EAGER: Nanoparticle Growth from Salting-in and Mobile Infrared Column Observations

这项研究包括开发一种新的移动仪器，用于提供大气中碳氢化合物对红外辐射的柱吸收数据，这一过程可能导致大气变暖。该项目的首席研究员还被邀请访问瑞士的保罗-谢勒研究所，在欧洲核子研究中心的CLOUD室设施设计一系列实验。该设施将使他能够研究在不同环境温度和压力条件下大气中二次有机气溶胶（SOA）的形成。了解导致二次有机气溶胶快速形成和增长的机制是很重要的，因为它们对预测空气质量和气候变化很重要。拟议的CLOUD室内实验将把重点放在“盐入”效应上，作为解释纳米颗粒加速生长速率的机制。在乙二醛的情况下，“盐化”是由水合乙二醛分子从硫酸盐离子的水合壳中置换水分子组成的。初步研究表明，在相对湿度（RH）高达20%的条件下，乙二醛可以有效地生长出高酸性纳米团簇。然而，目前还没有在相对湿度超过20%和中性纳米团簇的实验数据，其中多相化学有望通过不同的途径进行。拟议的研究将解决以下与大气中SOA（与乙二醛相关）形成相关的问题：(1)乙二醛开始帮助集群稳定/增长的“阈值集群大小”是多少；(2)稳定簇的生长速率如何依赖于相对湿度和pH？“盐入”机制已被纳入一个大气模型，成功地解释了乙二醛快速形成SOA的原因，这是在最近nsf支持的研究墨西哥城空气污染的实地活动中观察到的。移动太阳掩星通量仪的开发以及该仪器红外检索的新技术将为更好地量化大气成分和成分变化提供一种新方法。云室的实验可能会导致二次有机气溶胶形成和生长机制的变革性研究。这项研究是由探索性研究早期概念拨款（EAGER）项目资助的。

This research includes the development of a new mobile instrument for providing data on the column absorption of infrared radiation by hydrocarbons in the atmosphere, a process that can lead to an atmospheric warming. The Principal Investigator of the project also has been invited to visit the Paul-Scherrer Institute in Switzerland to design a series of experiments at the CLOUD chamber facility at CERN. This facility will enable him to study the formation of secondary organic aerosol (SOA) in the atmosphere under varying conditions of ambient temperature and pressure. It is important to understand the mechanisms that lead to the fast formation and growth of secondary organic aerosol since they are important in predicting air quality and climate change.The proposed CLOUD chamber experiments will focus on the 'salting-in' effect as a mechanism for explaining accelerated nanoparticle growth rates. In the case of glyoxal, 'salting-in' consists of the displacement of water molecules from the hydration shell of sulfate ions by hydrated glyoxal molecules. Preliminary studies show efficient growth from glyoxal at relative humidity (RH) of up to 20% for highly acidic nanoclusters. However, there are currently no experimental data available at RH above 20% and for neutral nanoclusters, where the multiphase chemistry is expected to proceed via different pathways. The proposed research will address the following questions related to the formation of SOA (associated with glyoxal) in the atmosphere: (1) What is the 'threshold cluster size' at which glyoxal begins to assists with the stabilization/growth of clusters; and (2) How does the growth rate of stable clusters depend on relative humidity and pH? The 'salting-in' mechanism has been incorporated in an atmospheric model to successfully explain the fast formation of SOA from glyoxal that was observed in a recent NSF-supported field campaign to study air pollution in Mexico City.The development of the mobile Solar Occultation Flux instrument and the acquisition of new expertise for IR retrievals from the instrument will offer a novel way to better quantify atmospheric composition and changes in composition. The experiments at the CLOUD chamber may result in transformative research on the mechanisms for formation and growth of secondary organic aerosol. This research is funded through the EArly-concept Grants for Exploratory Research (EAGER) program.