An Integrated Methodological Framework for the Characterization of Fine Urban Road Dust (<50 μm): Magnetic, Mineralogical, and Thermal Analyses

Urban road dust (<50 µm) is a primary reservoir for hazardous materials, but its geogenic matrix often masks anthropogenic pollutants. This study introduces an integrated framework combining magnetic susceptibility (χ), XRD, TG-MS, FTIR, and SEM to characterize road dust from Vienna. Results reveal a matrix dominated by geogenic quartz (25-45%) and carbonates (20-50%); however, quartz acts as a diamagnetic diluent, whereas technogenic magnetite governs the magnetic behavior (χ up to 374.8×10 -8 m 3 kg -1 ). Although trace iron (hydr-) oxide phases are below the XRD detection limits, thermomagnetic κ(T) curves and FTIR results identify stable single-domain magnetite. A key finding is the powerful performance of χ as a comprehensive proxy for carbonaceous pollutants, which is strongly correlated with Total Carbon (r=0.71), Total Organic Carbon (r=0.78), and Organic Matter (r=0.76). Crucially, analysis of magnetic extracts revealed that they are significantly enriched in hazardous anthropogenic components compared to the geogenic background. TG-MS and FTIR analyses of these extracts successfully identified concentrated signatures of bitumen, tire wear, and fuel residues via aliphatic C-H groups (2924, 2853 cm -1 ) and specific pyrolytic mass fragments (e.g, m/z 77, 78, 91, 105). This integrated approach effectively distinguishes harmless geogenic minerals from technogenic materials hazardous to the environment and human health. A novel application of TG-MS analysis enables quantitative and qualitative characterization of road dust components and is a promising tool for further investigation. Using χ as a rapid, nondestructive prescreening tool allows for high-resolution monitoring of pollution hotspots and public health risks associated with inhalable, magnetite-linked organic contaminants, providing a reliable strategy for urban air quality management. • IR and TG-MS signatures define the anthropogenic organic loading in dust. • Magnetic susceptibility is a rapid proxy for total organic carbon and organic matter. • Magnetite-associated aggregates concentrate hazardous organic pollutants. • TG-MS qualitatively and quantitatively characterized road dust components. • Identifying geogenic and anthropogenic dust requires integrated physicochemical analysis.