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The evaluation of 137Cs content in mushrooms and forest berries in the South Bohemia region
HÁLOVÁ, Jana
The collection and consumption of forest fungi and blueberries are among the most popular seasonal activities in Czech Republic. Due to the Chernobyl accident, however, these raw materials are believed to have contained increased amounts of radionuclides. The aim of the work is to evaluate the content of 137Cs in blueberries and fungi collected from South Bohemian region in the period of 1992 - 2020. Data of 137Cs mass activity obtained from the State Office for Nuclear Safety's MonRas database were re-examined for validation using samples of fungi (n = 318) and blueberries (n = 142). The results ranged widely as follows: (a) boletes fungus, from 0.18 to 6430 Bq / kg; (b) leafy fungus, from 0.28 to 4040 Bq / kg; and (c) blueberries, from 0.24 to 2046 Bq / kg. Between boletes fungus and leafy fungus, the former was seen to have a higher ability to accumulate the radionuclide 137Cs. The calculated effective dose caused by the consumption of fungi and blueberries was assessed as negligible, amounting only to less than 1% of the general limit for the population. Despite these favorable results, detailed monitoring of raw materials from nature needs to be continued and the safety of the food chain ensured.
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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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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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