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

Abstract

It is well established that airborne, magnetic nano- and microparticles accumulate in human organs (e.g. brain) thereby increasing the risk of various diseases (e.g. cancer, neurodegenerative diseases). Therefore, precise characterization of the material, including its origins, is a key factor in preventing further, uncontrolled emission and circulation. The magnetic fraction of 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 spectroscopy, and vibrating sample magnetometry (VSM) measurements). The magnetic fraction contains magnetite, hematite and α-Fe, as well as quartz, feldspar and pyroxene often attached to the magnetic particles. The magnetic particles vary in size, from over 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 indications of particles smaller than 100 nm present in the atmospheric dust. VSM measurements confirm that the strength of the magnetic signal can be treated as a measure of the anthropogenic impact on the suspended particulate matter, once again highlighting the presence of nanoparticles.