Date of Award
Doctor of Philosophy (PhD)
Joost de Gouw
Volatile organic compounds (VOCs) are ubiquitous in the troposphere. They can have significant human health effects, and contribute to the formation of ozone and secondary organic aerosol. The insight we gain from taking detailed, precise measurements of VOCs is essential to understanding chemical processes in the atmosphere, and to making informed policy decisions about air quality. This thesis describes the development of chemical ionization mass spectrometry (CIMS) techniques to measure VOCs, specifically H3O+ CIMS (proton-transfer-reaction mass spectrometry, PTR-MS) and NO+ CIMS, and the application of those techniques to VOC chemistry related to fossil fuel production and use.
Instrument development in this work includes (1) the development and characterization of a high-resolution H3O+ time-of-flight chemical ionization mass spectrometer (H3O+ ToF-CIMS, or PTR-ToF-MS) and (2) the development and evaluation of NO+ chemical ionization mass spectrometry (NO+ CIMS).
Applications have focused on air quality issues in oil and natural gas producing regions in the US, which have experienced a recent, rapid increase in production. In these regions, VOC and NOx emissions have raised concerns about the release of air toxics, greenhouse gases, and ozone precursors. This thesis describes the deployment of PTR-MS and H3O+ ToF-CIMS in two major field intensives investigating the oil and natural gas extraction industry: the Uintah Basin Winter Ozone Study in 2013, and the Shale Oil and Natural Gas Nexus study in 2015. An additional mobile laboratory project demonstrates the utility of NO+ CIMS to measure on-road VOC emissions.
H3O+ and NO+ CIMS are powerful techniques that provide detailed and highly time-resolved information about VOCs in ambient air. This thesis adds to our knowledge of VOCs in oil- and gas-producing regions, contributes a framework for interpreting PTR-ToF-MS measurements in oil and gas producing regions, and provides a foundation for NO+ CIMS measurements of ambient air.
Koss, Abigail R., "New Insights into Fossil Fuel Volatile Organic Compound Emissions and Chemistry Using H3O+ and NO+ Chemical Ionization Mass Spectrometry" (2017). Chemistry & Biochemistry Graduate Theses & Dissertations. 214.