Shining light on the sources, sinks and concentrations of singlet oxygen in the atmosphere

揭示大气中单线态氧的来源、汇和浓度

• 批准号: RGPIN-2021-02937
• 负责人: BorduasDedekind, Nadine
• 金额: $ 2.48万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=742287
• 关键词: Shining; light; sources; sinks; concentrations

The Earth's atmosphere is exclusively oxidizing, and consequently oxidation reactions govern the fate of most organic molecules in the gas and particle phases. The concentration, speciation and reactivity of atmospheric oxidants are necessary to predict the fate of atmospheric pollutants. My long-term research program centers on studying atmospheric oxidants as well as their oxidation mechanisms, with a short-term focus on an understudied and arguably underappreciated oxidant in the context of atmospheric chemistry: singlet oxygen (1O2) the first excited state of ground state triplet molecular oxygen. 1O2 is a well-known excited state molecule: in biology for photodynamic therapy for cancer treatment, in organic chemistry for enhanced reactivity in oxidation and cylcoaddition reactions, and in surface waters as a key oxidant in determining the fate of pollutants. The key ingredients necessary for the production of 1O2 in surface waters include a sensitizer, oxygen and light - all are indeed present in the atmosphere, yet only a handful of reports have described atmospheric 1O2. My proposed research program builds on recent work from my group demonstrating the efficacy of aqueous organic aerosols to act as sensitizers for 1O2 production under sunlit conditions. My team will elucidate the sources (Task 1) and sinks (Task 2) of 1O2 in organic aerosols in indoor and outdoor air, and will undertake groundbreaking studies on 1O2's gas phase chemistry (Task 3). Task 1 addresses two outdoor air projects (MSc1, MSc2) and an indoor air program (PhD1), kick-starting a burgeoning field of indoor air photochemistry. Task 2 will elucidate the sinks of 1O2 in atmospherically-relevant aqueous organic aerosol conditions (PhD2). Furthermore, Task 3 will demonstrate that 1O2 can partition to the gas phase and have unprecedented impact on gas-phase chemical reactions (Postdoc). These three tasks contribute to three impact goals: (A) predict 1O2 steady-state concentrations and quantum yields within organic aerosols; (B) compare the importance of 1O2 reactivity with other oxidants; and (C) demonstrate the presence and impact of 1O2 in the gas phase for the first time. Overall, this research program will train 1 postdoc, 2 PhDs, 2 MSc, and 10 undergraduates and is designed for high training value. Indeed, it is challenging, innovative, and impactful, yet feasible and designed with risk mitigation and EDI strategies. HQP will lead projects, use state-of-the-art photochemistry techniques and participate in multidisciplinary collaborations as part of a unique HQP training program under my leadership. The original scientific research output generated will provide quantitative data including concentrations, rate constants, product distributions and chemical mechanisms to improve fate modelling of key air quality components. This output will support the development of regulatory guidelines by government agencies, Environment and Climate Change Canada and Health Canada.

地球的大气是仅氧化的，因此氧化反应决定了气体和颗粒相中大多数有机分子的命运。为了预测大气污染物的命运，必要的大气氧化剂的浓度，规范和反应性是必要的。我的长期研究计划以研究大气氧化剂及其氧化机制为中心，在大气化学的背景下，短期关注理解并说是不容置疑的氧化剂：单链氧（1O2）是基态三重态三重态的第一个激发状态。 1O2是一种众所周知的激发态分子：用于癌症治疗的光动力疗法的生物学中，在有机化学中，在氧化和环膜加热反应中的反应性增强，以及在地表水中作为确定污染物脂肪的关键氧化物。在地表水中生产1O2所需的关键诱导包括传感器，氧气和光 - 确实存在于大气中，但只有少数报道描述了大气上的1O2。我提出的研究计划基于我小组的最新工作，证明了有机气溶胶在阳光条件下起到1O2生产的敏感性的有效性。我的团队将阐明室内和室外空气中有机气溶胶中1O2的来源（任务1）和下沉（任务2），并将对1O2的气相化学反应进行开创性研究（任务3）。任务1介绍了两个室外航空项目（MSC1，MSC2）和一个室内空气计划（PHD1），启动了室内空气光化学的隆起领域。任务2将阐明与大气相关的有机气溶胶条件（PHD2）中1O2的水槽。此外，任务3将证明1O2可以分配到气相，并对气相化学反应（PostDoc）具有前所未有的影响。这三个任务构成了三个影响目标：（a）预测有机气溶胶中的1O2稳态浓度和量子产量； （b）将1O2反应性与其他氧化物的重要性进行比较； （c）首次证明1O2在气相中的存在和影响。总体而言，该研究计划将培训1个博士后，2个博士学位，2个MSC和10名本科生，并专为高训练价值而设计。确实，IT HQP将领导项目，使用最先进的光化学技术并参加多学科合作，这是我领导下独特的HQP培训计划的一部分。产生的原始科学研究输出将提供定量数据，包括浓度，速率常数，产品分布和化学机制，以改善关键空气质量成分的命运建模。该输出将支持加拿大政府机构，环境和气候变化的制定监管指南。