Proceedings of the 12 th International Conference on Environmental Science and Technology Rhodes, Greece, 8 – 10 September 2011 A-238 ON THE MORPHOLOGY, GEOCHEMICAL CHARACTERISTICS AND MAGNETIC PROPERTIES OF URBAN ROAD DUST PARTICLES FROM THE HISTORIC CENTER OF THE CITY OF THESSALONIKI, GREECE A. BOURLIVA 1 , N. KANTIRANIS 1 , L. PAPADOPOULOU 1 , E. AIDONA 2 , C. CHRISTOFORIDIS 3 , and P. KOLLIAS 4 1 Department of Mineralogy-Petrology-Economic Geology, School of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece 2 Department of Geophysics, School of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece 3 Environmental Pollution Control Laboratory, Chemistry Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece 4 Department of Energy Technology, Royal Institute of Technology, SE-100 44 Stockholm Sweden e-mail: bourliva@yahoo.com EXTENDED ABSTRACT In the present study the combination of morphological, geochemical and magnetic methods was used to characterize urban road dust properties of the city of Thessaloniki, the second largest of Greece and one of the largest urban agglomerations in the Balkans. Samples of road dust were collected from the accumulated matter at the edges of major roads from eight selected sites in the historic center of the city of Thessaloniki. In order to compare the obtained results, samples from selected industrial areas were also collected. SEM-EDS analyses identified two groups of magnetic materials: angular/aggregate particles (2–100 μm) derived from motor vehicles circulation (e.g. vehicle exhaust emission, cycling of dust in suspension due to vehicular movement, dispersion of road construction materials, and abrasion of tires, brake linings, and road surface), and spherules (up to 90 μm) possibly originating from industrial and domestic heating systems. The spherules exhibit various surface textures and in a few cases they exhibit blocky surface crystallites. Chemical analysis of urban road dust samples yields the following maximum heavy metal contents: Cd (2.72 μg/g), Cr (119.40 μg/g), Cu (579.94 μg/g), Mn (581.60 μg/g), Ni (276.16 μg/g), Pb (411.26 μg/g) and Zn (570.12 μg/g). The mass–specific magnetic susceptibility (X lf ) shows high values ranging from 331.7– 591.7x10 -8 m 3 kg -1 . The magnetic susceptibility correlated significantly with Cr and Cu exhibit their common source. Additionally, the frequency dependent susceptibility indicates that the presence of super paramagnetic ferromagnetic minerals is not significant. The combined study of the road side samples emphasizes the applicability of various environmental techniques, to characterize and identify possible sources and factors responsible for road dust particles emissions. Additionally, the potential health risks resulting from the elevated heavy metal contents render essential further investigation regarding the problem of urban road dust. Keywords: road dust, spherules, heavy metals, magnetic susceptibility, Thessaloniki