Collaborative Research: Secondary Organic Aerosol Production in Real Atmospheric Waters

这个合作项目解决了一个新认识的（水）的途径，形成二次有机气溶胶（SOA）在大气中。 对SOA形成的认识不足是影响气候、能见度和健康的大气气溶胶浓度和性质预测的不确定性的主要来源。 目前的模型没有捕捉到测量的有机气溶胶浓度的大小，分布和动态，烟雾室实验形成SOA，这是大大减少氧化，因此，比老化的大气有机气溶胶吸湿性较低。 有越来越多的证据表明，这些和其他大气观测可以解释，至少部分地，由多相SOA的形成，涉及云，雾和湿气溶胶中的水反应。 当该过程包括在模型中时，通过水化学形成的预测SOA在量级上与通过传统途径形成的SOA相当（例如，气相反应和分配到颗粒有机物）在美国东北部和全球。 几种类型的大气测量也为这一过程提供了证据。该项目解决了以下问题：1）在现场是否可以清楚地观察到含水SOA的形成？2)含水SOA的形成如何影响有机气溶胶的氧碳比？3)有多少所观察到的含水SOA的产生可以用已知的机制来解释？哪些前兆是重要的？4)SOA的形成在多大程度上取决于光、液态水和有机物？有多少可归因于水的形成过程？在PEGASOS活动期间，将在意大利的波河流域进行实地测量，那里的条件非常适合通过气溶胶水中的反应形成SOA。 结合这些实地研究，将在实验室中进行受控水溶液光氧化实验，并使用1）从环境空气中擦洗的水溶性（过滤）化合物混合物，2）收集（过滤）的雾水，以及3）根据项目结果确定为潜在水溶液前体的选定化合物进行详细的化学分析和化学建模。更广泛的影响：这项工作将进一步阐明二次有机气溶胶形成的一个重要途径，并提供一个评估的相对重要性，这条途径的位置，条件是有利的SOA形成湿气溶胶和雾。 该项目将提供一个测量数据库和一个独特的雾样品档案，供其他调查人员使用。 这项研究的目的是最终有助于改善全球/区域对前体排放产生的气溶胶影响的预测。 该项目将促进科学家的教育。 计划中的K-12外联活动旨在接触大量学生，提高青年对科学发现过程的兴趣和理解。

This collaborative project addresses a newly recognized (aqueous) pathway for the formation of secondary organic aerosol (SOA) in the atmosphere. The poor understanding of SOA formation is a major source of uncertainty in predictions of atmospheric aerosol concentrations and properties that affect climate, visibility and health. Current models do not capture the magnitude, distribution and dynamics of measured organic aerosol concentrations, and smog chamber experiments form SOA that is substantially less oxygenated and, therefore, less hygroscopic than aged atmospheric organic aerosol. There is growing evidence that these and other atmospheric observations can be explained, at least in part, by multiphase SOA formation involving aqueous reactions in clouds, fogs and wet aerosols. When this process is included in models, predicted SOA formed through aqueous chemistry is comparable in magnitude to that formed through the traditional pathway (e.g., gas phase reaction and partitioning to particulate organic matter) in the northeastern United States and globally. Several types of atmospheric measurements also provide evidence for this process. This project addresses the following questions: 1) Is aqueous SOA formation clearly observable in the field? 2) How does aqueous SOA formation influence the oxygen-to-carbon ratio of the organic aerosol? 3) How much of the observed aqueous SOA produced can be explained by known mechanisms? What precursors are important? 4) To what extent does SOA formation depend on light, liquid water, and organic matter? How much can be attributed to aqueous formation processes?Field measurements will be conducted during the PEGASOS campaign in the Po Valley, Italy, where conditions are ideal for SOA formation through reactions in aerosol water. In conjunction with these field studies, controlled aqueous photooxidation experiments will be conducted in the laboratory with detailed chemical analysis and chemical modeling using 1) water-soluble (filtered) mixtures of compounds scrubbed from the ambient air, 2) collected (filtered) fog water, and 3) selected compounds identified as potential aqueous precursors based on project findings. Broader Impacts: This work will further elucidate an important pathway for secondary organic aerosol formation and provide an assessment of the relative importance of this pathway in locations where conditions are favorable to SOA formation in wet aerosols and fogs. This project will provide a measurements database and a unique archive of characterized fog samples for use by other investigators. This research is designed to contribute ultimately to improved global/regional prediction of aerosol effects from precursor emissions. This project will facilitate the education of scientists. The planned K-12 outreach is designed to reach large numbers of students and to increase interest in and understanding of the process of scientific discovery by youth.