Fate and transformation of diesel emissions

1233038JungOrganics是世界上许多地方大气颗粒物污染的主要贡献者。有机气溶胶要么直接从多种来源排放，要么通过气相有机物的化学反应在大气中形成二次有机气溶胶。最近的研究表明，有机气溶胶的形成比以前所知的要动态得多，有机气溶胶在大气中随稀释蒸发，在气相中反应生成挥发性较低的产品，并重新冷凝成颗粒相。由于稀释、其他有机物种在现有颗粒上的冷凝和化学反应等物理过程，有机气溶胶在大气中发生物理和化学变化。这些物理和化学变化导致颗粒物与新排放的颗粒物产生不同的健康和气候后果。最近的烟雾室研究发现，柴油排放等一次排放产生二次有机气溶胶，远远超过已知的二次有机气溶胶前驱物质的贡献。该项目将从空气质量的角度调查柴油排放的去向和转化。柴油发动机在世界各地得到广泛使用，美国在要求新的柴油配方和排放控制技术方面走在了前列。虽然新的规定明显减少了尾气排放，但它们对空气质量的全面影响，如柴油排放的二次有机气溶胶形成潜力，还没有得到很好的了解。该项目将建立一种通过柴油排放产生、表征和量化二次有机气溶胶形成的方法，以评估汽车尾气后处理系统的有效性。在许多部门，柴油的化学成分正在发生重大变化，特别是在燃料硫含量方面。本项目将研究燃料变化对柴油颗粒吸水率的影响。水的吸收损害了柴油颗粒的能见度和辐射强迫，因此对环境和气候变化都有影响。该项目将使用烟雾室和最先进的气溶胶仪器来研究柴油废气在受控条件下的化学和物理转化。该项目将为了解柴油废气在空气质量方面的去向和转化提供重要的见解。柴油发动机对空气污染的影响很大。有必要了解新技术的采用，如更广泛地使用替代燃料和后处理系统，如何影响空气污染。本研究的结果将为政府制定技术政策提供参考。这位调查者还将通过在博物馆举办展览向公众传播他的空气污染研究，以提高科学素养，并作为针对不同类别初中生的数学和科学教育模块的基础。

1233038JungOrganics are major contributors to particulate pollution in the atmosphere at many locations around the world. Organic aerosols are either directly emitted from a multitude of sources or are formed in the atmosphere through chemical reactions of gas phase organics forming secondary organic aerosol. Recent research has shown that formation of organic aerosol is much more dynamic than previously understood with organic aerosols evaporating in the atmosphere with dilution, reacting in the gas phase to produce lower volatility products and recondensing back to particle phase. Organic aerosol changes both physically and chemically in the atmosphere due to physical processes such as dilution, condensation of other organic species on existing particles, and chemical reactions. These physical and chemical changes cause the particles to have different health and climate consequences as compared to fresh emissions. Recent smog chamber studies have found primary emissions such as diesel emissions generate secondary organic aerosol, greatly exceeding the contribution from known secondary organic-aerosol precursors.This project will investigate the fate and transformation of diesel exhaust emissions in terms of air quality. Diesel engines are in widespread use throughout the world, and the United States is leading the way in requiring new diesel fuel formulations and emission control technologies. While there new requirements clearly reduce tailpipe emissions, their full impacts on air quality such as secondary organic aerosol forming potential of diesel emissions are not well understood. This project will establish a method to generate, characterize, and quantify secondary organic aerosol formation by diesel emissions to evaluate the effectiveness of vehicle exhaust after-treatment systems. A significant change in chemical composition of diesel fuels is underway in many sectors especially in terms of fuel sulfur level. This project will investigate the influence of fuel change on water uptake of diesel particles. The water uptake impairs visibility and radiative forcing of diesel particles therefore impacting both environment and climate change. The project will use a smog chamber and state-of-art aerosol instrumentation to investigate chemical and physical transformation of diesel emissions under well-controlled conditions.The project will provide important insights into the fate and transformation of diesel exhaust emissions in the atmosphere in terms of air quality. Diesel engines contribute significantly to air pollution. It is necessary to understand how incorporation of new technologies, such as wider use of alternative fuels and after-treatment systems, affect air pollution. The results of this study will inform government technology policy-making. The investigator will also disseminate his air pollution research to the public through exhibitions at museums to increase scientific literacy and serve as the basis for education modules in math and science aimed at diverse group of middle and high school students.