Acyl Peroxy Nitrates Link Oil and Natural Gas Emissions to High Ozone Abundances in the Colorado Front Range During Summer 2015

We present measurements of ozone (O3), acyl peroxy nitrates (APNs), and a suite of O3 precursors made at the Boulder Atmospheric Observatory in Erie, Colorado, during summer 2015. We employ an empirical analysis of the APNs and a previously described positive matrix factorization of the volatile organic compounds (VOCs) to investigate the contribution of different VOC sources to high O3 abundances at Boulder Atmospheric Observatory. Based on the ratio of peroxypropionyl nitrate (PPN) to peroxyacetyl nitrate (PAN), we find that anthropogenic VOC precursors dominate APN production when O3 is most elevated. Propane and larger alkanes, primarily from oil and natural gas emissions in the Colorado Front Range, drive these elevated PPN to PAN ratios during high O3 events. The percentage of OH reactivity associated with oil and gas emissions is also positively correlated with O3 and PPN/PAN. Idealized box model simulations are used to probe the chemical mechanisms potentially responsible for these observations. We find that observed abundances of long‐lived oil and natural gas‐related VOCs are likely high enough such that the oxidation of these VOCs in a single photochemical day produces sufficient peroxy radicals to contribute to O3 formation in the northern Colorado Front Range. Based on our empirical observations and box model simulations, we conclude that oil and natural gas emissions contribute to O3 production on high O3 days in this region during summer 2015. Key Points Anthropogenic VOC precursors dominate APN production when ozone is most elevated in the Colorado Front Range in summer 2015 Propane and n‐pentane, primarily from oil and natural gas emissions, drive elevated PPN/PAN ratios during high‐ozone events Emissions from the oil and natural gas sector contribute to O3 production on high O3 days