Search

A very-low volume sampler of particulate matter (PM) on membrane filters, recently developed with the purpose of allowing spatially-resolved determination of PM and of its chemical components, was employed from December 2016 to February 2018 in a wide and dense monitoring network across Terni, an urban and industrial hot-spot of Central Italy (23 sampling sites, about 1 km between each other). Terni basin can be considered as an open air laboratory for studying the spatial distribution of PM, as it includes several spatially disaggregated sources. PM10 samples were chemically characterized for the water-soluble and insoluble fraction of 33 elements (Al, As, Ba, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, K, La, Li, Mg, Mn, Mo, Na, Nb, Ni, Pb, Rb, Sb, Sn, Sr, Ti, Tl, U, W, Zn, Zr). Spatial variability of the element concentrations across Terni was then mapped by using the ordinary kriging interpolation method. Spatial distribution of the analyzed elements successfully traced the various PM10 sources. In particular, the spatial mapping of Ba (water-soluble fraction), Bi, Cu, Sb, Sn and Zr (insoluble fraction) traced PM10 emission from the rail network and vehicular traffic, Ce, Cs, La, Li, Rb, Sr and U (insoluble fraction) traced soil resuspension, Cd, Cs, K, Rb and Tl (water-soluble fraction) biomass burning and Co, Cr, Mn, Nb, Ni, Pb (insoluble fraction), As, Cr, Ga, Li, Mo, Mn, W and Zn (water-soluble fraction) the steel industry pole. Principal component analysis was performed on the spatially-resolved chemical data to cluster the elements tracing the main PM10 sources. The winter and summer size distribution of the water-soluble and insoluble elements was analyzed to verify their link with the emission sources. The proposed experimental approach promises to be very effective for the assessment of population exposure to different PM10 sources.

Domestic biomass heating and wildfires strongly affect particulate matter (PM) concentration in the atmosphere. The individuation of alternative chemical tracers may provide a valuable tool to apportion different possible contributions to biomass burning. In this study, we used a new experimental procedure, based on high spatial resolution analyses of PM10, to assess the spatial distribution of levoglucosan (LVG) and evaluate the possible use of alternative biomass burning tracers in the Terni basin, a wide urban and industrial hot-spot of Central Italy, which includes several spatially disaggregated sources. Spatially-resolved chemical characterization of PM10 was obtained through the use of innovative samplers working in parallel in a dense monitoring network (20 sampling sites, about 1 km between each other), during wintertime. PM10 samples were analyzed for LVG, water-soluble organic carbon (WSOC) and water-soluble and insoluble fraction of 33 elements. Principal component analysis (PCA) on the obtained spatially-resolved data allowed us to identify biomass burning tracers across the polluted study area. Analyses of size-segregated PM samples showed the presence of LVG, and water-soluble Cd, Cs, K, Rb and Tl in particles with size fraction smaller than 1 μm, confirming them as tracers of combustion processes (mainly related to biomass burning). Pearson correlation coefficients demonstrated that concentrations of WSOC and water-soluble Cd, Cs, K, Rb and Tl were well correlated with the spatial variability of LVG concentration. The combined use of spatially and dimensionally resolved data was found to be particularly advantageous for the identification of alternative source tracers, which were used to reliably trace the main local biomass burning sources in the study area.