Eduard Petrovský

Magnetic properties of alluvial soils contaminated with lead, zinc and cadmium

Several proxy methods have been used recently to outline increased levels of pollution. One of them is based on measurements of the concentration of (ferri)magnetic minerals of anthropogenic origin. This method has been used recently in the mapping of both polluted and unpolluted areas. In order to validate this method, a more detailed study of links between magnetic parameters characterising the physical shape of magnetic minerals and concentrations of heavy metals is needed. In this study, we analysed the magnetic characteristics of alluvial soils, formed as a result of several breakdowns of wet deposit sink of ashes from a lead ore smelter. The soils were previously analysed for concentration of lead, zinc and cadmium. Our results show that in this case of a shared source of heavy metals and magnetic minerals, simple measurements of magnetic susceptibility discriminate well between polluted and clean areas. In addition, the concentration pattern agrees with the concentrations of the heavy metals studied in deeper soil layers that were not affected by post-depositional changes due to climate and remediation efforts.

Identification of magnetic particulates in road dust accumulated on roadside snow using magnetic, geochemical and micro-morphological analyses.

The aim of this study is to test the applicability of snow surveying in the collection and detailed characterization of vehicle-derived magnetic particles. Road dust extracted from snow, collected near a busy urban highway and a low traffic road in a rural environment (southern Finland), was studied using magnetic, geochemical and micro-morphological analyses. Significant differences in horizontal distribution of mass specific magnetic susceptibility (χ) were noticed for both roads. Multi-domain (MD) magnetite was identified as the primary magnetic mineral. Scanning electron microscope (SEM) analyses of road dust from both roads revealed: (1) angular-shaped particles (diameter∼-300 μm) mostly composed of Fe, Cr and Ni, derived from circulation of motor vehicles and (2) iron-rich spherules (d∼2-70 μm). Tungsten-rich particles (d<2 μm), derived from tyre stud abrasion were also identified. Additionally, a decreasing trend in χ and selected trace elements was observed with increasing distance from the road edge.

Effect of different soil conditions on magnetic parameters of power-plant fly ashes

The effect of soil conditions on magnetic parameters of anthropogenic ferrimagnetics was studied. Fly ash from a coal burning power plant (Pocerady, Czech Republic) was used as original contaminant material, whereas soil-reactive medium was modelled by different soil solutions. Magnetic susceptibility, hysteresis parameters, and thermomagnetic curves were measured for samples that underwent different leaching time periods. Virtually constant magnetic susceptibility values were obtained independently on the soil medium (acid and neutral). On the other hand, the original highly nonstoichiometric maghemite phase has been rapidly transformed to stable magnetite. In some cases (model of free-draining soils), further decrease of Curie temperature (TC) to 550–560 °C is observed. Unstable maghemite phase was not identified in contaminated soil horizons in the surroundings of the power plant.

Magnetic stability of power-plant fly ash in different soil solutions

Abstract Temporal stability of magnetic parameters of anthropogenic ferrimagnetics in model soil conditions was studied. Fly ash from a power plant was used as original contaminant material, while soil reactive medium was modeled by different soil solutions. Changes in mass-specific magnetic susceptibility (χ), percentage frequency dependent magnetic susceptibility (χFD%), hysteresis parameters and thermomagnetic curves were measured for samples which underwent different leaching time periods. Virtually constant magnetic susceptibility values were obtained, independently on the soil medium (acid, neutral). On the other hand, the original highly non-stoichiometric maghemite phase rapidly transformed to stable magnetite. In some cases (model of free-draining soils) further decrease of Curie temperature (Tc) to 550–560°C is observed.

Magnetic anomalies of forest soils in the Upper Silesia–Northern Moravia region

Previous investigations revealed a strong magnetic anomaly due to soil magnetic enhancement in the industrialized cross-border area of Upper Silesia (Poland) and Northern Moravia (Czech Republic). Since industrial and urban dusts contain magnetic particles, this soil magnetic enhancement is assumed to be of anthropogenic origin, caused by a high concentration of atmospherically deposited magnetic particles, accumulated in topsoil layers. This assumption is proved by investigations of vertical profiles of magnetic susceptibility along a transect crossing the border area of the two countries. The results show that the population of magnetic minerals in the organic horizon is different from that in the mineral horizons. The vertical distribution of magnetic susceptibility and thermomagnetic analysis suggests negligible lithogenic contribution. The observed relationship between magnetic susceptibility and some heavy metals, confirmed by micromorphological observations and microchemical analysis of magnetic particles separated from the organic horizons of forest topsoil, has proved the usefulness of soil magnetometry for pollution study.

