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Spatial Characterization of the Composition and Sources of Submicron Aerosols in the Corpus Christi - San Antonio Area Based on Mobile Measurements
SHAN ZHOU, Fangzhou Guo, James Flynn, Sascha Usenko, Subin Yoon, Sergio Alvarez, Sujan Shrestha, Rebecca J. Sheesley, Manisha Mehra, Meghan C. Guagenti, Chun-Ying Chao, Robert Griffin, Rice University
Abstract Number: 572
Working Group: Urban Aerosols
Abstract
San Antonio is the seventh-most populous city in the US. However, in recent years, the air quality of San Antonio has worsened and aerosol mass concentrations have increased. There is a lack of characterization of the composition and chemistry of particulate matter pollution in this area. We investigated the spatial and temporal patterns in the concentration and composition of non-refractory submicron particulate matter (NR-PM1) in Corpus Christi (upwind of San Antonio) and San Antonio using a high-resolution time-of-flight aerosol mass spectrometer deployed in a mobile laboratory from April 1 to May 19, 2021. The average mass concentration of NR-PM1 in the Corpus Christi area was 8.2 ± 5.8 μg m-3, comprising 45% sulfate and 38% organic matter. We observed particles that varied based on air mass origin and emission regime, including polluted oceanic air masses from the Gulf of Mexico enriched in ammonium sulfate, transported biomass burning plumes from within Texas and possible wildfire plumes from Mexico dominated by organic matter, vehicle emissions from city centers, anthropogenic emissions from refineries, and biogenic emissions between the two cities. In addition, we observed high spatial heterogeneity in aerosol concentration and composition. Sulfate was the dominant aerosol component in the airmass transported into Corpus Christi from the Gulf of Mexico; the mass concentration decreased from a peak level of 35 μg m-3 to less than 2 μg m-3 as the sampling location moved inland. Due to the influence of different sources, organic aerosol composition and the degree of oxidation varied substantially; organics were less oxidized as air was advected from the coast through Corpus Christi. Results from positive matrix factorization analysis that investigate the sources and processes of organic aerosol observed in this study will be discussed.