A morphometric and compositional approach to the study of ambient aerosol in a medium industrial town of Italy

Morphometric and compositional studies have been performed on both PM10-2.5 and PM2.5 aerosol collected in the city of Prato, Italy. Chemical analysis has been carried out using PIXE technique and factor analysis was applied for the source apportionment process. Industrial emissions, vehicular traffic as well as crustal dust and marine aerosol were the sources identified. SEM-EDS analysis has been employed to individually characterize particles collected during a week of the sampling campaign. The morphometric study, performed on 43,671 particles, revealed that, for both the fine and coarse fraction, about 2/3 of particles display a high roundness coefficient, 1/3 of them a medium value, while only a small number of particles (from silicates and organics) exhibits a low roundness coefficient. Similarly, particles with small surface area represent the greater portion in both fractions. Particles classified as organics, metals and oxides, chlorides, carbonates, phosphates, sulphates and silicates have been detected in the PM10-2.5 while in the PM2.5 chlorides and phosphates are lacking. Silicates are about the same percentage, by concentration number, in the coarse and fine fraction (20.7% and 20.5% respectively) showing that this material, at least one fifth of the total PM, might be the result of crustal erosion and anthropic activities. The purpose of this work has been that of providing a contribution to the study of particulate matter and took an effort for relating morphometric and compositional features of urban aerosol collected in a medium size industrial city.