The combination of soil magnetometry with portable XRF spectroscopy as  an effective tool for the assessment of sources of trace elements in topsoil

The origin of potentially toxic elements (PTEs) may influence their persistence, mobility and determine the extent to which they pose a threat to the soil environment. Therefore, the research objective of this study was to obtain information on the origin of nine PTEs present in the soil at two Natura 2000 protected areas. The second objective was to test the usability of three popular soil indices in assessing soil pollution in the study area. The research was carried out in two forested areas belonging to the Natura 2000 network of European protected areas, located in the Cieszyn region (southern Poland) on the Polish-Czech border. The research involved the analysis of the distribution of elements in topsoil cores (to 30 cm depth), based on high-resolution measurements obtained from a combination of soil magnetometry and portable XRF spectrometer (pXRF). Measurement of the vertical distribution of volume magnetic susceptibility (κ) along the core was performed using a Bartington MS2C sensor and the analysis of PTE contents using an Explorer 7000 XRF spectrometer. Based on the obtained results, three popular geochemical indices of soil contamination with metals and metalloids were calculated: geo-accumulation index (Igeo), single pollution index (PI), and enrichment index (EF).Research has shown that the use of a pXRF spectrometer allows for the assessment of the distribution of PTEs in the soil profile with high accuracy, as well as a precise determination of the source of these elements and tracking the migration of pollutants deep into the soil profile. The peak of magnetic susceptibility values in the upper part of the profile strongly correlated with the contents of Pb, As and Zn, which confirmed the anthropogenic origin of these PTEs in the soil in both study areas. The distribution pattern of most of the remaining studied elements (Ti, V, Cr, Co, and Ni) in the soil profile and the analysis of geochemical indicators (Igeo , PI and EF) indicated their lithogenic and/or pedogenic origin.The use of a pXRF spectrometer allows the assessment of the distribution of PTEs in the soil profile with high measurement resolution and enables precise determination of the source of elements, tracking the migration of pollutants down the soil profile. The combination of soil magnetometry and pXRF, supported by the analysis of geochemical indicators, has proven to be a very effective tool in examining soil contamination and environmental site assessment.