Plutonium is long-lived radioactive element of high radiotoxicity. The presence of anthropogenic plutonium in the environment is mainly caused by nuclear tests, nuclear power plants accidents, leaks from nuclear fuel cycle facilities and radioactive waste storages. The radioactive waste storage facility located in Obninsk is one of the first radioactive waste storage facilities built in Russia. Radionuclides leak in the storage from 1998 over 1999 was registered. A set of specific protective engineering measures was carried out in 1999. In subsequent studies, the presence of local radioactive spots, mainly contaminated with 90Sr, was found in the territory of the radioactive waste storage facility and adjacent area. The article presents the results of the 239+240Pu content accumulated by the vegetation growing in the area near the Obninsk radioactive waste storage facility. The analysis of 239+240Pu content in samples was carried out by alpha spectrometry following radiochemical separation. It was found that the plutonium content in the roots of herbaceous plants ranges from (7.92.0)∙10-2 Bq/kg to (1.70.1)∙100 Bq/kg, in the above-ground part from (3.41.0)∙10-2 Bq/kg to (1.20.4)∙10-1 Bq/kg. The distribution of 239+240Pu content in different parts of herbaceous plants are consistent with published data, it means that plutonium is accumulated by the plants root system mainly. The range of 239+240Pu content in parts of shrubs is estimated from (4.0+/-1.4)∙10-2 Bq/kg in branches to (9.0+/-2.7)∙10-1 Bq/kg in white currant berries, and from (4.0+/-1.4)∙10-2 Bq/kg in branches to (3.0+/-0.9)∙10-1 Bq/kg in hazel leaves. The content of 239+240Pu in organs and tissues of woody vegetation varied from (3.4+/-1.0)∙10-3 Bq/kg to (4.2+/-1.3)∙100 Bq/kg. The highest content of plutonium was found in tree bark.

The paper provides results of a long-term natural experiment with fruit and berry crops, grown in conditions of radioactive contamination at the territory of the former Semipalatinsk Test Site. The aim of the research is to study peculiarities in accumulation of artificial radionuclides by different species of trees and shrubs. The paper considers only one pathway of the radionuclide's intake, i.e. absorption of the elements by roots from soil. As the result quantitative parameters of Am-241, Cs-137, Sr-90, Pu239+240 transfer and distribution in different parts of the fruit and berry crops were found. At that radionuclides are not uniformly distributed in plants' organs and in most cases, it obeys the following regularity: leaves > branches > fruits. The difference in accumulation of Cs-137, Sr-90, Am-241 and Pu239+240 for various organs can be range as follows 1.8-77, 1.6-750, 1.9-76 and 3-182 times respectively. The maximum concentrations of Cs-137 in leaves of the researched plants more often were registered at the initial stages of vegetation period. Unlike Cs-137 concentration of Am-241 and Sr-90 in leaves of the researched plants grows usually from the very beginning till the end of the entire vegetation period. The character of transuranium radionuclides accumulation during several years was determined for researched plants. Data obtained can become input parameters for models used to describe the behavior of radioactive substances and assess the risk of contaminated fruit and berry crops for territories having unfavorable radiological situation.

The article considers the issues of working out the suitable approaches for identifying zones with the presence of underground near-surface waters with increased concentrations of tritium discharged into a surface reservoir. The following methods were used as possible methods: determination of tritium content in snow cover, determination of tritium content in vegetation in the form of tritium of free water and organically bound tritium, determination of tritium content in river water and coastal vegetation. The studies were carried out at a previously identified site where groundwater with a tritium concentration of up to 6000 Bq/l is present, located in the vicinity of the city of Obninsk (Kaluga region, Russia).As a result of the conducted research, it was concluded that the analysis of the distribution of tritium in vegetation is an excellent methodological technique for identifying areas of location of near-surface underground waters contaminated with tritium. As a control parameter, both the concentration of tritium in the free water of plants and the content of organically bound tritium can be used. To detect underground tritium contamination the most promising use is the following indicator - the content of OBT in the shoots of woody plants. This parameter is very informative, and the sampling procedure for its determination has no seasonal restrictions, unlike such parameters as the content of tritium in grass and leaves, the content of tritium in snow cover, surface waters, which are preferably collected only in summer or winter.It should be noted that the control of surface waters of the groundwater discharge zone may not be a sufficiently informative indicator for identifying areas of polluted water inflow, since it depends on the ratio of the volumes of leaking polluted groundwater and the annual flow of the watercourse.

