Tatyana Aleksandrovna Paramonova

The possibility of using algorithm VERT_MIG the simulations of vertical migration of radionuclides in the soil are discussed. The algorithm was successfully used to develop models of migration 137Cs and 90Sr in radioactive contamination of different soils as a result of accidents at Chernobyl and Fukushima-1. The results of modeling are presented. The prospects for further use of this algorithm and some aspects of the use of simulation in this area are discussed.

The features of cesium-137 (137Cs) root uptake by spring oat (Avena sativa L.) and lettuce (Lactuca sativa L.) plants have been studied in a model experiment with simulation of radionuclide fallout into undisturbed monoliths of arable chernozems from the Plavsk radioactive spot. An integrated approach using digital autoradiography and γ-spectrometry methods has revealed a uniform pattern of vertical and lateral 137Cs distribution in the soil profile and low bioavailability of the radionuclide or root uptake by plants. Certain biological features of the test crops with respect to root uptake of 137Cs have been demonstrated: limited translocation of the element into shoots via its relative accumulation in roots for oats and limitation of general root uptake of 137Cs into plants, given its uniform distribution between roots and shoots for lettuce.

The levels of phthalate esters in the upper soil layers of Moscow-city were considered. The sum of concentrations of five phthalate esters (dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, di-n-butyl phthalate, di-(2-ethylhexyl) phthalate) in the soils falls in the range 4,39-397,00 mg/kg (with mean value of 62,70 mg/kg and median of 31,22 mg/kg) and was characterized by lognormal distribution. The shares of those phthalates in the sum of concentrations were 0,6; 0,7; 14,2; 57,9, and 26,6% correspondently. The significant positive correlations were found between concentrations of the phthalate esters. The sum of phthalate concentrations was higher in the soils of reserve and residential areas than that in the soils of roadside and park areas.

Some aspects of application of simulation modeling of radionuclide behavior in food chains of terrestrial ecosystems are discussed. The model of behavior of ¹³⁷Cs in the system of type soil-vegetation-herbivores-predators is described. The results of modeling, including the calculation of the dynamics of dose load on animals, are presented. It is shown that in the simplified “Chernobyl” scenario of the radiological situation, dose loads on herbivores are significantly lower than on predators. In general, in animals in the first 10 years, the main contribution to the dose load is made by external irradiation. Then the external and internal dose loads become approximately equal.

The simulation model of seasonal dynamics of ¹³⁷Cs in the components of the snytevoy oak forest ecosystem EcoradOak_CS_FW was further developed, which now includes first- and second-order consumers. The radiocesium redistribution in a full-scale food web of   a forest ecosystem of the type “soil—vegetation cover—herbivores—predators” is modeled. The algorithm used in the model allows us to take into account the influence of 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   on the contamination of animals with radiocesium obtained using the model 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.

The study of ¹³⁷Cs and K behavior in «soil-plant» system of chernozem zone in remote period after Chernobyl accident was carried out. Experimental plots in agrosystems such as wheat, soybean, buckwheat, rapeseed, sunflower, grass mixture, and natural biosystem of a dry meadow were selected in the central part of Plavsk radioactive hotspot in Tula region. The level of ¹³⁷Cs soil contamination was 171 ± 26 kBq/m² (498 ± 100 Bq/kg). Average gross K content in soils was 2,0 ± 0,1%, including exchangeable K — 235 ± 54 mg/kg and non–exchangeable K — 816 ± 116 mg/kg. Vertical distribution of ¹³⁷Cs within contaminated 30-cm soil layer of agrosystems, as well as gross K, was uniformly accumulative, while K_ex and K_non-ex distribution was regressive and accumulative. At the same time, ¹³⁷Cs microdistribution in root zone was invariant, and gradient enrichment of soil near the root surface was shown for mobile forms of potassium. Intensity of ¹³⁷Cs transfer from soils to plants for all studied crops was 1–2 orders lower than intensity of K root uptake. Element distribution between plant organs differed. ¹³⁷Cs distribution was acropetal for Cereals and basipetal for crops from other families, and K was distributed basipetally in all tested plants.

The article deals with issues related to the development of radioecology as an independent scientific discipline. The achievements of the past years, 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) — progressive development of radioecology; the forth modern stage of radioecology development falls at the beginning of the twentieth 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, 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 directions of this science.