Fate and transformation of diesel emissions

1233038 JungOrganics是全球许多地方大气中颗粒物污染的主要来源。有机气溶胶或者直接从多个来源排放，或者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理解的有机气溶胶在大气中蒸发稀释，在气相中反应产生低挥发性产物并重新冷凝回颗粒相的过程更具动态性。有机气溶胶由于稀释、其他有机物质在现有颗粒上的凝结和化学反应等物理过程而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物相比具有不同的健康和气候后果。最近的烟雾室研究发现，柴油机排放的一次排放物产生的二次有机气溶胶，远远超过已知的二次有机气溶胶前体物的贡献。本项目将从空气质量的角度研究柴油机废气排放物的归宿和转化。柴油发动机在全世界广泛使用，美国在要求新的柴油燃料配方和排放控制技术方面处于领先地位。 虽然这些新要求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，还没有得到很好的理解。该项目将建立一种方法来生成、表征和量化柴油排放形成的二次有机气溶胶，以评估车辆尾气后处理系统的有效性。柴油燃料的化学成分在许多领域正在发生重大变化，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性的影响。水的吸收会损害能见度和柴油颗粒的辐射强迫，从而影响环境和气候变化。 该项目将使用烟雾室和最先进的气溶胶仪器来研究在良好控制的条件下柴油排放物的化学和物理转化。该项目将为柴油废气排放物在大气中的归宿和转化提供重要的见解。柴油发动机对空气污染有很大影响。 有必要了解采用新技术，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。 这项研究的结果将为政府的技术政策制定提供信息。 调查员还将通过博物馆的展览向公众传播他的空气污染研究，以提高科学素养，并作为针对不同群体的初中和高中学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.