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dc.contributor.authorGouw, J. A. de
dc.contributor.authorParrish, D. D.
dc.contributor.authorBrown, S. S.
dc.contributor.authorEdwards, P.
dc.contributor.authorGilman, J. B.
dc.contributor.authorGraus, M.
dc.contributor.authorHanisco, T. F.
dc.contributor.authorKaiser, J.
dc.contributor.authorKeutsch, F. N.
dc.contributor.authorKim, S.‐W.
dc.contributor.authorLerner, B. M.
dc.contributor.authorNeuman, J. A.
dc.contributor.authorNowak, J. B.
dc.contributor.authorPollack, I. B.
dc.contributor.authorRoberts, J. M.
dc.contributor.authorRyerson, T. B.
dc.contributor.authorVeres, P. R.
dc.contributor.authorWarneke, C.
dc.contributor.authorWolfe, G. M.
dc.date.accessioned2019-10-30T17:04:01Z
dc.date.available2019-10-30T17:04:01Z
dc.date.issued2019-07-05
dc.description.abstractAbstract During an airborne study in the Southeast United States, measured mixing ratios of biogenic hydrocarbons were systematically lower in air masses containing enhanced nitrogen oxides from power plants, which we attribute to increased concentrations of hydroxyl (OH) radicals within the power plant plumes. Plume transects at successively further downwind distances provide a decreasing gradient of nitrogen oxides (NOx) concentrations, which together with the implied loss rates of isoprene, constrains the OH dependence on NOx. We find that OH concentrations were highest at nitrogen dioxide concentrations near 1–2 ppbv and decreased at higher and at lower concentrations. These findings agree with the dependence of OH on NOx concentrations expected from known chemical reactions but are not consistent with some studies reporting direct OH measurements higher than expected in regions of the atmosphere with low NOx (NO < 0.08 and NO2 < 0.46 ppbv) and high biogenic hydrocarbon emissions. Plain Language Summary Hydroxyl radicals are the main chemical species that removes trace gases from the atmosphere. They determine the atmospheric lifetime of some greenhouse gases and chemicals involved with the destruction of the stratospheric ozone layer. Hydroxyl reactions also play an important role in air pollution chemistry. Measuring hydroxyl radicals is very challenging because of their high reactivity and low concentrations. Some recent measurements have shown unexpectedly high concentrations in relatively clean conditions. In this work, we indirectly estimated the dependence of hydroxyl radicals on the concentration of nitrogen oxides downwind from power plants in the Southeast United States. We observed that mixing ratios of isoprene, a reactive hydrocarbon released from deciduous trees to the atmosphere, were systematically lower in power plant plumes, caused by higher hydroxyl radical concentrations at the elevated nitrogen oxide concentrations. These findings can be explained by known chemical reactions but are not consistent with some studies that found unexpectedly high hydroxyl concentrations in relatively clean conditions.en_US
dc.description.sponsorshipThe SENEX data used in this study arepublicly available at http://www.esrl.noaa.gov/csd/groups/csd7/measurements/2013senex/P3/DataDownload/. We acknowledgehelpful discussions with MichaelTrainer, Hendrik Fuchs, and KedingLu. This work was supported byNOAA's Health of the Atmosphere andAtmospheric Chemistry and ClimatePrograms. We are thankful for the staffat the NOAA Aircraft OperationsCenter and the WP‐3Dflight crew forthe help in instrumenting the aircraftand for conducting theflights. Theformaldehyde measurements weremade possible withfinancial supportfrom the STAR grant program of theU.S. EPA (3540601). This research hasnot been subjected to EPA review andtherefore does not necessarily reflectthe views of the agency, and no officialendorsement should be inferred. J.Kaiser acknowledges support fromNASA Headquarters under the NASAEarth and Space Science FellowshipProgram grant NNX14AK97H.en_US
dc.description.urihttps://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL083044en_US
dc.format.extent9 pagesen_US
dc.genrejournal articlesen_US
dc.identifierdoi:10.13016/m2teq5-uyvq
dc.identifier.citationde Gouw, J. A., Parrish, D. D., Brown, S. S.,Edwards,P.,Gilman,J.B.,Graus,M.,etal.(2019). Hydrocarbon removal in powerplant plumes shows nitrogen oxidedependence of hydroxyl radicals.Geophysical Research Letters,46,7752–7760. https://doi.org/10.1029/2019GL083044en_US
dc.identifier.urihttps://doi.org/10.1029/2019GL083044
dc.identifier.urihttp://hdl.handle.net/11603/16007
dc.language.isoen_USen_US
dc.publisherAmerican Geophysical Unionen_US
dc.relation.isAvailableAtThe University of Maryland, Baltimore County (UMBC)
dc.relation.ispartofUMBC Joint Center for Earth Systems Technology
dc.relation.ispartofUMBC Faculty Collection
dc.rightsThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
dc.rights©2018. American Geophysical Union. All Rights Reserved.
dc.rightsAccess to this item will begin on 2019-12-19
dc.subjectbiogenic hydrocarbonsen_US
dc.subjecthydroxyl (OH) radicalsen_US
dc.subjectpower plant plumesen_US
dc.subjectchemical speciesen_US
dc.subjectgreenhouse gasesen_US
dc.titleHydrocarbon Removal in Power Plant Plumes Shows Nitrogen Oxide Dependence of Hydroxyl Radicalsen_US
dc.typeTexten_US


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