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Kvalita multi-GNSS přesného určení polohy bodů pomocí stochastického modelování parametru hodin
Mikoś, Marcin ; Kazmierski, Kamil ; Sośnica, Krzysztof
The quality of the International GNSS Service (IGS) station coordinates depends, among other things, on the type of oscillator located at the station in undifferenced GNSS solutions. A distinction of the clock standards can be made between internal, rubidium, cesium, and hydrogen maser clocks. The stability of time standards can vary by several orders of magnitude depending on the type of clock. Highaccuracy clocks allow for the introduction of stochastic modeling in the absolute positioning algorithms which contributes to faster solution convergence and superior position accuracy. In the Precise Point Positioning (PPP) measurement technique based on multi-GNSS, the clock parameter may be determined in two ways. Either it is estimated separately for each system, or a single clock parameter is determined for all systems, taking into account the inter-system biases. In this paper, we analyze the impact of stochastic modeling imposed on clock parameters on positioning in a multi-GNSS PPP solution. We use selected IGS stations observing GPS, GLONASS, Galileo, and BeiDou satellites. All analyses for the clock parameter are conducted for different types of oscillators along with the performance characteristics for each system. An important advantage of modeling the clock parameter is to stabilize the station vertical coordinate component in multi-GNSS PPP solutions.
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Vertikální migrace Cs-137 v půdním profilu do hloubky 1m
NOVÁČKOVÁ, Jana
From the point of view of long-term environmental contamination, cesium-137 is the most important element because it is absorbed into the human body, but also into the root system of plants, mosses, fungi, wild berries and wild game meat. Above all, however, it remains in different layers of the soil. Several main factors affect the distribution of radionuclides in the soil, namely rainfall, water entry into the soil, diffusion, migration through root systems, human, animal activity, etc. Monitoring its occurrence in the environment is important and involves the interference of cesium-137 with potassium. It in absorbed in the human body (about 80%) and excreted in the urine. It remains most in soft tissues and its biological half-life is 110 days. We are exposed to ionizing radiation from natural sources and human activities. Human activity causes artificial radioactivity, which is relatively small, compared to natural radioactivity, but the impact on human health can be huge. The first part of the bachelor thesis relates to the issue with the use of theoretical and scientific information, standards, law. The next part includes the methodology and results of practical measurement of soil samples. The aim was to find out which layer of soil deposits the most radioactive cesium, because it is assumed that it is still a part of it. Soil samples were taken in the protected landscape area of Šumava, in the 2nd zone of the National Park, in the Železnorudsko area, locality Nová Hůrka (Kuchyně). The site choice presented the distribution of radioactive fallout in our territory. Soil samples were take in 1 cm increments to a depth of 1 m, dried, cleaned and prepared for measurement. The samples taken were measured in the standard way at the Regional Center of the State Office for Nuclear Safety (SÚJB) in České Budějovice. The spectra obtained by measurement were evaluated using GAMWIN software. In the practical part, soil layers with a thickness of 1 cm to a depth of 1 m were taken and after their processing and preparation for measurement, the activity of cesium-137 in soil samples was measured by semiconductor gamma spectrometry. The measured results were compared with the results of previous soil samples and they were evaluated and interpreted in the bachelor's thesis. The results of the measurements showed the depth to which the maximum of cesium-137, which comes from nuclear weapons testing, and especially from the radiation accident at Chernobyl, is currently located. The aim of the work was to find out what is the depth distribution of cesium-137 in uncultivated soils and whether its migration through the soil profile is still ongoing and to confirm or refute the hypothesis of what maximum amount still occurs in the range of plant root system.
