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，以提供大气中碳氢化合物对红外辐射的柱状吸收数据，这一过程可能导致大气变暖。该项目的首席研究员还受邀访问瑞士的保罗-谢雷尔研究所，在欧洲核子研究中心的云室设施中设计一系列实验。这一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非常重要，因为它们在预测空气质量和气候变化方面很重要。拟议中的云室实验将重点放在盐分效应上，作为解释纳米粒子加速生长速度的一种机制。在乙二醛的情况下，盐化包括水分子被水合的乙二醛分子从硫酸盐离子的水合壳层中置换出来。初步研究表明，对于高度酸性的纳米团簇，乙二醛在相对湿度(RH)高达20%的情况下可以有效地生长。然而，目前还没有RH超过20%和中性纳米团簇的实验数据，在中性纳米团簇中，多相化学预计将通过不同的途径进行。拟议的研究将解决与大气中SOA(与乙二醛有关)的形成有关的下列问题：(1)乙二醛开始帮助团簇稳定/生长的“阈值团团大小”是多少；以及(2)稳定团簇的增长率如何取决于相对湿度和pH值？“盐分”机制已被纳入大气模式，成功地解释了乙二醛从乙二醛快速形成SOA的现象，这是在最近一次由NSF支持的研究墨西哥城空气污染的野外活动中观察到的。移动太阳掩星通量仪器的发展以及从该仪器获取红外反演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的方法。云室的实验可能导致对二次有机气溶胶形成和增长机制的变革性研究。这项研究是由探索性研究早期概念补助金(AGERGE)计划资助的。

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.