Influence of road surface type on the magnetic susceptibility and elemental composition of road dust

The aim of the study was to determine the effect of the type of road surface (asphalt and concrete) and the presence of noise barriers (acoustic screens) on the magnetic susceptibility and chemical composition of road dust collected from national roads and motorways in central and southern Poland. Four roads with asphalt surfaces and four with concrete surfaces were selected for the study. Samples were taken at three control points: in the space between noise barriers, in the space without barriers and at road exits. Magnetic susceptibility measurements and elemental composition analysis (using an energy dispersive X-ray fluorescence spectrometer) were carried out. The results showed high variability with no clear differences between samples taken from asphalt and concrete roads. Magnetic susceptibility values were higher for road dust taken from asphalt pavements near noise barriers and motorway exits, while for open space samples the susceptibility values were about 1.3 times higher for dust from concrete pavements. A similar relationship was observed for the elemental composition. The results showed no clear differences between samples taken from asphalt and concrete roads. The location of the sampling point had a greater influence on the results: the surface of noise barriers, open spaces or motorway exits. Calculated enrichment factors indicated an extremely high enrichment of dust in elements such as Cr, Cu and Zn, a very high enrichment in Pb only for dust collected at motorway exits, and a significant and moderate enrichment in other elements.