Accumulation Of Radionuclides Research Articles

Changes in radioactive contamination of living ground cover plants in black alder stands since the Chornobyl accident in the forests of Zhytomyr Polissia

The results of research conducted over the past 30 years in the forest ecosystems of Zhytomyr Polissia, in the areas affected by radioactive contamination as a result of the Chornobyl accident. In the course of the research carried out at the Poliskyi Branch of the Ukrainian Research Institute of Forestry and Forest Melioration named after G. M. Vysotsky, methods of forest radioecology, botany, and forestry were used, and the results were processed using statistical analysis. The peculiarities of radioactive contamination of the most common herbaceous and dwarf-shrub plants in the stands of black alder in damp fairly fertile site types were studied. As indicators characterizing these features, we used 137Cs specific activity in the aboveground part of plants and the transfer factor of radionuclide to plant phytomass from the soil. It was found that the highest values of the transfer factor of 137Cs from the soil to the aerial part of the plant phytomass in 1999 are characteristic of ferns: for Dryopteris cristata (L.) A. Gray (276.9 m2∙kg-1∙10-3), Dryopteris carthusiana (Vill.) H. P. Fuchs (236.5 m2∙kg-1∙10-3), Thelypteris palustris Schott (171.2 m2∙kg-1∙10-3), and Athyrium filix-femina (L.) Roth (164.0 m2∙kg-1∙10-3). It was found that among the higher plants, the highest values of this indicator are for the Agrostis stolonifera L. (263.5 m2∙kg-1∙10-3), Galium uliginosum L. (155.8 m2∙kg-1∙10-3) and Maianthemum bifolium (L.) F. W. Schmidt (155.4 m2∙kg-1∙10-3). It was found out that the previously noted trends and interspecific differences in radionuclide accumulation persist after 22 years. It is shown, using the example of three plant species (Lysimachia vulgaris L., Galium uliginosum, and Maianthemum bifolium), that during the observation period (1991-2021) there is a gradual decrease in radioactive contamination of living ground cover plants and the intensity of 137Cs intake into them. This is explained by the decay of the radioactive element, its entry into various perennial components of forest ecosystems, some fixation in the soil, and, possibly, its removal beyond their borders. The established decrease in 137Cs specific activity in the aboveground part of plants is described by linear equations: for Lysimachia vulgaris – Am = –605.34a + 3745.6; R² = 0.98; Galium uliginosum – Am = –5107.5a + 30698; R² = 0.99; Maianthemum bifolium – Am = –4661.6 a + 28280; R² = 0.98. The identified peculiarities of radioactive contamination of various plant species, changes in 137Cs specific activity in them, and transfer factors of the radionuclide from the soil in stands of black alder in damp fairly fertile site types can be used in scientific works to predict possible changes in its redistribution within the ecosystem, as well as in the practice of harvesting medicinal plants in areas contaminated with radionuclides.

Accumulation of Technogenic and Natural Radionuclides in the Don Delta Sediments

The study of current sedimentation processes and radioactive contamination in the total area of the Don Delta is the research goal. The presented paper contains data analysis of radioecological and lithologic studies on bottom sediments, sampled in the northern part of the Don Delta in 2022. Based on the research results obtained, the authors provide the characteristics of the current conditions of sedimentation and specific activity of artificial and natural radionuclides in fluvial deposits, as well as indicate that similar in characteristics sandy-silty aleurites and sandy aleurite-clayish silts with inclusions of plant and shell detritus compose the bottom sediments of numerous braided channels. The authors determined the zonal accumulation character of both 137Cs technogenic and 226Ra, 40K, and 232Th natural radionuclides which conditions their accumulation and content increase from the lower delta to the upper delta areas. The velocity of currents in the braided channels (bayous) and related sedimentation conditions of suspended matter, as well as the lithotype of the bottom ground determine the indicated regularity. We assume that unlike 137Cs the distribution of natural radionuclides (40K, 226Ra, and 232Th) mainly depends on the mineral content of sediments entering the delta with the river runoff. Relatively low indices – on average ca. 9 Bq/kg of dry weight (d.w.) – characterise the current range of 137Cs radioisotope concentrations in the sediments of the Northern Don Delta. Such a level of specific activity is of no danger to the regional ecosystem.

Repurposing iron chelators for accurate positron emission tomography imaging tracking of radiometal-labeled cell transplants.