In the vegetation experiment, the plutonium, micro- and macroelements migration in the “soil–agricultural plant” system depending on soil moisture in the range from 15 to 40٪ of absolute soil moisture were studied. The content of 239Pu was analyzed by α-spectrometry with preliminary radiochemical isolation. The elemental composition was analyzed by the ICP-MS and ICP-AES methods. Beans (Fabaceae) variety “Amber” were used as a test culture. The plutonium transfer factor obtained in the vegetation experiments are in the range of of 5.3×10–4–1.5×10–2, with an average value of 5.4×10–3 for the aboveground part of bean and range of 4.5×10–2–2.7×10–1, with an average of 1.6×10–1 for bean roots. It was determined that the distribution of plutonium, micro and macro elements in the vegetative organs of plants is not equally, the transfer factor of plutonium for the aboveground part of plants is lower than for the root part. It has been established that the accumulation of plutonium, micro- and macroelements, depending on soil moisture, is different for the organs of beans. The dependence of plutonium accumulation by plants on soil moisture is significantly higher than for other considered elements. A decrease in the coefficient of accumulation of plutonium in the aerial part of the beans is recorded with an increase in soil moisture up to two orders of magnitude. There is a trend towards a slight decrease in the accumulation coefficients of Fe, Mg, Mn, Cr, Mo, Ni, Co, Cu. For the root system of beans, a clear dependence of the accumulation of the considered elements on soil moisture is not observed.

Numerous areas of the Semipalatinsk Test Site (STS) were subjected to radioactive contamination, including tritium. The tritium content in plants was determined in free water (TFWT) and in the organic component (OBT). It has been established that the OBT content in plants for the "Sary-Uzen" site between combat boreholes ranges from <7-125 Bq/kg and the background OBT content is 21.5 Bq/kg. The maximum OBT values in plants have been recorded in the vicinity of boreholes and range from 7.1 (near the borehole numbered 106) to 200,000 Bq/kg (near the borehole numbered 101). Overall, the tritium content in the vegetation cover at the "Sary-Uzen" site is negligible and does not pose a threat. Isolated cases of tritium content in drinking water exceeding the intervention level have been identified in plants in the "Lazurit" area, as well as near combat boreholes numbered 125 and 101.

During the growing experiment, the uptake of plutonium isotopes by green onions ( Allium cepa Centurion F1 ) grown on distilled water, Ellis nutrient solution and sod-podzolic soil was studied. The analysis of plutonium isotopes was carried out by alpha spectrometry with preliminary radiochemical separation. It has been determined that the uptake of 239+240 Pu by the green onions decreases in a row: distilled water > Ellis nutrient solution ≫ sod-podzolic soil. The transfer factors of plutonium isotopes in green onions were 1.7 ± 0.4 for distilled water; 0.7 ± 0.2 for Ellis nutrient solution; 0.0054 ± 0.0014 for soddy-podzolic soil.

