Accumulation of radionuclides in crop products can pose public health risks. Parameters of 137Cs root uptake by maize were investigated at four growth stages, from leaf development to ripening (June–September), in the post-Chernobyl area of the Plavsk radioactive hotspot (the Tula region of Russia). It was established that the chernozem of the agrosystem still contains about 180 kBq 137Cs m−2. Seasonal trends of 137Cs activity concentrations in above- and belowground parts of maize differ appreciably. In aerial parts, the 137Cs accumulation rate increases as vegetative organs develop from June to July, then drops when generative organs appear in August. In the belowground biomass, the 137Cs content increases with the growth of fine roots, which serve as relative concentrators of the radionuclide. However, at all stages of growth, radionuclide transfer to maize occurs with low intensity. It does not directly depend on changes in biomass, dry matter content, or 40K content, and only slightly relates to the ash content. The transfer factor is estimated to be 6.2 × 10−3 for cob kernels (grain) and 3.8 × 10−2 for stems and leaves, which corresponds to the IAEA-recommended values and ensures acceptable levels of 137Cs accumulation in crop products produced in the territory.

The purpose of this review is to systematize data on the level of soil pollution and the rate of erosion processes in the Republic of Kazakhstan (RK) and to identify river basins with the high probability of secondary soil pollution due to the lateral migration of pollutants transported together with sediments. Using the Google Scholar, Springer Link, Science Direct, Scopus, and RSCI search engines, publications on soil pollution with heavy metals (HMs), radionuclides of technogenic and natural origins, oil and petroleum products, and rocket fuel components, as well as characterizing the rates of water and wind erosion and the degree of soil erosion in the RK were collected. On the basis of these data, thematic maps of the RK showing river basins with increased concentrations of pollutants in soils were compiled. Using the maps of soil pollution and water and wind erosion, river basins with the high probability of secondary soil pollution due to the transport of contaminated soil particles by water-erosion processes and local transport by wind were identified. It was found that the most intense secondary pollution, primarily of alluvial soils, can occur in the basins of the Irtysh and Shu rivers. It should be taken into account that existing estimates of water erosion rates are based on calculations using erosion models, while estimates of wind erosion rates are based on semiquantitative data. In this regard, research is needed to verify calculations using erosion models based on field data.

Due to the need to achieve the principles of sustainable development and to understand the processes of formation of phytocenoses in areas that were adversely affected by the industrial impact, this study assessed the condition of the Grachevsky uranium mine (Kazakhstan), which underwent conservation procedures about 25 years ago. The purpose is to determine the level of water quality and phytocenosis of the shores of the reservoir accumulating natural effluents from reclaimed dumps and anthropogenic sites of a uranium mine, as well as quality indicators and toxicology. The assessment included a qualitative research method (analysis of documents) to determine agro-climatic conditions and empirical methods of collecting information. The authors studied the intensity of ionizing radiation of the gamma background of the water surface of the reservoir (and sections of the shoreline and territories adjacent to the reservoir), and hydrochemical parameters of the waters of the reservoir, and performed a description of the botanical diversity. The vegetation cover of the sections of the reservoir shore is at different stages of syngenesis and is represented by pioneer groupings, group thicket communities, and diffuse communities. Favorable ecological conditions for the settlement and development of plants develop within the shores of the reservoir. The intensity levels of ionizing radiation do not exceed the maximum permissible levels and practically do not affect the formation of phytocenoses. An anthropogenically modified dry meadow with the participation of plants typical of the steppe zone has been formed on the floodplain terrace. Concerning the indicators of quality and toxicology of this reservoir, the water can be used for household and drinking purposes under the condition of prior water treatment. It can be concluded that a high level of natural purification of the reservoir waters occurred within twenty years after the reclamation of the uranium mine.

The features of vertical distribution of 137Cs in the profile of clayeyilluvial agrochernozem, as well as biogenic migration of the radionuclide in the system “soil–plant” of potato agrocenosis have been studied. The research was conducted on the field, occupied by potato variety “Gala”, located in the central part of Plavsky radioactive hotspot of Tula region. It is shown that 35 years after the Chernobyl accident the density of surface radioactive contamination of arable soils in the region exceeds the permissible level by ≈5 times. The depth of 137Cs penetration down the soil profile is mainly determined by methods of agrotechnical soil treatment, and the main part of its inventories is concentrated in the upper 30-cm arable layer. This results in the direct contact of the radionuclide with underground organs of potato (roots, stolons and tubers). However, no more than 0.02% of the total 137Cs inventories contained in the system “agrochernozem–potato” is transferred to potato plants. It was also established that potato plants are characterized by contrasting distribution of 137Cs specific activity values wich varies with organs and tissues. Stolons and thin roots accumulate the radionuclide to the greatest extent per biomass, while tubers, on the contrary, – to the least extent. In general, the levels of 137Cs accumulation in the raw and dry weight of potato tubers, as well as in the products that have undergone culinary processing (boiling the unpeeled and peeled potatoes), correspond to sanitaryhygienic norms, which substantiates the low ecological risks of including potatoes in crop rotations on agricultural land in the area of the Plavsky radioactive hotspot of the Tula region.

