In Ukraine, as a result of the Chernobyl disaster, 2,218 villages and cities with a population of about 2.4 million residents were in the zone of radioactive contamination. Pollution has undergone almost the entire territory of Polesia and a significant part of the Forest-Steppe. The population living in radioactively contaminated areas receives an additional more natural dose level of external and internal exposure. External irradiation is due to the high content of 137Cs in soils, with the decay of which increases the power of gamma radiation on the ground. Internal exposure is caused by the ingestion of 137Cs and 90Sr during the consumption of food products. The rural population with the consumption of products grown in household plots, receives significantly higher doses of radiation than the city. The activity of 137Cs and 90Sr in milk, meat, potatoes and other vegetable products is grown on the backyards of residents of the villages Osypivka and Tarasivka of the Bila Tserkva district of the Kyiv region, who have been subjected to radioactive contamination due to the Chernobyl disaster. The research results show that milk, meat and vegetable products grown in radioactively contaminated areas of the forest-steppe zone meet the radiation safety criteria for 137Cs and 90Sr. The internal exposure dose of the residents of the Osypivka village with the consumption of food products is 0.065 mSv/year, and that of the Tarasivka village - 0.028 mSv/year. Consumption of milk and potatoes makes the greatest contribution to the dose of internal exposure. The external radiation dose due to pollution of the territory of the settlement of 137Cs residents of the Osypivka village is 0.72 mSv/year, and that of the Tarasivka village – 0.27 mSv/year. The annual effective dose to residents of the Osypivka village – 0.78 mSv/year, and the residents of the Tarasivka village - 0.30 mSv/year, which does not exceed the dose of radiation established by current legislation at 1 mSv/year

Regardless of the time after the Chernobyl disaster, the problem of radioactive contamination is very urgent. At present, 6.7 million hectares of our country remain contaminated, of which 1.2 million hectares of land are contaminated with 137Cs with a density of 42 to 589 kBq/m2 (1–15 Ci/km2). There are 2,161 settlements in the radioactively contaminated territories, where there are about 3 million inhabitants. For the inhabitants of rural areas of these settlements, the main part of food products belongs to the products obtained from the land, so the definition of plant contamination by artificial radionuclides 137Cs and 90Sr on the lands affected by radioactive contamination. The Chernobyl accident is relevant, since the internal dose of radiation is formed due to consumed products, grown in private plots. Reducing the transition of radionuclides 137Cs and 90Sr from soil to crop production is one of the main tasks of agricultural production on contaminated radionuclide lands. The realization of these researchers will clarify the current state of migration of data of radionuclides in the soil-vegetation link in the agro eco systems of the Central Forest-steppe of Ukraine. From the moment of the Chernobyl accident, leading scientists conducted a sufficiently large number of scientific studies on the migration of 137Cs and 90Sr in agricultural production facilities, their accumulation in food products and the assessment of human exposure doses. The focus of the scholars focused on the territory of Polissya. Preferably migration of 137Cs and 90Sr in separate links and systems of the trophic chain. In addition, somewhat more attention is paid to 137Cs, which is the main dose-forming radionuclide. In addition, in forest-steppe areas that are radioactively contaminated, a significant proportion of pollution occurs at 90Sr, whose migration rate, according to scientists, will gradually increase. All these data led to the need for a detailed study of the state of migration of 137Cs and 90Sr in the soil-vegetation chain of agro eco systems of agricultural enterprises and private parts of the central forest-steppe affected by radioactive contamination because of the Chornobyl accident in the remote period. The purpose of these studies was to study the migration of 137Cs and 90Sr in the chain of soil plants in the villages Yosypivka and Tarasivka of the Kyiv region of the central forest-steppe of Ukraine, as well as the determination of the coefficients of transition of 137Cs and 90Sr from typical black soil to vegetable products for the next prognostication. The investigated areas of the Bila Tserkva district are located in the north-eastern part of the right-bank forest-steppe region of Ukraine and are represented mainly by typical low-humus black soil in the forests within the boundary plains. In order to achieve this goal, selection of samples of crop production and soil was carried out on private plots of peasants of Yosypivska and Tarasivska villages of the Bila Tserkva district of Kyiv region according to generally accepted methods. The territory of these settlements fell into the zone of the "southern trace of radioactive contamination" and is associated with the third and fourth zones of radioactive contamination. After preparation of samples, the activity of 137Cs and 90Sr was determined in the life safety department of the Bila Tserkva National Agrarian University at the USK Gamma Plus spectrometric complex according to the methodology for this device. To determine 90Sr, selective radiochemical separation was performed by precipitation of oxalates. The 90Sr determination was performed on the USC Gamma Plus beta spectrometric path. These studies were processed using the statistical method using the Microsoft Excel program. The main vegetable crops grown on private plots were carrots, cucumbers, potatoes, cabbage, tomatoes, zucchini, onions, peppers and radish. These studies were conducted during 2016-2018. From the data of the research it is clear that the least activity of 137Cs was in potatoes, onions and cucumbers. In zucchini and pepper, it appeared twice, carrots and tomatoes – almost four times, beets and radish – almost in 8, and beans – 11 times higher. Our studies show that there is a direct proportional relationship between the activity of 137Cs and 90Sr in the yield of vegetable crops and the level of the soil contamination. The research results make it possible, on the basis of the explained coefficient of transfer of 137Cs and 90Sr, to predict the contamination by plant radionuclides that will be grown in radioactive contaminated territories of the Central Forest-steppe of Ukraine. The coefficients of transition of 137Cs from soil (typical black soil) to vegetable crops grown in the III zone of radioactive contamination accumulate from 0.01 to 0.09 and 90Sr – from 0.01 to 0.30. The lowest coefficient of transition of 137Cs in potatoes, onions and cucumbers (0.01). In cabbage, squash and pepper, the transition factor is twice as high (0.03), and in carrots and tomatoes it is three times higher (0.04), in beets – 5 times, radish – 6 and beans – in 9 times higher. The lowest transfer coefficient of 90Sr in onions (0.01), in tomatoes and cucumbers it is 2 times higher (0.02), in pepper – 4 times higher (0.04), potatoes and cabbage – nine times higher (0.09), and in beets, radishes, carrots and beans in 27–30 times higher. The research conducted by us proves that the studied vegetable production, obtained in the settlements of Yosypivka and Tarasivka, does not exceed DR-2006, that is, it is quite suitable for use. The coefficients of the transition of radionuclides 137Cs and 90Sr from the soil (in this case, this typical black soil) to crop production grown on peasants’ plots have been determined, which will allow to predict in the future the contamination of 137Cs and 90Sr of vegetable products on the radically contaminated territories of the Central Forest-Steppe data. The content of radionuclide contamination of vegetable products after 33 years of the Chernobyl disaster proves that the problem of monitoring, studying and forecasting of products is still very relevant. Key words: 137Cs and 90Sr radionuclides, pollution density, transition coefficient.

