90Sr Concentrations Research Articles

Assessment of the impact of the BN-800 reactor operation on the radionuclides content in local foodstuffs in the vicinity of Beloyarsk NPP

The research results are presented as an analysis of long-term data on the effect of gas-aerosol emissions and liquid discharges of Beloyarsk NPP and the Institute of Reactor Materials on the content of artificial radionuclides in local foodstuffs. It was noted that the distance and directions from radiation-hazardous facilities do not significantly affect the accumulation of 90Sr and 137Cs in potatoes and milk. The investigation of a wide range of foodstuffs from the private households of 23 settlements, forests, rivers, and a reservoir of the 30-km zone of the Beloyarsk NPP influence showed that the operation of the BN-800 reactor since 2016 did not lead to a registered increase in the content of artificial radionuclides in agricultural and natural foodstuffs. The maximum specific activities of 90Sr (0.84 Bq/kg) and 137Cs (0.26 Bq/kg) in root vegetables, potatoes, melons and vegetables were noted before the start of operation of the new power unit and were 45 and 300 times, respectively, lower than the current SanPiN standards. The highest content of 90Sr in milk (0.41 Bq/l) was 60 times lower than the requirements of SanPiN, 137Cs (0.11 Bq/l) was 900 times less than the permissible levels. In poultry, the specific activity of 90Sr (0.2-0.3 Bq/kg) and 137Cs (0.13-0.16 Bq/kg) has remained stable low in recent years, and the standardised content of 137Cs in beef (maximum 0.12 Bq/kg) more than 1.5 thousand times lower than the requirements of SanPiN. The highest concentration of 137Cs in wild berries, found in strawberries (1.27 Bq/kg), was 125 times less than SanPiN standards. The content of 90Sr in mushrooms was at the level of 0.1-2.5 Bq/kg, the content of 137Cs is slightly higher than - 0.6-5.8 Bq/kg. The maximum recorded specific activity of 137Cs in mushrooms was more than 80 times lower than the requirements of SanPiN. During the observation period, a decrease of up to 20% or more in the content of artificial radionuclides in samples of 5 fish species was noted; the maximum levels of 90Sr and 137Cs in it were 14 times lower than the strictest SanPiN standards (using fish for baby food). Selective radiation monitoring of foodstuffs of Beloyarsk NPP area aimed at 3H and 14C showed that the content of these radionuclides in foodstuffs was low, close to the background level. In agricultural products, 3H and 14C accumulated to a greater extent in potatoes and milk, and in natural products – in rough boletus and bream. There was noted a need to continue research on the accumulation of 3H and 14C in foodstuffs of Beloyarsk NPP vicinity.

Комплексный радиационно-экологический мониторинг водных экосистем в регионе размещения АЭС «Руппур» (Народная Республика Бангладеш)

