Suppression of New Particle Formation by Isoprene in Non-Pristine Mixed Forest Environments

在美国国家科学基金会化学部环境化学科学项目的支持下，亨茨维尔阿拉巴马大学的Shanhu Lee和Bernhard Vogler及其研究生将进行实验室动力学研究，以调查森林地区大气中异戊二烯（一种非常重要的生物烃）抑制新颗粒形成（NPF）的化学机制。NPF对全球云凝结核的产生有重要贡献，影响云和气候。最近的实验室研究表明，异戊二烯抑制生物源性新颗粒的形成，但这些研究大多局限于模拟原始森林条件的条件。本研究的重点是与美国混交林密切相关的条件，包括生物萜类和各种污染物。这些科学发现将被纳入UAH的外展计划，向从K-12到普通公众的多个年龄组传播气候和环境问题。该项目将采用由Lee和Vogler团队开发的名为TANGENT（串联气溶胶成核和生长环境管）的双流管系统，进行多组分成核和生长，涉及萜烯产生的HOMs（高氧有机分子）、硫酸、氨、胺和氮氧化物。tan系统将允许团队在受控的实验条件下独立研究成核和新粒子的后续生长。气相成核前体、气溶胶大小和颗粒相化学组成将用一系列最先进的化学和气溶胶仪器进行测量。这些研究是迄今为止最全面的实验室观察之一，旨在研究异戊二烯在具有代表性的非原始混合落叶林条件下以及在广泛的温度和相对湿度条件下对新颗粒成核和生长的作用。这项基础研究有望为这种重要的生物挥发性有机化合物-异戊二烯-在与云凝结和气候条件相关的颗粒形成中的作用提供新的见解。该奖项反映了美国国家科学基金会的法定使命，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。

With support from the Environmental Chemical Sciences Program in the Division of Chemistry at NSF, Shanhu Lee and Bernhard Vogler at the University of Alabama in Huntsville (UAH) and their graduate students will conduct laboratory kinetics studies to investigate chemical mechanisms related to the suppression of new particle formation (NPF) by isoprene, a very important biogenic hydrocarbon, in the atmosphere in forested areas. NPF contributes significantly to global cloud condensation nuclei production, impacting clouds and climate. Recent laboratory studies have demonstrated that isoprene suppresses biogenic new particle formation, but these studies were mostly limited to the conditions that mimic pristine forest conditions. This study focuses on conditions that are closely relevant to the mixed deciduous forests in the United States and include both biogenic terpenes and various pollutants. The scientific findings will be incorporated into outreach programs at UAH to communicate climate and environmental issues to multiple age groups ranging from K-12 to the general public.This project will employ a dual-flow tube system known as the TANGENT (Tandem Aerosol Nucleation and Growth ENvironment Tubes) system developed by the Lee and Vogler team to conduct multi-component nucleation and growth involving terpene-produced HOMs (highly oxygenated organic molecules), sulfuric acid, ammonia, amines, and NOx. The TANGENT system will allow the team to study nucleation and the subsequent growth of new particles independently under controlled experimental conditions. Gas-phase nucleation precursors, aerosol size, and particle-phase chemical composition will be measured with a series of state-of-the art chemical and aerosol instruments. These studies are will represent one of the most comprehensive laboratory observations yet made to study the role of isoprene on nucleation vs. growth of new particles under conditions representative of non-pristine mixed deciduous forests and at a wide range of temperature and relative humidity conditions. This fundamental research is expected to provide new insight into the role of this important biogenic volatile organic compound-isoprene-upon particle formation relevant to cloud condensation and hence climate conditions.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.