Application of different geophysical techniques to study Technosol developed on metallurgical wastes

Abstract

AbstractResearch conducted in a municipal park in a small town located in the Province of Silesia (southern Poland) showed that the park vegetation was growing on a Technosol, formed on highly magnetic anthropogenic material. The metallurgical waste came from the local steel mill and foundry and creates a subsoil in a significant part of the municipal park. This waste is covered with an organic layer of approximately 10 cm. Utilizing specific magnetic and geoelectrical properties of the wastes, we proposed a unique combination of integrated geophysical measuring techniques including soil magnetometry, electrical resistivity tomography (ERT) with varying unit electrode spacing, and electromagnetic profiling (EM) to assess continuity, thickness, and the depth of the anthropogenic layer of metallurgical wastes. The maximal thickness of the metallurgical wastes was identified in the western part of the studied area, and the same material was found in the eastern part of the park forming individual lenses or nests within 8 m deep zone in the area of a buried ravine where the historical railway line was located. The shallow ERT profiles (with unit electrode spacing 0.5 m) also revealed a thin layer of material with high resistivity (>500 Ωm). Thermomagnetic analyses have shown that the sources of the extremely high magnetic susceptibility of the wastes were magnetite and metallic iron (αFe). The detected high concentration of Fe and Mn was not accompanied by potentially toxic metals and, at relatively high pH values (6.5–9.0), does not constitute a significant ecological threat.