Galina Ivanovna Agapkina

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.

The article provides an overview of the results of long-term studies of the migration of radionuclides in the composition of lysimetric waters. The features of lysimetric studies at various stages of radioecology development are considered. It is noted that the use of lysimeters for a long time was limited to low levels of radionuclides in soil solutions, and large-scale studies began after the Chernobyl fallout (1986). It is shown that the greatest output of radionuclides in lysimetric waters occurs in forest, especially coniferous phytocenoses, the least — in meadow and agrophytocenoses. In the long-term dynamics, the maximum intensity of radionuclide migration in the lysimetric waters is observed in the initial period after aerial precipitation, in the seasonal period — in the summer. A small amount of radionuclides migrates with downward water flow. Annual outflow with vertical subsurface runoff varies depending on soil-climatic conditions, the period after precipitation, the thickness and depth of the layer. Annual outflow from the forest litter layer varies from tenths to units of percentage, from the layer 0–20 cm — from hundredths to tenths of a percentage from the total radionuclide supply in these layers. The relative output of ⁹⁰Sr is much bigger than ¹³⁷Cs. In soil solution from 70% to 90% radionuclides [¹⁴⁴Ce, ²³⁹Pu ¹⁰⁶Ru ,¹³⁷Cs and ⁹⁰Sr] are in the form of radionuclide-organic compounds of various molecular weights. 

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.

We studied morphological properties, pH, organic carbon content, and specific activity of ¹³⁷Cs and natural radionuclides (⁴⁰K, ²²⁶Ra, ²³²Th) in the upper horizons of soils in deactivated and slightly damaged areas of the city. The studies were carried out in the urban ecosystems of the city of Elektrostal (Moscow region) in 2019, i.e. 6 years after local precipitation of ¹³⁷Cs due to a radiation incident. Morphological features of the upper horizons of urban soils were: brownish-gray color, light-loamy composition, small-lumpy and lumpy structure, inclusions of construction and household waste. In the upper horizons of urbiquasizems and urban soils, a low carbon content (less than 1%) with high coefficients of variation - were detected. In the studied urban soils, a wide range of water pH values was noted: from acidic (4,6–5,5) to highly alkaline (>8,0) reaction. Correlation analysis showed that in the upper horizons of UR, the content of organic carbon was reduced and alkalinization of the soil environment was observed. The accumulative type of distribution of ¹³⁷Cs was recorded for soil profiles of polluted urban ecosystems in which decontamination measures were not carried out. The profiles of urban soils that were subjected to decontamination revealed low values of the specific activity of ¹³⁷Cs in surface bulk layers and maxima in buried contaminated horizons. In the bulk horizons of UR, which include a large amount of crushed stone, there is an increase in the specific activity of ²²⁶Ra. Some technogenic horizons UR and TCH, consisting mainly of quartz sand, are characterized by very low values of specific activities ²²⁶Ra and ⁴⁰K. Correlations of chemical and radiation indicators in the profiles of urban soils reflect the different composition and properties of upper horizons formed as a result of excavation and decontamination work.