Last updated: July 24, 2024
Article
Ozone pollution in Carlsbad Caverns tied to oil and natural gas development from the Permian Basin
NPS / B. Sive
Unhealthy levels of ozone levels can impact human health and harm vegetation in national parks. A new paper led by Colorado State University, in collaboration with the National Park Service Air Resources Division, shows that ozone concentrations at Carlsbad Caverns National Park often exceed the Environmental Protection Agency (EPA) health standard in the summer. More specifically, eight-hour ozone concentrations frequently exceed the EPA health standard of 70 parts per billion. Carlsbad Caverns National Park is located in southeast New Mexico and often sits downwind of the Permian Basin – one of the largest and most productive oil and natural gas areas in the country.
To determine the sources of the high ozone levels, researchers used measurements and models to explore potential sources of ozone precursors in the area. The data revealed that oil and natural gas development in the Permian Basin is a major driver of high ozone levels at Carlsbad Caverns. Activities like drilling and natural gas flaring were major contributors. The study also found that while both nitrogen oxides and volatile organic compounds contribute to ozone, local ozone production is most sensitive to nitrogen oxide levels. So, reducing nitrogen oxides will lead to more significant reductions in ozone.
Read more from the paper below.
Summertime Ozone Production at Carlsbad Caverns National Park, New Mexico: Influence of Oil and Natural Gas Development
Abstract
Southeastern New Mexico's Carlsbad Caverns National Park (CAVE) has increasingly experienced summertime ozone (O3) exceeding an 8-hr average of 70 parts per billion by volume (ppbv). The park is located in the western part of the Permian oil and natural gas (O&G) basin, where production rates have increased fivefold in the last decade. We investigate O3–precursor relationships by constraining the F0AM box model to observations of nitrogen oxides (NOx = NO + NO2) and a suite of volatile organic compounds (VOCs) collected at CAVE during summer 2019. O&G-related VOCs dominated the calculated VOC reactivity with hydroxyl radicals (OH) on days when O3 concentrations were primarily controlled by local photochemistry. Radical budget analysis showed that NOx levels were high enough to impose VOC sensitivity on O3 production in the morning hours, while subsequent NOx loss through photochemical consumption led to NOx-sensitive conditions in the afternoon. Maximum daily O3 was responsive to both NOx and O&G-related VOC reductions, with NOx reductions proving most effective. The model underestimated observed O3 during a 5-day high O3 episode that was influenced by photochemically aged O&G emissions, as indicated by back-trajectory analysis, low i-/n-pentane ratios, enhanced secondary VOCs, and low ratios of NOx to total reactive oxidized nitrogen (NOy). Model-observation agreement was improved by constraining model NOx with observed NOy, which approximates NOx at the time of emission, indicating that a large fraction of O3 during this episode was formed nonlocally.
Marsavin, A., Pan, D., Pollack, I. B., Zhou, Y., Sullivan, A. P., Naimie, L. E., et al. 2024. Summertime ozone production at Carlsbad Caverns National Park, New Mexico: Influence of oil and natural gas development. Journal of Geophysical Research: Atmospheres, 129, e2024JD040877. DOI: 10.1029/2024JD040877