Measurements of HOx Radical Chemistry in a Changing Forest Environment

该项目的总体目标是测量森林环境中羟基和羟基自由基的浓度和化学性质，以便更好地了解生物源排放对大气复杂光化学的影响。尽管在过去几年中，森林环境中羟基自由基的测量数量有所增加，但很少有在单个地点设计的测量来解决这些单个测量是否代表这些地区的整体化学，以及测量技术是否仍然存在未知的干扰。该研究将侧重于使用激光诱导荧光技术最大限度地减少对羟基检测的潜在干扰，以及在密歇根州北部的PROPHET（氧化剂研究计划：光化学、排放和运输）塔场扩展对森林冠层上下羟基、羟基、羟基反应性测量的记录。此外，还将进行实验室实验，测量各种生物源性挥发性有机化合物的一些氧化产物的反应速率常数，以提高对其氧化机制的认识。目前的大气化学数值模型无法解释森林环境中羟基和羟基自由基的测量浓度，这对当前的空气质量和气候变化问题具有重要意义，因为它使人们对生物源排放对大气中臭氧和气溶胶产生的贡献的理解产生疑问。臭氧除了是一种温室气体外，对人类和生物圈也有已知的影响，而大气气溶胶除了影响太阳辐射外，还被证明对健康有严重影响。该项目的结果将有助于提高对生物源性排放的化学性质、它们对臭氧和气溶胶形成的影响以及这种化学性质将如何随着未来气候变化而变化的理解。该项目还将为博士后、研究生和本科生提供研究和教育机会，包括一些来自代表性不足群体的学生。在印第安纳大学布卢明顿校区附近的新教学和研究保护区实验室设施中，仪器将在学年期间作为本科生和研究生的实验室大气化学课程的一部分进行操作，使学生能够参与获取和分析羟基，羟基，过氧化氢，臭氧和氮氧化物的环境测量。让他们通过发现体验科学的兴奋。

The overall goal of this project is to measure the concentration and chemistry of hydroxyl and hydroperoxyl radicals in a forest environment in order to improve understanding of the influence of biogenic emissions on the complex photochemistry of the atmosphere. Although the number of hydroxyl radical measurements in forested environments has grown over the past few years, there are few measurements at a single site designed to address whether these individual measurements are representative of the overall chemistry of these regions and whether there are still unknown interferences with the measurement technique. The research will focus on minimizing potential interferences with the detection of hydroxyl using laser-induced fluorescence techniques, as well as extending the record of hydroxyl, hydroperoxyl, and hydroxyl reactivity measurements both above and below the forest canopy at the PROPHET (Program for Research on Oxidants: PHotochemistry, Emissions and Transport) tower site in Northern Michigan. In addition, laboratory experiments will be conducted to measure the rate constants of reactions of some of the oxygenated products of various biogenic volatile organic compounds in order to improve understanding of their oxidation mechanisms. The inability of current numerical models of atmospheric chemistry to explain measured concentrations of hydroxyl and hydroperoxyl radicals in forested environments has important implications to current issues of air quality and climate change, as it calls into question understanding of the contribution of biogenic emissions to the production of ozone and aerosols in the atmosphere. In addition to being a greenhouse gas, ozone has known impacts on humans and the biosphere, while atmospheric aerosols have also been shown to have serious health impacts in addition to impacting solar radiation. The results of this project will help to improve understanding of the chemistry of biogenic emissions, their impact on ozone and aerosol formation, and how this chemistry will change with future climate change. This project will also provide research and educational opportunities for postdoctoral associates, graduate students and undergraduates, including several students from underrepresented groups. At the new Teaching and Research Preserve laboratory facility near the Indiana University Bloomington campus, instruments will be operated for periods during the academic year as part of a laboratory-based atmospheric chemistry curriculum for courses at both the undergraduate and graduate levels, allowing students to participate in obtaining and analyzing ambient measurements of hydroxyl, hydroperoxyl, ozone, and nitrogen oxides, allowing them to experience the excitement of science through discovery.