Because of the Chernobyl catastrophe, almost all the territory of Polissya and a significant part of the Forest-Steppe south of Kyiv suffered radioactive contamination. More than three decades have passed since the Chernobyl accident, but despite the time since the disaster, the problem of radioactive contamination is still very relevant. In radioactive contaminated agro landscapes, plant fodder becomes a source of 137Cs and 90Sr in the body of cows. In the organism of an animal, radionuclides of cesium mainly accumulate in muscle tissue, and strontium in bone and excreted with milk, urine and feces. Milk plays an important role in human nutrition, which necessitates constant monitoring of the radio ecological situation, estimates of the accumulation of 137Cs and 90Sr, and the determination of the laws governing the transition of these radionuclides into products. The aim of the research was to evaluate the supply of 137Cs and 90Sr with feed in the body of dairy cows and the accumulation of these radionuclides in milk and barnyard manure mass in radioactive contaminated agricultural landscapes of the Central Forest Steppe. The research was carried out at LLC "Agro-Leader Ukraine" Ltd. and "Nadiya" Ltd and on the peasants’ plots of Yosypivka, Tarasivka villages of the Bila Tserkva district of the Kyiv region who suffered from the radioactive contamination because of the Chernobyl catastrophe. Samples of soils, fodder, milk and barnyard manure mass for conducting research were selected. The activity of 137Cs and 90Sr was determined at the USM "Gamma Plus U" with the "Progress 2000" software in the laboratory of the Bila Tserkva NAU, department of life safety. The activity of 137Cs was determined by the method of scintillation gamma spectrometry in a Marinelli vessel of volume 1L in native samples or after their physical concentration, and 90Sr – after radiochemical isolation by scintillation beta spectrometry. The results of the studies indicate that the content of 137Cs and 90Sr in feed is directly proportional to the level of soil contamination by these radionuclides. At the same time, the least accumulated 137Cs and 90Sr in the green mass of corn, and most of all in the green mass of alfalfa and oats mixture. The intensity of the accumulation of 90Sr in the green mass of corn is 20 times, the alfalfa – in 1,5-2 times, the use of oatmeal mixture – 4 to 6 times higher than 137Cs. It has been established that the concentration of 137Cs and 90Sr in milk of cows is directly proportional to their activity in the diet. In the daily hopes of milk from cows from the diet 7,6 ± 0,55 % of 137Cs and 1,7 ± 0,42 90Sr passed from their activity in the diet. The coefficient of transition of 137Cs in 1 liter of milk on average was 0.76 % and 0.17 % 90Sr. The activity of 137Cs and 90Sr in milk does not exceed the permissible levels. At the same time, in the milk of households, the activity of 137Cs and 90Sr in the spring-summer period was two to three times higher than that of autumn-winter due to the grazing of cows in natural pastures, where the level of soil contamination is much higher than that of arable lands. The determinants of the formation of 137Cs and 90Sr activity in cow’s milk are the amounts of these radionuclides with feed from the daily ration, which depend on the composition of the diet and the density of soil contamination on which the forage crops are grown. Studies have shown that the main proportion of 137Cs and 90Sr (up to 90 %), coming from plant foods in the body of cows, is converted into a barnyard manure mass. The accumulation coefficient of 137Cs and 90Sr in the cow barnyard manure is 0.87. The barnyard manure mass of cows, when introduced into the soil, becomes a source of secondary soil contamination and promotes the migration and redistribution of 137Cs and 90Sr in agro landscapes. Obtained in radioactive contaminated areas of the barnyard manure mass of cattle must be used only within the farms in which it is produced. Studies have shown that fodder crops can be grown on the radioactive contaminated forest-steppe areas and it is possible to get milk without any restrictions. Key words: agro landscapes,radioactive contaminated areas, radionuclides, 137Cs, 90Sr, grass, dairy cows, milk, cow’s manure, forest-steppe zone.