Evaluating oil and gas contributions to ambient nonmethane hydrocarbon mixing ratios and ozone-related metrics in the Colorado Front Range

Lyu, Congmeng; Capps, Shannon L.; Kurashima, Kent; Henze, D. K.; Pierce, Gordon; Hakami, Amir; Zhao, Shunliu; Resler, Jaroslav; Carmichael, Gregory R.; Sandu, Adrian; Russell, Armistead G.; Chai, Tianfeng; Milford, Jana B.

doi:10.1016/j.atmosenv.2020.118113

Cited by 7 publications

(13 citation statements)

References 41 publications

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“…Although propane mole fractions were highly elevated at BAO over the 8 years of observations, there was no clear evidence for overall changes in propane mole fractions during this time period in either the NE quadrant or south sector samples. Lyu et al (2021) reported lower propane values in 2015 data compared to 2013 from Platteville, which is located more toward the center of the DJB. The high year-to-year variability demonstrated in the 8years BAO data indicates that such short-term differences cannot be deemed representative of longer term changes.…”

Section: Discussionmentioning

confidence: 79%

Atmospheric oil and natural gas hydrocarbon trends in the Northern Colorado Front Range are notably smaller than inventory emissions reductions

Oltmans¹,

Cheadle

Helmig³

et al. 2021

Elementa: Science of the Anthropocene

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From 2008 to mid-2016, there was more than a 7-fold increase in oil production and nearly a tripling of natural gas production in the Colorado Denver–Julesburg Basin (DJB). This study utilized air samples collected at the Boulder Atmospheric Observatory (BAO) tower in southwestern Weld County in the DJB to investigate atmospheric mole fraction trends of methane and volatile organic compounds (VOCs). Elevated methane and propane mole fractions and low values (<1) in the ratio of i-pentane to n-pentane at BAO were found to be associated with flow patterns that transport air from the northeast (NE) to east (E) sector to the site, the direction where the primary locations of oil and natural gas (O&NG) extraction and processing activities are located. Median mole fractions of the O&NG tracer propane at BAO were 10 times higher than background values when winds came from the NE quadrant. This contrasts with lower mole fractions of O&NG-related constituents in air parcels arriving at BAO from the south, the direction of the major urban area of Denver. None of O&NG tracers, for example, methane and propane, show statistically significant trends in mole fraction (relative to the background) over the study period in air transported from the DJB. Also, longer term acetylene mole fraction changes were not seen in NE quadrant or south sector samples. A significant decline in the mole fraction ratio of i-pentane to n-pentane in the NE sector data provides evidence of an increasing influence of O&NG on the overall composition of VOCs measured at BAO, a change not seen in measurements from the south (urban) sector. These results suggest that O&NG emissions and resulting atmospheric mole fractions have remained relatively constant over 2008–2016. The behavior in the observations is in contrast to the most recent VOC emissions inventory. While the inventory projects O&NG total VOC emission reductions between 2011 and 2020, of –6.5% per year despite the large production increases, the best estimate of the propane emission rate of change for the DJB-filtered data during 2008–2016 is much smaller, that is, –1.5% per year.

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Section: Discussionmentioning

confidence: 79%

Atmospheric oil and natural gas hydrocarbon trends in the Northern Colorado Front Range are notably smaller than inventory emissions reductions

Oltmans¹,

Cheadle

Helmig³

et al. 2021

Elementa: Science of the Anthropocene

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“…Lyu et al. (2021) report a 33%–56% contribution from O&G sources to 6–9 a.m. MST Denver CAMP NMHC. Ortega et al.…”

Section: Resultsmentioning

confidence: 99%

“…Three‐hour samples were collected with summa canisters from 6 to 9 a.m. every six days, and the chemical constituents were analyzed following EPA Compendium Method TO‐15 (USEPA, 1999). Ethane and NMHC concentrations at Platteville are largely from O&G sources (Lyu et al., 2021). Ethane trends at this site are representative of O&G emission trends.…”

Section: Data Sources and Methodsmentioning

confidence: 99%

“…In a source‐apportionment study that considered trends from 2013 to 2016, Lyu et al. (2021) show a reduction of approximately 50% in NMHCs at the CDPHE Platteville site which is located within the DJ Basin in Weld County. They report that new state regulations and changes in operating practices made by the industry might explain the reductions in NMHC mixing ratios between 2013 and 2016.…”

Section: Introductionmentioning

confidence: 99%

“…Ortega et al (2021) found a positive trend of 0.9 ppb ±0.3% per year for ethane at a site north of Boulder from 2010 to 2019 using a solar absorption Fourier Transform InfraRed instrument. In a source-apportionment study that considered trends from 2013 to 2016, Lyu et al (2021) show a reduction of approximately 50% in NMHCs at the CDPHE Platteville site which is located within the DJ Basin in Weld County. They report that new state regulations and changes in operating practices made by the industry might explain the reductions in NMHC mixing ratios between 2013 and 2016.…”

mentioning

confidence: 99%

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Downward Trend in Methane Detected in a Northern Colorado Oil and Gas Production Region Using AIRS Satellite Data

Reddy

Taylor

2022

Earth and Space Science

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The oil and gas (O&G) sector is estimated to be the largest contributor to anthropogenic methane (CH4) emissions in Colorado. Since 2004, the State of Colorado has implemented multiple regulations to significantly reduce emissions from the O&G sector. The Denver‐Julesburg Basin (DJ Basin) is a significant O&G producing region in northern Colorado, and O&G production here has steadily increased over the last decade. To assess CH4 trends in Northern Colorado, we selected CH4 retrievals from the NASA Atmospheric Infrared Sounder (AIRS) instrument for 2003–2020. The study grid cell includes Denver, Boulder, and much of the dense O&G production in the DJ Basin. We computed mean June‐August ascending node AIRS 700 hPa CH4 for each year and subtracted mean June–August CH4 sampled at NOAA's Niwot Ridge (NWR) station, a high‐altitude background site. Differences represent estimated enhancement over background. Linear regression shows an annual change of −2.84 ppb ± 0.8 ppb from 2012 to 2020 (R2 0.90) and an estimated reduction of 56% for 2012–2020, despite substantial increases in O&G production. Local CH4 enhancement is strongly correlated with surface measurements of ethane at Platteville which is in the center of the O&G fields (correlation coefficient 0.96), and this is evidence that reductions in O&G emissions are driving reductions in CH4. We conclude that AIRS CH4 can be used to measure the efficacy of emissions control programs in this region and that regulatory requirements are having an effect.

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VOC source apportionment: How monitoring characteristics influence positive matrix factorization (PMF) solutions

Frischmon,

Hannigan

2024

Atmospheric Environment: X

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Evaluating oil and gas contributions to ambient nonmethane hydrocarbon mixing ratios and ozone-related metrics in the Colorado Front Range

Cited by 7 publications

References 41 publications

Atmospheric oil and natural gas hydrocarbon trends in the Northern Colorado Front Range are notably smaller than inventory emissions reductions

Atmospheric oil and natural gas hydrocarbon trends in the Northern Colorado Front Range are notably smaller than inventory emissions reductions

Downward Trend in Methane Detected in a Northern Colorado Oil and Gas Production Region Using AIRS Satellite Data

VOC source apportionment: How monitoring characteristics influence positive matrix factorization (PMF) solutions

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