Представлен опыт создания и ведения системы радиационно-экологического мониторинга водных экосистем в регионе АЭС «Руппур» (Бангладеш). Компоненты водных экосистем в зоне влияния АЭС являются как наиболее информативными для определения состояния окружающей среды, так и важными с точки зрения ведения хозяйственной деятельности. Именно поэтому оценка и прогнозирование качества водных экосистем в районе АЭС — актуальная проблема для обеспечения радиационной и экологической безопасности. Разработана детализированная программа мониторинга; выбраны пункты наблюдения за состоянием поверхностных и подземных вод на разном расстоянии от АЭС «Руппур»; определены объекты мониторинга (вода, донные отложения, высшая водная растительность, рыба), перечень исследуемых параметров, регламент наблюдений, а также методы и нормативно-техническое обеспечение. В числе контролируемых показателей рассмотрены: физико-химические характеристики воды и донных отложений; радионуклидный состав компонентов водных экосистем, включающий природные (40K, 226Ra, 232Th) и техногенные (90Sr, 137Cs, 3H) радионуклиды; содержание 19 тяжёлых металлов, а также химических загрязнителей. Мониторинговые исследования проведены в 2014–2017 гг. на фоновом уровне и на этапе строительства АЭС «Руппур» с учётом климатических особенностей региона в различные периоды года. Радионуклиды в объектах окружающей среды определены методами спектрометрии и радиохимии, тяжёлые металлы — атомно-абсорбционным и плазменно-эмиссионным методами анализа. Установлено, что высшая водная растительность в реке Падма (Ганг) встречается не во все сезоны. В декабре она фактически отсутствует; максимальное видовое разнообразие отмечено в июне. Выделены различия между поверхностными и подземными водами в регионе АЭС «Руппур» по ряду физико-химических характеристик. Показатели общей минерализации и жёсткости в питьевой воде выше, чем в поверхностной, в 2–3 раза, что обусловлено составом вод р. Падма, основа которых — талые воды ледников гор и дождевая вода. Содержание в поверхностных и подземных водах органических загрязнителей ниже или на уровне порога их обнаружения приборами (бензпирен — менее 0,01 мкг·л−1; фенолы — 1,3–3,5 мкг·л−1; нефтепродукты — 0,01–0,043 мг·л−1). Объёмная активность в водах р. Падма 137Cs за весь период наблюдений не превышала 0,18 Бк·л−1 при среднем значении 0,07 Бк·л−1. Содержание 90Sr было в диапазоне 0,02–0,12 Бк·л−1, а 3H — в пределах 0,8–2,1 Бк·л−1. Средняя удельная активность 90Sr в донных отложениях варьировала в диапазоне 0,5–1,8 Бк·кг−1, а 137Cs — 0,8–2,1 Бк·кг−1. Удельная активность 3H в донных отложениях составляла менее 3 Бк·кг−1, за исключением трёх проб в 2017 г. (12–30 Бк·кг−1), что обусловлено, по всей видимости, локальным загрязнением. Удельная активность 90Sr в высшей водной растительности была на уровне 0,4–3,9 Бк·кг−1, а 137Cs — 0,4–1,0 Бк·кг−1. В питьевой воде объёмная активность нормируемых радионуклидов колебалась в следующих диапазонах: 137Cs — 0,03–0,27 Бк·л−1, что в 40 раз ниже уровня вмешательства по НРБ-99/2009; 90Sr — 0,01–0,16 Бк·л−1 (в 30 раз ниже норматива); 3H — 0,4–1,2 Бк·л−1 (более чем в 6 тыс. раз ниже уровня вмешательства). Удельная активность 90Sr в рыбе варьировалась в диапазоне 0,02–1,6 Бк·кг−1, что в 60 раз ниже российских и международных стандартов. Содержание 137Cs в рыбе было в пределах 0,26–0,3 Бк·кг−1, что в 400 раз ниже российских нормативов и более чем в 3 тыс. раз — международных. Анализ данных наблюдений за уровнями загрязнения тяжёлыми металлами компонентов водных экосистем в регионе АЭС «Руппур» показал, что по ряду элементов зарегистрированы их повышенные концентрации, бόльшая часть которых относится к сезону муссонов. Так, в поверхностных водах р. Падма отмечено периодическое увеличение содержания As, Cd, Mn, Al, а в донных отложениях — As, Cd, Ni, Co, Zn, что связано с антропогенным влиянием и с усиленным стоком загрязняющих веществ в период муссонных дождей. В питьевой воде 30-километровой зоны АЭС «Руппур» зафиксированы периодические повышенные концентрации As и Mn, а в отдельных пробах — Fe и Al, что может быть обусловлено как природными особенностями региона (относительно высокое содержание As в водоносных горизонтах), так и состоянием систем водоснабжения. Заложенная сеть радиационно-экологического мониторинга водных экосистем позволяет регистрировать изменение ситуации в регионе размещения АЭС «Руппур» и выявлять влияние работы атомной электростанции на человека и окружающую среду.

Activity Concentrations of Sr-90 and Cs-137 in Seawater and Sediment in the Gulf of Tonkin, Vietnam

