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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.

该奖项由化学部环境化学科学计划资助。约翰霍普金斯大学的教授霍华德费尔布拉泽和阿夸A。马里兰州大学帕克分校的Asa-Awuku博士得到了支持，以发展一种分子水平的理解，了解烟尘（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。黑碳颗粒从森林火灾、生物质燃烧以及煤和柴油发动机释放到地球大气中。实验证据提供了强有力的支持的想法，黑碳颗粒吸收水的能力取决于黑碳颗粒表面上的吸水官能团的存在。然而，大气中的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处理，这是气候预测中最大的不确定性来源。黑碳颗粒的表面化学是复杂的，并且由于碳源、燃烧条件和随后在空气中的氧化（老化）的差异而变化很大。该项目旨在更好地了解表面反应性如何影响炭黑作为云凝结核的能力。建立大气中BC颗粒的表面化学和CCN特性之间的关系，提高了全球气候模型的预测能力，并增强了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，学生将受益于获得表面化学和大气科学方面的技能。马里兰州圣母大学是一所以教学为主的地方院校，现已启动一项旨在让女本科生参加理科专业学习的计划。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作为云凝结核（CCN）的能力。这一目标是通过测量和分析一组黑碳颗粒的CCN特性来实现的，这些黑碳颗粒的表面化学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大气相关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效应。表面氧化物的表面组成和分布的详细信息是通过各种分析技术获得的，包括X射线光电子能谱，通过化学衍生和红外光谱增强。其他杂原子对CCN性能的影响也进行了探讨，以及CCN活化和更基本的BC表面性能，如水吸附能之间的关系。