Impact of artifacts on topsoil magnetic susceptibility enhancement in urban parks of the Upper Silesian conurbation datasets

Abstract

Urban and industrial dusts of various origins contain technogenic magnetic particles (TMPs) that exhibit ferro- or ferrimagnetic properties. Their deposition leads to topsoil magnetic susceptibility enhancement. TMPs are commonly known as carriers of many trace elements, including heavy metals, which have accumulated in the uppermost horizons of the soil profile. Soils of urban parks display a different stage of anthropogenic transformation of the soil profile as well as physical and chemical degradation. Besides TMPs deposited on the uppermost soil horizon, artifacts play a significant role in the magnetic properties of soil. Analysis of the vertical distribution of volume magnetic susceptibility (κ) values were conducted in 106 topsoil cores taken in areas of four urban parks of the Upper Silesian Conurbation. In order to examine the relationship between heavy metal concentrations and mass-specific magnetic susceptibility (χ) values, 57 soil samples from A horizons were taken for detailed analysis. Additionally, the κ and χ values of artifacts, sampled from the topsoil of the studied urban parks, were measured. Results pointed out that magnetic susceptibility enhancement in topsoil cores was significantly influenced by artifacts and translocations of topsoil horizons. In order to assess the level of anthropogenic transformation on topsoil horizons, we introduced the Topsoil Transformation Factor (TTF) on the basis of soil core magnetic susceptibility measurements. Low TTF corresponds to high positive Pearson correlation coefficients (r) between magnetic susceptibility and heavy metal contents in analyzed soil samples. TTF seems to be a promising indicator to improve soil magnetic susceptibility screening in urban and industrial areas where topsoil transformations and the presence of artifacts are common. In areas where natural sequences of the uppermost soil horizons were observed, the vertical distribution of κ value exhibits a one-peak curve, which is characteristic of TMP accumulation. In human modified soils, containing artifacts, a multipeak curve of the vertical distribution of κ value is commonly observed. Magnetic susceptibility measurements of individual artifacts display a wide range of κ and χ values.