Increased Ozone Levels Linked to Oil and Gas Emissions

A study published in the journal Environmental Science and Technology suggests a strong link between oil and gas emissions and the high production of ozone in the atmosphere during the winter months in the Uintah Basin in Utah, USA.1 Scientists from the Institute of Arctic and Alpine Research (INSTAAR) at the University of Colorado in the USA performed continuous measurements of ozone, methane, and a suite of nonmethane hydrocarbons (NMHCs) above the basin between January and February in 2012 and 2013.

The Utah Department of Environmental Quality state on their website that ozone in the Basin is unique because it only occurs during the wintertime; previous studies have only looked at summertime ozone levels. This is an issue because the problem of ozone accumulation is clear but the reasons why it occurs are not fully understood. The team from INSTAAR set out to investigate the effects of oil and gas production on the production of ozone that is created as a byproduct of volatile organic compounds (VOCs) reacting with nitrogen oxides. According to a press release from the institute,² two of the highest producing oil and gas fields are based in the Uintah Basin with an estimated 4300 oil- and 6900 gas‑producing wells, and proposals for another 25,000.²

Lead author Detlev Helmig of INSTAAR told The Column: “Exceedances of the ozone National Air Quality Standard in air near the surface in the Uintah Basin oil and gas development region have been more frequent and higher than in the most polluted US inner cities. This study was part of a multi-agency campaign to study the emissions and chemistry leading to this high ozone production.”

Samples were collected from sampling inlets on a tower and a tethered balloon on the northern edge of a gas field in the Basin at a height of 500 m. UV absorption monitors were used to measure ozone, and other gases were measured with a gas chromatograph–flame ionization detector (GC–FID). According to the paper, the measurements identified highly elevated levels of VOCs at 200–300 times above regional and seasonal background levels at the same time as ozone accumulation.

Helmig said: “Our findings demonstrate that leakage from oil and gas operations results in highly elevated levels of volatile organic compounds in the near-surface atmosphere, and that these high levels of VOC play a crucial role in fueling the ozone production chemistry.” - B.D.

References
1. D. Helmig et al., Environmental Science and Technology DOI: 10.1021/es405046r (2014).
2. Institute of Arctic and Alpine Research, University of Colorado Boulder, http://instaar.colorado.edu/news-events/instaar-news/uintah-basin-ozone-study-is-acs-editors-choice/ [Last accessed 28 April 2014].

This article is from The Column. The full issue can be found here: