Chemical characterization and source apportionment of size-segregated aerosol in the port-city of Venice (Italy)

The sources impacting size-segregated aerosol were studied in Venice (Italy), in the framework of the ECOMOBILITY project (ECOlogical supporting for traffic Management in cOastal areas By using an InteLlIgenT sYstem, Interreg Italy-Croatia). The importance of this work lies in the fact that aerosol can have a different impact on human health, based on the particle size: nanoparticles could be potentially more dangerous with respect to coarse and fine particles; at the same time, they are poorly studied. The aim of this work is to perform an overview of the chemical composition of size-segregated aerosol, for carrying out a size-dependent source apportionment of aerosol in the urban area of Venice. Aerosol was collected with a MOUDI 110 cascade impactor. After the gravimetric analysis, filters were divided in three parts and each piece underwent a different analytical procedure, for the analysis of trace metals, carbonaceous and ionic species. Source apportionment was conducted using two different approaches: i) approximate formulae; ii) Positive Matrix Factorization. Sea spray aerosol was found mainly in the coarse fraction. The fine fraction was dominated by secondary inorganic aerosol and organic aerosol. Primary anthropogenic aerosol increased as particle dimension decreased. For the first time, the contribution of shipping emission was investigated using chemical tracers on different size ranges below 1 µm and reaching nanoparticles (<0.1 µm): the primary contribution of ship traffic was higher in fine and nanoparticles, with respect to the coarse ones, reaching the maximum value in nanoparticles (average 7% on particles mass).