New Insights into the Formation and Evolution of Air Pollutants Via Atmospheric Multiphase Chemistry

大气气溶胶是指悬浮颗粒物的直径是普通人类头发的1/10到1/1000。尽管气雾剂的体积很小，但它对21世纪可以说是最紧迫的两个环境问题产生了巨大的影响：空气污染和气候变化。携带有害化学物质的气雾剂可以深入呼吸道，影响人类健康。2012年，全球有700万人死于环境和室内气溶胶。此外，悬浮气溶胶可以通过反射阳光来抵消温室气体的变暖效应，这会对地球产生降温效应。*了解气溶胶的化学成分目前是一项重大的科学挑战。气溶胶冷却效应的毒性和程度仍然高度不确定。气溶胶最不为人所知的方面之一也是它的一个主要组成部分，称为二次有机气溶胶(SOA)，它包含数百种通过复杂的大气化学作用产生的不明有机化合物。这里提出的研究计划旨在解开导致大气中SOA形成和持续演化的复杂化学物质。拟议的研究结果将指导大气化学家、环境毒物学家和流行病学家以及气候学家更好地评估气溶胶对环境的影响。这种评价为政策，并最终为可持续的未来提供了基本的指导方针。*拟议的研究计划有两个研究方向。在第一个方向中，我们将分析复杂的、未解决的SOA部分，它目前是理解SOA化学的主要障碍。我们将开发创新的分析方法进行直接测量，避免过多的样品制备和处理，因为在这些过程中可能会丢失精致和活性的化合物。利用新开发和成熟的分析技术，我们将调查在SOA中发生的未知化学物种和未发现的化学反应。*在第二个方向，我们将针对一个紧迫的环境问题：燃烧固体燃料造成的空气污染。固体燃料，包括煤、木柴、农业残渣和动物粪饼，全世界有30亿人用来做饭。固体燃料燃烧造成的空气污染是全球范围内第三大健康风险因素。我们将分析固体燃料燃烧产生的气溶胶的化学成分，这些化学成分知之甚少。我们将进一步研究固体燃料燃烧排放的大气化学，这种排放会产生有毒化学污染物，并在局部到区域范围内影响空气质量。

Atmospheric aerosol refers to suspended particles with diameters 1/10 to 1/1000 that of an average human hair. Although small in size, aerosol exerts a huge impact on two of the arguably most emergent environmental issues of the 21st century: air pollution and climate change. Carrying harmful chemicals with it, aerosol can penetrate deep into the respiratory tract, affecting human health. In 2012, 7 million deaths worldwide were associated with ambient and indoor aerosol. Additionally, suspended aerosol can offset the warming effect of greenhouse gases by reflecting sunlight, which gives rise to a cooling effect on the planet. ******Understanding the chemistry of aerosol is currently a major scientific challenge. The toxicity and the magnitude of the aerosol cooling effect remain highly uncertain. One of the least understood aspects of aerosol is also a major fraction of it, referred to as Secondary Organic Aerosol (SOA), that contains hundreds of unidentified organic compounds produced through complex atmospheric chemistry. The research program proposed here aims to unravel the complex chemistry that leads to the formation and continuous evolution of SOA in the atmosphere. The outcome of the proposed research will guide the efforts of atmospheric chemists, environmental toxicologists and epidemiologists, as well as climatologists to better evaluate the environmental impact of aerosol. Such evaluations provide essential guidelines for policies, and ultimately, for a sustainable future. ******The proposed research program has two research directions. In the first direction, we will analyze the complex, unresolved fraction of SOA that is currently a major obstacle in understanding the SOA chemistry. We will develop innovative analytical methods for a direct measurement that avoids excess sample preparation and treatment, since delicate and reactive compounds can be lost during such processes. Employing both newly-developed and well-established analytical techniques, we will investigate the unidentified chemical species and undiscovered chemical reactions taking place in SOA. ******In the second direction, we will target an urgent environmental problem: air pollution from solid fuel burning. Solid fuel, including coal, firewood, agriculture residue and animal dung cake, is used by 3 billion people worldwide for cooking. Air pollution from solid fuel burning is the third most important health risk factor on the global scale. We will analyze the poorly understood chemical composition of aerosol arising from solid fuel burning. We will further study the atmospheric chemistry of emissions from solid fuel burning, which can give rise to toxic chemical pollutants and affect the air quality at a local to regional scale.