AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Relationship between the Redox Cycling Activity and Chemical Properties of Oxidized Soot Particles
MARIA ANTIÑOLO, Megan D. Willis, Shouming Zhou, Jonathan Abbatt, University of Toronto
Abstract Number: 416 Working Group: Health Related Aerosols
Abstract The formation of carbon containing particles in combustion processes has been widely studied, and it is believed that such soot particles have toxic health effects. However, the reactivity of these particles with different tropospheric oxidants remains unclear, including how these aging processes can drive health effects. Oxidative stress is one of the major mechanisms thought to induce the toxicological effects of the particulate matter (PM). In these redox-cycling reactions, a catalyst such as quinones or transition metals is reduced whereas reducing agents within the cell are consumed. The catalyst is then reoxidized by reducing oxygen to Reactive Oxygen Species (ROS), allowing the cycle to repeat. To assess the capability of a species to be a catalyst in this cycle, the dithiothreitol (DTT) assay has been widely used.
In this work, soot was obtained from a propane-air diffusion flame. Different measurements were performed on untreated soot and soot exposed to ozone. In particular, Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) was used to observe changes in chemical composition of the surface of soot collected on a filter. Other experiments were done in an atmospheric simulation chamber, where a Scanning Mobility Particle Sizer (SMPS) allowed monitoring the physical properties of the soot, and the chemical properties of the particles were observed with a Soot Particle Aerosol Mass Spectrometer (SP AMS). The DTT assay was performed with oxidized and non-oxidized soot collected from the DRIFTS cell and from the chamber to evaluate the effect of ozone oxidation on the redox cycling activity of the carbonaceous particles.