Aerosol Science 41 (2010) 13 -- 22 Contents lists available at ScienceDirect Aerosol Science journal homepage: www.elsevier.com/locate/jaerosci Chemical characterisation of marine aerosol at Amsterdam Island during the austral summer of 2006–2007 Magda Claeys a , Wan Wang b , Reinhilde Vermeylen a , Ivan Kourtchev a , Xuguang Chi b , Yasmeen Farhat a, c , Jason D. Surratt d , Yadian Gómez-González a , Jean Sciare e , Willy Maenhaut b, ∗ a Department of Pharmaceutical Sciences, University of Antwerp (Campus Drie Eiken), Universiteitsplein 1, BE-2610 Antwerp, Belgium b Department of Analytical Chemistry, Institute for Nuclear Sciences, Ghent University, Proeftuinstraat 86, BE-9000 Gent, Belgium c Laboratoire de Radiochimie, Sciences Analytiques et Environnement (LRSAE), Université de Nice Sophie-Antipolis, Institut de Chimie de Nice, Parc Valrose, F-06108 Nice, France d Department of Chemistry, California Institute of Technology, Pasadena, CA 91125, USA e Laboratoire des Sciences du Climat et de l'Environnement, CNRS-CEA-IPSL, Orme des Merisiers, F-91191 Gif-sur-Yvette, France ARTICLE INFO ABSTRACT Article history: Received 28 February 2009 Received in revised form 5 August 2009 Accepted 7 August 2009 Keywords: Marine aerosols Water-soluble organic carbon Secondary organic aerosol Organosulphates Isoprene Atmospheric aerosols were collected in separate fine ( < 2.5 m) and coarse ( > 2.5 m) size fractions in the period December 2006–March 2007 at Amsterdam Island in the southern In- dian Ocean. A major objective of the study was to assess biogenic impact on the marine aerosol. The samples were analysed for organic carbon, water-soluble organic carbon, major inorganic ionic species, and organic species, including methanesulphonate (MSA), dicarboxylic acids, and organosulphates. The concentrations of sea salt, non-sea-salt sulphate, and water-soluble and water-insoluble organic matter (WSOM and WIOM) were estimated. Sea salt dominated the composition of the aerosol and accounted for 83% and 91% of the sum of the mass of the four aerosol types in the fine and coarse size fractions, respectively. WSOM, which can serve as a proxy for biogenic secondary organic aerosol (SOA), accounted for only 2.8% of the sum of the mass of the four aerosol types in the fine size fraction. MSA was the dominating organic compound with a median concentration of 47 ng m -3 . The organosulphates were char- acterised as sulphate esters of hydroxyl acids and a dihydroxylaldehyde, which may originate from the oxidation of algal/bacterial unsaturated fatty acid residues. No evidence was found for isoprene SOA. © 2009 Elsevier Ltd. All rights reserved. 1. Introduction A chemical characterisation was carried out of marine aerosols that were collected at Amsterdam Island in the southern Indian Ocean during a period of high biogenic activity. The aim of the study was to examine whether the remote ocean is an important source of secondary organic aerosol (SOA) from biogenic origin that could serve as cloud condensation nuclei (CCN). It is well-known that oceanic areas of high primary productivity emit dimethylsulphide (DMS) (Kettle & Andreae, 2000), which is converted into submicrometer-sized sulphate and methanesulphonate aerosols within the atmosphere, and that these aerosols can affect cloud albedo and climate (Charlson, Lovelock, Andreae, & Warren, 1987). In addition, a comparison of satellite-derived cloud properties and radiation over and near phytoplankton blooms in the Southern Ocean (Meskhidze & Nenes, 2006) found a doubling of cloud droplet concentration over the blooms and a decrease of 15 W m -2 in short-wave radiation flux at the top ∗ Corresponding author. E-mail address: willy.maenhaut@ugent.be (W. Maenhaut). 0021-8502/$ - see front matter © 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.jaerosci.2009.08.003