Assessment of the sources of the inorganic fraction of aerosol in a conurbation

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Two intensive sampling campaigns for coarse (PM2.5–10) and fine (PM2.5) particulate matter were carried out in August 2003 and March 2004 in the multi-impacted centre of the Athens (Greece) conurbation. Receptor modelling by means of Positive Matrix Factorization was utilised in order to provide an insight to the poorly characterised sources of the chemically analysed inorganic fraction of the sampled aerosol mass. Using elemental concentrations, seven factors have been resolved for both fractions for August 2003. Combining elemental and ionic concentrations, nine factors were resolved in the coarse particulate matter and eight in the fine particulate matter for March 2004. The greatest contributors of primary origin are (re)suspended dust/soil and sea salt. Secondary aerosol contributions were resolved in the form of secondary sulphate, secondary nitrate as well as an aged sea salt factor which was characterised by the replacement of chloride with sulphate and, secondarily, nitrate. Furthermore, throughout sites and fractions, primary anthropogenic emissions were identified in a series of factors, including a Pb-rich profile, representing non-catalytic exhaust emissions, a Cu-Mo-Sb-rich profile representing brake emissions, a Zn-Ba-rich profile representing tyre-wear and heavy vehicle brakes, and, lastly, a V-Ni-rich factor representing industrial heavy oil-combustion. Local anthropogenic emissions predominated, outweighing long-range transport as it was suggested by the lack of direct relationship between changes in the wind speed and direction and species mass burdens, as well as factor contributions.