Formation of photo-oxidants and processing of organic species in aerosol liquid water

该项目的目标是提高对大气中高活性凝聚相物质如何影响大气颗粒物的化学和组成的理解。颗粒和液滴中的许多反应是由高度反应性的光氧化剂驱动的，当某些有机和无机分子吸收阳光时，这些光氧化剂在凝聚相中形成。这项研究的结果将有助于阐明这些物种在颗粒有机物的形成、转化和损失中的作用，并有助于减少颗粒物空气污染的监管工作。该项目的目标是：（1）测量颗粒物的浓度和动力学（即，在加州戴维斯一年内收集的细颗粒物的相对稀的水提取物中，光吸收有机化合物（3C*）、单线态分子氧（1 O2 *）和羟基自由基（·OH）的三重态的形成速率和寿命;（2）开发新的方法，以量化环境大气中存在的高度浓缩气溶胶液态水条件下的光氧化剂浓度;（3）探讨3C* 和1 O2 * 在颗粒物中转化有机物种的重要性;以及（4）整合结果，以提高社区对颗粒物和液滴中光氧化剂的理解。主要研究人员计划与合作者合作，对生物质燃烧羽流中的颗粒和气相化学进行建模，并探索凝聚相光氧化剂在有机气溶胶形成和演变中的作用。这项工作包括对博士后研究员以及研究生和本科生的指导，和活动，以提高他们对颗粒物空气污染的理解。这个奖项反映了NSF的法定使命，并已被认为是值得支持，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。

The goal of this project is to improve the understanding of how highly reactive, condensed phase species in the atmosphere influence the chemistry and composition of atmospheric particles. Many reactions in particles and droplets are driven by highly reactive photo-oxidants that are formed within the condensed phase when certain organic and inorganic molecules absorb sunlight. The results of this research will help to elucidate the role of these species in the formation, transformation, and loss of particulate organics and assist with regulatory efforts to reduce particulate matter air pollution.The objectives of the project are to: (1) Measure the concentrations and kinetics (i.e., formation rates and lifetimes) of the triplet states of light-absorbing organic compounds (3C*), singlet molecular oxygen (1O2*), and hydroxyl radical (•OH) in relatively dilute water extracts of fine particles collected over the course of a year in Davis, California; (2) Develop new methods to quantify photo-oxidant concentrations under the very concentrated aerosol liquid water conditions present in the ambient atmosphere; (3) Explore the importance of 3C* and 1O2* in transforming organic species in particles; and (4) Integrate the results to improve the community’s understanding of photo-oxidants in particles and drops. The principal investigators plan to work with a collaborator to model the particle- and gas-phase chemistry in biomass-burning plumes and explore the role of condensed phase photo-oxidants in the formation and evolution of organic aerosols.This effort includes the mentoring of a postdoctoral fellow and both graduate and undergraduate students, and activities with middle and high school students to improve their understanding of particulate matter air pollution.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.