The Colorado Front Range (CFR) currently violates the 8-hour National Ambient Air Quality Standard for ozone. Ground level ozone (O3) is produced when volatile organic compounds (VOCs) are oxidized in the presence of NOx, and either precursor class can be limiting. The emissions of VOCs from oil and gas development in the CFR are poorly constrained and thus their contribution to regional and local photochemistry is uncertain. The Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) was an extensive aircraft and ground-based campaign aimed at characterizing the regional chemical environment in the CFR. Two campaign goals were to constrain the emissions of O3 precursors and the subsequent O3 formation rates. A large suite of trace gases and aerosols were measured during FRAPPÉ at the Boulder Atmospheric Observatory (BAO), including O3, NOx, NOy, CH4, CO, CO2, and several PAN homologues. The BAO, located 35 km north of Denver and on the southwestern side of the Denver-Julesburg Basin, affords the opportunity to sample a wide variety of air masses, including those impacted by emissions from oil and gas development, agriculture, and the urban Denver plume. PANs were measured with a custom gas chromatograph with an electron capture detector at a 5-minute sampling resolution. Preliminary results indicate average PAN values over the intensive to be 238 pptv, with 4 days in exceedance of 1000 pptv. Average PPN values were 36 pptv. High PPN and PAN values were associated with O3 &gt; 80 ppbv. Preliminary analyses indicate that when PAN is elevated, there is a PPN/PAN ratio (~20%) indicative of chemistry dominated by anthropogenic VOCs. Ongoing analyses include: 1) using a Lagrangian transport and dispersion model (FLEXPART) to determine the importance of emissions from oil and gas development during high PAN days, 2) examining PAN/NOy ratios to determine the impact of the emissions from nearby oil and gas development on reactive nitrogen partitioning, and 3) using the observed PAN speciation to untangle contributions of VOC sources to local O3 production.

Observations of acyl peroxyl nitrates (PANs) during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) field campaign

249th National Meeting (2015)

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