Articles | Volume 14, issue 21
Atmos. Chem. Phys., 14, 11557–11569, 2014
Atmos. Chem. Phys., 14, 11557–11569, 2014

Research article 05 Nov 2014

Research article | 05 Nov 2014

Composition of 15–85 nm particles in marine air

M. J. Lawler1,2, J. Whitehead3, C. O'Dowd4, C. Monahan4, G. McFiggans3, and J. N. Smith1,2,5 M. J. Lawler et al.
  • 1Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, USA
  • 2Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
  • 3Centre for Atmospheric Science, University of Manchester, Manchester, UK
  • 4School of Physics and Centre for Climate & Air Pollution Studies, National University of Ireland Galway, Ireland
  • 5Finnish Meteorological Institute, Kuopio, Finland

Abstract. The chemical composition of 15–85 nm diameter particles was measured at Mace Head, Ireland, during May 2011 using the TDCIMS (thermal desorption chemical ionization mass spectrometer). Measurable levels of chloride, sodium, and sulfate were present in essentially all collected samples of these particles at this coastal Atlantic site. Acetaldehyde and benzoic acid were also frequently detected. Concomitant particle hygroscopicity observations usually showed a sea-salt mode and a lower hygroscopicity mode with growth factors near to that of ammonium sulfate. There were many periods lasting from hours to about 2 days during which the 10–60 nm particle number increased dramatically in polar oceanic air. These periods were correlated with the presence of benzoic acid in the particles and an increase in the number of lower hygroscopicity mode particles. Very small (< 10 nm) particles were also present, suggesting that new particle formation contributed to these nanoparticle enhancement events.

Short summary
This work describes the chemical and physical characterization of very small (< 100 nm diameter) particles in the marine atmosphere. We show that sea salt is present even at very small sizes and present evidence that organic species are important contributors to apparent new particle formation events over the ocean.
Final-revised paper