MAGNETIC, GEOCHEMICAL AND MICROSCOPY CHARACTERIZATION OF SOIL POLLUTION IN THE CITY OF ZAPORIZHZHIA – BASELINE TO TRACK FUTURE CHANGES RESULTING FROM THE WAR SITUATION

ДЕРЖАВНА СЛУЖБА УКРАЇНИ З НАДЗВИЧАЙНИХ СИТУАЦІЙ

Bondar Kseniia¹, Tsiupa Iryna², Sachko Anastasiia³, Nasiedkin Ievhen⁴

1 Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland, kbondar@igf.edu,pl 2 Taras Shevchenko National University of Kyiv, Kyiv, Ukraine 3 Yuriy Fedkovych Chernivtsi National University, Chernivtsi, Ukraine 4 State Scientific Institution "Center for Problems of Marine Geology, Geoecology and Sedimentary Ore Formation of the NAS of Ukraine, Kyiv, Ukraine

https://doi.org/10.15407/conf_UHMI_CGO_2024.049

Metallurgical industries incorporated into the living environment of the city cause significant enrichment of the topsoil with harmful substances including small size particulate matter, which contains heavy metals and magnetic iron oxides. The present study is focused on characterization of magnetic and geochemical pollution accumulated by urban soils in the city of Zaporizhzhia. Industrial dusts from the most powerful emmitants of airborne pollution are also analyzed.

The aim of the study was to conduct magnetic and geochemical characterization of soils in Zaporizhzhia as a pre-war reference point. This characterization will serve as a baseline for comparison in future studies investigating changes in pollution rates resulting from the war situation that began in 2022. Magnetic measurements, determination of concentrations of heavy metals (HM) and electron microscopy and granulometry investigations were performed to characterize the technogenic magnetic phases in industrial dusts collected in chimneys and filters. The magnetic mineralogy of dusts and soils is deduced from temperature behavior of magnetic susceptibility. We access the spreading of magnetic pollution over the topsoil of the city and investigated statistical correlations between magnetic properties and contents of HM.

Two types of magnetic industrial emissions were discriminated to contribute in urban soil magnetization: spread of coarse-grained magnetite-bearing particles is limited to industrial zone, while smaller magnetic spherules were traced to settle far from the pollution sources bringing significant amounts of heavy metals to the soil (Figure 1). Magnetic susceptibility, saturation remanence and anhysteretic ratio of soil samples show strong relationship with heavy metals contents and Pollution Load Index. Thus magnetic parameters can serve as reliable proxies for complex urban and industrial pollution of soils.

Airborne dust is an important constituent in the diffuse emissions escaping metallurgical plants of Zaporizhzhia and may affect the air quality and soil properties in the city whilst settled. Sintering dusts contain fragments 10-100 μm in size, enriched with magnetite. In high-temperature steel and non-ferrous production dusts spherules with size of <10 μm dominante. Maghemite and substituted magnetite are recognized to be the main iron oхides in these dusts, absorbing the variety of heavy metals (Mn, Ni, Cu, Zn, Pb), detected by SEM-EDX and AAS methods.

The magnetic susceptibility of urban topsoil varies widely, χ values observed in the main industrial zone are only one order of magnitude lower than those obtained for pure dusts, indicating extremely heavy pollution of the area. On the maps of χ, Mrs, kfd, χARM/χ of urban soils the industrial area is clearly delineated by magnetic enhancement and predominance of magnetic oxides in PSD-MD state. Magnetic mineralogy of soils in Zaporizhzhia is controlled by technogenic magnetite and maghemite.

Sources of pollution in the city of Zaporizhzhia are not limited to metallurgical industries as suggested from magnetic and geochemical maps and results of PCA and cluster analysis. A variety of anthropogenic factors must be considered when interpreting the origin of the magnetic signal in Zaporizhzhia topsoil. Spatial distribution of Cu, Pb, Zn, Ni, Mn indicates multiple sources of pollution in the city, besides metallurgy, related to traffic and other industries.

Statistically significant Spearman correlations are observed between magnetic parameters and contents of Cu, Pb, Ni, Zn, Mn. The PLI index strongly correlates with χ, Mrs, χARM/χ proving these parameters to be a reliable proxies of topsoil HM pollution in the city.

Although this work does not claim to be exhaustive data on soil pollution in the city of Zaporizhzhia, we were able to obtain information on magnetic and geochemical signal in the urban topsoil to be used as a background rate in further quantification of any alterations or pollution that may have occurred as a result of the ongoing war.

Acknowledgements. The results are related to the project PAN.BFB.S.BWZ.394.022.2023 being implemented through the Long-term program of support of the Ukrainian research teams at the Polish Academy of Sciences carried out in collaboration with the U.S. National Academy of Sciences with the financial support of external partners. Funding for this research was party provided by Ministry of Education and Science of Ukraine (grant for the perspective development of the scientific direction “Mathematical sciences and natural sciences“ at the Taras Shevchenko National University of Kyiv).

Keywords: magnetic properties, iron oxides, heavy metals, industrial pollution, Zaporizhzhia