The article deals with issues related to the development of radioecology as an independent scientific discipline. The achievements of past years and the studies that are currently being carried out, as well as promising areas of development in this area are analyzed. A corrected periodization of the stages of development of radioecology is proposed, taking into account the experience accumulated to date in the field of this discipline. At the initial stage (1895–1929), empirical material was collected; at the first stage (1930–1960), the theoretical foundation was laid and radioecology was formed as an independent discipline; at the second stage (1961–1990), intensive development of radioecology was noted; and, at the third stage (1991–2010), there was progressive development of radioecology; the fourth—modern—stage of the development of radioecology is in the beginning of the 21st century (2011–present). For each stage, the main scientific achievements and evolution of ideas in the field of radioecology are considered. It is postulated that, at present, the development of this discipline is associated with the further improvement of world nuclear technologies, the elimination of the consequences of a number of radiation incidents (the accident at the Fukushima nuclear power plant in 2011), the revision of the concept of radiation protection of the environment and a number of other provisions. Particular attention is paid to forest radioecology, one of the most important main areas of this science.

После Чернобыльской аварии один из наиболее загрязненных радионуклидами (прежде всего, 137Cs) участков черноземов сформировался в Плавском районе Тульской области в пределах полузасушливой лесостепной зоны Среднерусской возвышенности. Цель исследования: выявить современный уровень загрязнения почв Плавского радиоактивного пятна и определить соответствие стандартам качества картофеля, возделываемого на этой территории, по содержанию 137Cs. Исследования выполняли в центральной части Плавского района Тульской области. Работы проводили с 2014 по 2022 год с учетом изменений в структуре посевных площадей хозяйства. Отбор проб для настоящего исследования проводили в 2017–2018 году. Непосредственными объектами исследований послужили почвы обследуемой территории и растения картофеля. Пробы отбирали в конце августа в период полной спелости. На участке производили пробоотбор монолитов почв ненарушенного сложения с помощью кольцевого пробоотборника ПГ-450 с площади 300 см2, послойно с шагом по 10 см до глубины 30 см в трехкратной повторности с расстоянием между точками 15–20 м. Надземную часть растительности отбирали методом сплошного укоса с площади 2500 см2. Пробоотбор подземной части растительности исследуемых площадок производили с такой же площади и до глубины 30 см. Плотность радиоактивного загрязнения почв 137Cs в профиле черноземов (кБк/м2) рассчитывали с учетом удельной активности радионуклида, толщины слоя почвы и плотности сложения (с учетом фиксированной площади пробоотборника). Спустя 30 лет после аварии на Чернобыльской АЭС черноземы Плавского радиоактивного пятна все еще загрязнены техногенным 137Cs со значительным превышением допустимых уровней его накопления в почве. Однако перенос 137Cs из черноземов в клубни картофеля и другие компоненты урожая не является интенсивным, а современные уровни накопления радионуклида в клубнях значительно ниже заявленных требований санитарно-гигиенической безопасности продуктов питания человека. After the Chernobyl accident, one of the most contaminated with radionuclides (primarily 137Cs) areas of chernozems was formed in the Plavsky district of the Tula region within the semi-arid forest-steppe zone of the Central Russian Upland. The purpose of the study: to identify the current level of soil contamination of the Plavsky radioactive spot and to determine compliance with the quality standards of potatoes cultivated in this area, according to the content of 137Cs. The research was carried out in the central part of the Plavsky district of the Tula region. The work was carried out from 2014 to 2022, taking into account changes in the structure of the acreage of the farm. Sampling for this study was carried out in 2017–2018. The immediate objects of research were the soils of the surveyed territory and potato plants. Sampling was carried out at the end of August during the period of full ripeness. At the site, monoliths of undisturbed soils were sampled using a PG-450 annular sampler, from an area of 300 cm2, in layers in increments of 10 cm to a depth of 30 cm in triple repetition with a distance between points of 15–20 m. The aboveground part of the vegetation was selected by the method of continuous mowing from an area of 2500 cm2. Sampling of the underground part of the vegetation of the studied sites was carried out from the same area and up to a depth of 30 cm. The density of radioactive contamination of 137Cs soils in the profile of chernozems (kBq/m2) was calculated taking into account the specific activity of the radionuclide, the thickness of the soil layer and the density of addition (taking into account the fixed area of the sampler). 30 years after the Chernobyl accident, the chernozems of the Plavsky radioactive spot are still contaminated with technogenic 137Cs with a significant excess of permissible levels of its accumulation in the soil. However, the transfer of 137Cs from chernozems to potato tubers and other crop components is not intensive, and the current levels of radionuclide accumulation in tubers are significantly lower than the stated requirements for sanitary and hygienic safety of human food.

