Aleš Kapička

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.

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.

Changes of anisotropy of the magnetic susceptibility of rocks induced by a magnetic field

SummaryThe changes of the anisotropy of magnetic susceptibility of igneous rocks, induced by a magnetic field, are studied. It is proved that changes in the degree of anisotropy of susceptibility and of the orientation of the susceptibility ellispoid of specimens occur due to the configuration of the domain structure under the effect of the magnetic field. The influence of this effect on the total anisotropy of rocks depends on the degree of anisotropy due to the shape factor and on the stability of the domain structure. A model concept is presented, explaining the qualitatively different pattern of the changes of the anisotropy of susceptibility under the effect of the magnetic field in various directions of the specimens.

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 and geochemical characterization of Andosols developed on basalts in the Massif Central, France

Identification of Andosols is primarily based upon the content of their colloidal constituents—clay and metal-humus complexes—and on the determining of andic properties. This needs time and cost-consuming geochemical analyses. Our primary aim of this study is to describe the magnetic and geochemical properties of soils rich in iron oxides derived from strongly magnetic volcanic basement (in this case Andosols). Secondary aim is to explore links between magnetic and chemical parameters of andic soils with respect to genesis factors: parent material age, precipitation, and thickness of the soil profile. Six pedons of andic properties, developed on basaltic lavas, were analyzed down to parent rock by a set of magnetic and geochemical methods. Magnetic data of soil and rock samples reflect the type, concentration, and particle-size distribution of ferrimagnetic minerals. Geochemical data include soil reaction (pH in H2O), cation exchange capacity, organic carbon, and different forms of extractable iron and aluminum content. Our results suggest the following: (1) magnetic measurements of low-field mass-specific magnetic susceptibility can be a reliable indicator for estimating andic properties, and in combination with thermomagnetic curves may be suitable for discriminating between alu-andic and sil-andic subtypes. (2) In the studied Andosols, strong relationships were found between (a) magnetic grain-size parameters, precipitation, and exchangeable bases; (b) concentration of ferrimagnetic particles and degree of crystallization of free iron; and (c) parameters reflecting changes in magneto-mineralogy and soil genesis (parent material age + soil depth).

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.

Magnetic susceptibility anisotropy of deformed rocks

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A precursory study of magnetic fabrics in the transition zone between magmatic and metamorphic textures in the Askersund granitoid, Sweden

Abstract The Askersund granitoid (age 1845–1850 Ma) is the oldest member of the Transscandinavian Igneous Belt which forms a major structure in the Scandinavian peninsula. The external, metamorphic and gneissic parts of this older generation have the same age as the more central and isotropic parts. A petrographical investigation of samples collected in two traverses from the macroscopically isotropic part to the gneissic part of the intrusion has been complemented with studies of the anisotropy of the magnetic susceptibility of the rocks. The mean degree of anisotropy (PJ ) is different from site to site and increases from the macroscopically isotropic part to the gneissic part. The shape of the susceptibility ellipsoid is slightly oblate in the former part and prolate in the latter. Under the microscope this change can be correlated with a change in textures indicating deformation in a partly crystallized magma to more solid state deformation structures. A major conclusion of this investigation with reg...