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

地球的大气层完全是氧化性的，因此氧化反应支配着气相和颗粒相中大多数有机分子的命运。大气氧化剂的浓度、形态和反应性是预测大气污染物命运的必要条件。我的长期研究计划集中于研究大气氧化剂及其氧化机制，短期研究重点是在大气化学背景下研究不足且可能被低估的氧化剂：单线态氧（1O2），基态三态分子氧的第一激发态。o2是一种众所周知的激发态分子：在生物学中用于光动力治疗癌症，在有机化学中用于增强氧化和环加成反应的反应活性，在地表水中作为决定污染物命运的关键氧化剂。在地表水中产生1O2所需的关键成分包括增敏剂、氧气和光——所有这些都确实存在于大气中，但只有少数报告描述了大气中的1O2。我提出的研究计划建立在我的小组最近的工作基础上，该工作证明了在阳光条件下，水性有机气溶胶作为o2产生的增敏剂的功效。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（Task 1）和汇（Task 2），并将对1O2的气相化学（Task 3）进行开创性的研究。任务1涉及两个室外空气项目（MSc1, MSc2）和一个室内空气项目（PhD1），启动了一个新兴的室内空气光化学领域。任务2将阐明在与大气相关的水性有机气溶胶条件下（PhD2） 1O2的汇。此外，任务3将证明1O2可以分裂到气相，并对气相化学反应产生前所未有的影响（博士后）。这三个任务有助于实现三个影响目标：(A)预测有机气溶胶中o2的稳态浓度和量子产率；(B)与其他氧化剂比较o2反应性的重要性；(C)首次证明了气相中1O2的存在及其影响。本项目培养博士后1人、博士2人、硕士2人、本科生10人，具有较高的培养价值。事实上，它具有挑战性、创新性和影响力，但可行，并设计了风险缓解和EDI策略。在我的领导下，HQP将领导项目，使用最先进的光化学技术，并参与多学科合作，作为HQP独特培训计划的一部分。所产生的原始科学研究成果将提供定量数据，包括浓度、速率常数、产品分布和化学机制，以改进关键空气质量成分的命运模型。这一产出将支持政府机构、加拿大环境和气候变化以及加拿大卫生部制定监管准则。

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.