The behavior of 137Cs and K in the soil–plant system of the Chernozemic Zone long after the Chernobyl accident was studied. Experimental plots were laid in the central part of Plavsk radioactive hotspot of Tula oblast in wheat, soybean, buckwheat, rapeseed, sunflower, and grass–legume agrocenoses and in natural biogeocenoses of a dry meadow. The mean soil contamination with 137Cs was 171 ± 26 kBq/m2 (498 ± 100 Bq/kg), and the mean content of total K in soils was 2.0 ± 0 1

Ecological and geochemical characteristics of urbanozems (Urbic Technosols) were evaluated, using an integrated analysis of official data of the Russian Meteorological Service on the content of priority heavy metals (Cd, Pb, Zn, Cu, and Ni) in soils of 23 cities in Volga Federal District and of the data of the Federal Service of State Statistics on socio-economic parameters of these settlements. Possible relationships between parameters of soil pollution and urban features of cities were revealed with the help of multivariate statistical analyzes (cluster and factorial). Admissible levels of Cd, Pb, Zn, and Cu were established for soils of most cities in the region with mean socio-economic parameters, average concentrations of which are close to abundance values in urban soils in Russia. The APC of Ni in soils is exceeded in small and medium cities of the Republic of Bashkortostan, which reflects regional natural and anthropogenic geochemical anomaly in the east of Volga Federal District, but no correlations between nickel pollution and socio-economic parameters of settlements are revealed. Moderately hazardous level of complex pollution in urbanozems with dominant Cd accumulation and significantly lower concentrations of other heavy metals (the cities of Belebei, Davlekanovo, and Dzerzhinsk) is not correlated with demographic parameters of settlements. In case of more complicated profile of soil pollution (Cd–Zn in Penza or Cu–Cd–Zn in Mednogorsk), the total birth rate is lower and the mortality rate is higher as compared with the mean regional parameters. Different directions of gradients of increasing concentrations of Cd, Pb, Zn, and Cu in soils, as well as of the Zc total parameter of soil pollution in relation to indices of natural population growth and the absence on the ordination diagram of a noticeable relationship between ecological and geochemical characteristics of soils and the age of the city, the number and density of the population, and the density of the street road network are shown, using the example of cities in the Volga Federal District.

An algorithm has been developed for the simulation model of carbon behavior in herbaceous communities of various types, both autonomous and as a part of complex phytocenoses. The influence of external factors is taken into account, such as solar radiation, precipitation, air temperature, clouds, and wind speed. The dynamics of soil moisture level and temperature are reproduced. The algorithm can be modified, depending on the discreteness of consideration of the simulated processes. The algorithm is tested in modeling the dynamics of the phytomass of a community of ground elder ( Aegopodium podagraria L.) that is dominant in the herbaceous cover of the ground elder oak grove on dark-gray forest soil. The EcoGrass model is used to conduct numerical experiments to study the impact of the potential global climate change and consumption of phytomass by animals on the productivity of this community. Threshold values of influence factors have been determined upon reaching which the normal functioning of the community is disrupted.

On the territory of the Plavsky radioactive hotspot of the Tula region of Russia, formed as a result of the accident at the Chernobyl nuclear power plant in 1986, an assessment of the radiation safety of growing carrots and beets was carried out in 2019. It has been established that at present the content of 137Cs in arable leached chernozems of the surveyed lands is 90–170 kBq/m2 , which is 2.5–4.5 times higher than the permissible level of density of surface radioactive contamination of soils. However, the specific activity of the radionuclide in carrot and beetroot crops does not exceed 5 Bq/kg, which is significantly less than the maximum permissible level of 137Cs accumulation in vegetables (600 Bq/kg for absolutely dry weight). The accumulation coefficients of 137Cs in the total biomass of carrots and beets are 2.0·10−2 and 7.5·10−2, and in eaten root crops – 1.1·10−2 and 2.0·10−2, respectively, which is in good agreement with the IAEA estimate for the intensity of the transition 137Cs in the production of vegetable roots from loamy and clayey soils.

