Origin and source regions of PM 10 in the Eastern Mediterranean atmosphere Mustafa Koçak a , Nikos Mihalopoulos b , Nilgün Kubilay a, ⁎ a Institute of Marine Sciences, Middle East Technical University, P.O. Box 28, 33731, Erdemli-Mersin, Turkey b Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, P.O. Box 2208, Gr-71003 Voutes, Heraklion, Greece article info abstract Article history: Received 22 July 2008 Received in revised form 14 January 2009 Accepted 18 January 2009 A set of daily PM 10 (n = 281) samples collected from April 2001 to April 2002 at a rural site (Erdemli), located on the coast of the Eastern Mediterranean, were analyzed applying Mass Closure (MC), absolute principal factor analysis (APFA) and Positive Matrix Factorization (PMF) to determine source contributions. The results from the three techniques were compared to identify the similarities and differences in the sources and source contributions. Source apportionment analysis indicated that PM 10 were mainly originated from natural sources (sea salt + crustal ≈60%) whilst secondary aerosols and residual oil burning accounted for approximately 20% and 10% of the total PM 10 mass, respectively. Calculations for sulfate showed that on average 8% and 12% of its total concentration were originated from sea salt and biogenic emissions, respectively. However, the contribution by biogenic emissions may reach up to a maximum of ~40% in the summer. Potential Source Contribution Function (PSCF) analysis for identification of source regions showed that the Saharan desert was the main source area for crustal components. For secondary aerosol components the analysis revealed one source region, (i.e. the south-Eastern Black Sea), whereas for residual oil, Western Europe and the western Balkans areas were found to be the main source regions. © 2009 Elsevier B.V. All rights reserved. Keywords: Source apportionment Mass closure Absolute principle factor analysis Positive matrix factorization PM 10 1. Introduction Atmospheric aerosols (or particulate matter, PM) have the potential to play an important role in modifying and/or altering climate, hydrological cycles, chemistry of the atmo- sphere, biogeochemical cycles and public health (Mamane and Gottlieb, 1992; Lelieveld et al., 2002; Markaki et al., 2003; Carbo et al., 2005; Griffin et al., 2007). The PM 10 fraction of aerosols is defined as particles with diameters smaller than 10 μm. Owing to the potential adverse health and environ- mental impacts, legislation of the PM concentration limits has been established in many regions of the world including the European Union. The annual and daily PM 10 values have been limited to 40 μg m −3 and 50 μg m −3 (which may only be exceeded for 35 days), respectively while annual PM 2.5 value has been limited to 17 μg m −3 as addressed by Directive 2008/50/EC of the European Parliament and the Council of 21 May 2008 on ambient air quality and cleaner Europe. Identification of the concentration, composition, origin, transport and geographical distribution of PM in Mediterra- nean atmosphere has been the subject of research activities since the last two decades as it is heavily affected by two contrasting sources; namely mineral dust (mainly from Sahara Desert) and various anthropogenic (from industria- lized/semi-industrialized countries) emissions (Dulac et al., 1987; Kubilay and Saydam, 1995; Avila et al., 1998; Moulin et al., 1998). In recent years there has been an increasing number of studies published on PM 10 concentrations in the western Mediterranean (Artinano et al., 2001; Rodriguez et al., 2002; Querol et al., 2004; Salvador et al., 2004; Viana et al., 2008). These studies have evaluated the natural and anthropogenic contributions to ambient PM 10 in western Mediterranean atmosphere. The general findings may be summarized as follows: (a) PM 10 concentrations in the western Mediterranean atmosphere increase from rural to kerbside, (b) the contribution to PM 10 of anthropogenic sources decreases from urban/industrialized/kerbside sites towards rural sites, and (c) PM 10 levels observed both in rural and urban sites are considerably affected by high mineral dust Atmospheric Research 92 (2009) 464–474 ⁎ Corresponding author. Tel.: +90324 5213434; fax: +90324 5212327. E-mail address: kubilay@ims.metu.edu.tr (N. Kubilay). 0169-8095/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.atmosres.2009.01.005 Contents lists available at ScienceDirect Atmospheric Research journal homepage: www.elsevier.com/locate/atmos