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Content of cesium-137 in fungi in selected localities in the Novohradské hory
SCHNEIDEROVÁ, Kateřina
The Novohradské Mountains were increasingly contaminated with cesium-137 in places where large amounts of radiocesium were washed out of the radioactive cloud caused by the accident of the Chernobyl nuclear power plant on April 26, 1986. Another source of cesium-137 was the testing of nuclear weapons, which was in the 50s and 60s of the 20th century carried out in the atmosphere of nuclear powers. From contaminated soil, cesium-137 enters the food chain and thus causes internal contamination of the population. For this reason, the activity concentration of cesium-137 in food (especially in edible mushrooms) is regularly determined. The aim of this thesis was to compare the activity concentrations of cesium-137 in samples of edible fungi collected in selected localities of the Novohradské Mountains. Transfer factors in individual fungal species were determined and compared. The thesis also focused on the comparison of the activity concentration of cesium-137 in the cap and in the stem of the mushroom. The samples were measured by gamma spectrometry. The values of activity concentration of cesium-137 in edible mushrooms differed according to their classification into the systematic group. Higher values of activity concentrations were measured in basidiomycete fungi compared to lower values recorded in gill fungi. High values of activity concentrations of cesium-137 have been repeatedly found, especially in the imleria badia (Xerocomus badius). The lowest value of the activity concentration of cesium-137 was measured in the representative of the parasol mushroom (Macrolepiota procera). The transfer factor as a ratio between the activity concentration of cesium-137 in the mushroom and the activity of cesium-137 in the soil is an important parameter for estimating the dose of internal exposure to radionuclides that a person receives in contaminated foods. The highest determined transfer factors were calculated for imleria badia (Xerocomus badius), the blusher (Amanita rubescens) and golden chanterelle mushroom (Cantharellus cibarius). Out of a total of 58 samples, in 78 % of the samples the values of the activity concentration of cesium-137 in the cap were higher than the values of the activity concentration in the stem and in 22 % of the samples the activity concentrations in the cap were lower than in its stem. The determined cap/stem ratio confirmed that three quarters of the edible mushrooms examined preferentially accumulated cesium-137 in the cap and one quarter of the mushrooms more accumulated cesium-137 more in their stem.
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Determination of the transfer factor for Cs-137 for forest berries
MACUROVÁ, Michaela
The diploma thesis was prepared on the topic of determination of the transfer factor for Cs-137 for forest berries. Despite the fact that 35 years have passed since the accident at the Chernobyl power plant, soils and subsequently also forest berries are still contaminated with Cs-137. The aim of the work was to determine the transfer factor for Cs-137 on the basis of measuring the activity of Cs-137 in forest soils and in samples of forest berries. Furthermore, compare the results with the values published in the literature and published in the MonRaS database. To this end, a research question was set: "Are the results of the calculated transfer factors for forest berries comparable to the values published in the literature". In order to achieve the set goals and answer the research question, a practical research was carried out, during which samples of blueberry fruits and soil samples in their subsoil were taken from 10 localities, according to the established methodology. A total of 60 samples were taken. Subsequently, the samples were measured using gamma spectrometric analysis at The State Office for Nuclear Safety in České Budějovice. Graphs were created from the measured values and then compared according to the criteria to meet the set goals. Transfer factors for wild berries were determined. The objectives of the work were fulfilled and the research question was confirmed, which means that the results of the calculated transfer factors for forest fruits are comparable with the values published in the literature. The research carried out in this diploma thesis can serve as another part of the ongoing monitoring of the contamination of our territory by the radiation fallout from the Chernobyl accident. At the same time, it can be useful in the selection of sampling sites for further research or serve as study material for students of the study program of population protection and related fields.
