Survey of the Distribution and Time-Dependent Increase of Platinum-Group Element Accumulation Along Urban Roads in Ioannina (NW Greece)

Abstract

The emission of platinum group elements (PGEs) from automobile catalytic converters has led to rapid increases in Pt, Pd, and Rh concentrations in roadside media. This article represents the first systematic study in Greece to assess PGE levels in road dust and roadside soil and their temporal variation on a seasonal basis over a 12-month period. Road dust and roadside soil samples were analyzed by graphite furnace atomic absorption spectrometry following microwave digestion. Concentrations of PGE in all samples were above the average upper crust values and local background levels, with maximum values of 306.4 ng/g Pt, 18.2 ng/g Pd, and 64.6 ng/g Rh in road dust and 225 ng/g Pt, 14.0 ng/g Pd, and 49.5 ng/g Rh in roadside soil. PGE ratios were not consistent with known catalytic converter composition throughout the sampling period reflecting the high emission of Rh from new catalytic converters. Spatial variations were influenced by various factors like driving style, matrix composition, diurnal change in traffic volume, and climatic conditions. With regard to seasonal variations, systematic changes in the temporal distribution of PGE levels were observed and followed a similar pattern between the two matrices. Except PGEs, Pb levels were determined, since it has been a typical indicator of vehicle-derived environmental lead pollution. The data indicate that despite the use of unleaded gasoline, traffic-related sources of Pb that induce levels above the local background have not been eliminated.