Evidence from firn air for recent decreases in non-methane hydrocarbons and a 20th century increase in nitrogen oxides in the northern hemisphereVisa övriga samt affilieringar
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2012 (Engelska)Ingår i: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 54Artikel i tidskrift (Refereegranskat) Published
Abstract [en]
The atmospheric evolution of eight non-methane hydrocarbons (ethane, acetylene, propane, n-butane, isobutane, n-pentane, isopentane and benzene) and five alkyl nitrates (2-propyl, 2-butyl, 3-methyl-2-butyl and the sum of 2+3-pentyl nitrates) are reconstructed for the latter half of the 20th century based on Arctic firn air measurements. The reconstructed trends of the non-methane hydrocarbons (NMHCs) show increasing concentrations from 1950 to a maximum in 1980 before declining towards the end of last century. These observations provide direct evidence that NMHCs in the northern hemisphere have declined substantially during the period 1980-2001. Benzene concentrations show a smaller increase between 1950 and 1980 than the other NMHCs indicating that additional sources of benzene, other than fossil fuel combustion, were likely important contributors to the benzene budget prior to and during this period. The declining benzene concentrations from 1980 to 2001 would suggest that biomass burning is unlikely to be important in the benzene budget as biomass burning emissions were reportedly increasing over the same period. Methyl and ethyl nitrate show growth patterns in the firn that suggested perturbation by in-situ production from an unidentified mechanism. However, the higher alkyl nitrates show evidence for increasing concentrations from 1950 to maxima in the mid 1990s before decreasing slightly toward the end of the last century. The differing atmospheric evolution of the alkyl nitrates relative to their parent hydrocarbons indicate an increase in their production efficiency per hydrocarbon molecule. Using a steady state analysis of hydrocarbon oxidation and alkyl nitrate production and loss we show that reactive nitrogen oxide (NOx) concentrations in the northern hemisphere have likely increased considerably between 1950 and 2001. (C) 2012 Elsevier Ltd. All rights reserved.
Ort, förlag, år, upplaga, sidor
2012. Vol. 54
Nyckelord [en]
Alkyl nitrates Hydrocarbons Benzene Firn air Atmospheric trends Nitrogen oxides volatile organic-compounds polar firn alkyl nitrates atmospheric transport lower stratosphere hydroxyl radicals carbon-monoxide emissions trends greenland Environmental Sciences & Ecology Meteorology & Atmospheric Sciences
Forskningsämne
SWEDARCTIC
Identifikatorer
URN: urn:nbn:se:polar:diva-1945DOI: 10.1016/j.atmosenv.2012.02.084OAI: oai:DiVA.org:polar-1945DiVA, id: diva2:810205
Anmärkning
ISI Document Delivery No.: 971JQ Times Cited: 4 Cited Reference Count: 57 Worton, David R. Sturges, William T. Reeves, Claire E. Newland, Mike J. Penkett, Stuart A. Atlas, Elliot Stroud, Verity Johnson, Kristen Schmidbauer, Norbert Solberg, Sverre Schwander, Jakob Barnola, Jean-Marc Worton, David/A-8374-2012 Worton, David/0000-0002-6558-5586 Natural Environmental Research Council (NERC); Energy, Environment and Sustainable Development Programme [EVK-CT2001-00116]; Agency in Denmark (SNF); Agency in Belgium (FNRS-CFB); Agency in France (IFRTP and INSU/CNRS); Agency in Germany (AWI); Agency in Iceland (Rannls); Agency in Japan (MEXT); Agency in Sweden (SPRS); Agency in Switzerland (SNF); Agency in United States of America (NSF) DRW acknowledges the Natural Environmental Research Council (NERC) for PhD, funding. This work is a contribution to the European Commission project CRYOSTAT (EVK-CT2001-00116) funded under the Energy, Environment and Sustainable Development Programme; 1998-2002. The North GRIP project is directed and organized by the Department of Geophysics at the Niels Bohr Institute for Astronomy, Physics and Geophysics, University of Copenhagen. It is being supported by Funding Agencies in Denmark (SNF), Belgium (FNRS-CFB), France (IFRTP and INSU/CNRS), Germany (AWI), Iceland (Rannls), Japan (MEXT), Sweden (SPRS), Switzerland (SNF) and the United States of America (NSF). 4 Pergamon-elsevier science ltd Oxford Environmental Sciences; Meteorology & Atmospheric Sciences
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