In this study, we measured the activity concentrations of Cs-137 and Sr-90 in surface seawater and surface sediments at the Tra Co, Bach Long Vi, and Ky Anh locations in the Gulf of Tonkin, Vietnam, from December 2018 to October 2019. The average activity at the selected locations was 1.22, 1.43, and 1.33 Bq/m3 for Cs-137 and 0.88, 1.17, and 1.09 Bq/m3 for Sr-90 in surface seawater samples and 0.74, 1.01, and 0.81 Bq/kg dry for Cs-137 and 0.49, 0.49, and 0.43 Bq/kg dry for Sr-90 in sediment samples. The ratio of the average activity concentration (Cs-137/Sr-90) in the surface seawater was 1.42, 1.22, and 1.22 at the Tra Co, Bach Long Vi, and Ky Anh locations, respectively. These are somewhat low compared to the global ratios (1.6 and 1.8). Meanwhile, Cs-137/Sr-90 ratios in the sediment samples at the selected locations were 1.51, 2.06, and 1.88, respectively, which is equal to or greater than the corresponding value for global sedimentation according to the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Correlations between Sr-90, Cs-137, and organic carbon content were detected in this study. The results showed that Cs-137 has a high correlation with the organic carbon content in sediment, while Sr-90 has a low correlation.

Current Levels of Artificial Radioisotopes in Biota from the Arctic Continental Shelf (2013–2018)

This paper analyzes data on the concentration and dynamics of 137Cs and 90Sr in marine organisms on the Arctic shelf under modern conditions (2013–2018). It is shown that the radiation pollution of the Arctic sea biota is low and poses no danger to humans. The dynamics of radionuclide pollution of macrophyte and fish suggests that self-purification of the biotic component of the ecosystem occurred in several stages determined by a change in the generations in the hydrobiont populations. Fish are most sensitive to radiation pollution and the most studied component of marine biota. In the study of modern radioactive contamination of the Arctic seas, attention should be focused on local waters, where an increase in isotope concentrations could be possible owing to the episodic leakage of radioactive materials.

Accumulation and distribution of radionuclides in higher aquatic plants during the vegetation period

The long-term observations of the dynamics of 90Sr and 137Cs concentration, as well as the physicochemical forms of these radionuclides in 10 species of higher aquatic plants during the vegetation period of Glyboke Lake in the Chornobyl Exclusion Zone were presented. The accumulation of radionuclides depends on the influence of environmental factors and species characteristics of the studied plants. It has been shown that the accumulation of 90Sr and 137Cs by plants mainly occurs in accordance with the physiological stages of their development. Under conditions of intensive growth and accumulation of biomass in the juvenile period, plants disproportionately uptake 137Cs from the environment; during the seed ripening period at the stage of aging, plants mainly accumulate 90Sr, as evidenced by the non-correlation of this radionuclide concentration in water and plants in the considered periods. The specific features of the accumulation of radionuclides by plants were studied by the method of analysis of physicochemical forms, which consists in the sequential extraction of radionuclides from plant preparations and makes it possible to quantitatively investigate potentially exchange and fixed forms. The analysis of physicochemical forms confirmed the patterns of seasonal distribution of radionuclides, as well as their accumulation in cells, tissues and in the whole plant obtained from long-term observations.

RADIATSIONNYI REGIME OF SOILS OF AGRICULTURAL LANDS OF SIBERIA IN CONDITIONS OF VARIOUS INTENSITY OF CHEMICAL USE AND PROLONGED AFTEREFFECT CHEMICAL RECLAMATION

Presents the results of radiation monitoring local soils agricultural land in Siberia. At the level of the constituent entities of the Russian Federation appreciated the power of gamma radiation exposure dose (MJeDG), technotronic and content of natural radionuclides in different types of soils in Siberia. Set MJeDG change within 8.0–12.2 mcr/h, 137Cs content in the range of 4.3–9.9 Bq/kg, 90Sr-1.0–5.4 Bq/kg, 226Ra-15–37 Bq/kg, 232Th-16–40 Bq/kg. Comparison with similar parameters obtained, characterizing the radiation situation in soils of agricultural land in Russia. MJeDG, the content of 90Sr and content of natural radionuclides in soils of Siberia correspond to those for Russia. Content of 137Cs in soils in –2.6 1.7 times, in crop production in –2.3 1.6 times lower than in Russia. Content of natural radionuclides in soils of Siberia close to the contents in the soils in Russia on average and the planet. According to local monitoring radiation situation in agricultural fields.