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Determination of selected metals in edible mushrooms in the Příbram district
DVOŘÁKOVÁ, Hana
The aim of this work was to determine the concentrations of rubidium, cesium, lithium, strontium and supplemental elements of copper, iron, manganese and zinc in samples of edible mushrooms and to compare the measured concentrations with the studies mentioned in the literary research. In addition to the results of the studies, the literary research contains brief informations about mushrooms, individual elements, the used method and the monitored location. For the purposed of the practical part, 19 samples of nine edible mushrooms species were collected from the vicinity of a lead smelter in the village of Podlesí near Příbram. The samples were the first processed by microwave digestion and then analyzed by AAS (atomic absorption spectrometry). The whole practical part of the thesis was carried out in the laboratory of the Departemnt of Applied Chemistry, Faculty of Agriculture of the University of South Bohemia in České Budějovice. The analysis results were recorded in tables, statistically and graphically processed an evaluated in the discussion. From the analysis we found the species of mushoom with the most cumulate metals ability is a toadstool rosacea. Among the analyzed samples we found the highest concentration of strontium (22,5 mg/kg), lithium (0,6 mg/kg), iron (223,0 mg/kg) and manganese (69,7 mg/kg). On the other hand, the least cumulative species was boletus brown with the lowest concentrations of copper (10,1 mg/kg), iron (29,5 mg/kg) and manganese (5,2 mg/kg) being determined. The less cumulative species was also boletus edulis, which was found to have at least strontium (2,2 mg/kg) and lithium (0,3 mg/kg). It is worth mentioning the larch bolete, in which we have determined the greatest concentration of rubidium (364 mg/kg) and cesium (11,7 mg/kg), but the least of zinc (68,7 mg/kg). Likewise, a parasol mushroom absorps copper to a large extent (255 mg/kg), but on the contrary it contained the least cesium (0,5 mg/kg) and rubidium (11,8 mg/kg).
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Cs-137 content monitoring by spectrometric measurement in soil
LEPIČ, Daniel
The aim of the thesis is to compare the results from in situ spectrometry and laboratory determination of the area activity of Cs-137 in samples taken from uncultivated soils. To fulfil the goal, the research question has been determined: Are the results from in situ measurement of the area activity of Cs-137 in uncultivated soil comparable with the results from laboratory measurement of collected soil samples? The theoretical part of the work has been written based on research of book publications, foreign scientific articles and electronic sources, which deal with the issue of radioactivity and its impact on the environment and the principle of semiconductor gamma spectrometry. The practical part of the work deals with the spectrometric measurement using in situ method and the laboratory determination of the area activity of Cs-137 in the soil samples using a semiconductor gamma spectrometer. The measurement and the soil sampling took place in the territory of the Šumava National Park and its adjacent areas in Pilsen Region. There were selected five locations (Nová Hůrka, Prášily, Srní, Nový Brunst and Hadí vrh). By in situ spectrometric measurement the highest values were determined of the area activity of Cs-137 in the location Nová Hůrka (19526 Bq / m2) and the lowest in the location Hadí vrh (5398 Bq / m2). The spectrometric measurements of the soil samples in the laboratory revealed the highest values of the area activity of Cs-137 in the sample from the location Nová Hůrka (10000 Bq / m2) and the lowest values of Cs-137 in the location Hadí vrh (2060 Bq / m2). The contribution of this work is the comparison of in situ spectrometric measurement with the measurement of taken soil samples using the gamma semiconductor spectrometer. The results of this monitoring can provide data on the radiation situation in individual locations in Šumava. By the comparison of the results of the area activity of Cs-137, there has been found a correlation between in situ spectrometric measurements and the laboratory measurements of the soil samples. The results of the area activity of Cs-137 are in an order of magnitude comparable. The differences between the results are probably caused by the measurement conditions.
