学反应器研究和新的分析方法测定亚洲颗粒物中含氧多环芳烃产物的形成；3)测量从亚洲和美国西北部太平洋地区收集的颗粒颗粒的含氧多环芳烃组成。实验室将使用的方法包括2D气相色谱-飞行时间质谱（GCxGC/ToF-MS）用于分析多环芳烃、多环芳烃馏分和羟基多环芳烃（OH-PAH）馏分，以及气相色谱-高分辨率质谱（GC/HRMS）来确认化合物的身份。先前从中国、日本和韩国获得的样本将进行分析，以代表亚洲运输的颗粒物特征。将评估先前从华盛顿和俄勒冈州获得的样本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模型将用于计算采样气团的4天前、后轨迹。气象数据和CO、O3、NO、SO2的浓度以及气溶胶散射将被用来帮助解释有关多环芳烃潜在来源的数据。该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运输到美国西海岸的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.