Volatile Organic Compound Emissions from Oil and Gas Development and Impacts on Aerosol Formation

KATARINA KONON, Pearl Abue, Leif Jahn, Lea El Khoury, Austin Turner, Daniel C. Blomdahl, Evelyn Deveraux, Chou-Hsien Lin, Mrinali Modi, Kristi McPherson, David T. Allen, Pawel K. Misztal, Lea Hildebrandt Ruiz, University of Texas at Austin

     Abstract Number: 465
     Working Group: Coast to Coast Campaigns on Aerosols, Clouds, Chemistry, and Air Quality

Abstract
Oil and gas development (OGD) in the United States continues to grow thanks to technologies such as hydraulic fracturing and horizontal drilling. However, the effects of OGD on air quality, climate, and human health are poorly characterized. We took gas-phase and particle-phase measurements in the spring and fall of 2023 in Karnes City, a rural town located within a large oil and gas production region in south-central Texas called the Eagle Ford Shale. This work focuses on gas-phase volatile organic compound (VOC) emissions measured using a Vocus high resolution proton transfer reaction time-of-flight mass spectrometer (Vocus), iodide high resolution time-of-flight chemical ionization mass spectrometer (CIMS), and automated gas chromatograph (GC). Overall, we find that OGD emits VOCs with high potential to form secondary pollutants such as organic aerosol.

Throughout both campaigns, we observed intermittent plumes of alkanes and aromatic hydrocarbons. These plumes vary in duration from a few minutes to a few hours and their intermittent behavior cannot be fully explained by meteorology, suggesting that the plumes are due to OGD emissions. We observed a maximum concentration of 5.4 parts per million (ppm) methane, which is over two times background levels (~2 ppm). The average ratio of ethane to methane in plumes was 0.18, which is consistent with previously reported shale gas characteristics in the Eagle Ford Shale. In the Vocus data, we see some larger molecules (>C10) that are often not detected by traditional GC analysis and can contribute substantially to secondary organic aerosol formation. In the CIMS data, we see chlorine which is a highly reactive oxidant. Chlorine and other oxidants react with VOCs to form secondary pollutants including ozone and secondary organic aerosol, which is a problem for human health and compliance with federal air quality standards in downwind regions such as San Antonio.