Collaborative Research: Quantifying Secondary Organic Aerosol Formation from the Reactive Uptake of Isoprene-derived Epoxides to Submicron Aerosol Particles

在这个由化学系环境化学科学项目资助的项目中，华盛顿大学(UW)的Joel A.Thornton教授、北卡罗来纳大学(UNC)的Jason D.Surratt教授和Avram Gold教授正在研究陆地植被(例如落叶树木)的排放被转化为大气中颗粒物(PM)的过程。PM是空气质量下降的主要原因，对人类健康有负面影响，还通过散射或吸收阳光或改变云层的性质来影响气候。陆地植被每年向大气中排放大量的异戊二烯(约500太克C)。一旦进入大气，异戊二烯的光化学氧化就会产生气相环氧化物中间体。这些环氧化物的副产物在酸性溶液中是活性的，因此在大气颗粒物中的吸收和反应可以产生可溶的低挥发性有机化合物，这些化合物留在颗粒物相中，从而增加PM该项目的更广泛影响包括对颗粒物来源分配的更准确解释，以及对气溶胶-气候影响和空气质量评估的改进研究。此外，该项目的一个关键要素是通过让本科生、研究生和博士后研究员参与培训高技能的年轻科学家和工程师，并通过一系列外联活动吸引公众参与。在这个项目中，Joel A.Thornton教授将领导华盛顿大学和北卡罗来纳大学的合作，测量控制主要异戊二烯衍生环氧化物在大气现实颗粒中的反应性、扩散和产品形成的关键物理化学参数。100-500纳米尺寸的颗粒将是无机盐、液态水和有机物的混合物，这比使用大量宏观解决方案的研究提供了进步，这些宏观解决方案无法模拟大气颗粒的非理想、往往过饱和的组成，也无法模拟反应介质的形态。

In this project, funded by the Environmental Chemical Sciences program in the Division of Chemistry, Professor Joel A. Thornton of the University of Washington (UW) and Professors Jason D. Surratt and Avram Gold from the University of North Carolina (UNC) are studying a process by which emissions from terrestrial vegetation (e.g., deciduous trees) are converted to particulate matter (PM) mass in the atmosphere. PM is a major cause of reduced air quality, with negative impacts on human health, and also affects climate by scattering or absorbing sunlight or by altering the properties of clouds. Terrestrial vegetation emits large quantities (~500 teragrams C) of isoprene to the atmosphere each year. Once in the atmosphere, photochemical oxidation of isoprene leads to gas-phase epoxide intermediates. These epoxide byproducts are reactive in acidic solutions, and therefore uptake and reaction in atmospheric particles can produce soluble low-volatility organic compounds that remain in the particle phase thereby increasing PM. The broader impacts of this project include more accurate interpretations of PM source-apportionment and improved studies of aerosol-climate effects and air quality assessments. In addition, a key element of the project involves the training of highly skilled young scientists and engineers by involving undergraduate students, graduate students, and postdoctoral research fellows, and engaging the general public through a range of outreach activities. In this project, Professor Joel A. Thornton will lead a collaboration between UW and UNC to measure the key physico-chemical parameters governing reactivity, diffusion, and product formation of synthesized authentic standards of the predominant isoprene-derived epoxides in atmospherically realistic particles. The 100-500 nanometer sized particles will be mixtures of inorganic salts, liquid water, and organic matter, providing an advance over studies using bulk macroscopic solutions which cannot simulate the non-ideal, often super-saturated compositions of atmospheric particles, nor the morphologies of the reaction medium.