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The Cs-137 content in wild game
HÁKOVÁ, Veronika
The surrounding world has been influenced by ionizing radiation ever since. From the beginning they were only the natural sources as cosmic and solar rays or earth's radiation. Technical development of society brought discovery of artificial sources of ionizing radiation. In the beginning scientists studied them with noble aims. Eventually the negative side of utilization of nuclear fission was discovered in nuclear weapons. Artificial sources of ionizing radiation are mainly nuclear weapon's testing products from fifties and sixties in last century and nuclear power plant's accidents' products. When it comes to environment's contamination by Cesium radionuclide Cs-137 (further only Cs-137) and by inhabitants influencing, in The Czech Republic territory the biggest effect came from Chernobyl nuclear power plant failure. The aim of Bachelor Thesis is comparison of Cs-137 amount in meat of some species of forest or wild animals by semiconductor gamma spectrometry. The research question is whether amount of Cs-137 depends on animal species, or not. In The Thesis's introduction the general findings concerning ionizing radiation are described. What actually the ionizing radiation is and what a radionuclide and a half-life are. The next is a short set of quantities coming with ionizing radiation. Whereas the amount of Cs-137 in wild animal meat is examined, next part deals with Cesium and its isotope Cs-137. The amount of Cs-137 is very often compared with amount of natural Potassium K-40 (further only K-40) which is one of the most widely spread radionuclide in environment. Other part of The Thesis is devoted to nuclear weapon development. It actually began in between World Wars in the beginning of 20th century. The second most significant source of Cs-137 in our area was the crash of the 4th reactor of nuclear power plant Chernobyl, which occurred on April 26, 1986. By the way in this year has passed 30 years from one of the biggest nuclear catastrophe ever. In the next part a summary of wild animal species is given. Such animals were ahead selected and their meat was used as samples for measurement of Cs-137 mass activity. Mass activity was measured by means of semiconductor gamma spectrometry in Regional Centre of State Office for Nuclear Safety in České Budějovice. Due to availability of game animals was chosen Jindřichův Hradec region. Samples available for measurement reason were taken from the following kinds of hunting game: wild boar, fallow deer, roe deer, fox and hare. From each, under permission hunted piece was taken specimen of about 500 grams. After cleaning and cutting meat vas put to special Marinelli measurement bowls and frozen. Later was measured Cs-137 mass activity and for comparison also K-40 one. Measured values of Cs-137 mass activity oscillated from 1,9 Bq.kg-1 to 191 Bq.kg-1. In both cases it was meat of wild boar. Figures K-40 mass activity were from 47,4 Bq.kg-1 up to 201 Bq.kg-1. Where the lowest value came from meat sample of wild boar, then the highest value came from meat sample of roe deer. The numbers of Cs-137 and K-40 mass activities in meat sample of fox were almost the same. The mass activity values of any sample never reached the threshold value 600 Bq.kg-1, which is given by Announcement about radiation protection no. 307/2002 Sb. Measured values shows that amount of C-137 vary with the type of wild animals. According to statistic data the average game consumption is 700 grams per adult per year. In case of our family the consumption is even 7 200 grams per adult per year. Just for interest was calculated committed effective dose for consumption of 700 grams and also for estimated consumption of 7 200 grams. With consumption about 700 grams per adult per year the committed effective dose is 0,0017 mSv and with consumption about 7 200 grams is 0,018 mSv. The result is - effective dose values are not of great significance, contamination of hunting game meat by Cs-137 is
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The contents of caesium-137 in different soil types in selected locations in CR
ČADOVÁ, Michaela
Caesium-137 is one of the major artificial radioactive elements, whose sources are atmospheric nuclear tests carried out in the 20th century and nuclear power plant incidents such as Chernobyl. Because of uneven precipitation, there were significant differences in radioactive fallout levels in different areas of the Czech Republic during the passage of the radioactive cloud from Chernobyl. Due to the high solubility of Caesium-137 in water and easy distribution in the environment, there is contamination of the lower soil levels where the plant root systems are located. The aim of this work is to collect soil samples from selected localities, where in 1986 significant contamination was detected as originating from Chernobyl, determination of their Caesium-137 content by gamma semiconductor spectrometry and comparison depending on the type of soil. The research question was set as: Does Caesium-137 content differ in different soil types? As part of this study, samples of uncultivated agricultural land and forest land were collected from layers 0-5, 5-10 and 10-15 cm in Kvilda, Zadov and Churanov. For comparison, results were also collected from a locality where the radioactive fallout was not so significant. This locality is around the village Straz nad Nezarkou, which is found on the protected nature reserves of Trebon. From the results of measuring the soil it was found that even after thirty years since the Chernobyl disaster occurred, Caesium-137 is still found in the upper layers of soils, specifically to depths of 5 cm. The highest specific activity of Caesium-137 was measured in the forest soils in Zadov at depths of 0-5 cm (364 Bq.kg-1) from the total range of all samples, 2,24 Bq.kg-1 to 364 Bq.kg-1. The highest specific activity of potassium K-40 was measured in uncultivated agricultural land in the locality of Kvilda at depths of 0-5 cm (883 Bq.kg-1).
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The Cesium-137 content in wild game in Šumava.