The analysis of radioecological monitoring results in the vicinity of the Kursk Nuclear Power Plant

The research presents the data of long-term observations of the impact of the Kursk Nuclear Power Plant operation on the radioecological situation in the region of its location. The dynamics of the content of natural and artificial radionuclides in the components of agricultural ecosystems was studied due to the data based on the information from the radioecological monitoring network developed in 2003. Samples of soils, agricultural products and animal feeds were taken at 11 control sites located on arable lands and grasslands in the vicinity of the Kursk Nuclear Power Plant, and, in settlements, locally produced food was sampled. It was shown that for the period of studies of 2003-2019, the average specific activity of90Sr in the soils of agroecosystems of the 10 km influence zone of the Kursk Nuclear Power Plant varied within 2.7-4.3 Bq/kg, and specific activity of137Cs was 14.6-40.8 Bq/kg. At the same time, there were found no trends of increase in the content of artificial radionuclides in soil over time and at different distances from the NPP, and the increased specific activity of137Cs in soil compared to the global background is explained by the Chernobyl fallout. The variability of the average content of natural radionuclides in the soil for40K was 481-625 Bq/kg,226Ra – 20.6-29.5 Bq/ kg,232Th – 28.2-39.2 Bq/kg, which corresponded to all-Russian data. The average specific activity of90Sr in grain was 0.24-0.43 Bq/kg, and137Cs – 0.19-0.37 Bq/kg. Even the maximum levels of artificial radionuclides in grain were 44 times for90Sr and 85 times for137Cs lower than the current SanPiN standards. The highest specific activity values of137Cs and90Sr in potatoes, vegetables, and gourds were 160 times lower than the SanPiN standards. It was noted that the maximum content of90Sr in milk was more than 540 times lower than the SanPin standard, and for137Cs this difference was 330 times. The maximum content of137Cs in beef turned out to be over 850 times lower than the SanPiN standard for this radionuclide. About 70 Bq/a of90Sr and 200 Bq/a of137Cs enter the population diet with locally produced food, which is almost 400 times for137Cs and 200 times for90Sr lower than the annual limit. Milk (46%), meat (31%), potatoes and vegetables (14%) make the main contribution to the formation of the internal dose from agricultural products containing137Cs, and contribution to dose from90Sr is made by milk (14%) and crop products (potatoes, vegetables, bread) – up to 78%. In general, we concluded that over the past 17 years, the operation of the Kursk Nuclear Power Plant did not lead to a deterioration of the radioecological situation in the region of its location, because during the survey period there was no significant increase in the content of artificial radionuclides in agricultural products, foods and environmental components.

Impact of distance from the glacier on the content of 137Cs and 90Sr in the lichen Cetrariella delisei

The Arctic region is substantially a pristine area, but this unique part of the globe has also been contaminated by anthropogenic radioactive nuclides, and now there is still measurable activity of anthropogenic isotopes, even though more than 50 years have passed since the main source. Radionuclides in the Arctic, especially 90Sr have seldom been studied despite their considerable environmental importance. This manuscript covers the results of 90Sr and 137Cs measurements in soil and lichen Cetrariella delisei collected from the Svalbard in 2012. In both lichen thalli and surface soils high activities of 90Sr and 137Cs were recorded and ranged between 3.69 and 28.1 Bq kg−1 90Sr and 5.38–280.1 Bq kg−1137Cs in thalli and between 4.53 and 12.78 Bq kg−1dw 90Sr and 60.6–426.1 Bq kg−1dw 137Cs in surface soil layer. The activity of 90Sr and 137Cs in lichen thalli was influenced by distance from the glacier. This showed that during radionuclide biomonitoring of particular area with the use of lichens, it is important to take into account influence of environmental variability on radionuclides contents.

Simulating dissolved 90Sr concentrations within a small catchment in the Chernobyl Exclusion Zone using a parametric hydrochemical model

Strontium-90 (90Sr) is the major long-lived radionuclide derived from the Chernobyl accident, and is still being detected in the heavily contaminated catchments of the Chernobyl Exclusion Zone. This study examines the long-term decrease in the dissolved-phase 90Sr concentration and the concentration–discharge (90Sr-Q) relationship in stream water since the accident. We show that the slow decline in 90Sr follows a double-exponential function, and that there is a clear relationship between 90Sr and Q. This study is the first to reveal that the log(90Sr)-log(Q) slope has been gradually decreasing since the accident. This trend persists after decay correction. Thus, it is not caused by the physical decay of 90Sr and environmental diffusion, but implies that the concentration formation processes in stream water have been changing over a long period. We propose a hydrochemical model to explain the time-dependency of the 90Sr-Q relationship. This paper presents a mathematical implementation of the new concept and describes the model assumptions. Our model accurately represents both the long-term 90Sr trend in stream water and the time-dependency of the 90Sr-Q relationship. Although this paper considers a small catchment in Chernobyl, the conceptual model is shown to be applicable to other accidental releases of radionuclides.

