Magneto-chemical characterisation of Saharan dust deposited on snow in Poland.

Recent research has convincingly shown the advantages of combining environmental magnetism and geochemical analyses for the proxy estimation of anthropogenic pollution due to their atmospheric deposition in local environments. Few studies have also focused on anthropogenic particles deposited on snow. However, papers reporting on Sahara dust particles deposited on snow in central Europe and which involve magnetic methods are missing. To the best of our knowledge, this is the first study investigating the magnetic features of the SDE recorded in snowfall in this part of Europe (i.e. Poland). Our aim was to provide the magnetic characteristics and chemical elemental compositions of a snow horizon containing Saharan dust deposited near the Polish Jakuszyce meteorological station during a snowfall event that occurred from the 1st to the February 7, 2021. Samples of snow with and without Saharan dust were analysed with respect to iron oxide contents (magnetic susceptibility, hysteresis loop, magnetic remanence acquisition) and compared with chemical compositions. Our results revealed the presence of both ferrimagnetic magnetite and antiferromagnetic hematite in the dust-enriched horizon, and the diamagnetic behaviour of the reference layer consisting of 'pure' snow. The samples recorded the presence of geogenic elements such as Al, Fe, Mn, and Ti, anthropogenic elements such as As, Co, Cr, Cu, Ni, Pb, and Zn, and nutrients including Ca and K. The total concentrations of geogenic elements, nutrients, and anthropogenic elements in the snow samples with deposited Saharan dust were, respectively, >3700, >320, and >110 times greater than in the samples without Saharan dust. These findings may serve as reference data for a variety of environmental magnetic studies.

Quantification of pedogenic particles masked by geogenic magnetic fraction.

Pedogenic magnetic fraction in soils is attributed to fine-grained particles, i.e. superparamagnetic grains. In the case of a strongly magnetic geogenic fraction, pedogenic magnetic contribution is hard to detect. To the best of our knowledge, detailed research into the masking of pedogenic superparamagnetic grains and quantification of this effect has not yet been carried out. The principal aim of our research is to quantify the influence of coarse-grained ferrimagnetic fraction on the detection of the superparamagnetic grains. In order to describe the masking phenomenon, volume and frequency-dependent magnetic susceptibility were determined on a set of laboratory prepared samples composed of natural substances: a diamagnetic quartz matrix, detrital coarse-grained ferrimagnetic crystals from alkaline and ultra-alkaline igneous rocks, and superparamagnetic soil concretions formed in the Haplic Cambisol. Mineralogy, concentration, type and grain size of the tested material were described by parameters of environmental magnetism. The magnetic parameters distinguish both geogenic multidomain and pedogenic superparamagnetic grains. The magnetic signal of the superparamagnetic grains is gradually masked by the increasing proportion of multidomain grains of magnetite/maghemite. The experiment clearly describes the masking effect and brings new insight to studies dealing with strongly magnetic soils of natural and/or highly contaminated origin as a tool for estimation of superparamagnetic pedogenic contribution.

Soil texture as a key driver of polycyclic aromatic hydrocarbons (PAHs) distribution in forest topsoils.

Due to the dynamic development of civilization and the increasing demand for energy, pollution by harmful chemicals, including polycyclic aromatic hydrocarbons (PAHs) compounds, is a serious threat to forest soils. The aim of the study was to determine the role of texture in the distribution of polycyclic aromatic hydrocarbons (PAHs) and trace elements in forest soils. The areas with different texture ranging from sand through sandy loam to silt loam were selected for the study. The study was carried out in the Chrzanów Forest District in southern Poland (50° 7' 18 N; 19° 31' 29 E), which in one of the most intensive industrial emission zones in Europe. The soil samples for properties determination were collected from locations distributed on a regular grid 100 × 100 m (20 points). The samples were collected from the humus horizon (0-10 cm) after removing organic horizon. Basic chemical properties, heavy metal content, polycyclic aromatic hydrocarbons (PAHs) content and magnetic susceptibility values were determined in soil samples. Additionally, enzymatic activity and microbiological biomass was determined in the samples. Our study confirmed the importance of texture in PAHs distribution. A strong correlation between PAHs content and silt content in the soils studied was noted. The regression tree analysis confirmed the importance of the silt content, followed by soil organic carbon in PAHs distribution. Organic carbon content and nitrogen content played a predominant role in controlling the microbial activity. In our study, we did not note a relationship between enzymatic activity, microbiological soil biomass and the amount of PAHs. This may be due to the effective sorption and immobilization of PAHs by particles of fine fractions, especially silt. Obtained results confirmed the usefulness of magnetic susceptibility in the assessment of heavy metals contamination of forest soils. We noted high correlation between magnetic susceptibility value and heavy metals content. Moreover, the relationship between magnetic susceptibility and soil texture of the topsoil was also observed.

Combination of different geophysical techniques for the location of historical waste in the Izery Mountains (SW Poland).

An initial magnetic survey conducted on the soil surface in the Orle forest glade, located in the Izery Mountains (south-western Poland), indicated the existence of a strong magnetic anomaly. Most cores collected in the glade outside the area of magnetic anomaly show a vertical distribution of magnetic susceptibility typical for soils formed on a diamagnetic or paramagnetic background, in unpolluted areas and influenced only by natural processes. The different patterns of magnetic susceptibility values exhibited by cores collected in the area of the magnetic anomaly reveal the source of the magnetic signal as an anthropogenic layer of waste buried in the subsoil, which was dumped in this area during the historical activity of a glass factory that was active in Orle in the 18th and 19th centuries. Topsoil measurements of magnetic susceptibility revealed that this anthropogenic material has completely different magnetic properties than the natural geological background, therefore making possible the use of magnetic and geoelectrical techniques to determine the location of buried historical waste. Application of different magnetic and geoelectrical methods (soil magnetometry, magnetic gradiometry, EM profiling, electrical resistivity tomography), in combination with a previous magnetic survey, enabled assessment of the location, depth and thickness of the anthropogenic layer. The anthropogenic layer consisted of historical slags and ashes from glass production mixed with modern bottom ashes and construction waste dumped here during the second part of the 20th century. The anthropogenic material occurs in the form of a nonhomogeneous layer characterized by high magnetic susceptibility (>100 × 10-5 SI units) and low resistivity (<200 Ωm) as well as high and variable apparent conductivity (>25 mS/m). These properties are firmly different from the properties of the natural soil and parent rocks and enable fairly precise location of the anthropogenic layer using magnetic and geoelectrical measurements.