The use of radiolabeled cells for positron emission tomography (PET) imaging tracking has been a promising approach for monitoring cell-based therapies. However, the presence of free radionuclides released from dead cells during tracking can interfere with the signal from living cells, leading to inaccurate results. In this study, the effectiveness of the iron chelators deferoxamine (DFO) and deferiprone in removing free radionuclides 89Zr and 68Ga, respectively, was demonstrated in vivo utilizing PET imaging. The use of DFO during PET imaging tracking of 89Zr-labeled mesenchymal stem cells (MSCs) significantly reduced uptake in bone while preserving uptake in major organs, resulting in more accurate and reliable tracking. Furthermore, the clearance of free 89Zr in vivo resulted in a significant reduction in radiation dose from 89Zr-labeled MSCs. Additionally, the avoidance of free radionuclide accumulation in bone allowed for more precise observation of the homing process and persistence during bone marrow transplantation. The efficacy and safety of this solution suggest this finding has potential for widespread use in imaging tracking studies involving various cells. Moreover, since this method employed iron chelator drugs in clinical use, which makes it is a good prospect for clinical translation.

Technogenic Radionuclides in Hydrobionts of the Northern Ukraine Water Bodies

The peculiarities of accumulation of artificial radionuclides by higher aquatic plants and fish of water bodies of the Chernobyl exclusion zone and the territories of the western and southern traces of the Chernobyl accident release were analyzed and compared. In 2020-2021, <sup>90</sup>Sr activity concentration in higher aquatic plants of the cooling pond of the Chernobyl Nuclear Power Station, Lake Daleke, and the Yanivsky backwater accounted for 10-46 kBq/kg, <sup>137</sup>Cs - 5.4-47.0 kBq/kg, whereas in the Azbuchyn, Vershyna, and Glyboke lakes - respectively 64-419 kBq/kg and 9.3-63.4 kBq/kg. The activity concentration of <sup>90</sup>Sr in fish of the cooling pond of the Chernobyl NPS, Lake Daleke, and the Yanivsky backwater was 1.4-8.6 kBq/kg and <sup>137</sup>Cs -2.3-3.2 kBq/kg, whereas in the Azbuchyn, Vershyna, and Glyboke lakes - respectively 21-213 kBq/kg and 4.2-6.2 kBq/kg. In 2020-2021 in many studied water bodies located outside the Chernobyl exclusion zone, the levels of <sup>90</sup>Sr accumulation in helophytes did not differ reliably and accounted for about 10 Bq/kg. In helophytes of Lake Lisove, <sup>90</sup>Sr activity concentration attained 181 Bq/kg. The maximum activity concentration of <sup>137</sup>Cs in helophytes of the Kaniv Reservoir and the Irsha River was not more than 30 Bq/kg and in Lake Lisove it accounted for 16 920 Bq/kg, whereas in other water bodies located outside the Chernobyl exclusion zone - 65- 515 Bq/kg. The maximum activity concentration of <sup>137</sup>Cs in hydatophytes of the Bile, Luky, and Lisove lakes accounted for respectively 639, 1066, and 6417 Bq/kg and in other water bodies it was not more than 150 Bq/kg. The activity concentration of <sup>90</sup>Sr in fish organism of Lake Lisove attained 23 Bq/kg, whereas in other water bodies it was not more than 11.3 Bq/kg. The maximum activity concentration of <sup>137</sup>Cs in fish of Lake Lisove and Lake Bile accounted for respectively 1400 and 314 Bq/kg, in the Povchanske and Kyiv reservoirs - 154 and 124 Bq/kg, whereas in other water bodies it was not more than 38 Bq/kg.

Activity Concentrations of Cs-137, Sr-90, Am-241, Pu-238, and Pu-239+240 and an Assessment of Pollution Sources Based on Isotopic Ratio Calculations and the HYSPLIT Model in Tundra Landscapes (Subarctic Zone of Russia)

The paper is devoted to the assessment of the content of anthropogenic radionuclides in tundra landscapes of the subarctic zone of Russia. The authors of the article studied the features of accumulation and migration of anthropogenic radionuclides and identified probable sources of their entry into environmental objects. Peat samples were collected on the territory of the Kaninskaya Tundra of the Nenets Autonomous Okrug (Northwest Russia). A total of 46 samples were taken. The following parameters were determined in each peat sample: (1) activity and pollution density of anthropogenic radionuclides; (2) isotopic ratios of anthropogenic radionuclides; (3) activity ratios of each radionuclide for layers 10–20 cm and 0–10 cm. The results of the studies showed that the pollution density of the Nes River basin with the radionuclides Cs-137 and Sr-90 is up to 4.85 × 103 Bq×m−2 and 1.88 × 103 Bq×m−2, respectively, which is 2–5 times higher than the available data for the Kanin tundra, as well as for Russia and the world as a whole. The data obtained for Am-241, Pu-238, and Pu-239+240 showed insignificant activity of these radionuclides and generally correspond to the values for other tundra areas in Russia and the world. It was found that some tundra areas (“peat lowlands”) are characterized by increased radionuclide content due to the process of accumulation and migration along the vertical profile. Calculations of isotope ratios Sr-90/Cs-137, Pu-238/Pu-239+240, Pu-239+240/Cs-137, Am-241/Pu-239+240 and air mass trajectories based on the HYSPLIT model showed that the main sources of anthropogenic radionuclide contamination are global atmospheric fallout and the Chernobyl accident.

