Assessing the impact of oil and gas activities on ambient hydrocarbon concentrations in North Texas: A retrospective analysis from 2000 to 2022

Over the past two decades, significant advancements in shale gas extraction technologies have led to a vast increase in oil and gas production in the Barnett Shale region of North Texas. This study provides a detailed analysis of the trends in air pollutants, such as total nonmethane hydrocarbons (NMHC), linked to oil and gas production changes in the Barnett shale region from 2000 to 2022. The analysis spans urban (Dallas - DAL), semi-urban (Fort Worth - FWNW), and non-urban (Denton - DEN) ambient air quality monitoring sites operated by the Texas Commission on Environmental Quality (TCEQ), highlighting how varying levels of urbanization and industrial activities influence air quality. DEN recorded the highest NMHC concentrations at an average of 210.27 ppb-C, significantly exceeding those at FWNW (83.14 ppb-C) and DAL (62.50 ppb-C). Alkanes were the predominant NMHCs across all sites, forming 96% at DEN, 89% at FWNW, and 67% at DAL. The i/n-pentane ratio at DEN suggests oil and gas activities as the main NMHC source, whereas DAL, and FWNW indicate substantial influences from urban traffic alongside industrial emissions. NMHC concentrations at DEN and FWNW correlated strongly with gas and condensate production, demonstrating a shift from condensate to gas over the study period.