Volatile Organic Compound and Ozone Measurements at Carlsbad Caverns National Park: Impacts of Oil and Natural Gas Operation Emissions on Park Air Quality

Air Monitoring, Methods, and Technology
Oral Presentation

Prepared by B. Sive1, K. Benedict2, Y. Zhou2, L. Naimie2, I. Pollack2, E. Fischer2, A. Prenni1
1 - National Park Service, Air Resources Division, 7333 W. Jefferson Ave, Lakewood, CO, 80235, United States
2 - Colorado State University, Department of Atmospheric Science, Fort Collins, CO, United States


Contact Information: [email protected]; 303 987 6947

ABSTRACT

Carlsbad Caverns National Park (CAVE) has recently experienced elevated ozone levels that exceed the EPA’s National Ambient Air Quality Standards (NAAQS) 70 ppb standard (10 8-hour exceedances in 2018, 8 in 2019), while there were no ozone NAAQS exceedances from 2013 through 2017. The Carlsbad Caverns Air Quality Study (CarCavAQS) was designed to examine the influence of regional sources, including urban emissions, increased oil and gas development, wildfires and other biogenic sources on the park and provide key insight into our understanding of the elevated ozone levels. The special study was conducted from 25 July through 4 September 2019, with a comprehensive suite of gaseous and particulate measurements made at the CAVE Biology Building. Volatile organic compounds (VOCs) were measured using a continuous real-time gas chromatographic (GC) system and a quadrupole proton-transfer reaction mass spectrometer (PTR-MS). Whole air samples were also collected in canisters around the region to aid in characterizing air mass transport from the source regions to the park. A signature of elevated nonmethane hydrocarbon mixing ratios was observed throughout the entire study period. Moreover, the C2-C5 alkane mixing ratios were approximately an order of magnitude greater than regional background levels. Light alkane mixing ratios at CAVE were similar to various other sites influenced by oil and gas emissions, and the i-pentane to n-pentane ratio clearly demonstrates the widespread impact from oil and gas production emissions throughout the region. Results from the CarCavAQS study will be presented, with an emphasis on VOC and ozone distributions.