Peculiarities in accummulation of radionuclides by fruit and berry trees and shrubs

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 241Am, 137Cs, 90Sr, 239+240Pu 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 137Cs, 90Sr, 241Am and 239+240Pu 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 137Cs in leaves of the researched plants more often were registered at the initial stages of vegetation period. Unlike 137Cs concentration of 241Am and 90Sr 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 study of gross beta-radioactivity of some medicinal plants in conditions of outdoor hydroponics and soil culture in Ararat Valley

Background: Technogenic and natural radionuclides (RN) along the biogeochemical chains of agrocenoses may enter the human body through irrigation water- soil- plants- agricultural animals, likewise in hydroponic systems through nutrient solution substrate plants, leading to the development of dangerous diseases. Thus, control of herbal raw material’s gross β-radioactivity and obtaining radioactively safe medicinal raw material are priority issues. Since 1996 we have carried out radio monitoring research in the Ararat valley (where the Armenian Nuclear Power Plant (ANPP) is located) in water, soil, and plant systems in zones of the ANPP with a radius of 2-15, 20 (the territory of Ashtarak city), 30 km (Yerevan, territory of Institute of Hydroponics Problems) (IHP), as well as Dilijan Forest Experimental Station (DFES) (the zone of ANPP with 90 km radius). Studies have shown that in natural waters (artesian water, Hrazdan, Qasakh, Metsamor rivers), soils and in various crops (vegetables, fruit of trees, etc.) of Ararat Valley the content of technogenic RN 90Sr (T1/2=28.6 years) and 137Cs (T1/2=30.1 years) did not exceed maximum allowable concentrations (for drinking water MAC 90Sr=5.0 Bq/L, MAC 137Cs=11.0 Bq/L; for vegetables and fruits MAC 90Sr=50 Bq/L, MAC 137Cs=130 Bq/L). Based on these studies, a complex of practical recommendations in this region will give the opportunity of obtaining ecologically pure agricultural products.Objective: Considering that the accumulation of RN in medicinal plants poses a particularly great threat to obtaining radioecologically safe medicinal raw materials, during 2017-2022 we studied the specificities of gross β-radioactivity and accumulation of controlled technogenic RN (90Sr and 137Cs) in medicinal plants under hydroponics and soil conditions in the Ararat valley (the zone of ANPP with 30 km radius). This has a specific practical significance, as it will enable to obtain the most radio-ecologically safe plant material.Methods: Gross β-radioactivity and content of 90Sr and 137Cs of samples (artesian water (irrigation water), nutrient solution, soil layers with depth of 0 - 30 cm and number of medicinal plants) in it were defined with radio-chemical extraction methods through the radiometer UMF-1500 (made in Russia) with low background. 90Sr was determined by the oxalate method with 90Y. RN were determined in dry sediments of waters, nutrient solution, the ash of plants, and soils. The following chemical reagents were used for the analysis: C2H2O4, HNO3, HCl, CH3COOH, CsCl, Y2O3, YCl3, K2SO4, KI, Sr(NO3)2, CeCl3, Ni(NO3)2, SbCl3, K4[Fe(CN)6] 3H2O and others.Results: The radio-chemical studies showed that the gross β-radioactivity of herbs in hydroponics fluctuated between 250 – 740 Bq/kg, and in soil: 140 – 690 Bq/kg. Thus, the medicinal raw material from the medicinal plants cultivated in outdoor hydroponics and soil, is radioecologically safe, since its gross β-radioactivity does not exceed the threshold of 1.0 Bq/g. Medicinal plants grown in hydroponics and soil, with a slight deviation, show the same gross β-radioactivity decreasing pattern as follows: Peucedanum caucasicum (M.Bieb.) K. Koch. > Lycium barbarum > Eleutherococcus senticosus (Rupr. & Maxim.) > Teucrium polium = Humulus lupulus, variety “Crystal” > Echinacea purpurea (L.) Moench > Humulus lupulus, variety “Chinook” > Humulus lupulus, variety “Newport” > Colchicum speciosum Stev. > Moringa oleifera Lam. Our studies have shown that the proportion of 90Sr and 137Cs together in gross β-radioactivity in different medicinal plants fluctuated between 1.0-7.4 % of dry mass in hydroponics and 1.7-10.1 % of dry mass in soil. In the gross β-radioactivity of medicinal plants the share of 90Sr and 137Cs in hydroponics was 1.2-3.0 and 1.3-2.3 times lower than that of soil plants.Conclusion: In artesian waters, gray soils and different medicinal plants grown in hydroponic settings and soil of Ararat Valley the content of controlled technogenic RN (90Sr and 137Cs) did not exceed MAC. Both medicinal raw materials grown in hydroponic settings and soil in Ararat Valley are radioecologically safe.Keywords: technogenic radionuclides, nutrient solution, herbal raw materials, 90Sr, 137Cs

