Sources and Ambient Concentration of VOCs in San Antonio, Texas
Abstract
Volatile organic compounds (VOCs) play an important role in the photochemical ozone (O3) production in the urban atmosphere. To better characterize sources of VOCs in San Antonio, TX, the University of Houston, Rice and Baylor University deployed the Mobile Air Quality Lab (MAQL) at two urban sites (San Antonio- Travelers' World (TW) and University of Texas San Antonio (UTSA)) in May 2017. Proton transfer reaction- mass spectrometry (PTR-MS) was operated in the MAQL to conduct real-time measurements of VOCs. Simultaneous measurement of trace gas pollutants (i.e. O3, NO, NOx, SO2 and CO), wind speed and wind direction provide a unique opportunity to study the role of VOC emission on O3 production and improve source characterization. Higher concentration of biomass burning tracer VOCs, acetonitrile and acetaldehyde, were observed during the initial days of measurement. In comparison to the non-event period, a strong correlation (r2 = 0.77) was observed between these tracers during the biomass burning period. Back trajectory analysis is planned to determine potential source regions for this biomass burning. For biogenic VOCs, isoprene peaked during the daytime while monoterpene concentration was consistent throughout the day. In addition, monoterpene concentration was similar at both sites whereas isoprene concentration was higher at UTSA compared to TW indicating more spatio-temporal differences. Furthermore, the correlation between isoprene and its photooxidation products (methyl vinyl ketone and methacrolein) was higher during daytime compared to nighttime (r2 increased from 0.43 to 0.50 at TW site and 0 to 0.22 at UTSA site). Benzene concentration was higher during morning and evening rush hours, indicating contributions from vehicular emission. The concentration of formaldehyde was comparatively higher in the afternoon. Detailed results on source apportionment of VOCs using positive matrix factorization (PMF) through conditional probability function plots will be presented during the conference.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A23M3069S
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0315 Biosphere/atmosphere interactions;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0345 Pollution: urban and regional;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE