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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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