High variability of plutonium transfer factors presented in publications makes it relevant to study the mechanisms that affect plutonium migration ability and its availability for vegetation. Varying transfer factors are explained by different properties of soils, since the redox potential and soil acidity can affect significantly the plutonium mobility. Plutonium migration in the soil–agricultural plant system was studied for different soils in a vegetation experiment. The content of 239+240Pu was analyzed by alpha spectrometry with preliminary radiochemical isolation. Plutonium migration parameters were determined using barley (Hordeum) and beans (Fabaceae) as test cultures. Plutonium transfer factors obtained in the course of vegetation experiments range within 3.1 × 10–4–6.8 × 10–3 with the average value of 3.8 × 10–3 for the aboveground part of barley; and they range within 9.2 × 10–3–7.6 × 10–2 with the average value of 3.8 × 10–2 for the root system of barley. The transfer factor range was 1.5 × 10–3–5.7 × 10–3 (with the average value of 3.7 × 10–3) and 5.8 × 10–2–6.5 × 10–2 (with the average value of 6.2 × 10–2) for the aboveground and root parts of beans, respectively. The mode of plutonium distribution by the vegetative organs of the considered crops was found to be nonuniform. On average, the transfer factor of plutonium is 40 times lower in the aboveground part of plants than in their roots. The accumulation of plutonium in the aboveground parts of plants growing on different soil types was found to be not the same for individual species/organs of agricultural plants. For the aboveground part of the agricultural crops under consideration, the transfer factors differ up to several orders of magnitude. In general, the accumulation of plutonium by vegetation growing on different soils forms the following sequence: soddy-podzolic (Retisol) and gray forest (Phaeozem) > low-moor peatbog (Histosol) ≫ typical chernozem (Chernozem). The smallest accumulation of plutonium by vegetation is observed in soils with a high content of organic matter. For the root system of plants, the dependence of plutonium transfer factors on soil properties is uncertain.

Статья посвящена оценке уровней содержания плутония и цезия в почве и разнотравье Калужской области. Анализ концентраций 137Cs проводили гамма-спектрометрическим методом, 239+240Pu – методом альфа-спектрометрии с предварительным радиохимическим выделением при полном разложении образцов. Установлено, что для Калужской области наблюдается большой диапазон значений концентраций для цезия – от 2,9 Бк/кг на границе с Московской областью до 2400 Бк/кг в южной части Калужской области. Значительно меньшее расхождение в содержании плутония – от 0,1 до 0,47 Бк/кг. Среднее содержание рассматриваемых радионуклидов в 20 см слое составляет ~95 %, а в поверхностном слое (5 см) ~ 35 %. Коэффициенты накопления плутония разнотравьем Калужской области равны 2,1·10-2- 4,4·10-2 на все растение. The article is devoted to the assessment of the levels of plutonium and caesium in the soil and various grasses of the Kalugaregion. Concentrations of 137Cs were analyzed by gamma-spectrometric method, 239+240Pu – by alpha-spectrometry with preliminary radiochemical isolation with complete decomposition of samples. It was found that for the Kalugaregion there is a large range of concentrations for caesium – from 2.9 Bq/kg on the border with the Moscow region to 2400 Bq/kg in the southern part of the Kalugaregion. A much smaller distribution is observed in the plutonium content – from 0.1 to 0.47 Bq/kg. The average content of the radionuclides under consideration in the 20 cm layer is ~95%, and in the surface layer (5 cm) ~ 35%. The coefficients of accumulation of plutonium by various grasses of the Kaluga region are equal 2,1·10-2- 4,4·10-2 for the whole plant.

Information about the sources and mechanisms of plutonium release into the environment is summarized. The magnitudes and distribution of global plutonium fallout, as well as data on technogenic sources of plutonium isotope releases into the environment, are reviewed. For this purpose, the supply of plutonium as a result of nuclear explosions at test sites, such as Nevada, Semipalatinsk, Novaya Zemlya, etc., and the scale of environmental contamination as a result of tests were considered. The data on the intake of plutonium after nuclear and radiation accidents at nuclear power plants (Chernobyl nuclear power plant, Fukushima, etc.) and at enterprises of the nuclear complex (Kyshtym accident, etc.) are presented. Separately, plutonium intake into the natural environment through emissions and discharges of nuclear complex enterprises (Sellafield, MCC (Krasnoyarsk), etc.) is considered. Information about the levels and content of plutonium isotopes in various media and environmental objects, as well as information about the parameters characterizing the migration of plutonium in various media and the transition between them is generalized and presented. Forms of plutonium occurrence in soils (distribution by granulometric fractions, chemical forms, “hot” particles, etc.) are considered, and information on the characteristic levels of plutonium concentrations in soils for various objects is summarized. Data on the concentrations of plutonium in the air are given. Information on the forms of plutonium in the aquatic environment, as well as on the characteristic levels of plutonium concentrations in various water bodies, including the World’s oceans, is presented. Information on the transition coefficients of plutonium isotopes in the soil–plant system is summarized. Particular attention is paid to plutonium isotopes in biological objects and the human body.

