AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Characterization of Particulate Matter in Summer Using High-Resolution Aerosol Mass Spectrometry in San Antonio
FANGZHOU GUO, Alexander Bui, Edward Fortner, Benjamin Schulze, Sujan Shrestha, Subin Yoon, Rebecca J. Sheesley, Sascha Usenko, Tara Yacovitch, James Flynn, Robert Griffin, Rice University
Abstract Number: 534 Working Group: Urban Aerosols
Abstract Currently the seventh most populous city in the United States and the second most populous city in Texas, San Antonio has been one of the most rapidly growing cities in the country over the past decade. As demonstrated by an ozone design value in violation of the federal threshold, the city suffers from poor air quality. To understand the sources of particulate matter (PM) that contribute to the degradation of San Antonio’s air quality, we deployed a mobile air quality laboratory (MAQL) in locations to the southeast (Traveler’s World RV Park (TW)) and northwest (University of Texas at San Antonio campus (UTSA)) of downtown San Antonio in May, 2017. Aerodyne’s mobile laboratory (AML) was also deployed at UTSA and measuring during May 12 – 16 and 27 – 31. Chemical characterization of non-refractory submicron PM (NR-PM1) was conducted using two Aerodyne high-resolution time-of-flight aerosol mass spectrometers (HR-ToF-AMS) at each site. Additional measurements included meteorological parameters, trace gas mixing ratios (of ozone, total nitrogen oxides, total reactive nitrogen, carbon monoxide, and volatile organic compounds), and off-line speciation of PM collected using filters. Results from both HR-ToF-AMS indicate large organic and sulfate aerosol plumes, with maximum 1-minute averaged concentrations of 35.65 and 11.30 µg/m3 respectively. At TW site, PMF analysis of the high-resolution spectra identifies hydrocarbon-like OA (HOA, 14.2%), a less oxygenated OA (LO-OOA, 48.4%), and a more oxygenated OA (MO-OOA, 37.4%), which allows us to estimate the fraction of PM in San Antonio in summer that is local and anthropogenic. A Lagrangian analysis is being performed to quantify the variations in chemical composition, aging processes of organic aerosol, and potential source factors of organic portion of NR-PM1 across the city.