Distributions of 137Cs and 90Sr activity concentrations in trunk of Scots pine (Pinus sylvestris L.) in the Chernobyl zone

Possibility of the economical utilization of forests in the radioactive contaminated areas depends on compliance of the radionuclide activity concentrations in wood with the hygiene norms or national standards that are established by the governments or regulators. Since such regulations consider wood as a whole, development of the sampling methods for assessment of compliance of wood to the norms or standards requires the adequate addressing the issues related to heterogeneity of the radionuclide distributions within the tree trunks.In this paper we present spatial distributions of the 90Sr and 137Cs activity concentrations in the trunk wood of mature Scots pine (Pinus sylvestris L.) trees in the Chernobyl exclusion zone in the late stage (30 years) after the deposition. Four 52–53 year old model trees were sampled in the forest stand located in approximately 5 km from the accidental nuclear reactor. The radionuclide concentrations were measured in 156 wood samples collected from the wood disks cut off the tree trunks at the set of heights. To address variability of the tree sizes and radionuclide concentrations between the individual trees, we applied the corresponding relative indices enabling identification of the general patterns of the spatial distributions of 90Sr and 137Cs. We demonstrated significant differences in bioavailability and distribution trends between the studied radionuclides. 137Cs is translocated to the younger parts of the tree trunk, while the 90Sr concentrations are higher in heartwood and in senescing tissues, which is explained by the different chemical properties of Cs and Sr and by different physiological roles played in plant development by their chemical analogs and major plant nutrition elements, Ca and K respectively. In this reason, the principal distribution patterns of the studied radionuclides in the trunk wood do not significantly change with time, and the results of our study generally are in good agreement with those obtained in the earlier stage after the deposition. The above trends are clearly expressed in both radial and longitudinal directions and result in systematic deviation of the concentrations estimated based on core sampling from the average concentrations in the whole tree trunk.

Sequential determination of 90Sr and 210Pb in bone samples using molecular recognition technology product AnaLig® Sr-01

Both radioactive isotopes, 210Pb and 90Sr, accumulate in bones and procedures for their determination usually include radiochemical methods prior their detection. This work describes a novel method for simultaneous determination of 210Pb and 90Sr in bone samples by using molecular recognition technology product AnaLig®Sr-01 gel, commercially available from IBC’s Technologies Inc. This material is initially used for strontium isolation. Important drawback is that it also binds lead ions. This fact is used to develop a simple and rapid method for their simultaneous determination. The use and effectiveness of AnaLig®Sr-01 gel was validated by analysis of certified reference animal bone material, supplied by International Atomic Energy Agency (IAEA A-12) and 210Pb reference sample. The developed single column method was used to determine the activity concentrations of 90Sr and 210Pb in bones of wild boars, deers and goats from different regions of Slovakia and Croatia. The proposed simple and effective method can easily be implemented in any radiochemical laboratory and the obtained results could be used for monitoring environmental areas of interest. The recoveries of both isotopes were high in all tested samples, 100% for Pb and around 80% for Sr, which is very important in sense of low activity concentration of radionuclides in environmental samples. The activity concentration of 210Pb correlated good with age of the animal (R2 = 0.94), whereas of 90Sr no correlation was found (R2 = 0.05).

