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氢过氧基的浓度和化学，以便更好地了解生物排放对大气复杂光化学的影响。尽管森林环境中的羟基自由基测量数量在过去几年中有所增加，但在单个地点进行的测量很少，以解决这些单独的测量是否能代表这些地区的整体化学，以及测量技术是否仍存在未知的干扰。这项研究将专注于最大限度地减少对使用激光诱导荧光技术检测羟基的潜在干扰，并扩大在密歇根州北部的PROPHET(氧化剂研究计划：光化学、排放和运输)塔址森林树冠上方和下方的羟基、羟基过氧化和羟基反应性测量记录。此外，还将进行实验室实验，测量各种生物挥发性有机化合物的某些氧化产物的反应速率常数，以加深对其氧化机理的了解。目前的大气化学数值模式无法解释森林环境中测得的羟基和过氧化氢自由基浓度，这对当前的空气质量和气候变化问题具有重要影响，因为这使人们对生物排放对大气中臭氧和气溶胶产生的贡献的理解产生了疑问。臭氧除了是一种温室气体外，对人类和生物圈也有众所周知的影响，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。该项目的成果将有助于更好地了解生物排放的化学，它们对臭氧和气溶胶形成的影响，以及这种化学将如何随着未来的气候变化而变化。该项目还将为博士后助理、研究生和本科生提供研究和教育机会，包括来自代表性不足群体的几名学生。在印第安纳大学布鲁明顿校区附近的新的教学和研究保护区实验室设施中，仪器将在学年内运行一段时间，作为本科和研究生课程以实验室为基础的大气化学课程的一部分，允许学生参与获取和分析环境中羟基、过氧化氢、臭氧和氮氧化物的测量，使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.