Formation of Secondary Organic Aerosol by Aqueous-phase Reactions of Phenols

酚类水相反应形成二次有机气溶胶

• 批准号: 1036675
• 负责人: Cort Anastasio
• 金额: $ 29.87万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-12-01 至 2014-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1036675&HistoricalAwards=false
• 关键词: Formation; Secondary; Organic; Aerosol; Aqueous

Atmospheric particles have a wide range of impacts, from damaging human health to altering the earth's climate. And yet a great deal is still not known about the sources of these particles, especially for carbon-containing particles formed in the atmosphere, i.e., secondary organic aerosols (SOA). Until recently it was thought that SOA was only formed from reactions of organic gases in the atmosphere, but more recent work has shown that SOA can also be formed from reactions in cloud and fog drops and aerosol particles containing small amounts of water. One group of compounds that is likely to make a significant contribution to SOA via aqueous phase reactions are the phenols. Large amounts of phenols are emitted from the combustion of wood and other biomass through sources such as residential wood combustion and wild fires. These compounds are quite water soluble and react rapidly in solution to efficiently form large, low volatility products. Given these properties, it is likely that phenols are a significant source of aqueous-phase SOA. The few available studies of atmospheric phenols are consistent with this idea, but there has been no thorough study of the aqueous-phase reactions of phenols as a source of secondary organic aerosol. The research will thoroughly characterize aqueous phenol reactions as a source of SOA and will estimate the contribution of this pathway to the atmospheric burden of particles. This will be accomplished through four objectives: 1) Measure the rates of SOA formation from aqueous phenols under a variety of conditions to mimic both cloud/fog drops and aqueous aerosol particles; 2) Quantify the yields of SOA from aqueous-phase reactions of phenols; 3) Chemically characterize the SOA using three complementary techniques; and 4) Use the rate, yield, and characterization data to estimate the significance of phenol oxidation in aqueous phases as a source of SOA. Most of the research will be performed using well-defined laboratory solutions of individual and mixed phenols studied in the laboratory using specific reaction pathways that are important in atmospheric water drops and water-containing particles. The formation of SOA from aqueous reactions of the complex mixture of gases emitted from the combustion of wood will also be studied. SOA yields will be determined using gravimetric mass, high-resolution Aerosol Mass Spectrometry (HR-AMS), and Fourier Transform Infrared spectrometry (FTIR). These latter two techniques, in conjunction with liquid chromatography coupled to high-resolution mass spectrometry, will also be used to characterize the elemental, functional group, and molecular characteristics of the SOA.Three graduate students will be mentored through the research. The principal investigators will also integrate some of the approaches and results from this research project into their undergraduate and graduate teaching, including a new graduate course on advanced atmospheric instrumentation. The project will also include an outreach component in conjunction with the University of California - Davis Air Quality Research Center: students (primarily in middle school) will come to campus for a one- or two-day program to receive hands-on lessons about atmospheric particles and air pollution.

大气颗粒物具有广泛的影响，从损害人类健康到改变地球气候。然而，关于这些颗粒的来源，特别是大气中形成的含碳颗粒，二次有机气溶胶（SOA）直到最近，人们还认为SOA只由大气中的有机气体反应形成，但最近的研究表明，SOA也可以由云滴、雾滴和含有少量水的气溶胶颗粒反应形成。 可能通过水相反应对SOA做出显著贡献的一组化合物是酚类。木材和其他生物质的燃烧会排放大量的酚类物质，其来源包括住宅木材燃烧和野火。这些化合物是相当水溶性的，并且在溶液中快速反应以有效地形成大的、低挥发性的产物。 考虑到这些性质，酚类很可能是水相SOA的重要来源。 目前对大气酚类的研究很少，这与这一观点是一致的，但还没有对酚类作为二次有机气溶胶来源的水相反应进行深入研究。这项研究将彻底表征水酚反应作为SOA的来源，并将估计这一途径对大气颗粒物负担的贡献。 这将通过四个目标来实现：1）测量在各种条件下从含水酚形成SOA的速率以模拟云/雾滴和含水气溶胶颗粒; 2）量化来自酚的水相反应的SOA的产率; 3）使用三种互补技术对SOA进行化学表征;和4）使用速率、产率和表征数据来估计水相中苯酚氧化作为SOA来源的重要性。 大多数研究将使用实验室中研究的单个和混合酚的定义明确的实验室溶液进行，这些溶液使用在大气水滴和含水颗粒中很重要的特定反应途径。 还将研究木材燃烧产生的复杂气体混合物的水反应形成SOA。 将使用重量质量、高分辨率气溶胶质谱法（HR-AMS）和傅里叶变换红外光谱法（FTIR）测定SOA产率。 后两种技术，结合液相色谱和高分辨率质谱，也将被用来表征SOA的元素，官能团和分子特征。三名研究生将通过这项研究得到指导。 主要研究人员还将把本研究项目的一些方法和结果纳入他们的本科和研究生教学，包括一门关于先进大气仪器的新的研究生课程。 该项目还将包括与加州大学戴维斯分校空气质量研究中心合作的外展部分：学生（主要是中学学生）将来到校园参加为期一天或两天的课程，接受有关大气颗粒物和空气污染的实践课程。