Seasonal Measurements of Hydrogen Oxide Radical (HOx) Chemistry in Forests

该项目的目标是进一步测量不同森林环境中羟基自由基和过氧自由基的浓度，以便为目前的大气化学模型提供可靠的测试。这些测量将在几个不同的森林环境中进行，包括布卢明顿校区附近的印第安纳大学研究与教学保护区野外实验室和密歇根州北部的PROPHET（氧化剂研究项目：光化学、排放和运输）塔。羟基自由基和过氧自由基控制着大气中许多重要微量气体的寿命，如甲烷。羟基自由基反应还会引发一氧化碳和挥发性有机化合物的氧化，在氮氧化物的存在下，会导致大气中臭氧和二次气溶胶的产生，而臭氧和二次气溶胶是光化学烟雾的主要成分。准确了解这种化学反应对于评估由于控制战略和环境变化而导致的排放变化对大气成分的影响是很重要的。为了捕捉异戊二烯和其他生物源性挥发性有机化合物排放影响大气时的化学变化，测量将在季节过渡期间进行，测量将在春季叶片开花之前进行，之后一直持续到夏季。同时测量亚硝酸（HONO），它可能是羟基自由基（OH）的重要来源，以及测量总OH反应性，以量化自由基来源和汇。将在森林冠层上方和下方进行测量，包括测量过氧自由基（RO2）通量，以提高我们对这些环境中自由基源和汇的认识，并确定在森林冠层上方和下方是否存在大量自由基的运输。这项研究将作为研究生大气化学和环境科学跨学科培训的一个组成部分。此外，新开发的空气污染模块将用于印第安纳大学面向高中生的暑期可持续发展与环境体验营，重点关注代表性不足的少数民族、第一代大学生和经济困难的学生。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The goal of this project is to make additional measurements of the concentration of hydroxyl radical and peroxy radicals in different forest environments in order to provide robust tests of current models of atmospheric chemistry. These measurements will occur in several different forest environments, including the Indiana University Research and Teaching Preserve field lab near the Bloomington campus and the PROPHET (Program for Research on Oxidants: PHotochemistry, Emissions and Transport) tower site in northern Michigan. The hydroxyl radical and peroxy radicals control the lifetimes of many important trace gases in the atmosphere, such as methane. Hydroxyl radical reactions also initiate the oxidation of carbon monoxide and volatile organic compounds, that in the presence of nitrogen oxides can lead to the production of ozone and secondary aerosols in the atmosphere, the primary components of photochemical smog. An accurate understanding of this chemistry is important to assess the impact of changes in emissions as a result of control strategies and environmental change on the composition of the atmosphere.To capture the change in chemistry as isoprene and other biogenic VOCs emissions impact the atmosphere, measurements will be conducted during the seasonal transition, with the measurements conducted just prior to leaf bloom in the spring and continuing afterwards into the summer. Concurrent measurements of nitrous acid (HONO), which can be a significant source of hydroxyl radicals (OH), along with measurements of total OH reactivity will be made in order to quantify radical sources and sinks. Measurements will be made both above and below the forest canopy, including measurements of peroxy radical (RO2) fluxes, in order to improve our understanding of the sources and sinks of radicals in these environments and to determine whether there is significant transport of radicals above and below the forest canopy.The research will be used as a component of interdisciplinary training in atmospheric chemistry and environmental science for graduate students. In addition, a newly developed air pollution module will be implemented for Indiana University’s Summer Experience in Sustainability and the Environment camp for high school students, focusing on underrepresented minorities, first generation college, and financial need students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.