Articles | Volume 14, issue 19
Atmos. Chem. Phys., 14, 10439–10464, 2014

Special issue: Megapoli-Paris 2009/2010 campaign

Atmos. Chem. Phys., 14, 10439–10464, 2014

Research article 01 Oct 2014

Research article | 01 Oct 2014

Volatile and intermediate volatility organic compounds in suburban Paris: variability, origin and importance for SOA formation

W. Ait-Helal3,2,1, A. Borbon3, S. Sauvage2,1, J. A. de Gouw5,4, A. Colomb6, V. Gros7, F. Freutel8, M. Crippa9,*, C. Afif10,3, U. Baltensperger9, M. Beekmann3, J.-F. Doussin3, R. Durand-Jolibois3, I. Fronval2,1, N. Grand3, T. Leonardis2,1, M. Lopez7, V. Michoud3, K. Miet3, S. Perrier3,**, A. S. H. Prévôt9, J. Schneider8, G. Siour3, P. Zapf3, and N. Locoge2,1 W. Ait-Helal et al.
  • 1Université Lille Nord de France, 59000, Lille, France
  • 2École des Mines de Douai, Département Chimie et Environnement, 59508 Douai CEDEX, France
  • 3LISA, UMR-CNRS 7583, Université Paris Est Créteil (UPEC), Université Paris Diderot (UPD), Institut Pierre Simon Laplace (IPSL), Créteil, France
  • 4Chemical Sciences Division, Earth System Research Laboratory, NOAA, Boulder, Colorado, USA
  • 5Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
  • 6LaMP, UMR-CNRS 6016, Clermont Université, Université Blaise Pascal, Aubière, France
  • 7LSCE, CNRS 8212, CEA, Université de Versailles Saint-Quentin en Yvelines, Gif sur Yvette, France
  • 8Max Planck Institute for Chemistry, Mainz, Germany
  • 9Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen, Switzerland
  • 10Centre d'Analyses et de Recherche, Faculty of sciences, Université Saint Joseph, Beirut, Lebanon
  • *now at: EC Joint Research Centre (JRC), Inst. Environment & Sustainability, Via Fermi, 2749, 21027 Ispra, Italy
  • **now at : ISA, UMR-CNRS 5280, Université Lyon 1, ENS-Lyon, Villeurbanne, France

Abstract. Measurements of gaseous and particulate organic carbon were performed during the MEGAPOLI experiments, in July 2009 and January–February 2010, at the SIRTA observatory in suburban Paris. Measurements comprise primary and secondary volatile organic compounds (VOCs), of both anthropogenic and biogenic origins, including C12–C16 n-alkanes of intermediate volatility (IVOCs), suspected to be efficient precursors of secondary organic aerosol (SOA). The time series of gaseous carbon are generally consistent with times series of particulate organic carbon at regional scale, and are clearly affected by meteorology and air mass origin. Concentration levels of anthropogenic VOCs in urban and suburban Paris were surprisingly low (2–963 ppt) compared to other megacities worldwide and to rural continental sites. Urban enhancement ratios of anthropogenic VOC pairs agree well between the urban and suburban Paris sites, showing the regional extent of anthropogenic sources of similar composition. Contrary to other primary anthropogenic VOCs (aromatics and alkanes), IVOCs showed lower concentrations in winter (< 5 ppt) compared to summer (13–27 ppt), which cannot be explained by the gas-particle partitioning theory. Higher concentrations of most oxygenated VOCs in winter (18–5984 ppt) suggest their dominant primary anthropogenic origin. The respective role of primary anthropogenic gaseous compounds in regional SOA formation was investigated by estimating the SOA mass concentration expected from the anthropogenic VOCs and IVOCs (I / VOCs) measured at SIRTA. From an integrated approach based on emission ratios and SOA yields, 38 % of the SOA measured at SIRTA is explained by the measured concentrations of I / VOCs, with a 2% contribution by C12–C16 n-alkane IVOCs. From the results of an alternative time-resolved approach, the average IVOC contribution to SOA formation is estimated to be 7%, which is half of the average contribution of the traditional aromatic compounds (15%). Both approaches, which are based on in situ observations of particular I / VOCs, emphasize the importance of the intermediate volatility compounds in the SOA formation, and support previous results from chamber experiments and modeling studies. They also support the need to make systematic the IVOCs' speciated measurement during field campaigns.

Final-revised paper