Generation of Hydroxyl Radical from San Joaquin Valley Particles in a Cell-Free Solution

HUIYUN SHEN (1), Abdul I. Barakat (1), Cort Anastasio (1)

(1) University of California, Davis

     Abstract Number: 298
     Last modified: November 9, 2009

Abstract
Epidemiological studies have shown a correlation between exposure to ambient particulate matter (PM) and adverse health effects. While the pathways involved remain to be clarified, one proposed mechanism is the generation of reactive oxygen species (ROS), which then causes oxidative stress. The major ROS species include superoxide (O2-•), hydrogen peroxide (HOOH), and hydroxyl radical (•OH), with •OH being the most reactive species, capable of reacting with cell membrane lipids, proteins, and DNA. The amount of each specific ROS generated from PM is largely unknown, but such information is needed to more quantitatively address the link between ROS and the health effects of PM. To address this gap, we are quantifying the generation of •OH by fine (PM2.5) and coarse (PMcf; 2.5 – 10 microns) particles collected at an urban (Fresno) and rural (Westside) site in the San Joaquin Valley of California during summer and winter. These particles were collected by other researchers in the EPA-funded San Joaquin Valley Aerosol Health Effects Research Center (SAHERC) at UC Davis.

We will discuss several topics related to our measurements of •OH generation: (1) site (urban vs. rural), season (summer vs. winter), and size (fine vs. coarse PM) differences, (2) the contribution of transition metals in general – and Fe and Cu in particular, and (3) the importance of added reductant (ascorbate).