Source apportionment of PM10 in Terni (Central Italy) and spatial mapping of atmospheric element concentrations using high spatial resolution chemical data

Very-low volume, low-cost and automatic devices for PM sampling on membrane filters have been employed in Terni, an urban and industrial hot-spot of Central Italy, to evaluate the spatial distribution of PM10 and its main chemical components. The samplers, worked in parallel for 15 months at 23 monitoring sites and PM10 samples were analyzed for PM mass, ions, levoglucosan and water-soluble and insoluble elements. Principal component analysis (PCA) and positive matrix factorization (PMF) on the obtained spatially-resolved data allowed us to individuate the chemical tracers of the main emission sources of the study area and to trace the source profiles. Spatial distribution of the atmospheric elements was mapped by using universal kriging. Spatial variability of Ni, Cr, Fe, Mn, Pb, Nb, Ti (insoluble fraction) and Mo (water-soluble fraction) concentrations showed the steel plant role in the emission of PM10. Spatial distribution of Sb, Sn, Zr and Cu was found to be correlated with rail network and vehicular traffic. Rb, K, Cs, Tl, Cd, (water-soluble fraction) appeared to be good tracers of biomass burning. The new experimental approach promises to be effective for the validation of dispersion models without the high costs associated to an air quality monitoring network.