Collaborative Research: A Halogen Oxidant Flow Reactor: Development and Use in Laboratory and Field Studies

该项目是三个机构之间的合作努力，目的是开发一种研究大气中涉及氯和溴等卤素的化学反应的技术。最近，该项目的首席科学家开发了一种类似的技术，使用氧化流动反应器(OFR)来研究大气中涉及羟基的反应，羟基是大气中最活跃的氧化物种。OFR的发展极大地提高了科学家在实验室研究和了解大气反应过程的能力。这项研究的总体目标是开发在OFRs中产生氯(Cl)和溴(BR)的方法，在具有潜在氯/溴影响的源区部署卤素OFR原型以及最新的质谱学技术，并对生物和人为前体的氯氧化产生的产物的化学成分和产率进行OFR和环境室(EC)的相互比较研究。这些研究将评估OFRS进行实验室和现场研究氯/溴引发的氧化老化过程的能力。这项工作基于调查以下问题：(1)暴露于OFR中卤素原子的环境空气中含氧挥发性有机化合物(OVOC)和二次有机气溶胶(SOA)的形成潜力是什么？它是如何随着卤素类型、综合氧化剂暴露和来源区域的变化而变化的？(2)由VOC+Cl反应产生的实验室SOA的产率和化学成分是否独立于用于产生它的方法(OFR或EC)？(3)当由氯/溴引发时，实验室和环境中的OVOC/SOA的化学成分和产率与羟基自由基氧化相比如何？多氧化剂-OFR方法是否对OVOC/SOA前体提供了额外的限制？该项目包括对本科生和研究生的实验室培训以及一名博士后研究员。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project is a collaborative effort among three institutions to develop a technique for studying chemical reactions in the atmosphere that involve halogens, such as chlorine and bromine. Recently, the lead scientist on this project developed a similar technique, using an oxidation flow reactor (OFR), for the study of atmospheric reactions involving the hydroxyl radical, the most active oxidizing species in the atmosphere. The development of the OFR has advanced significantly the ability of scientists to study and understand atmospheric reaction processes in the laboratory.The overall goals of this research are to develop methods to generate chlorine (Cl) and bromine (Br) in OFRs, deploy a prototype halogen OFR along with state-of-the-art mass spectrometry techniques in source regions with potential Cl/Br influence, and conduct OFR and environmental chamber (EC) intercomparison studies of the chemical composition and yields of products generated from Cl oxidation of biogenic and anthropogenic precursors. These studies will evaluate the ability of OFRs to conduct laboratory and field studies investigating Cl/Br-initiated oxidative aging processes.The effort is based on investigating the following questions: (1) What is the oxygenated volatile organic compound (OVOC) and secondary organic aerosol (SOA) formation potential of ambient air exposed to halogen atoms in an OFR? How does it change as a function of halogen type, integrated oxidant exposure and source regions? (2) Is the yield and chemical composition of laboratory SOA generated by VOC + Cl reactions independent of the method used to generate it (OFR or EC)? (3) How does the chemical composition and yield of laboratory and ambient OVOC/SOA compare when initiated by Cl/Br versus hydroxyl radical oxidation? Does the multi-oxidant-OFR approach provide additional constraints on OVOC/SOA precursors?This project includes laboratory training for undergraduate and graduate students and a postdoctoral research fellow.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.