Constraining the Degradation Pathways of Siloxanes in the Atmosphere

从化学和大气和地球空间科学司的大气化学计划的部门环境化学科学计划的这个奖项支持教授埃莉诺·布朗和她的研究生和本科生。他们研究有机硅化合物（称为硅氧烷）在大气中的降解过程。硅氧烷是高产量的化合物，用于各种用途，包括作为粘合剂、涂料和个人护理产品的组分。硅氧烷可以在世界各地的环境样品中检测到，包括偏远的北极地区。由于这些化合物的环境持久性及其对水生生物的毒性，硅氧烷的环境化学是一个新兴的关注领域。在环境中，硅氧烷优先分配到大气中，在那里它们经历化学反应以形成新的产物。这些产品可能具有与原始化合物不同的命运。该项目提高了对硅氧烷大气降解的时间尺度和产物的理解，并提供了评估其环境归宿所需的数据。通过这个项目，研究生、本科生和高中生接受大气化学技术和分析仪器方面的培训。学生还通过创建描述工作的视频来培养科学沟通技能。研究结果被纳入本科教育材料。 该项目使用实验室实验来研究硅氧烷的多代大气化学。测量了常见的线性和环状硅氧烷与羟基自由基和氯原子的反应速率，以了解化合物的寿命。这项工作调查的机制和产品的气相氧化硅氧烷的条件下接近城市，农村和偏远的大气。探索氧化产物进入颗粒的实验探索气相硅氧烷和亚微米颗粒之间的相互作用。该奖项反映了NSF的法定使命，并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，被认为值得支持。

This award from the Environmental Chemical Sciences Program in the Division of Chemistry and the Atmospheric Chemistry Program in the Division of Atmospheric and Geospace Sciences supports Professor Eleanor Browne and her graduate and undergraduate students. They study the atmospheric degradation processes of the organosilicon compounds known as siloxanes. Siloxanes are high-production compounds manufactured for a variety of uses, including as components of adhesives, coatings, and personal care products. The siloxanes can be detected in environmental samples worldwide including in remote Arctic regions. Due to the environmental persistence of these compounds and concerns over their toxicity to aquatic organisms, the environmental chemistry of siloxanes is an emerging area of interest. In the environment, siloxanes preferentially partition to the atmosphere where they undergo chemical reactions to form new products. These products may have a different fate than the original compound. This project improves the understanding of the timescale and products of the atmospheric degradation of siloxanes and provides the data necessary to evaluate their environmental fate. Through this project, graduate, undergraduate, and high-school students receive training in atmospheric chemistry techniques and analytical instrumentation. Students also develop scientific communication skills by creating videos describing the work. Results are incorporated into undergraduate educational materials. This project uses laboratory experiments to investigate the multigenerational atmospheric chemistry of siloxanes. The reaction rates of common linear and cyclic siloxanes with the hydroxyl radical and chlorine atom are measured to understand the lifetime of the compounds. The work investigates the mechanism and products of the gas-phase oxidation of siloxanes under conditions approximating urban, rural, and remote atmospheres. Experiments probing the uptake of oxidation products into particles explore the interactions between gas-phase siloxanes and submicron particles. Both reactants and products are measured in real time with chemical ionization mass spectrometry.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.