Browsing by Author "Min, K.-E."
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Item Airborne measurements of the atmospheric emissions from a fuel ethanol refinery(AGU Pubication, 2015-04-08) Gouw, J. A. de; McKeen, S. A.; Aikin, K. C.; Brock, C. A.; Brown, S. S.; Gilman, J. B.; Graus, M.; Hanisco, T.; Holloway, J. S.; Kaiser, J.; Keutsch, F. N.; Lerner, B.M.; Liao, J.; Markovic, M. Z.; Middlebrook, A. M.; Min, K.-E.; Neuman, J. A.; Nowak, J. B.; Peischl, J.; Pollack, I. B.; Roberts, J. M.; Ryerson, T. B.; Trainer, M.; Veres, P. R.; Warneke, C.; Welti, A.; Wolfe, G. M.Ethanol made from corn now constitutes approximately 10% of the fuel used in gasoline vehicles in the U.S. The ethanol is produced in over 200 fuel ethanol refineries across the nation. We report airborne measurements downwind from Decatur, Illinois, where the third largest fuel ethanol refinery in the U.S. is located. Estimated emissions are compared with the total point source emissions in Decatur according to the 2011 National Emissions Inventory (NEI‐2011), in which the fuel ethanol refinery represents 68.0% of sulfur dioxide (SO₂), 50.5% of nitrogen oxides (NOₓ = NO + NO₂), 67.2% of volatile organic compounds (VOCs), and 95.9% of ethanol emissions. Emissions of SO₂ and NOₓ from Decatur agreed with NEI‐2011, but emissions of several VOCs were underestimated by factors of 5 (total VOCs) to 30 (ethanol). By combining the NEI‐2011 with fuel ethanol production numbers from the Renewable Fuels Association, we calculate emission intensities, defined as the emissions per ethanol mass produced. Emission intensities of SO₂ and NOₓ are higher for plants that use coal as an energy source, including the refinery in Decatur. By comparing with fuel‐based emission factors, we find that fuel ethanol refineries have lower NOₓ, similar VOC, and higher SO₂ emissions than from the use of this fuel in vehicles. The VOC emissions from refining could be higher than from vehicles, if the underestimated emissions in NEI‐2011 downwind from Decatur extend to other fuel ethanol refineries. Finally, chemical transformations of the emissions from Decatur were observed, including formation of new particles, nitric acid, peroxyacyl nitrates, aldehydes, ozone, and sulfate aerosol.Item Eddy covariance fluxes of acyl peroxy nitrates (PAN, PPN and MPAN) above a Ponderosa pine forest(Copernicus, 2009-01-27) Wolfe, G. M.; Thornton, J. A.; Yatavelli, R. L. N.; McKay, M.; Goldstein, A. H.; LaFranchi, B.; Min, K.-E.; Cohen, R.C.During the Biosphere Effects on AeRosols and Photochemistry EXperiment 2007 (BEARPEX-2007), we observed eddy covariance (EC) fluxes of speciated acyl peroxy nitrates (APNs), including peroxyacetyl nitrate (PAN), peroxypropionyl nitrate (PPN) and peroxymethacryloyl nitrate (MPAN), above a Ponderosa pine forest in the western Sierra Nevada. All APN fluxes are net downward during the day, with a median midday PAN exchange velocity of −0.3 cm s⁻¹; nighttime storage-corrected APN EC fluxes are smaller than daytime fluxes but still downward. Analysis with a standard resistance model shows that loss of PAN to the canopy is not controlled by turbulent or molecular diffusion. Stomatal uptake can account for 25 to 50% of the observed downward PAN flux. Vertical gradients in the PAN thermal decomposition (TD) rate explain a similar fraction of the flux, suggesting that a significant portion of the PAN flux into the forest results from chemical processes in the canopy. The remaining "unidentified" portion of the net PAN flux (~15%) is ascribed to deposition or reactive uptake on non-stomatal surfaces (e.g. leaf cuticles or soil). Shifts in temperature, moisture and ecosystem activity during the summer – fall transition alter the relative contribution of stomatal uptake, non-stomatal uptake and thermochemical gradients to the net PAN flux. Daytime PAN and