Size-resolved comprehensive characterization of airborne particulate matter E. Cuccia a , D. Massabò a , V. Ariola a , M.C. Bove a , P. Fermo b , A. Piazzalunga c , P. Prati a, * a Department of Physics, University of Genoa & INFN, Via Dodecaneso 33, 16146 Genoa, Italy b Department of Chemistry, Università degli Studi di Milano, Via Golgi 19, 20133 Milan, Italy c Department of Environmental and Territorial Sciences, Università degli Studi di Milano-Bicocca, Piazza della Scienza 1, 20122 Milan, Italy highlights < Size distribution of aerosol components has been obtained without using impactors. < The new methodology can follow the temporal evolution of aerosol size distribution. < Validation of in-field data against a 13-stage cascade impactor has been performed. article info Article history: Received 20 July 2012 Received in revised form 23 October 2012 Accepted 29 October 2012 Keywords: Particulate matter Size distribution Optical counter Positive matrix factorization abstract An update of a methodology to extract both the size-segregated source apportionment of atmospheric aerosol and the size distribution of each detected element or compound, is presented. The approach is based on the parallel use of standard low-volume samplers to collect particulate matter (PM) and of an Optical Particle Counter (OPC). The methodology was introduced and validated in previous works for the average size distribution of elemental components of PM: it has now been extended to PM compounds such as ions and carbonaceous aerosol (namely, organic end elemental carbon, OC and EC). Furthermore, the methodology has been now adopted in the frame of a field campaign, proving that it is able to provide not only an average size distribution but also information on the time evolution of the size distribution of specific PM species. Samples were collected in the urban area of Genoa (Italy) and their composition was measured by Energy Dispersive X-ray Fluorescence (ED-XRF), Ion Chromatography (IC) and Thermo-optical analysis. Positive Matrix Factorization (PMF) was applied to time series of daily concentration values in PM10 and PM2.5 (i.e. fraction of PM mass with aerodynamic diameter lower that 10 mm and 2.5 mm, respectively) to identify major PM sources, and both PM mass concentration and size- segregated particle number concentration were apportioned. Seven and six sources were respectively resolved in PM10 and PM2.5, with processes related to secondary aerosol formation accounting for about 53% and 57% of PM levels in the two fractions. The new methodology is complementary to size- segregated PM sampling, and it was actually tested against a 13-stage nanoMOUDI cascade impactor. Size distributions obtained with the new methodology and directly measured by the nanoMOUDI turned out to be in good agreement (R 2 > 0.60) with discrepancies observed for SO 2 4 only. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction The characterization of atmospheric aerosols requires much information, such as the temporal behaviour of PM and its composition on a short time basis (i.e. from minutes to hours, especially in urban and/or industrial areas), the size-segregated distribution of PM and of its components as well as the particles number distribution with high-time resolution. All these features help both in the source characterization through receptor models (Gordon, 1988) and in the assessment of health effects (HEI, 2002; Pope et al., 2002; Balásházy et al., 2003; and references therein). Size-segregated elemental concentration is commonly mea- sured by cascade impactors (Hillamo and Kauppinen, 1991; Marple et al., 1991; Maenhaut et al., 1996) but difficult these samplers can be used to obtain long temporal trends since each set of collecting foils is usually kept under sampling for a few hours and then manually substituted. As a matter of fact, sampling campaigns using impactors often last few days with a quite limited number of collected samples (Salma et al., 2005; and references therein). In previous works (Mazzei et al., 2007; Cuccia et al., 2010), we introduced and developed a method to obtain a size-segregated * Corresponding author. E-mail address: prati@ge.infn.it (P. Prati). Contents lists available at SciVerse ScienceDirect Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv 1352-2310/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.atmosenv.2012.10.045 Atmospheric Environment 67 (2013) 14e26