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.

地球大气完全是氧化性的，因此氧化反应决定了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、形态和反应性对于预测大气污染物的命运是必要的。重点研究大气氧化剂及其氧化机制，短期重点关注大气化学背景下尚未充分研究且有争议且未被充分认识的氧化剂：单线态氧(1O2) 基态三重态分子氧的第一激发态 1O2 是一种众所周知的激发态分子：在生物学中用于癌症治疗的光动力疗法，在有机化学中用于增强氧化和环加成反应的反应性，以及在地表水中作为光动力疗法。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敏化剂、氧气和光 - 所有这些都确实存在于大气中，但只是存在于大气中。一些报告描述了大气 1O2。我提出的研究计划建立在我的小组最近的工作基础上，该工作证明了水性有机气溶胶在阳光照射下作为 1O2 产生的敏化剂的功效。我的团队将阐明其来源（任务 1）和汇。 （任务 2）室内和室外空气中有机气溶胶中的 1O2，并将对 1O2 的气相化学进行突破性研究（任务3) 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），启动了室内空气光化学的新兴领域，任务 2 将阐明与大气相关的水性有机气溶胶中的 1O2 汇。此外，任务 3 将证明 1O2 可以分离到气相并对气相化学反应产生前所未有的影响。 （博士后）这三项任务有助于实现三个影响目标：（A）预测有机气溶胶中的 1O2 稳态浓度和量子产率；（B）比较 1O2 反应性与其他氧化剂的重要性；总体而言，该研究项目将培训 1 名博士后、2 名博士、2 名硕士和 10 名本科生，确实具有很高的培训价值。它具有挑战性、创新性和影响力，但又可行，并且在设计时考虑了风险缓解和 EDI 策略，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，作为我的独特 HQP 培训计划的一部分。产生的原始科学研究成果将提供包括浓度、速率常数、产品分布和化学机制在内的定量数据，以改进关键空气质量成分的命运模型。该成果将支持政府机构、环境和气候变化制定监管指南。加拿大和健康加拿大。