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As a result of climate change, forest fires are becoming a common factor in the dynamics of ecosystems in the forest zone of Ukraine, but the assessment of the consequences of this shift in the ecological situation is in the process of pilot studies. In the spring of 2020, a number of large ecosystem fires occurred in the Central Polissia region, which affected forests the most. Among other things, a large fire occurred in ecosystems located in the Exclusion Zone and the Zone of Unconditional (Mandatory) Resettlement, which was formed as a result of the Chornobyl accident. The ecosystems of the Chornobyl Radiological and Ecological Biosphere Reserve located within its boundaries were also affected by the fire. The consequences of this fire were assessed a year later, using mouse-like rodents as a model group. The purpose of the study was to assess and compare the communities of mouse-like rodents in areas that were affected by two degrees of fire damage—where there was a surface fire and those that were most affected (highland fire). Four polygons were created in the control-impact scheme. Each of the pairs of plots was identical in terms of typical forest vegetation conditions. Sherman traps were used for trapping. A total of 560 trap-days were processed, and 101 animals were captured. The presence of four species of rodents from the genera Apodemus, Sylvaemus, and Myodes was recorded, namely the striped field mouse, the yellow-necked wood mouse, the European wood mouse, and the bank vole. The main indicators of species diversity were calculated using information indices—species richness, evenness, and similarity. The surveys revealed both negative and positive changes in areas affected by fires. Areas characterised by relatively higher values of species diversity indices compared to the control had a high intensity of vegetation recovery. They belonged to areas with wet, relatively fertile (sugrud) and infertile (subor) forest types. The plots with low intensity of vegetation recovery had a depleted community structure and belonged to fresh and dry boreal forest. Based on this, it is possible to create a forecast of ecosystem restoration by assessing the type of forest vegetation conditions.

Methods for dose estimation of 137Cs in mouse-like rodents, specifically bank voles (Myodes glareolus), commonly found within the research sites in the Chornobyl Exclusion Zone, are being proposed. The International Commission on Radiological Protection recommends using the specially developed "BiotaDC" software, but it needs to be adapted to solve specific applied issues. It is shown that the "BiotaDC" approach adequately describes dose accumulation of 137Cs for external exposure inside nest chambers if the mean integral value of soil activity concentration at a depth of 0.5 m is used, for external exposure above soil – if the mean integral value of soil activity concentration at a depth of 0.2 m is used. However, the authors propose a method considering the age of animals at the time of capture and the age-related dynamics of changes in such parameters as excretion and accumulation of radioisotopes for internal dose estimation using the "BiotaDC" software. A detailed dose estimation algorithm is being proposed. Dose estimates for internal irradiation according to the authors' method and the method of the International Commission on Radiological Protection are being compared.

Methods for dose estimation of 137Cs in mouse-like rodents, specifically bank voles (Myodes glareolus), commonly found within the research sites in the Chornobyl Exclusion Zone, are being proposed. The International Commission on Radiological Protection recommends using the specially developed “BiotaDC” software, but it needs to be adapted to solve specific applied issues. It is shown that the “BiotaDC” approach adequately describes dose accumulation of 137Cs for external exposure inside nest chambers if the mean integral value of soil activity concentration at a depth of 0.5 m is used, for external exposure above soil – if the mean integral value of soil activity concentration at a depth of 0.2 m is used. However, the authors propose a method considering the age of animals at the time of capture and the age-related dynamics of changes in such parameters as excretion and accumulation of radioisotopes for internal dose estimation using the “BiotaDC” software. A detailed dose estimation algorithm is being proposed. Dose estimates for internal irradiation according to the authors’ method and the method of the International Commission on Radiological Protection are being compared. [ABSTRACT FROM AUTHOR]

The results of radioecological monitoring of the research sites located on the drained areas and the coastal of the ChNPP cooling pond are presented. The features of the spatial distribution of the exposure dose rate, the density of soil radionuclide contamination by the emergency radionuclides were determined. The content of incorporated radionuclides in representatives of the genera Myodes and Sylvaemus were studied, the individual and interspecies variability of 137Cs and 90Sr levels in animals within the limits of one research site was determined. Currently, the indicators of radioactive contamination of biota in the drained areas of the cooling pond are within the variation of those values that are characteristic of most areas of the Chornobyl exclusion zone.

Studies of radiobiological effects in murine rodents exposed to internal radiation in the wild or in laboratory experiments require dosimetric support. The main problem of bone marrow (BM) dosimetry for bone-seeking β-emitters is dosimetric modeling, because the bone is a heterogeneous structure with complex microarchitecture. To date, there are several approaches to calculating the absorbed dose in BM, which mostly use rough geometric approximations. Recently, in the framework of studies of people exposed to 90Sr in the Urals, a new approach (SPSD) has been developed. The aim of the current study was to test for the first time the possibility of extension of the SPSD approach elaborated for humans to mice. For this, computational phantoms of femur bones of laboratory animals (C57BL/6, C57BL/6 J, BALB/c, BALB/cJ) aged 5–8 weeks (growing) and > 8 weeks (adults) were created. The dose factors DFSr-90(BM ← TBV + CBV) to convert the Sr isotope activity concentration in a bone tissue into units of dose rate absorbed in the bone marrow were 1.75 ± 0.42 and 2.57 ± 0.93 μGy day−1 per Bq g−1 for growing and adult animals, respectively, while corresponding values for DFSr-89(BM ← TBV + CBV) were 1.08 ± 0.27 and 1.66 ± 0.67 μGy day−1 per Bq g−1, respectively. These results are about 2.5 times lower than skeleton-average DFs calculated assuming homogenous bone, where source and target coincide. The results of the present study demonstrate the possibility of application of the SPSD approach elaborated for humans to non-human mammals. It is concluded that the study demonstrates the feasibility and appropriateness of application of the SPSD approach elaborated for humans to non-human mammals. This approach opens up new prospects for studying the radiobiological consequences of red bone marrow exposure for both laboratory and wildlife mammals. [ABSTRACT FROM AUTHOR]

The results of radioecological monitoring of the research sites located on the drained areas and the coastal of the ChNPP cooling pond are presented. The features of the spatial distribution of the exposure dose rate, the density of soil radionuclide contamination by the emergency radionuclides were determined. The content of incorporated radionuclides in representatives of the genera Myodes and Sylvaemus were studied, the individual and interspecies variability of 137Cs and 90Sr levels in animals within the limits of one research site was determined. Currently, the indicators of radioactive contamination of biota in the drained areas of the cooling pond are within the variation of those values that are characteristic of most areas of the Chornobyl exclusion zone. [ABSTRACT FROM AUTHOR]