Analysis of radiouclide contamination of forestry products on the territory of Ukraine 2013–2019

The analysis of the results of radiological studies of food and feed conducted by the specialists of the state laboratories of the State Consumer Service for 2013–2019 is performed. The analyzed results show that in the territories assigned to the radiation contamination zones, samples with a radionuclide content exceeding the maximum admissible levels of 137Cs and 90Sr are constantly detected. Even 33 years after the Chernobyl accident, the specific activity of 137Cs in mushrooms and berries remains high. Specialists of the state laboratories of the State Consumer Service during this period carried out radiological examinations of food and feed for the contents of 137Cs and 90Sr. Exceedance of the maximum permissible levels (DR) of 137Cs was detected in 3.253 samples, of which 1.277 were fresh mushrooms and yagi and 729 were dried and dried mushrooms and berries. It is established that forest mushrooms and berries (fresh and dried) are the critical dose-forming foods, accounting for the largest proportion of about 62 % of the total positive samples. A much better situation was observed in detecting an excess of DR 90Sr. During the study period, contamination of 90Sr food and feed is of a single nature. The dynamics of detecting excesses of DR 137Cs in forest mushrooms and berries (fresh and dried) for 2013–2019 have significant fluctuations related to environmental conditions and the multidirectional migration of man-made radionuclides in forest ecosystems. The use, even in small quantities, of forest origin products with a maximum specific activity of 137Cs can play a significant role in the internal exposure of long-lived radionuclide to the local population. Therefore, the largest proportion of forest food products (62 %) is in the balance of radionuclide-contaminated products during the last seven years. (2013–2019) and other products and feeds are the basis for further radiological control by their state laboratories of the State Consumer Service.

Applying process-based models to the Borssele scenario

The objective of this paper is to consider the implications of employing process-based models on predictions for radionuclide activity concentrations in grass and cow milk. The FDMT (Food Chain and Dose Module for Terrestrial Pathways as used in the JRODOS and ARGOS decision support systems) model has been transferred to a modelling platform enabling sub-models to be modified and replaced. Primarily, this has involved invoking process-based models for 137Cs and 90Sr that account for soil chemistry in simulating bioavailability and plant transfer. The implementation of such models can lead to quite dramatic differences in predicted activity concentrations of radionuclides in grass and milk compared to a default FDMT set-up for time periods later than a few weeks post deposition. Considering transfer within a spatial context, by combining information from the outputs of process-based models with illustrative soil maps, leads to the observation that the most elevated 137Cs and 90Sr concentrations in grass and milk might not necessarily occur in areas where deposition is highest. Not accounting for soil type when modelling food chain transfer might lead to the sub-optimal allocation of resources or misidentification of the most vulnerable areas in the long-term after an accidental release.

Results of the fourth combined scientific expedition for the radition monitoring in the Kurily-Kamchatka region of the Pacific ocean

This paper continues the series of publications on evaluation of the consequences of the Fukushima-1 nuclear power plant accident and the impact of the emergency radionuclide discharges on the contamination of the sea biota and coastal areas of the Far-East regions. In autumn 2019, the fourth scientific expedition of the Russian geographic society on the monitoring of the radiation situation in Kurily-Kamchatka region was performed on the training vessel «Professor Khlyustin». The expedition included 9 specialists from noncommercial organization «Polar research Fund «Polar Fund», «Russian state hydrometeorological institute», «Radium institute after V.G. Khlopin» of the State Corporation «Rosatom», «Kurchatov institute», «SaintPetersburg research institute of radiation hygiene after prof. P.V. Ramzaev» and «Marine state university after admiral G.I. Nevelsky». The aim of the fourth expedition was to evaluate the radiation situation in the Sea of Japan and Kurily-Kamchatka region after the Fukushima-1 NPP accident as a continuation of the similar marine expeditions in 2011, 2012 and 2014. The survey was performed in the water area of the sea of Japan and Okhotsk sea. The results indicate that the concentration of 137Cs and 90Sr in sea water, hydrobionts, soil, ground and sea vegetation is still on the baseline level due to the global fallouts.

Sr-90 soil to plant transfer factor reduction using calcium and polymer soil amendments

Introducing calcium into soils can inhibit Sr-90 uptake by plants. To test the efficacy of calcium amendments on the inhibition of Sr-90 uptake by edible plants, a number of different calcium applications, including calcium nitrate, calcium thiosulfate and a mixture of both liquid solutions, were used in this study. Pea plants (Pisum sativum 'Sabre') grown in Sr-90 contaminated soil from seeds to maturity were watered with these calcium solutions. Two different polymers, one inert and one nutrient enriched, were incorporated into the contaminated soil where pea seeds were sowed to ascertain a continuous supply of calcium and essential nutrients. Results show that the heterogeneity of Sr-90 distribution in soil translated to disparate Sr-90 contents in plant tissues. However, on average, irrigation with calcium solutions in conjunction with the usage of polymers consistently yielded a reduction in Sr-90 uptake by the plants. The lowest soil-to-plant transfer factor (TF) values were measured in the edible pea part of the plant, followed by the flowers, roots, stems, pea shells and then leaves. TF values for pea shells were between 4.9 and 20.9, and between 0.3 and 2.8 for the peas. Results do not allow the identification of one particular chemical solution that would systematically be the best choice to minimize Sr-90 uptake.

