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Statistical and graphical interpretation of 90Sr vertical distributions in soil profiles up to a depth of 1.0 m was presented based on the study of the typical Scots pine stands forest at 14 experimental sites within the Chernobyl exclusion zone. Significant differences were found between 90Sr activity distribution in soil profiles collected at different sites. The part of 90Sr activity below of a depth of 30 cm varied from 15 to 71 %. 90Sr transfer factors from soil to anatomical structures of the stem wood were estimated based on values of soil contamination density, which were calculated for the depth of 0.3 and 1.0 m. The statistically significant correlation between the transfer factors of 90Sr to stem wood (heartwood, sapwood) and its vertical distributions in soil profiles have not been observed. Among the forest inventory parameters for pine stands only the average diameter of trees significantly correlated with 90Sr transfer factors to stem wood.

A probabilistic approach on description of radionuclide contamination of agricultural land as well as crops grown on the land was suggested. The approach can be used to substantiate the possibility to make available the land for agricultural use. The approach allows to assess not only the average value of the activity concentration of radionuclides in crop, but also the probability of exceeding permissible levels. Method was successfully tested in the fields, which are allocated to the second zone of radioactive contamination. These fields are located in Narodichy district of Zhytomyr region and Polisskyi district of Kyiv region.

The transfer factors of iodine isotopes from the daily diet to milk of the cows in the pasture period for different soil and landscape conditions of Ukraine were evaluated and analyzed. It was shown that the possible values of the considered coefficient of the transition is a random variable, which is satisfactorily described by the lognormal distribution law of probabilities. The resulting estimates of medians (GM = 0.046 ± 0.003) and the geometric standard deviation (GSD = 1.79) for possible iodine conversion coefficient of the daily diet in cow's milk were obtained. They refine the IAEA reference data for specific soil-landscape conditions of continental Ukraine and allow obtaining less conservative estimates when predicting the specific content of iodine isotopes in the milk of cows in the pasture period.

Analysis of the results of the selective monitoring of 137Cs in cow milk in settlements, where values of the milk contamination have not met requirements of the permissible levels since the Chernobyl accident, was performed. Monitoring network, which was created at the Institute, is covering the most critical settlements of Zhytomyr, Rivne and Volyn regions. The article presents data on radionuclide contamination of cow milk for the last 5 years (2011 - 2015), while observations are carried out since the 90-s of the last century. Long-term data show that the current dynamics of contamination of cow milk in these settlements is comparable to the decrease of 137Cs activity due to its physical decay.

Uniqueness of radioecological situation in Ukraine is due to the presence of large areas of peat soils spread, for which abnormally high rates of radioactive cesium in plants are observed. Even in 30 years after the Chernobyl accident, agricultural products exceeding the requirements of AS-06 on peat soils with levels of contamination by 137Cs of about 37 kBk/m2 is produced. Developed and tested traditional antiradiation measures did not receive, due to some circumstances, the state support for the contaminated area. Therefore, we proposed alternative approaches to improve the radioecological situation on the contaminated peat soils.

Averaged assessments of radiological effectiveness dynamics of mineral fertilizers of long-term application at the late phase of ChNPP accident have been carried out on the base of 3-5-years experiments. The influence of mineral fertilizers, used in different doses for agricultural plants, has been shown for intensity of 137Cs accumu-lation by plants on various soil-climatic conditions of radioactively contaminated territory of the Ukraine.

Current radiological conditions and the possibility of returning to economic use of radionuclide-contaminated agricultural lands of the Narodychi United Territorial Community of the Korosten District of the Zhytomyr Region were assessed. The lands had been withdrawn from use in accordance with the Law of Ukraine "On the Legal Regime of the Territory Exposed to Radioactive Contamination as a Result of the Chornobyl Disaster" (Law) and marked in the State Land Cadastre of Ukraine as "radioactively contaminated land". It is shown that in accordance with the requirements of the Law on soil contamination density with 137Cs, 90Sr, 238-240Pu the lands currently do not belong to the zone of unconditional (mandatory) resettlement and even the zone of guaranteed voluntary resettlement and have no legal grounds for restrictions on their use. Predictive assessment of contamination of crops with 137Cs and 90Sr growing on the considered fields was performed. The assessments show which from the fields can be used to produce without countermeasure products below the permissible levels.

A radiological assessment of hayfields and pastures (Narodychy district, Zhytomyr region), which were taken out of economic use due to contamination after the Chornobyl accident, was performed. The possibility and ways of returning the lands to original use were considered. Maps of 137Cs and 90Sr soil contamination densities for the field were made and the corresponding statistical characteristics of the contamination were estimated. Estimates of 137Cs and 90Sr activity concentration in natural grasses, cow milk, and meat as well as the risks of exceeding by the values the permissible levels have been calculated. The possibility of using the land for the production of milk and meat has been shown in the example of the considered radioactively contaminated pastures.