AGS-PRF: Understanding the Early Growth of Atmospheric Nanoparticles

Lea Hildebrandt博士被授予大气和地球空间科学博士后研究奖学金，与波特兰州立大学和明尼苏达大学的同事一起在科罗拉多州博尔德市的国家大气研究中心开展研究项目。她的项目结合了理论、实验室和现场测量，使用新开发的仪器来解释影响大气中纳米颗粒生长速度的化学和物理过程。这项工作的一个主要目标是了解有机酸(例如甲酸或醋酸)和碱(例如甲胺、二甲胺或三甲胺)反应形成的有机盐被预先存在的已知大小的颗粒所吸收的过程。20-50纳米大小的种子颗粒将从硫酸和铵盐以及有机化合物的成核中产生。温度、相对湿度、pH和有机物的影响将有所不同，以评估颗粒生长的机制以及胺和有机酸对颗粒生长的贡献。将在博尔德和一个乡村地点进行户外测量，以了解不同条件下颗粒的形成和生长。这些数据将被用来开发和约束纳米颗粒生长速度的模型。纳米颗粒的尺寸大约在1到10纳米之间。这些大气粒子通过散射或吸收太阳辐射直接影响地球气候，并间接作为水凝结的种子，从而影响云的形成和性质。纳米颗粒还会通过破坏呼吸系统和心血管系统等方式影响人类健康。新粒子形成的基本过程尚不清楚，因此不能可靠地预测粒子浓度。计划中的工作将提供对大气颗粒物形成的化学和物理过程的洞察。该项目还将带来教育和培训方面的好处，因为它通过指导、学习新技术和技能的机会以及发展更广泛的大学网络来支持青年科学家的职业发展。

Dr. Lea Hildebrandt was awarded an Atmospheric and Geospace Sciences Postdoctoral Research Fellowship to conduct a research project at the National Center for Atmospheric Research in Boulder, Colorado and with colleagues at Portland State University and the University of Minnesota. Her project combines theoretical, laboratory and field measurements using newly developed instruments to explain chemical and physical processes affecting the growth rates of nanoparticles in the atmosphere. A main objective of the work is to understand the processes by which organic salts formed by reactions of organic acids (e.g., formic or acetic acid) and bases (e.g., methylamine, dimethylamine or trimethylamine) are taken up onto preexisting particles of known size. Seed particles 20-50 nanometers in size will be generated from sulfuric acid and ammonium salts, as well as from the nucleation of organic compounds. The effects of temperature, relative humidity, pH and organics will be varied to assess mechanisms of particle growth and the contribution of the amines and organic acids to this growth. Outdoor measurements will be taken in Boulder and at a rural site to learn about particle formation and growth under different conditions. The data will be used to develop and constrain models for nanoparticle growth rates.Nanoparticles range in size from about 1 to 10 nanometers. These atmospheric particles affect Earth's climate directly by scattering or absorbing solar radiation and indirectly by acting as seeds for water condensation and thereby influencing the formation and properties of clouds. Nanoparticles also affect human health by, for example, damaging respiratory and cardiovascular systems. The fundamental processes underlying new particle formation are not yet understood and consequently particle concentrations cannot be predicted reliably. The planned work will provide insights into the chemical and physical processes of atmospheric particle formation. Improved understanding of atmospheric particles will enable better prediction of cloud formation and development of better-informed policy actions concerning health effects.This project will also have education and training benefits because it supports the career development of a young scientist through mentorship, an opportunity to learn new techniques and skills, and development of a broader collegial network.