Radioecological Analysis of the Contamination Area in the Volyn Region of Ukraine

Lack of scientific knowledge on the patterns of formation of soil and plant complexes, including the concentration of contaminants in them (especially radionuclides and heavy metals) leads to serious errors in the selection of objects and sites of management, negative environmental consequences. The peculiarities of the propagation of Сs-137, Sr-90 radionuclides and heavy metals in soil and plants within the area of radioactive contamination of the Volyn region are analyzed. The maximum concentration of Сs-137, Sr-90 content was determined. Exceeding of the permissible levels of heavy metals content in crop production is revealed.
 Generalization of the actual material on the content of radionuclides and heavy metals of different types of soils, agricultural plants in different natural conditions is a necessary condition for clarifying the patterns of formation, their influence on the geo-ecological state; this makes it possible to raise the state of their study to a new theoretical level, to carry out radiation monitoring and to provide radiation protection the for local population. Taking into account the similarity of physical and geographical conditions and existing soil and plant complexes, the typicality for the territory of Ukrainian Polissya, the complexity of analytical data can be considered to be representative for the area of coniferous-deciduous forests of the Eastern European plain. These data are necessary for estimating the present state and forecasting the future states of pollution, for extrapolating them in space and time.

90Sr Content in the Stemwood of Forests within Ukrainian Polissya

The consequences of the Chernobyl disaster continue to threaten humans and ecosystems across fallout gradient in Northern Ukraine and nearby. Forest ecosystems contain substantial stocks of long-lived radionuclide 90Sr which was leached from the fuel matrix during the disaster. Nowadays, there is a lack of information about current transfer factors (TF) of this radionuclide from soil to the stemwood of native tree species. We have estimated 90Sr content in the forest stemwood of three tree species utilizing models of their growth and yield and collected woody samplings. TFs provided here vary greatly across studied tree species (18.0 × 2.1±1, 8.7 × 2.8±1, and 10.4 × 6.0±1 n × 10−3 m2·kg−1 (geometrical mean (GM) ± geometrical standard deviation, GSD) for the above species, respectively) and together with indicators of soil contamination allow us to reliably assess local stocks in the stemwood. Silver birch stands are estimated to deposit the highest 90Sr stocks. Herewith, at 25 years old Black alder stands could accumulate higher stocks (up to 35 MBq·ha−1) under rich growth conditions. TFs obtained in this study substantially exceed values provided by the International Atomic Energy Agency for studied tree species and thus could entail respective restrictions on use of firewood across large areas in Ukrainian Polissya. Data provided here may be harnessed to support decisions of respective stakeholders to provide credibly safe management of the contaminated forest ecosystems.

Does Salinity Affect the Distribution of the Artificial Radionuclides 90Sr and 137Cs in Water of the Saline Lakes? A Case of the Crimean Peninsula

In the framework of radioecological monitoring, the features of the distribution of the post-Chernobyl nuclear power plant (NPP) accident artificial radionuclides of 137Cs and 90Sr in the Crimean saline lakes were studied. Samples were collected from 12 Crimean lakes with a salinity range from 2 to 400 g/L in 2014–2017. Concentration of 90Sr varied from 5.9 to 313.6 Bq/m3, and 137Cs from 0.8 to 106.7 Bq/m3. Closing of the North Crimean Canal resulted in a decrease in radionuclide concentration in the lakes. About 61% of the total variability of 90Sr and 33% of 137Cs in lake water can be explained by salinity changes. The salinity affects the behavior of radionuclides in water, mainly influencing their solubility, on isotope exchange between the solution and bottom sediments, and also, probably, through its influence on accumulation of isotopes by aquatic organisms. Salinity is not the alone factor determining the behavior of radionuclides in the lakes, it only acts by interacting with other factors.

