Determination of Platinum Group Elements and Evaluation of Their Traffic-Related Distribution in Italian Urban Environments

摘要

The platinum (Pt) distribution in urban matrices, soils and dusts was studied in five cities, from north (Padova), central (Rome and Viterbo), and south (Naples and Palermo) Italy, in order to obtain a large set of data concerning pollution from autocatalysts. Quantitative analyses, made by inductively coupled plasma mass-spectroscopy (ICP-MS), show a beginning of Pt enrichment in urban soils, with concentration ranges of 0.1-5.7ng/g (Padova), 7-19.4ng/g (Rome), 4.9-20ng/g (Viterbo), 4.7-14.3ng/g (Naples), and 0.2-3.9ng/g (Palermo). These results can be related to vehicular traffic, because the concentrations decrease with the distance from the roads. The high concentrations found in road and tunnel dusts (up to 1177ng/g) confirm these samples as the major reserve of the particulate matter that is released with the exhaust fumes (which is responsible for the Pt enrichment). Qualitative analyses by laser-ablation-ICP-MS (LA-ICP-MS) were used, in addition, to determine the real presence of the catalyst particles in the urban dusts. The association of the analytical signals of cerium, platinum, and rhodium was used as a fingerprint to distinguish the catalyst particles from the other components of the urban dusts. The scanning electron microscopy (Energy Dispersive Spectrometer-Scanning Electron Microscope; EDS-SEM) qualitative analysis was also used to characterize the morphology of the autocatalyst and its related elemental distribution.