Ozone mixing ratio exceeds 100 parts per billion multiple times per winter in areas of heavy gas and oil exploration in remote Utah and Wyoming basins, but the exact chemistry that leads to elevated ozone remains unclear. A visible haze consisting principally of organic and, to a lesser extent, nitrate aerosol is formed during these events. This aerosol has significant impacts on the gas-phase chemistry that regulates ozone formation. Aerosol particles play an important role in the oxidized nitrogen budget, formation of nitrous acid, and release of chlorine atoms after particle-phase formation of nitryl chloride from dinitrogen pentoxide and particle-phase chloride. This project aims to study the source, formation mechanism, and impact of aerosol particles formed during wintertime high-ozone events. Aerosol composition will be measured with an aerosol mass spectrometer (AMS) during a six-week field campaign from mid-January to early March, 2012 titled, "Energy and Environment - Uintah Basin Winter Ozone Study (E&E UBWOS)". The study includes a wide array of instrumentation to measure volatile organic compounds, gas-phase nitrogen oxide species, and oxidants. These gas-phase measurements will add significant context and depth to the AMS measurements of particulate mass and chemistry.
Aerosol formed during high-ozone events degrades visibility and is a health concern for the people of Utah and Wyoming. The results of E&E UBWOS will be compiled into a final report that will be referenced by the Utah Department of Environmental Quality during future decisions on how to address the ozone and aerosol problems in the region. The data will also be publically available after one year. Data from the AMS will be analyzed by graduate students, presented at national conferences, and written up for publication in relevant journals with graduate student co-authors. Data from this study will be integrated into the atmospheric chemistry course in the Department of Atmospheric Science at the University of Wyoming as a locally relevant case study. Participation in this study will establish a new relationship between scientists in the department and in the Earth Systems Research Laboratory at NOAA.
The aim of this project was to determine the magnitude and mechanism of particle formation in areas of oil and gas exploration that experience high ozone events. Ozone concentrations exceed 100 ppb multiple times per winter in certain Utah and Wyoming basins, but the exact chemistry that leads to elevated ozone was unclear before this project. A visible haze consisting principally of organic, and to a lesser extent, nitrate aerosol is formed during high-ozone events. During this project, we successfully deployed an aerosol mass spectrometer (AMS) in 2012 to the Uintah Basin near Vernal, Utah. The deployment of the AMS was part of a large field campaign inolving numerous universities and national labs. The mass spectrometer ran nearly continuously and collected data during January and February. High ozone is only observed in winters where there is significant snow cover and strong inversions. Neither of these conditions existed during our 2012 deployment focused on aerosol composition. Nonetheless we were able to observe the formation of organic aerosol and to correlate it with the oxidation of gas-phase VOC. The organic aerosol showed no obvious correlation with combustion tracers, suggesting that it is secondary and not emitted directly from a source. Chemically-resolved size distributions also showed that the organic aerosol was in a different size mode than background aerosols. All of these results together suggest that the organic aerosol is formed in the gas and oil fields in the Uintah Basin and not imported from other areas. During 2012 the amount of organic aerosol formed was relatively modest, reaching a maximum concentration of approximately 6 micrograms per cubic meter. While this amount is well below National Ambient Air Quality Standards (NAAQS), it is significant in a region where visibility is of vital concern to National Parks and Wilderness. Subsequent measurements of aerosol mass and composition have been carried out by other researchers in 2013 and 2014. In 2013 numerous high ozone events were observed. Work is currently underway to integrate our size and chemically resolved measurements from 2012 with their measurements form subsequent years to determine the magnitude of secondary organic aerosol formation during high ozone events. In 2013 we deployed a mass spectrometer (PTR-TOFMS) that measures gas-phase VOC. The goal of this deployment was to better understand the oxidation of VOC occurring in the gas-phase leading to organic aerosol and ozone formation. The PTR-TOFMS ran nearly continuously from late January to late February fo 2013. The results give insight into the degree of VOC oxidation and the species formed in the gas phase. Measurements form the PTR-TOFMS have been integrated into a chemical model that is able to simulate the high–ozone events that occurred in 2013. Additionally, it was shown that the PTR-TOFMS results matched older technologies to measure VOC but with improved sensitivity and improved identification of individual compounds. The PTR-TOFMS also successfully observed H2S, a hazardous air pollutant, and this data was utilized to estimate the flux of H2S from the Uintah Basin. Data from the PTR-TOFMS in 2013 and aerosol data from 2012 and 2013 gives us the ability to begin to unravel how much aerosol is being formed and if current aerosol models can successfully predict this formation.