Investigation of radioactivity concentration of 137Cs, 90Sr and 129I radioisotopes in thyroid samples

In this study, the gross alpha and beta activities and 137Cs, 90Sr and 129I radionuclide concentrations in the feeds and thyroid samples obtained from a certain number of sheep, which were fed by Fırat University (Elazığ) Faculty of Veterinary Medicine with varying amounts of fresh lucerne, fodder, silage, straw and concentrate feed were determined. The 137Cs, 90Sr and 129I radionuclide transfer coefficients were also determined. 90Sr and 129I are beta-emitting radionuclides. Sheep with high 90Sr and 129I radionuclide concentrations also have high gross beta radioactivity levels. When an intragroup comparison is performed, the radionuclide concentration in a sheep fed with maximum feed is at the highest level and vice versa. Moreover, the 137Cs, 90Sr and 129I radionuclide transfer coefficients (Ff) for the thyroid samples obtained from the sheep vary between 0.4 × 10−1 – 8.1 × 10−1 d kg−1, 0.4 × 10−2 − 6.1 × 10−1 d kg−1 and 0.4 × 10−1 − 7.3 × 10−1 d kg−1, respectively, and are higher than the expected Ff values and the results obtained in similar studies. The Ff values calculated for the thyroid samples of the straw and fodder group are lower than the Ff values calculated for the thyroid samples of the silage and fresh lucerne group. The radionuclide concentrations for 129I were found to be higher than 90Sr's in the thyroid samples.

COMPREHENSIVE RADIOLOGICAL AND HYGIENIC MONITORING OF PARTICULAR SETTLEMENTS OF KYIV REGION IN 2019.

to identificate the main factors and assess their impact on the formation of radiation doses to the population of radioactively contaminated areas of Kyiv region at the current stage of the accident based on complexradiation and hygienic monitoring in the reference settlements in 2019. Comprehensive radiological and hygienic monitoring was carried out in eight settlementsof Kyiv region - villages of Ragivka, Lygovyky, Mar'yanivka, Zelena Poliana of Polis'kyi district and villages ofHornostaipil, Dytiatky , Pisky, Karpylivka of Ivankiv district. The content of incorporated 137Cs was determined withdirect measurement on whole body counters (WBC) samples of basic foodstuffs were collected to determine the content of radionuclides 90Sr and 137Cs, residents were interviewed about the levels of consumption of these products,and work was performed to estimate external radiation doses. Mathematical, dosimetric, radiochemical methods areused in the work. There was a further decrease in annual doses of internal radiation in the surveyed settlements in 1.3 times, bothin Polis'kyi district (0.041 mSv · year-1 in 2016, 0.030 mSv · year-1 in 2019) and in Ivankiv district (0.023 mSv · year-1in 2016, 0.018 mSv · year-1 in 2019). It is possible to state a slowdown in the reduction of radiation doses comparedto previous years: from 2010 to 2013, the annual doses of internal radiation in the surveyed settlements decreasedby 1.8-2.4 times, from 2013 to 2016 - by 2.3-3.6 times. The content of 137Cs and 90Sr in milk and potatoes in theinspected settlements is lower than the permissible level of the Hygienic Standard HS 6.6.1.1-130-2006 and the useof these foods can not significantly affect the formation of the internal radiation dose. The content of 90Sr in milksamples in the settlements of Ivankiv district is in the range of 2.1-9.9 Bq · kg-1 (in 2016: 1.3-7.4 Bq · kg-1), whichdoes not exceed the permissible level of 20 Bq · kg-1, but due to the dynamics needs further monitoring. The content of 137Cs in samples of dried mushrooms collected from residents of Kyiv region in 2019, as in previous years, issignificantly (up to 100 times) higher than permissible level, and has a high uncertainty - from 1.4 kBq · kg-1 to223.7 kBq · kg-1. It is established that the annual effective radiation doses of the population in the surveyed settlements in the current year are formed due to internal radiation doses that do not exceed 0.46 mSv · year-1 in Ivankivdistrict and 0.51 mSv · year-1 in Polis'kyi district, which below the RCT criterion 1 mSv · year-1. The main factor that forms the dose of internal radiation of the residents of the surveyed state of emergency of Kyiv region is the intake of 137Cs in the body with forest products, primarily mushrooms.