The study was carried out in the territory of the Polesie State Radioecological Reserve. For the study of long-term environmental effects of the Chernobyl accident in the territory of Belarus, the Polesie State Radioecological Reserve was established in 1988. It is located in the Belarus sector of the Chernobyl exclusion zone. The objective of the study was to estimate the content of plutonium isotopes in the environmental samples inside and outside of the Reserve area. Determination of plutonium isotopes was carried out by alpha spectrometry. The method includes complete decomposition of samples, radiochemical purification, preparation of alpha sources, alpha spectrometric analysis. The content of Pu-239+240 and Pu-238 in soil samples is in the range of 1.8-141 and <0.82-55 Bq/kg, respectively. The concentration of Pu-239+240 was at the level of n·10Е+0 Bq/kg in areas of the Kozeluga branch of the Khoiniki forestry, located outside the Reserve. Plutonium isotopes concentration outside the Reserve was an order of magnitude higher than it was in global fallout. The concentration of Pu-239+240 in pine cones in the study areas was <0.001-0.0041 Bq/kg. The Pu-239+240 transfer factor in Scots pine cones grown in the Reserve territory was at the level of n·10-4. The obtained value of the plutonium transfer factors for pine cones was comparable with the plutonium transfer factor for pine needles grown in the Reserve territory.

The paper provides study of the radioactive contamination of near-surface soil at the Sary-Uzen site in the Semipalatinsk test site (STS). Increased values of natural radionuclides in the studied area were not detected, which indicates the absence of possible geochemical anomalies that could create an elevated radiation background. Radioactive contamination by technogenic radionuclides is caused by two factors. The first factor is fallout of radioisotopes from the atmosphere because of an explosion on September 24, 1951 at the "Experimental field" site. The fallout plume extended from the north-western part of the site to the very south. The range of activity concentration values for 241Am in soil varies from <0.3 Bq/kg to 390 Bq/kg, with an average value of 5 Bq/kg; for 137Cs from <1.1 Bq/kg to 330 Bq/kg, with an average value of 55 Bq/kg. A second, but more significant factor is the fallout of radioisotopes due to underground nuclear tests with radioactive release that took place in boreholes on the site itself. The largest area of contamination (about 8 km) is the fallout from testing borehole No. 101 (241Am to 920 Bq/kg and 137Cs to 12150 Bq/kg).

One of the sources of radionuclides released into the environment are radioactive waste storage. The plutonium isotopes concentration in the soils of the territory adjacent to the former radioactive waste storage facility in Obninsk was estimated. The cause of pollution was the depressurization of one of the storage tanks and the release of radionuclides due to its overflow with surface and ground waters in the period from 1998 to 1999. Samples were analyzed by alpha spectrometry with preliminary radiochemical isolation with complete decomposition of soil samples. The Pu-239+240 content range in the surface soil layer was 3.7-9.6 Bq/kg, with an average value of 6.7 Bq/kg, which is an order of magnitude higher than the level of its global fallout. In some samples, significant amounts of Pu-238 are observed, the relative content of which is 10-50% of Pu-239+240, that exceeds the its relative content due to the global fallout which is 2-5%. The depth distribution of plutonium isotopes has been studied. It has been established those significant concentrations of plutonium are observed to the depth of 95 cm for this territory. There is no definite dependence of the distribution of plutonium isotopes along the vertical soil profile. The random distribution of plutonium to the soil depth indicates that the source of Pu-239+240 are groundwater. Elevated concentrations of plutonium isotopes in the soil surface of the territory under consideration, its significant concentrations at soil depth indicates that the contamination is a consequence of the leakage of plutonium isotopes from the radioactive waste storage facility in Obninsk. The same concentrations can be expected in the lowland of the adjacent territory.

