Magnetic fraction of the atmospheric dust in Kraków – physicochemical characteristics and possible environmental impact

Abstract. Magnetic fraction of the atmospheric dust was collected in Kraków using a static sampler and analysed using several methods (scanning electron microscopy with energy dispersive spectrometry, transmission electron microscopy with energy dispersive spectrometry, X-ray diffraction, Mössbauer spectrometry, and vibrating sample magnetometer (VSM) measurements). The magnetic fraction contains magnetite, hematite and α-Fe, as well as quartz, feldspar and pyroxene. The magnetic particles vary in size from above 20 μm to nanoparticles below 100 nm, as well as in morphology (irregular or spherical). Their chemical composition is dominated by Fe, often with Mn, Zn, Cr, Cu, Si, Al, S, Ca and other elements. Mössbauer spectroscopy corroborates the composition of the material, giving further indication of smaller than 100 nm particles present in the atmospheric dust. VSM measurements confirm that the strength of the magnetic signal can be treated as a meter of the anthropogenic impact on the suspended particulate matter, once again highlighting the presence of nanoparticles.