Collaborative Research: Impact of Surface Chemistry for Black Carbon Cloud Droplet Formation

合作研究：表面化学对黑碳云液滴形成的影响

• 批准号: 1708330
• 负责人: Howard Fairbrother
• 金额: $ 27.36万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1708330&HistoricalAwards=false
• 关键词: Collaborative; Research; Impact; Surface; Chemistry

This award is funded by the Environmental Chemical Sciences Program in the Division of Chemistry. Professors Howard Fairbrother of Johns Hopkins University and Akua A. Asa-Awuku of the University of Maryland College Park are supported to develop a molecular level understanding of how the chemical composition of the surface of soot (black carbon, BC) influences its ability to act as Cloud Condensation Nuclei (CCN) and form rain droplets. Black carbon particles are released into the Earth's atmosphere from forest fires, biomass burning, and coal and diesel engines. Experimental evidence provides strong support for the idea that the ability of black carbon particles to uptake water depends on the presence of water-attracting functional groups on the black carbon particle surface. However, atmospheric black carbon is considered water-repellant in scientific models and thus not aptly addressed in aerosol-cloud climate interactions, contributing to the largest source of uncertainty in climate predictions. The surface chemistry of black carbon particles is complex and varies considerably due to differences in the carbon source, combustion conditions and subsequent oxidation (aging) in air. This project seeks a better understanding of how surface reactivity influences black carbon's ability to act as cloud condensation nuclei. Establishing relationships between the surface chemistry and CCN properties of BC particles in the atmosphere improves the predictive capabilities of global climate models and enhances our scientific understanding of air quality and climate, two important societal concerns. While conducting the project, the students benefit from acquiring skills in surface chemistry and atmospheric science. A plan that targets the participation of female undergraduate students in science majors at the Notre Dame University of Maryland, a local, primarily teaching, institution is initiated. The project aims to develop a molecular level understanding of how the chemical composition of the surface of black carbon influences its ability to act as Cloud Condensation Nuclei (CCN). The goal is accomplished by measuring and analyzing the CCN properties of a suite of black carbon particles whose surface chemistry has been systematically varied via exposure to different oxidizing conditions. The specific tasks are to develop experimental methods to modify and characterize the chemistry and surface properties of atmospherically-relevant aerosol, and to address unknown contributions of BC to atmospheric CCN and the subsequent aerosol-indirect effect. Detailed information on the surface composition and distribution of surface oxides is obtained with various analytical techniques, including X-ray Photoelectron Spectroscopy, augmented by chemical derivatization and infrared spectroscopies. The effect of other heteroatoms on CCN properties is also explored as well as the relationship between CCN activation and more fundamental BC surface properties, such as water adsorption energies.

该奖项由化学系环境化学科学项目资助。约翰霍普金斯大学的Howard Fairbrother教授和马里兰大学帕克学院的Akua A.Asa-Awuku教授被支持开发分子水平的知识，以了解碳烟(黑碳，BC)表面的化学成分如何影响其作为云凝聚核(CCN)和形成雨滴的能力。森林大火、生物质燃烧、煤炭和柴油发动机将黑碳颗粒释放到地球大气层中。实验证据有力地支持了黑碳颗粒吸水能力取决于黑碳颗粒表面是否存在吸水官能团的观点。然而，大气中的黑碳在科学模型中被认为是拒水的，因此在气溶胶-云气候相互作用中没有得到适当的处理，这是气候预测的最大不确定性来源。由于碳源、燃烧条件和随后在空气中的氧化(老化)的不同，黑碳颗粒的表面化学是复杂的，并且变化很大。这个项目试图更好地理解表面反应性如何影响黑碳作为云凝聚核的能力。建立大气中BC颗粒的表面化学和CCN性质之间的关系可以提高全球气候模式的预测能力，并增强我们对空气质量和气候这两个重要的社会问题的科学理解。在进行该项目时，学生们从获得表面化学和大气科学方面的技能中受益。一项针对马里兰圣母大学理科专业女本科生参与的计划已经启动，该大学是当地的一所主要从事教学的机构。该项目旨在从分子层面了解黑碳表面的化学成分如何影响其作为云凝聚核(CCN)的能力。这一目标是通过测量和分析一组黑碳颗粒的CCN性质来实现的，这些黑碳颗粒的表面化学通过暴露在不同的氧化条件下而发生了系统的变化。具体任务是开发实验方法，以修改和表征与大气相关的气溶胶的化学和表面性质，并解决BC对大气CCN的未知贡献和随后的气溶胶间接影响。通过各种分析技术，包括X射线光电子能谱，再加上化学衍生化和红外光谱，可获得关于表面氧化物表面组成和分布的详细信息。探讨了其他杂原子对CCN性质的影响，以及CCN的活化与BC表面更基本的性质，如水的吸附能之间的关系。