This paper reports the speciation of 137Cs, 241Am, 90Sr and 239+240Pu in the soil samples of the Experimental Field (EF). The EF is a testing ground of the Semipalatinsk nuclear weapons test site used for surface and atmospheric tests. The study revealed low mobility of artificial radionuclides in the EF site soils. The revealed high radionuclide concentrations in soil mainly exist in tightly bound form. On average, the content of the tightly bound form of 137Cs was revealed to be below 98%, that of 90Sr - 94%, 241Am - 89%, and 239+240Pu - 98%. The radionuclides occurrence forms were analyzed in correlation with the physicochemical parameters of soils. Reliable relationships have been established between the content of carbonates and the content of the exchangeable, acid-soluble and strongly bound 90Sr forms in soils, as well as the content of the water-soluble salts and the content of the strongly bound 239+240Pu form in the soil. Similarly, we compared the distributions of the radionuclides speciation and their stable isotopes with their analogous elements in the soil. Unlike 137Cs and 90Sr, which are in a tightly bound form in the soils of the Experimental Field site, the main content of soil "competitors" of the 137Cs radionuclide - K and Cs is observed in an exchange form, less significantly in an acid-soluble form. The alkaline earth metals (analogous elements for 90Sr) are mainly observed as a composition of the exchangeable and acid-soluble forms. The results allow to conclude that there is no equilibrium distribution of the physicochemical forms of radionuclides introduced into the soil and the natural presence forms of their stable analogs in the soil. Such equilibrium distribution can only be achieved at a complete isotopic exchange in phases and soil components, which under the conditions of the Experimental Field is not possible in the near future. It can be concluded that the behavior of the studied radionuclides in soils is stipulated by the initial form delivered by the fallouts from tests at the EF site.

This study is devoted to the estimation of radionuclides global fallout levels in the soils of Commonwealth of Independent States (CIS) and Eastern Europe territory as a result of nuclear explosions. 58 standard soil samples were used, which were selected in different soil and climatic areas of the territory of CIS and Eastern Europe in 1978-2018. All samples were measured by gamma spectrometry. Determination of plutonium isotopes and strontium was performed according to the method of the joint determination of these radionuclides from one sample. IN the samples considered in this work, the content of( 60)Co,Eu- 154,Eu- 155 was below the detection limits, which were 0.4; 1.0 and 1.0, respectively. Natural radionuclides analysis results indicated that the obtained samples are typical soil samples without its abnormal contents. The content of( 137)Cs, Sr-90,Pu 239+240 in a 20 cm soil layer due to global fallout is (3.9 +/- 1.7), (2.2 +/- 0.8), (0.18 +/- 0.08) Bq/kg respectively, which considering the distribution of these radionuclides by depth and average soil density is (1.2 +/- 0.5) kBq/m(2) for Cs-137, (0.42 +/- 0.15) kBq/m(2)- Sr-90 and (55.0 +/- 24.0) Bq/m(2)-Pu 239+240. The isotopic ratios(137)Cs/Sr-90 and Cs-137/Pu239+240 for the territory of CIS and Eastern Europe are at the level (2.0 +/- 0.71) and (25 +/- 15), respectively.

Data, despite being crucial for internal dose assessment, is lacking on the transfer of artificial radionuclides from the environment to the food supply. Expanding the available information on these factors is important for the improvement of dose models for specific scenarios. This paper describes the results of a 70 day field experiment with broiler chickens on the dynamics of excretion of Cs-137 and Am-241 from the muscle, liver and bone of broilers after a 30 day application of contaminated feed. The radionuclide concentrations in the feed and the thigh muscle, thigh bone and liver of 54 chickens divided between grass meal and soil contaminated feed groups were evaluated by gamma spectrometry for Am-241 and Cs-137. The obtained results confirm previous data on the dynamics of the excretion of cesium from organs, which can be described with a fast and a slow exponential curve of excretion. On the 70th day, following the 30-days application, 2-8% of the first-day activity concentrations of Cs-137 in organs (muscle, liver, bone) were detected. In the first two days, activity concentration of Am-241 decreases twofold in both liver and bone. 35% of the maximum activity concentration of Am-241 remained in bone and 15% in liver on the last day of the experiment.