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The influence of trees on contamination of soil with 137Cs
TRNKOVÁ, Michaela
Nuclear weapons testing in the atmosphere and accidents in nuclear energy facilities in the last 50 years caused significant contamination of the environment. Half-life of certain leaked radionuclides is several decades and therefore they are still present in today's environment. That is the reason why there is still on going monitoring of radiation situation in the Czech Republic in order to determine the behaviour and kinetics of anthropogenic radionuclides in the environment and the severity of radiological impact on humans. The results of this monitoring serve to review the radiation situation, observe long-term trends and last but not least to gain new knowledge that could facilitate the management od radiological emergencies. The aim of this thesis was to measure the content of 137Cs in soils under and around leafy tree crowns in the area affected by radiation fall and to find out whether the tree's crown has an effect on the distribution of 137Cs in the soils below them. To this end, a research question has been set: Do tree crowns affect the distribution of cesium in the soils below them? For better intelligibility, the introduction of the thesis is devoted to information about ionizing radiation, basic terms and quantities in the field of ionizing radiation, sources of radionuclide contamination, especially the Chernobyl nuclear power plant accident, environmental and population contamination, and elements important for the practical part of this work. The theoretical part is followed by research methodology. The soil samples were collected under five leafy trees of the Walnut species that met the set criteria for collection. Under each tree, samples were taken in three directions at an angle of 120° always at the trunk, in the middle of the crown, at the edge of the crown and outside the crown. Thus, 12 samples per tree, a total of 60 samples. Dry and purified soil samples were measured by semiconductor gamma spectrometry which determined 137Cs radionuclide mass activity values as well as naturally occurring radionuclide40K. Graphs were generated from the measured values. Despite the frequent deviations that may be caused by natural phenomena or human activities, it was found out that tree crowns affect the distribution of 137Cs in the soils below them.
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The content of selected group 1 and 2 metals in edible mushrooms
MÁCHOVÁ, Nikola
Edible mushrooms are able to accumulate elements, especially some heavy metals and radionuclides, in their fruiting body. This work engages in accumulation of chosen metals (Groups 1 and 2) in basidiomycete fungi and soil. The first picking happened in autumn 2017. Eleven mushroom specimens were found - several fruiting bodies of each type. The soil where the mushrooms had grown was also taken. During the other picking in autumn 2018 ten types of mushrooms were taken. The locality in the Czech Republic (Ledenice) was chosen, because these fungi were frequently found there: Agaricus campestris, Boletus edulis, Suillus variegatus, Xerocomellus chrysenteron, Neoboletus luridiformis, Leccinum rufum, Macrolepiota procera, Suillus luteus, Imleria badia, Leccinum scabrum, Lactarius deliciosus, Agaricus silvaticus, Suillus bovinus and Amanita rubescens. The chosen metals were Lithium (Li), Strontium (Sr), Cesium (Cs) and Rubidium (Rb). I used methods of atomic absorption spectrometry (AAS). In both analysis (2017 and 2018) the largest content of Lithium was recorded in Agaricus campestris fruiting body (2.3 mg/kg and 1.6 mg/kg) and the largest content of Strontium in Leccinum rufum (3.7 mg/kg and 6.6 mg/kg). It was shown that varieties of the Bolete family demonstrated the biggest accumulation of Rubidium (Boletus edulis 519 mg/kg, Neoboletus luridiformis 398.6 mg/kg). The biggest content of Cesium (about 1.1 mg/kg) was recorded also in this family.
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Involvement of AtKT/HAK/KUP high-affinity transporters in plant K+ and Cs+ uptake
Šustr, Marek ; Tylová, Edita (advisor) ; Maršík, Petr (referee)
Potassium is essential macroelement and large amount of potassium is taken up by plants, because it's the major osmotic of plant cell. Due to various potassium availability in different kinds of soil, plants have evolved transport system that can maintain sufficient K+ uptake between several orders of magnitude of potassium concentration. In Arabidopsis thaliana mechanism of K+ acquisition is well understood and it's known that AtHAK5 is mainly involved in K+ uptake in its very low concentrations. AtHAK5 belongs to KT/HAK/KUP family that consist 13 members in A. thaliana. There's known function for some members for example in auxin transport in root tip (TRH1) or in K+ efflux in stomatal closure (KUP6). In this thesis possible involvement of yet unstudied transporters KUP5, KUP7, KUP9 and KUP10 in K+ acquisition and homeostasis in A. thaliana was investigated. In vitro cultivation showed that kup9 mutant has very short lateral roots in K+ deficiency. On the other hand kup5 mutant showed significantly higher dry weight in K+ deficiency than Col-0. Kup9 phenotype was successfully replicated in subsequent cultivations and anatomy of lateral root apical meristems was investigated. Root tips of kup9 were differently organized in K+ deficiency and they showed signs of early termination of meristems. To...