To assess the transfer of macro (K, P, S, Mg, Ca, as well as Si, Na, Fe, Al, Mn and Ti) and microelements (Zn, Ba, Cu, Sr, Mo, as well as As, Zr, Pb, Co, Ni, V and Cr) from Luvic Chernozems (Aric, Loamic, Pachic) into agricultural plants, we studied the inventories of chemical elements in three agrocenoses (wheat, soybean, Galega orientalis Lam. and Bromopsis inermis Leyss grass mixtures) from the Plavsk upland (Tula Region). This territory is subjected to intensive industrial and agricultural impacts: it is 40 km away from the town of Shchekino with a nitrogen fertilizer plant and a thermal power plant, 60 km away from Tula with large metallurgical enterprises, 70 km away from the town of Novomoskovsk with several chemical enterprises and state district power plant. In soils, the total content of elements was determined by the X-ray fluorescence spectrometry. The elemental composition of plants after autoclave decomposition with a mixture of concentrated nitric acid and hydrogen peroxide and the content of the bioavailable fraction (extracted by an ammonium acetate buffer with pH 4.8) of elements in soil were estimated by the atomic emission spectrometry with inductively coupled plasma. In topsoil (a 10-cm layer), maximal inventories are typical for total Si (40 ± 4 kg/m2), Al (7.0 ± 0.8 kg/m2) and Fe (3.4 ± 0.3 kg/m2) and for bioavailable Ca (570 ± 48 g/m2), Mg (43 ± 4 g/m2), K (22 ± 6 g/m2). In plants, the main inventories (g/m2) of K, P, S, Mg, Si, Mn, Zn, Ba, Cu, Mo occur in the above ground phytomass. The most effectively plants assimilate bioavailable fractions of K, P, Ti, Mo, As, Zr, V. Based on the resource method for soil quality assessment, the studied Chernozems are characterized by a low level of Ni contamination, a moderate supply of bioavailable K with a lack of bioavailable P.

Anna A. Oleshkevich, Specific features of change in enzymate activity in

The simulation model of seasonal dynamics of 137Cs in the components of the oak forest ecosystem EcoradOak_CS_FW has been further developed, which now includes first- and second-order consumers. The radiocesium redistribution is modeled in a full-scale food web of a forest ecosystem of the soil–vegetation–herbivores–predator type. The algorithm used in the model allows us to take into account the effects of the soil, meteorological, phenological, and physiological factors on the behavior of radionuclide in the food web and predict radiological situations under various conditions of radioactive fallout. Data obtained with the model on the contamination of animals with radiocesium are used to calculate the dynamics of the internal dose. The results of modeling can be used in the rationing of forest products of deciduous forests. The model is also applicable to the study of potassium redistribution in the trophic chain of a deciduous forest ecosystem.

Some aspects of the application of simulation modeling of radionuclide behavior in food chains of land ecosystems are discussed. A model of behavior of 137Cs in the soil–vegetation–herbivores–predators system is described. The results of modeling, including the calculation of the dynamics of the dose load on animals, are presented. It is shown that according to the simplified Chernobyl scenario of the radiological situation, dose loads on herbivores are significantly lower than on predators. In general, the main contribution to the dose load in animals during the first ten years is made by external irradiation. Then, the external and internal dose loads become approximately equal.

The results of studies of three sites of agrocenoses are presented: wheat (seed cereals), soybeans (legumes) and legume-cereal (rumpgoatskin) perennial grass mixtures to identify the peculiarities of the transition of stable and radioactive pollutants (including substances of hazard classes 1 and 2 and 137Cs) in the system "agro-chernozems – agricultural plants" with soil testing and quality control of aerial and underground plant phytomass. In this radioactively contaminated area, the elemental composition of wheat, soybean, rump and goatskin does not differ from the composition of the corresponding species in the background. Legumes have an increased need for alkaline earth metals (Ca, Mg, Sr) and also contain more Ni and Mn, cereals – in Si. Within the studied part of Plavsky radioactive spot, the quality of agricultural products meets the relevant standards for the content of heavy metals and 137Cs.