UW Researchers Contribute to Paper Examining High Winter Ozone Levels

Three University of Wyoming researchers participated in a study about high winter ozone levels near an oil and gas field in Utah, an analysis that could help inform future monitoring and mitigation strategies for air quality impacts from oil and gas extraction -- and provide broader insight into the response of winter ozone to primary pollutants.

Shane Murphy, an assistant professor in the UW Department of Atmospheric Science, and Robert Field and Jeff Soltis, both associate research scientists in the department, contributed to a research paper, titled “High Winter Ozone Generated by Carbonyl Photolysis in a Shale Gas and Oil Producing Region,”  published in the Oct. 1 issue of Nature. Nature is an international weekly journal of science that publishes peer-reviewed research in all fields of science and technology.

Researchers learned that wintertime ozone production in the Uintah Basin occurs at lower concentrations of nitrogen oxides (NO) and much larger volatile organic compound (VOC) concentrations compared to summertime zone production in most urban areas. Data for the study were gathered from the basin in northeastern Utah during January and February of 2012, 2013 and 2014.

“In 2013, if you were living near Vernal, Utah, you were actually exposed to more ozone than Riverside, Calif.,” Murphy says.

The chart he pointed to showed Riverside, in traditionally smog-laden Southern California, had 28 days in which maximum air quality standard ozone levels were exceeded. Vernal, Utah, by comparison, had 49 days when air quality standard ozone levels were exceeded. High ozone levels can cause or exacerbate health problems, especially with breathing, Murphy says.

Vernal is a city that sits on the edge of the Uintah Basin, an area of intensive oil and gas development with approximately 11,000 gas wells.

Ground-level ozone is a major component of smog and is created by chemical reactions between NO and VOCs. In a meteorological occurrence called inversion, these pollutants are trapped in a thin layer of air near the ground.

The phenomenon of wintertime ozone near oil and gas operations was first reported in scientific literature in 2009 based on observation from Wyoming’s Upper Green River Basin near Pinedale by Russ Schnell, deputy director of the Global Monitoring Division at the National Oceanic and Atmospheric Administration (NOAA ) and a 1974 UW graduate.

Unhealthy ozone levels typically are associated with hot, sunny days in urban environments. But the paper’s findings reveal the phenomenon has occurred in the Uintah Basin during the winter on sunny days when snow is on the ground and temperatures are near or below freezing, Murphy says.

“Recent observations in oil and gas-producing basins in the western United States have identified ozone mixing ratios well in excess of current air quality standards, but only during the winter season,” the paper states. “Our understanding of winter ozone production in these regions is scientifically challenging, as it occurs during cold, snow-covered periods when meteorological inversions concentrate air pollutants from oil and gas activities. But (its) when solar irradiance and absolute humidity, both required to initiate conventional photochemistry essential for ozone production, are at a minimum.”

“The paper explains the chemistry that forms ozone around oil and gas fields in the winter,” Murphy says. “It’s affected Utah. It’s affecting Wyoming and probably other places we don’t know about. So, why understand the chemistry? Why does it matter? It helps us to figure out how to fix the problem.”

The United States is experiencing the most rapid expansion in oil and gas production in four decades due, in large part, to the use of new extraction technology, such as horizontal drilling combined with hydraulic fracturing. Environmental impacts of this development -- from water quality to the climate influence of increased methane leakage -- have been a matter of intense debate, according to the paper.

“The big picture matters. There’s no sign we’ll reduce oil and gas expansion,” Murphy says. “I think both people and the industry want to reduce this ozone problem.”

To reduce VOCs, oil and gas companies would have to reduce or eliminate leakage from their operations, Murphy says.

“We have a mobile lab we drive around and can measure the amount of methane and VOC coming from individual oil and gas wells,” Murphy says of the research vehicle that contains numerous instruments to measure the levels of different compounds. “We can ask, ‘Where are the leaks coming from? How big are the leaks?’”

The Nature paper has 35 co-writers. Other agencies and universities involved in the study include: NOAA’s Earth System Research Laboratory; Air Quality Research Division, Environment Canada in Toronto; the University of Houston; the University of Colorado-Boulder; UCLA; University of York in the UK; University of Innsbruck in Innsbruck, Austria; and Memorial University of Newfoundland.

 

Hear Atmospheric Scientist Shane Murphy summarize the UW research published in the journal Nature.