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

环境化学科学计划的这一奖项支持布朗大学的Meredith Hastings教授研究亚硝酸。亚硝酸是大气化学中的一种关键物质，对室内和室外的空气质量具有重要影响。该项目的重点是解决难以解决的大气亚硝酸源和汇。亚硝酸通常通过二氧化氮、硝酸或颗粒硝酸盐的反应在环境表面上产生。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。它建立在测量同位素签名从以前的工作，并导致更好地了解从每个源和途径的相对贡献大气亚硝酸预算。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。它还提供了一个潜在的工具，以更好地预测和决策有关的排放，导致亚硝酸的生产。该奖项还促进了博士后科学家和研究生的职业发展。研究结果正在被纳入布朗大学新开发的空气质量课程。Hasting教授的实验室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，用于氮和氧同位素的稳定同位素表征。该技术已被用于区分亚硝酸的同位素特征，包括车辆，土壤和生物质燃烧排放的主要来源。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，以同位素表征在实验室制备和在实际环境中收集的环境代表性表面上非均匀产生的亚硝酸。该项目的结果将限制大气亚硝酸的收支，并追踪从区域到全球范围内的活性氮物质循环。该奖项反映了NSF的法定使命，并被认为值得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。

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.