Laboratory Studies of Heterogeneous Oxidation of Organic Aerosols

Carnegie Mellon University, Pittsburgh PA

Investigators

Abstract

This project is focused on investigating the lifetimes and chemical degradation pathways of specific compounds in organic aerosols. There are two major objectives of the proposed research. The first is to conduct well-controlled experiments using complex, atmospherically relevant mixtures to help bridge the gap between existing laboratory data on simple systems and atmospheric observations. To better simulate actual atmospheric aging, the decay rate will be measured for approximately 30 organic compounds in aerosol particles generated from two complex mixtures: motor oil and meat cooking grease. These mixtures contain thousands of individual organics and are surrogates for important classes of primary organic aerosol. The new data will be compared to existing data for simple systems to assess the significance of heterogeneous aging on atmospheric aerosol composition. The second major objective is to investigate heterogeneous oxidation by hydroxyl (OH) radicals. OH may be the most important oxidant given that the vast majority of the identified organic aerosol mass is comprised of saturated compounds. This will be investigated by conducting smog chamber experiments with aerosolized motor oil and simple engineered mixtures. Airborne particles influence climate, degrade visibility, and impact human health. The results will help improve atmospheric models used to understand the origin of organic aerosols. These models are widely used to assess the potential effects of aerosols on global climate, regional visibility, and air quality, which are all important societal problems. The project will also support the education of a number of undergraduate and graduate students.