Among the most abundant particles in the troposphere are those emitted in combustion processes. It is important to know how atmospheric exposure to tropospheric oxidants affects the ability of combustion particles to catalyze redox cycling in cells and to understand the associated chemical change in the particles. In particular, particles emitted from combustion sources have negative health effects, with some components (quinones and metals) believed to act as catalysts for redox cycling that result in the formation of reactive oxygen species (ROS). In this work, we exposed soot particles to different O3 concentrations and measured their redox cycling activity by using the DTT (dithiothreitol) assay, a common acellular assay. At the same time, chemical changes were monitored by infrared spectroscopy and an Aerodyne Soot-Particle Aerosol Mass Spectrometer (SP-AMS). The uptake coefficient of the reaction of the PAHs (Polycyclic Aromatic Hydrocarbon) present on soot particles with O3 was also measured with the SP-AMS, and a relationship was established between particulate redox cycling activity and the observed kinetics of PAH loss when exposed to O3. Similar experiments were done with soot coated with benzo[e]pyrene (BeP) to assess the role of an individual PAH on soot particles. In addition, particles were coated with bis(2-ethylhexyl)sebacate (BES), an oil, to simulate the condensation of primary organic aerosol (POA) material on soot particles. Evidence is presented that the formation of quinones or quinone-like functional groups on the soot surfaces gives rise to the increased activity.

Oxidation of soot particles with O<sub>3</sub>: Changes in redox-cycling activity and composition

248th National Meeting (2014)

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Oxidation of soot particles with O3: Changes in redox-cycling activity and composition

Oxidation of soot particles with O₃: Changes in redox-cycling activity and composition