The article presents working results of radiation status survey in the territory adjacent to the “Atomic lake”, a venue of the first USSR excavation explosion. In the course of research, a picture of areal radiation contamination has been obtained in the territory with technogenic radionuclides 137 Cs , 241 Am , 152 Eu . A pattern of radionuclide distribution in depth is shown at different spots (crater bank, Shagan river floodplain, the area of the external reservoir). Data is presented on concentrations of technogenic radionuclides 3 H, 239 + 240,238 Pu , 90 Sr , 60 Co , 154 Eu , 152 Eu in soil.

This paper provides results of assessment of the tritium distribution in the vegetation cover in the areas of underground nuclear explosions at the Semipalatinsk Test Site (STS). The research was conducted at the former "Degelen" test site along the streams that are one of the main channels of tritium migration from underground nuclear explosions epicenters. The dominant plant species Carex supine and Achnatherum splendens that belong to different ecological groups in relation to humidity were selected as representatives of the vegetation cover. The TFWT (tissue free water tritium) and OBT (organically bound tritium) activity concentrations in the vegetation cover were measurement. TFWT activity concentration in the samples of both plant species had high values with an average of up to 30 kBq kg-1. The OBT activity concentration was 1-2 orders of magnitude lower than the TFWT in all plant samples. The TFWT and OBT activity concentrations in vegetation samples are closely correlated (r = 0.75, p < 0.05). No statistically significant difference was found between the content of tritium in the samples of Carex supine and those of Achnatherum splendens taken at the same locations. OBT/HTO ratios for vegetation samples of both species were close to equilibrium ratio used in environmental transfer models. In some cases, OBT/HTO ratios were significantly lower than one, which indicates that simple environmental transfer models may not accurately predict the behavior of HTO and OBT in different environmental compartments. The average OBT/HTO ratio for soil samples (0.6 +/- 0.1) close to the equilibrium value indicates the equilibrium condition at the research area. The obtained [OBT]plant/[OBT]soil ratios indicate that soil organic matter accumulates tritium from year to year. However, in some locations with high tritium contamination ratios [OBT]plant/[OBT]soil were more than one due to OBT activity in soils is almost the same as OBT activity in plants. It was found that the nature of the spatial distribution of tritium in the vegetation cover in the areas of underground nuclear explosions is complex, and obviously depends on the location of the tunnels in which nuclear tests were conducted, as well as on the peculiarities of the hydrological regime of underground and surface waters, which are the main channels of tritium migration in the research area. Thus, the vegetation cover reflects the spatial distribution of tritium contamination in the sites of underground nuclear explosions and can be used as an indicator of the radiation situation when monitoring radiation-hazardous areas.

A study to determine 137Cs, 90Sr, 241Am, 239+240Pu radionuclides in vegetation cover of the area of craters produced by underground nuclear explosions at the Semipalatinsk test site (STS) is summarised in this paper. Transfer factors (Tf) required for the quantitative description of the radionuclides transition from the soil to aboveground plant parts were found to be highest for sagebrush (Artemisia sublessingiana), Tf values for 90Sr were gradually decreasing with increasing distance from the dump zone. When arranging the radionuclide transferring factors in descending order, the following sequence was obtained: 90Sr Tf > 137Cs Tf > 241Am Tf > 239+240Pu Tf, which is consistent with International data. All Tf derived are much higher than those ones derived earlier for epicenters of aboveground nuclear tests and are closest to values for conventionally "background" areas at the Semipalatinsk test site.

— Data on concentrations and distribution of tritium in soils of the “Atomic” Lake excavation explosion area of Semipalatinsk Nuclear Test Site (Kazakhstan, East Kazakhstan oblast) are discussed. The concentrations of tritium in surface soil horizons and in soil profiles have been determined in the bulk soil samples and in different particle-size fractions. Tritium concentration in soils reaches 240 000 Bq/kg. A correlation has been found between tritium and europium concentrations in soils. Presumably, tritium formation is controlled by two mechanisms. One of them is the neutron activation process, i.e., nuclear reactions with lithium, boron, and nitrogen isotopes present in the soil; the other mechanism is related to the capture of tritium that was initially in the charge of mineral particles formed upon condensation from the red-hot explosion zone.