AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Exploring the Composition of Urban and Rural Organic Matter Found in Coarse Particles (PM$_(10-2.5)) in Northeastern Colorado
NICHOLAS CLEMENTS, Tiffany Duhl, Eunkyung Lee, Bounkheana Chhun, Fernando Rosario-Ortiz, Jana Milford, Shelly Miller, Michael Hannigan, University of Colorado at Boulder
Abstract Number: 372 Working Group: Urban Aerosols
Abstract Elevated concentrations of coarse particulate matter (PM$_(10-2.5)) have been associated with negative health effects, such as an increased risk of mortality and respiratory disease. Despite many studies analyzing the inorganic fraction of PM$_(10-2.5), the organic fraction is currently poorly understood. To contribute to our general understanding of PM$_(10-2.5), the Colorado Coarse Rural-Urban Sources and Health (CCRUSH) study is investigating the composition and health impacts of PM$_(10-2.5) in urban and rural environments in Colorado. Twenty-four hour samples were collected on quartz filters every sixth day for a year using 50 lpm dichotomous samplers at four monitoring sites in the Colorado Front Range region. Two sites were located in Denver (urban) and two in Greeley (rural). Previous results from the CCRUSH study show that PM$_(10-2.5) in Colorado contains crustal materials, vehicle-wear particles, roadway deicing salt in winter, and biological particles (bacteria, fungi, and pollen). To understand the organic fraction of PM$_(10-2.5), we measured bulk elemental and organic carbon concentrations from quartz filter punches. Aqueous extractions of filter composite sets were performed at neutral and elevated pH and analyzed using a bulk dissolved organic carbon analyzer, UV-vis spectrometer, spectrofluorometer, and size-exclusion chromatography. Content of endotoxin, a lipopolysaccharide found in the cell wall of Gram-negative bacteria, was quantified with a limulus amebocyte lysate (LAL) assay. PM$_(2.5) and reference natural organic matter samples were analyzed with the same suite of instruments for comparison. Measurements of the organic fraction of PM$_(10-2.5) will be combined with total mass concentrations, elemental concentrations, biological particle concentrations, and meteorological observations to understand the seasonal variability of sources of PM$_(10-2.5) organic matter, and to explore how sources vary between urban and rural environments.