AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Contrasting Profiles of the Oxidative Properties of Ambient Aerosols Collected from Urban and Rural Environments in Atlanta
VISHAL VERMA, Ting Fang, Rodney Weber, Georgia Institute of Technology
Abstract Number: 225 Working Group: Health Related Aerosols
Abstract In recent years, numerous studies have been conducted to trace the oxidative properties of ambient particulate matter (PM) from their specific components. Many of these studies were focused in typical urban environments where the atmospheric PM is heavily dominated by primary vehicular emissions and their secondary reaction products. The chemical properties of ambient particles can dramatically vary depending upon their sources and meteorology in a particular environment such as rural and near-road site. The variations in the chemical composition of ambient aerosols lead to their dissimilar oxidative properties and the subsequent health effects.
As part of our SCAPE center (Southeastern Center for Air Pollution & Epidemiology), we aim to measure the oxidative potential of ambient aerosols in different environmental settings ranging from urban background to rural environment. Here we present the contrast in the oxidative potential of ambient particles collected from two characteristically different sites in Atlanta – Jefferson street which is characterized as an urban background site, and Yorkville which represents a typical rural environment. Ambient fine particles (Dp< 2.5 micro-meter) were collected at both sites on the quartz filters (23 hours integrated samples, N = 32 for each site) using a high-volume sampler (Thermo Anderson) in summer (June-July) 2012, and the particles were extracted in deionized water. Oxidative potential of the extracted water-soluble particles was measured by the dithiothreitol (DTT) assay. To better understand the sources of PM oxidative potential, hydrophobic compounds from the PM extracts were removed using a C-18 column and the remaining hydrophilic fraction was also analyzed for DTT assay. Preliminary results show that there is significant variability both at the spatial and temporal scales in the oxidative potential of ambient particles. The DTT activity was unsymmetrically partitioned in the hydrophobic and hydrophilic components for different samples; however, the average contribution of hydrophobic compounds was significantly higher in Yorkville (56±17 %) compared to Jefferson street (44±21 %). Chemical analyses of these samples are underway but these findings indicate that PM components governing the aerosol oxidative potential at two sites have different chemical signatures, some of which could potentially be revealed by their sequential extraction in a series of non-polar solvents such as hexane, dichloromethane, and methanol. The sources of these differential profiles of oxidative potential in relation to their specific driving components would be further explored by extending this comparison to different seasons and sites in Atlanta.