Characterization of Road Dust, PM_x and Aerosol in a Shopping-Recreational Urban Area: Physicochemical Properties, Concentration, Distribution and Sources Estimation

Road transport is a source of exhaust and non-exhaust emissions of particulate matter (PM). Non-exhaust PM emissions include road surface wear, tires, brakes and road dust resuspension. An important part of PM in urban air consists of particles that originate from the resuspension of road dust. This study focused on the analysis of the physicochemical properties of road dust and PM10, PM2.5 and PM1 (PMx) in the air (size, concentration, distribution, content of chemical elements), the properties of urban aerosol (number, mass and area distribution), and at the same time, the interconnection between the detected chemical elements in road dust and individual PM fractions in the air in order to reveal the sources of PM in the Zilina City, Slovakia. The presence of various chemical elements was found in road dust, of which the highest concentrations (more than 100 mg/g) were the elements Ca, Si and Al (specifically 373.3 mg/g, 351.4 mg/g and 113.9 mg/g on average from four sampling sites). The concentrations of PM10, PM2.5 and PM1 were, on average, 27.2 mu g/m(3), 19.5 mu g/m(3) and 14.5 mu g/m(3) during the measurement period according to the reference gravimetric method. The chemical elements K, S, Cd, Sb, Pb, Ni and Zn were detected and the most represented (more than 60%) in the fine PM2.5 fraction, and the chemical elements Mg, Al, Si, Ca, Cr, Cu, Fe and Ba were the most represented in the coarse PM2.5-10 fraction. The analysis of the aerosol in the range of 12 nm-20 mu m revealed a bimodal distribution of the collected sample of the investigated urban aerosol. This study provides a comprehensive view of the properties of road dust, airborne PM and aerosol (up to the size of nanoparticles), which can contribute to the expansion of knowledge in this field.