Wojas, Anna
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nauki o Ziemi i środowisku
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Item type:Article, Access status: Open Access , Investigation of the magnetic properties of soils in the Cisna-Wetlina Landscape Park(Wydawnictwa AGH, 2016) Gonet, Tomasz; Wojas, AnnaA magnetic study of 16 samples of topsoil and 2 soil profiles (11 samples) in the area of Cisna-Wetlina Landscape Park was carried out. The whole collection of the samples represents typical Carpathian soils – brown and sour. Magnetic susceptibility, frequency, dependence of magnetic susceptibility, temperature dependence of magnetic susceptibility, thermal decay of saturation, isothermal remanent magnetization, parameters of hysteresis loop and anhysteretic remanent magnetization of the samples were measured in a laboratory. Mass magnetic susceptibility of topsoil specimens is below 40 $\cdot$ 10$^{-8}$ m$^{3} \cdot$ kg$^{-1}$, which indicates that the investigated area is probably not polluted currently. The study of the samples from two soil profiles reveals a slight enhancement of magnetic susceptibility in the upper horizons, presumably related to natural processes. The temperature dependence of magnetic susceptibility and saturation isothermal remanence of four soil samples show that the presence of iron sulphide minerals (pyrrhotite) and maghemite is associated with hematite. The occurrence of other iron sulphide minerals in the soil is also possible. The saturation isothermal remanence curves do not confirm the presence of magnetite. Studies of the hysteresis loop reveal a significant role of paramagnetics among magnetic minerals occurring in the samples. Hysteresis parameters (coercive force, coercivity of remanence, saturation magnetization, isothermal remanent magnetization) and anhysteretic remanent susceptibility allowed the authors to evaluate the grain size distribution and reveal the presence of pseudo-single domain (PSD) grains.Item type:Article, Access status: Open Access , Relative secular variations of the Earth’s magnetic field in the years 1966–2016 along the profile across the main tectonic units of Poland (Zgorzelec-Wiżajny profile)(Wydawnictwa AGH, 2019) Wojas, Anna; Grabowska, TeresaThe paper summarizes 50 years of research on relative local secular variations of the total magnetic intensity (TMI) along Zgorzelec-Wiżajny profile (Z-W profile) through the years 1966–2016. The Z-W profile (approximately 650 km length) cuts through Europe’s major tectonic units, including a zone of Variscan folds in the Paleozoic platform (PP), the Trans-European Suture Zone (TESZ) and the Polish part of the East European Craton (EEC). Measurements of TMI were made at 31 sites of the profile and reduced to the base recordings at the Central Geophysical Observatory in Belsk. Based on linear approximations of relative geomagnetic field values changes in time, relative annual changes in time (relative secular variations) expressed in nanoteslas [nT] per year were calculated. The study on relative geomagnetic field values revealed slower secular variations of the geomagnetic field in EEC as compared to those in PP and TESZ. However, they show lower amplitudes of these variations. An interesting phenomenon are rapid changes in the time of the relative values (trends) of TMI starting from the year 2000, also expressed as the relative secular variations per year, particularly visible in PP area. In the qualitative sense, relative secular variations show a correlation with the main geological units in the Polish territory and also important elements in the seismic and geothermal model of the lithosphere.Item type:Article, Access status: Open Access , Rekonesansowe badania podatności magnetycznej utworów przypowierzchniowych na wybranych obszarach południowej Polski(Wydawnictwa AGH, 2010) Wojas, Anna; Rolirat, Anna; Grabowska, TeresaIn the article, the reconnaissance investigations of the magnetic susceptibility of soils and ochre are presented. Field investigations have been performed in southern Poland, namely in the Łąki Nowohuckie area of Krakow, the eastern surroundings of the city of Trzebinia, and the hamlet of Czerwonki near Rzeszów. Laboratory magnetic analyses have been completed. An increase of soil susceptibility has been observed in the studied areas with high anthropopression (Krakow and Trzebinia). It has been proven that iron particles collected in the soil come from urban-industrial emissions. The higher susceptibility of soils in the Łąki Nowohuckie area, than in the vicinity of Trzebinia, has also been affirmed. The diversity of the low values of soil susceptibility in the Trzebinia area is not connected to the Zn-Pb ores which occurred there. The investigations of ochre susceptibility at Czerwonki Hermanowskie have confirmed its quite strong magnetic properties in comparison with properties of the soil situated in a nearby deposit. The large differentiation of ochre susceptibility has been observed. It is probably connected with the mineral composition of ochre and the processes that occurred in the deposit. The ochre deposit slightly disturbs the geomagnetic field (microanomalies) as is shown on the micromagnetic anomaly map.Item type:Article, Access status: Open Access , Badania podatności magnetycznej gleb miejskich w Krakowie(Wydawnictwa AGH, 2009) Wojas, AnnaIn the presented paper, the results of field and laboratory investigations of magnetic susceptibility of soils in Kraków are described. Low susceptibility was observed for soils under the forest terrain whereas higher susceptibility was measured on the open area. The presence of magnetic particles of the anthropogenic origin in soils of Lasek Łęgowski and Łąki Nowohuckie areas was discovered.