Magnetic parameters of forest top soils in Krkonoše mountains, Czech Republic

Abstract Magnetic properties of vertical profiles of forest soils (podzols, cambisols, peat bogs) in Krkonose (Giant Mountains) National Park are reported. Values of low-field magnetic susceptibility were obtained by detailed in-situ measurements using a field probe. Thermomagnetic analysis, acquisition of remanent magnetization, alternating-field demagnetization of saturation remanence, and further magnetic characteristics, such as frequency-dependent magnetic susceptibility and coercive parameters for individual soil subhorizons were acquired in laboratory. The uppermost layer, which is dominated by magnetically soft magnetite, most probably of anthropogenic origin, can be reliably identified in the soil profiles over the whole region in concern. Subsoil horizons are characterised by significantly different magnetic properties. Our results suggest that magnetic mapping can be beneficially used also in areas with comparatively low pollution impact.

Transformation of hematite to maghemite as observed by changes in magnetic parameters: Effects of mechanical activation?

A natural hematite of hydrothermal origin shows evidence of time-dependent behavior related to the sample preparation procedure (involving significant crushing and milling). A strongly magnetic phase with a Curie temperature (∼630°C) corresponding to that of maghemite is present after storage for one-and-a-half-years, while being absent in the original sample material. The magnetic properties of the hematite-maghemite in relation to mechanical treatment are compared and possible mechanisms of the hematite transformation are discussed. The hematite-maghemite transformation is suggested to have resulted primarily from recrystallization induced by shear stress resulting from crushing and milling.

Immunomagnetic sulfonated hypercrosslinked polystyrene microspheres for electrochemical detection of proteins

Poly(styrene-co-divinylbenzene) microspheres of narrow size distribution were prepared by (2-hydroxypropyl)cellulose-stabilized dispersion copolymerization of styrene and divinylbenzene in a 2-methoxyethanol/ethanol mixture under continuous addition of divinylbenzene. The copolymerization was initiated with dibenzoyl peroxide. The obtained microspheres were chloromethylated using several chloromethylation agents and then hypercrosslinked. Their porous structure was analyzed by nitrogen adsorption and mercury porosimetry. Superparamagnetic iron oxide nanoparticles were precipitated within the pores of microspheres from Fe(II) and Fe(III) chloride solution. The Fe content in the microspheres was determined by carbon analysis, atomic absorption spectroscopy and thermogravimetric analysis. Magnetic properties of the microspheres were characterized by magnetization curves and the temperature dependence of magnetic susceptibility. Finally, sulfo groups were introduced into the microspheres to prepare an immunomagnetic electrochemical biosensor for protein detection with ovalbumin as a model substance.

Comparison of in-situ Field Measurements of Soil Magnetic Susceptibility with Laboratory Data

Results of magnetic susceptibility mapping around a coal-burning power plant were used to verify the field in situ measurements with data acquired in laboratory on soil samples collected at approximately the same measurement grid sites at different distance from the source. This comparison enables quantifying the field data obtained using the Bartington MS2 meter and to relate them, at least approximately, to mass specific values. Moreover, it is shown that certain diversity in the grid points of field measurements and soil sampling can slightly bias the field measurements. However, this shift is of minor significance and Bartington field readings can be considered as reliable.

Magnetic particles in atmospheric particulate matter collected at sites with different level of air pollution

Magnetic measurements of deposited atmospehric dust can serve as an additional parameter in assessing environmental pollution. This method is based on the assumption that atmospherically deposited particles contain significant portion of ferrimagnetic iron oxides of anthropogenic origin, which can be easily detected. Aim of this paper is to identify clearly magnetic fraction of daily samples of particulate matter less than 10 μm (PM10), routinely used for air quality assessment and monitoring. We used combination of thermomagnetic analyses and other physical and chemical methods, including scanning electron microscopy (SEM) and Mössbauer spectroscopy. Our results show that daily samples of PM10, collected at sites with different degree of atmospheric pollution, contain magnetite of spherical shape, which is presumably of industrial origin. Thus, magnetic methods can be applied directly to the same substances, which are used routinely in air quality assessment and monitoring.