VENČOVSKÁ, Petra
Our territory was the artificial radionuclide cesium-137 (hereafter 137Cs) contaminated by radioactive contamination during nuclear testing in the atmosphere and to the largest nuclear accident occurring in Chernobyl. Contamination of the environment and its components 137Cs is still being monitored due to the long half-life of this radionuclide. The stated goal of the work is to compare the mass activity of 137Cs in the forest species from the Šumava region. This also results in the research question as to whether there is a difference in 137Cs in the mass of different animal species living in forests in the Šumava region. According to the availability of samples, the administrative districts of Vimperk and Horní Planá were selected. From these localities, there are also 14 measured samples of fur animals, which were provided for this research. Consequently, the content of 137Cs was determined by gamma semiconductor spectrometry, which, besides mentioned 137Cs, was also used for comparison with potassium-40 (hereinafter only 40K), which is the most widely used natural radionuclide. The measurement results also show that higher concentrations of 137Cs were in samples from the Vimperk region, and also that higher mass activity of 137Cs was measured in herbivores. The highest value of 40K was measured in both herbivores and omnivores. Effective dose ranges were calculated from the results obtained to express the level of contamination that would occur in the case of the consumption of contaminated meat. Calculated values of effective dose ranges due to internal contamination as well as other sources of radioactivity are not significant and their effect on the health of our population is negligible.
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Contents od caesium-137 in mushrooms
ČADOVÁ, Michaela
The aim of this work is to compare the presence of Cs-137 in different kinds of mushrooms in selected locations using semiconductor gamma-ray spectrometry. Research question was determined: Does Cs-137 content amount vary depending on the fungal species? The first part deals with basic knowledge of ionizing radiation, which is important for the complex understanding of thematic problems. This concerns basic radiobiological terms such as radioactivity, ionizing radiation, its biological effects and basic units and quantities used in radiobiology and radiation protection. Further I deal with the above mentioned measured radionuclide Cs 137, which resources in our country include the Chernobyl nuclear plant accident and tests of nuclear weapons in the 20th century. I also pay attention to this element in the cycle of nature, its distribution in the body and the effects on our environment. Shortly I even deal with basic knowledge of the Cs-137 accumulation in mushrooms. Another point mentioned is the research methodology, a brief introduction to semiconductor gamma spectrometry. As sampling sites I selected Zadov, Churáňov and Kvilda in Šumava, where in 1986 there was detected the biggest radiation fallout. For comparison, I also measured samples of mushrooms from localities of less significant fallout. These are sites around a village of Příbraz and in the woods of Jemčina within Třeboň region. A total of 26 mushroom samples were taken. Mass activity was measured by semiconductor gamma spectrometry in the Regional Center of the State Office for Nuclear Safety in České Budejovice. In addition to Cs 137 there was also measured a content of a natural isotope Potassium-40. It is a Cs 137 chemical homologue, which has similar properties and is present homogeneously throughout the whole ecosystem. For comparison I also measured mass activity of other forest ecosystem components such as moss, bark, cones and ground. Measuring time of the mushroom samples was for about 24 hours. The other forest ecosystem components measuring time ranged from 24 to 48 hours. The measured spectra were analysed by using the GAMAT software tool. The highest measured mass activity of Cs-137 was detected in a pine bolete sample from the site of Churanov in Sumava (4 265 Bq.kg-1). Also Russula emetica from Zadov shows relatively high activity (3 050 Bq.kg-1). The smallest amount of Cs 137 was measured in Cystolepiota high, originating in the locality of Jemčina in Třeboň region (5.6 Bq.kg-1) and in a sample of Lactarius volemus from the nearby village Příbraz (34.7 Bq.kg-1). The highest mass activity of natural radionuclide K-40 was measured in a sample of blusher from the village Příbraz site (4 329 Bq.kg-1). High value was probably caused by the use of fertilizers or pesticides near this sample. Large number of K-40 was also seen in Laccaria amethystina, also coming from the village Příbraz (2 901 Bq.kg-1). On the contrary, the least of this element was found in Cystolepiota high sample from Jemčina forests (971.8 Bq.kg-1) and in Lactarius volemus from Příbraz (999,6 Bq.kg-1). According to the measured values, we can conclude that the measured mass activity differs a lot. Individual sites may have different values because of uneven rainfalls in our country at the time of the radioactive cloud passage after the Chernobyl explosion. However, specific species of fungi from the same sites differ, which is due, inter alia, to soil characteristics and mycelium depth. The results correspond to the fact that the mushroom-shaped fungi show a greater amount of Cs-137 unlike gilled fungi presented as well by other authors.
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