Composition of 15–85 nm particles in marine air
- 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.