Characterizing Chemical Production and Loss of Nitrous Acid (HONO) Via Stable Isotopes

该奖项由环境化学科学项目颁发，支持布朗大学的梅雷迪思·黑斯廷斯教授研究亚硝酸。亚硝酸是大气化学中的一种重要物质，对室内和室外的空气质量都有重要影响。本项目重点解决大气中难以分辨的亚硝酸源和汇。亚硝酸通常是由二氧化氮、硝酸或硝酸盐颗粒在环境表面反应产生的。该项目利用这些物种的稳定同位素分析来确定气态亚硝酸生产的潜在途径。它建立在以前工作的同位素特征测量的基础上，并使人们更好地了解每个来源和途径对大气硝酸收支的相对贡献。这对理解空气质量、气候变化及其对人类和生态系统健康的影响具有重要意义。它还提供了一种潜在的工具，可以更好地预测和决策与导致亚硝酸生产的排放有关的问题。该奖项还促进了博士后科学家和研究生的职业发展。研究结果将被纳入布朗大学新开设的一门关于空气质量的课程。黑斯廷斯教授的实验室已经开发并验证了一种新方法，可以有效地捕获空气中的亚硝酸，以进行氮和氧同位素的稳定同位素表征。该技术已被用于从主要来源（包括车辆、土壤和生物质燃烧排放）中区分亚硝酸的同位素特征。在这个项目中，正在设计和建造一个流动反应器，与收集技术相结合，对在实验室制备和在实际环境中收集的具有环境代表性的表面上不均匀产生的硝酸进行同位素表征。该项目的结果将限制大气中亚硝酸盐的收支，并追踪从区域到全球尺度的活性氮物种循环。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。

This award from the Environmental Chemical Sciences Program supports Professor Meredith Hastings at Brown University to study nitrous acid. Nitrous acid is a key species in atmospheric chemistry, with important implications for air quality both indoors and outdoors. This project focuses on addressing the difficult-to-resolve sources and sinks of atmospheric nitrous acid. Nitrous acid is typically produced on an environmental surface by reactions of nitrogen dioxide, nitric acid or particulate nitrate. The project uses stable isotopic analysis of these species to determine potential pathways of gaseous nitrous acid production. It builds on measurements of isotopic signatures from previous work and leads to improved understanding of the relative contributions from each source and pathway to the atmospheric nitrous acid budget. This has strong implications for understanding air quality, climate change, and their impact on human and ecosystem health. It also provides a potential tool for better prediction and decision making related to emissions that lead to nitrous acid production. This award also advances the career development of a postdoctoral scientist and a graduate student. Results are being integrated into a newly developed course on air quality at Brown University. A new method has been developed and verified in Professor Hasting's lab to efficiently capture nitrous acid in the air for stable isotopic characterization of nitrogen and oxygen isotopes. This technique has been used to distinguish the isotopic signature of nitrous acid from major sources including vehicle, soil and biomass burning emissions. In this project, a flow reactor is being designed and built to couple with the collection technique to isotopically characterize the nitrous acid heterogeneously produced on environmentally representative surfaces that are both prepared in the lab and collected in the actual environment. The results from this project will constrain atmospheric nitrous acid budget and trace reactive nitrogen species cycling from regional to global scales.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.