AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Distribution of Ambient Atmospheric Water-soluble Metals in the Southeastern United States and Insights into Their Complexation States
TING FANG, Vishal Verma, Richard E. Peltier, Hongyu Guo, Laura King, Rodney Weber, Georgia Institute of Technology
Abstract Number: 505 Working Group: Linking Aerosols with Public Health in a Changing World
Abstract Water-soluble metals in ambient particles have been shown to generate reactive oxygen species (ROS) by Fenton reactions. Certain metals such as Cu, Mn, and Fe have even been associated with the response of various oxidative assays such as the Ascorbate (AA), Dithiothreitol (DTT) and macrophage ROS assays, typically used to measure the toxicological properties of ambient particles. As part of the Southeastern Center for Air Pollution & Epidemiology (SCAPE) project, we measured the concentration of water-soluble metals in PM2.5 in southeastern United States. In this study, 530 PM2.5 filter samples were collected over a yearlong period from contrasting environments, i.e. urban (Atlanta), rural (Yorkville and Centreville), industrial (Birmingham) and roadside (near I-85 freeway in Georgia Tech) sites. Water-soluble metals in the filter extracts were measured using an online XRF (X-ray fluorescence) instrument (Xact™ 625 Monitoring System) by coupling to an ultrasonic nebulizer (CETAC, U5000 AT+) to aerosolize filter extracts and the system was automated by using a Dionex autosampler (Dionex 40AS). The oxidative potential (ROS generating capability) of these particles were also measured using the dithiothreitol (DTT) assay. As an additional step to identify the oxidative particle components, we passed these extracts through a C-18 solid phase extraction (SPE) columns (octadecyl carbon chain bonded silica, Sorbent Technologies) and measured the metals concentration in both passed-through (hydrophilic) and retained on the column fraction (hydrophobic). Among all sites, industrial (Birmingham) and roadside sites have the highest levels of water-soluble metals (e.g. Ca, Mn, and Zn), while the concentrations are generally low in the rural environment (Yorkville and Centerville). Urban background sites in Atlanta have moderate levels of the water-soluble metals. Some of these metals, particularly Fe, Mn and Zn were well correlated with the DTT activity in urban and roadside sites. The partitioning behavior of these metals on the C-18 column would further help to understand the complexation states of these metals with organic compounds and their availability to induce the oxidative stress in biological cells.