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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

基本信息

批准号：
1708337
负责人：
Akua Asa-Awuku
金额：
$ 25.1万
依托单位：
University of Maryland, College Park
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-09-01 至 2021-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1708337&HistoricalAwards=false
关键词：
Collaborative Research Impact Surface Chemistry

项目摘要

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分校的 Akua A. Asa-Awuku 教授在分子水平上研究烟灰（黑碳，BC）表面的化学成分如何影响其作为云凝结核（CCN）和形成雨滴的能力。森林火灾、生物质燃烧以及煤炭和柴油发动机都会将黑碳颗粒释放到地球大气中。实验证据有力地支持了这样的观点：黑碳颗粒吸水的能力取决于黑碳颗粒表面吸水官能团的存在。然而，大气黑碳在科学模型中被认为是防水的，因此在气溶胶-云气候相互作用中没有得到适当的解决，从而成为气候预测不确定性的最大来源。黑碳颗粒的表面化学很复杂，并且由于碳源、燃烧条件和随后在空气中的氧化（老化）的不同而变化很大。该项目旨在更好地了解表面反应性如何影响黑碳充当云凝核的能力。建立大气中BC颗粒的表面化学和CCN特性之间的关系可以提高全球气候模型的预测能力，并增强我们对空气质量和气候这两个重要社会问题的科学理解。在进行该项目时，学生受益于获得表面化学和大气科学方面的技能。马里兰圣母大学（一家当地主要教学机构）启动了一项针对女本科生参与科学专业的计划。该项目旨在从分子水平上了解黑碳表面的化学成分如何影响其充当云凝结核（CCN）的能力。该目标是通过测量和分析一组黑碳颗粒的 CCN 特性来实现的，这些颗粒的表面化学性质通过暴露于不同的氧化条件而系统地变化。具体任务是开发实验方法来修改和表征与大气相关的气溶胶的化学和表面特性，并解决BC对大气CCN的未知贡献以及随后的气溶胶间接影响。有关表面成分和表面氧化物分布的详细信息可通过各种分析技术获得，包括 X 射线光电子能谱，并通过化学衍生化和红外光谱进行增强。还探讨了其他杂原子对 CCN 性质的影响，以及 CCN 活化与更基本的 BC 表面性质（例如水吸附能）之间的关系。