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Uptake and metabolism of 137Cs in plants
Šustr, Marek ; Tylová, Edita (advisor) ; Maršík, Petr (referee)
Plants are able to uptake radiocesium from soil, which is the potential route to enter the food chain. Cesium mobility in soil is determined by clay particles. Cesium can be reversibly ad- sorbed on their surface or can be fixed between layers. Mineral illit has the highest selectivity for cesium due to its frayed edges. Organic matter determines cesium mobility only in soil with organic matter content above 90 %. Cesium is more available for plants in this soil. Cesium uptake varies among species. Many plant species accumulating big amounts of cesium belong to family Chenopodiaceae. Cesium uptake is affected by other cations in soil solution. Potassium is the most effective one. Increasing of external potassium concentration from 50 μM to 250 μM decreased cesium uptake thirty-fold. Potassium affects cesium mobili- ty in soil and plant uptake. Due to chemical similarities of cesium and potassium some potassium transporters efficiently transport both cations. Potassium transporters are therefore considered the main entrance site in plant roots. Great contribution to cesium uptake is dedi- cated to high-affinity potassium transporter HAK5. Another great part of cesium uptake is mediated by non-selective cation channels. Plants can uptake up to 80 % of cesium applied on shoot surface. Cesium is highly...
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Effect of potassium on stable cesium uptake by Calla palustris from aqueous solution
Petrůvová, Nicola ; Komínková, Dana (advisor) ; Petr, Petr (referee)
The aim of the thesis was to evaluate the effect of potassium on receiving of stable cesium and evaluate the appropriateness of Marsh Calla (Calla palustris) for phytoremediation. The experiment was conducted in a green-house environment where the plants were grown in an aqueous solution. The plants were exposed then to a stable isotope of cesium (133Cs) at a concentration of 1 mM CsCl. Potassium was added to the plants in the form of potassium sulphate (K2SO4), in five different concentrations (0.5 mM, 1 mM, 2 mM, 5 mM and 10 mM). Plants were exposed for 8 days. The largest average income of cesium (9,37 %) had a plant without added potassium. The root part of the plants showed a greater cesium content than the ground part. Based on the total intake of cesium from an aqueous solution, calla marsh can be estimated as a plant usable for phytoremediation.
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Impact of nitrogen on accumulation of Cs by Calla palustris
Benediktová, Eva ; Komínková, Dana (advisor) ; Petr, Petr (referee)
This work deals with the evaluation of Calla palustris utilization for phytoremediation and clarifying how nitrogen influences the uptake of cesium from aqueous solution. The plants were subjected to nitrogen exposure, which consisted of five different concentrations of NH4+ and NO3- and 0.5 mM CsCl, for eight days. The greatest amount of cesium (13.5%) accumulated the plants without the addition of nitrogen, the smallest amount accumulated plants with concentrations of 6: 3 (3.9%), 8: 4 (3.6%) and 10: 5 NH4NO3: NH4Cl (3.5%). Calla has proved to be suitable for phytoremediation, however with the need for longer exposure. Besides these main hypotheses it has been moreover shown that the state of plants affected the uptake of cesium and that nitrogen influenced the condition of the plant. Further it has not been observed noticeable difference in uptake of cesium in roots and stems with leaves.
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