MPAN exchange velocities are a factor of 3 smaller than those of PPN during the first two weeks of the measurement period, consistent with strong intra-canopy chemical production of PAN and MPAN during this period. Depositional loss of APNs can be 3–21% of the gross gas-phase TD loss depending on temperature. As a source of nitrogen to the biosphere, PAN deposition represents approximately 4–19% of that due to dry deposition of nitric acid at this site.Item Observations of atmosphere-biosphere exchange of total and speciated peroxynitrates: nitrogen fluxes and biogenic sources of peroxynitrates(Copernicus Publications, 2012-10-29) Min, K.-E.; Pusede, S. E.; Browne, E. C.; LaFranchi, B. W.; Wooldridge, P. J.; Wolfe, G. M.; Harrold, S. A.; Thornton, J. A.; Cohen, R. C.Peroxynitrates are responsible for global scale transport of reactive nitrogen. Recent laboratory observations suggest that they may also play an important role in delivery of nutrients to plant canopies. We measured eddy covariance fluxes of total peroxynitrates (ΣPNs) and three individual peroxynitrates (APNs ≡ PAN + PPN + MPAN) over a ponderosa pine forest during the Biosphere Effects on AeRosols and Photochemistry EXperiment 2009 (BEARPEX 2009). Concentrations of these species were also measured at multiple heights above and within the canopy. While the above-canopy daytime concentrations are nearly identical for ΣPNs and APNs, we observed the downward flux of ΣPNs to be 30–60% slower than the flux of APNs. The vertical concentration gradients of ΣPNs and APNs vary with time of day and exhibit different temperature dependencies. These differences can be explained by the production of peroxynitrates other than PAN, PPN, and MPAN within the canopy (presumably as a consequence of biogenic VOC emissions) and upward fluxes of these PN species. The impact of this implied peroxynitrate flux on the interpretation of NOx fluxes and ecosystem N exchange is discussed.Item On the temperature dependence of organic reactivity, nitrogen oxides, ozone production, and the impact of emission controls in San Joaquin Valley, California(Copernicus Publications, 2004-04-04) Pusede, S. E.; Gentner, D. R.; Wooldridge, P. J.; Browne, E. C.; Rollins, A. W.; Min, K.-E.; Russell, A. R.; Thomas, J.; Zhang, L.; Brune, W. H.; Henry, S. B.; DiGangi, J. P.; Keutsch, F. N.; Harrold, S. A.; Thornton, J. A.; Beaver, M. R.The San Joaquin Valley (SJV) experiences some of the worst ozone air quality in the US, frequently exceeding the California 8 h standard of 70.4 ppb. To improve our understanding of trends in the number of ozone violations in the SJV, we analyze observed relationships between organic reactivity, nitrogen oxides (NOₓ), and daily maximum temperature in the southern SJV using measurements made as part of California at the Nexus of Air Quality and Climate Change in 2010 (CalNex-SJV). We find the daytime speciated organic reactivity with respect to OH during CalNex-SJV has a temperature-independent portion with molecules typically associated with motor vehicles being the major component. At high temperatures, characteristic of days with high ozone, the largest portion of the total organic reactivity increases exponentially with temperature and is dominated by small, oxygenated organics and molecules that are unidentified. We use this simple temperature classification to consider changes in organic emissions over the last and next decade. With the CalNex-SJV observations as constraints, we examine the sensitivity of ozone production (PO₃) to future NOₓ and organic reactivity controls. We find that PO₃ is NOₓ-limited at all temperatures on weekends and on weekdays when daily maximum temperatures are greater than 29 °C. As a consequence, NOₓ reductions are the most effective control option for reducing the frequency of future ozone violations in the southern SJV.