Project Number: 20-028

Research

Title: Quantification and Characterization of Ozone Formation in Central San Antonio

Institution(s) Represented: Drexel University

Lead PI: Ezra Wood

AQRP Project Manager: Vincent Torres

TCEQ Project Liaison: Erik Gribbin

Awarded Amount: $71,369.00

Abstract

Ozone concentrations in Bexar county have exceeded the Environmental Protection Agency's Air Quality Standard. To develop and implement ozone mitigation strategies, regulators and air quality planners require information regarding the mechanisms by which ozone is formed in San Antonio, including information on its dependence on the emissions of nitrogen oxides and volatile organic compounds.

In 2017, during the San Antonio Field Study, a team of researchers conducted a field study focused on ozone air pollution in the greater San Antonio Area. Included in the study were measurements of the concentration of total peroxy radicals which allow for the instantaneous gross ozone formation rate to be directly calculated. As a result of the analysis of the data collected, the team concluded that in Floresville (usually upwind of San Antonio during the most common wind patterns) and at the University of Texas at San Antonio (usually downwind), ozone formation was limited by the emissions of nitrogen oxides and that biogenic volatile organic compounds accounted for a large (almost half) of the OH reactivity. These results strongly suggest that controls on volatile organic compound emissions were unlikely to be effective in mitigating high ozone events.

Measurements of total peroxy radicals were not collected in the central urban core of San Antonio, where nitrogen oxide concentrations were measured to be much greater at times than those at the upwind and downwind sites. As a result there is considerable uncertainty regarding how much ozone is formed in central San Antonio and how sensitive ozone concentrations might be to emissions of nitrogen oxides and volatile organic compounds. To address these knowledge gaps, the research team will participate in a field deployment to central San Antonio. This project entails four research tasks:

Prepare for the field deployment in San Antonio. This will consist of logistical planning with the other participants in the study (Rice University, Baylor University, and the University of Houston) and improvements to our analytical methods in the laboratory.
Field deployment in San Antonio. This will occur either in September 2020, or need be postponed to Spring 2021 because of the COVID-19 pandemic. Similar to the 2017 San Antonio Field Study, the Drexel team will deploy its "ECHAMP" sensor that quantifies concentrations of peroxy radicals.
Data Quality Assurance. The data from the field deployment will be quality assured and prepared for the subsequent analysis.
Preliminary Data Analysis. Using the collected measurements of peroxy radicals and nitric oxide, we will calculate the instantaneous ozone formation rates and characterize their dependence on concentrations of nitrogen oxides and volatile organic compounds.

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Research

Research

FY 2020 - 2021

Project Number: 20-028