EAGER: Advancing the Analysis of Secondary Organic Aerosols Through Innovations in Soft Ionization Aerosol Mass Spectrometry

University Of Vermont & State Agricultural College, Burlington VT

Investigators

Abstract

This project involves developing a more comprehensive understanding of the formation, growth, and aging of biogenic and anthropogenic secondary organic aerosols (BSOA and ASOA, respectively). Atmospheric aerosols play a central role in the atmosphere by influencing global and regional radiative energy balance, visibility, the hydrological cycle, regulation of greenhouse and reactive gases, and human health. SOA is the predominant contributor to submicron atmospheric aerosols, therefore developing an improved understanding of its life cycle in the atmosphere is of great importance. Most chamber-based SOA studies to date have placed emphasis largely on understanding the impact of monoterpenes on the formation and growth of BSOA whilst studies that focus on ASOA typically only employ benzene derivatives with emphasis on toluene, trimethylbenzene, and xylene. There is a need to understand the role of less commonly studied volatile and semivolatile organic compounds (VOC and SVOC, respectively) in SOA formation and atmospheric processing. The goal of this exploratory project is to expand these boundaries to include compounds of basic character (such as amines) which, although potentially important in SOA formation and transformation, have received little attention to date, in large part due to the paucity of suitable analytical methods. The approach will be to develop and utilize an enhanced aerosol mass spectrometry system (i.e., near-infrared laser desorption/ionization AMS, NIR-LDI-AMS) capable of simultaneous measurement of the acidic and basic organic components of SOA, while abnegating extensive fragmentation and rearrangement of ions associated with more vigorous ionization AMS methods. The new, dual-mode instrument will use symmetric reflectron time-of-flight mass spectrometers to measure positive and negative ions from the same aerosol sample. Focus will be placed on the influence of organic nitrogen compounds (ON, such as amines and urea) on the formation, growth and aging of SOA. The studies will include addressing the formation and growth of SOA directly from ON VOCs; and the effects of reactive uptake of ON on SOA, as well as primary organic aerosols (POA). Undergraduate and graduate students will play key roles in implementing and executing experiments in the laboratory as well as disseminating results through presentations and preparation of manuscripts. Students will be trained in several areas, including mass spectrometry, gas/aerosol generation and control, and atmospheric chemistry. The project will also enhance collaborations that have been initiated between the Principal Investigator's group and groups at Harvard University and Amherst College. Results garnered from the studies will be disseminated at national and international conferences, as well as at less formal meetings such as the New England Summer Conference Day on aerosols and atmospheric chemistry, where students and post-doctoral scholars from institutions in the Northeast present results and exchange ideas.