Bioaccumulation of contaminants in Scarabaeidae and Silphidae beetles at sites polluted by coal combustion residuals and radiocesium

Anthropogenic contamination from coal-fired power plants and nuclear reactors is a pervasive issue impacting ecosystems across the globe. As a result, it is critical that studies continue to assess the accumulation and effects of trace elements and radionuclides in a diversity of biota. In particular, bioindicator species are a powerful tool for risk assessment of chemically contaminated habitats. Using inductively coupled plasma mass spectrometry (ICP-MS) and auto-gamma counting, we analyzed trace element and radiocesium contaminant concentrations in Scarabaeidae and Silphidae beetles (Order: Coleoptera), important taxa in decomposition and nutrient cycling, at contaminated and reference sites on the Savannah River Site, South Carolina, U.S. Our results revealed variability in trace element concentrations between Scarabaeidae and Silphidae beetles at uncontaminated and contaminated sites. Compared to Scarabaeidae, Silphidae had higher levels of chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), and zinc (Zn). Unexpectedly, concentrations of Cr, Cu, and Ni were higher in both taxa at the uncontaminated sites. Scarabaeidae and Silphidae beetles at the coal combustion waste site consistently had high concentrations of arsenic (As), and Scarabaeidae had high concentrations of selenium (Se). Of the 50 beetles analyzed for radiocesium levels, two had elevated radioactivity concentrations, both of which were from a site contaminated with radionuclides. Our results suggest carrion beetles may be particularly sensitive to bioaccumulation of contaminants due to their trophic position and role in decomposition, and thus are useful sentinels of trace element and radionuclide contamination.

Evaluation of Cs-137 and natural radionuclides on different marine biota (crustacean and fishes) along Beheira governorate Coast-Egypt: RESRAD biota

Purpose This work will focused on the environmental and radio-ecological impacts occurred on an Egyptian coastal region, based on the radiochemical measurement of 238U, 137Cs, 232Th, 40K. The novelty of the study was cleared by the using of new technique showing the integration of two biological RESRAD models, lead to a probabilistic estimation of the radionuclides bioaccumulation in different consumed marine organisms and determination the probability of human cancer risk at different ages. Material and methods The 20 water samples were collected and mounted into clean containers, and their decay products, were measured in Bq.L−1, using different quality assurance tools. The study will used different statistical analysis and different RESRAD modeling codes were used in the study to predict the degree of environmental and radio-ecological impacts at the studied area, this will be helpful in order to define the impacts resulted from the transferring and accumulation of different radionuclides. Results showed that the highest human dose conversion factor values of (5, 10, 15, with adult ages) were measured in Th-232 (mrem/pCi) while the lowest ingestion conversion factors values were observed in artificial 137Cs. On the other hand the highest values of external risk factor in case of (5, 10, 15 with adult age) were observed in artificial Cs-137(mrem/pCi), while the lowest value of external risk factor with the same ages were observed in U-238. This will lead to continual monitoring of artificial Cs-137 in different marine coastal regions. The arrangement of the bioaccumulation value (BIV) in Bq.kg−1 which being calculated by using RESRAD-Biota in case of crustacean animals will be as follow: U-238 > Th-232 > Cs-137, while the arrangement of BIV in case of fish animals will be: Cs-137 > U-232 > Th-232. On the other hand the arrangement of Internal Dose Conversion factors in case of crustacean animals will be: U-238 > Th-232 > Cs-137. While the arrangement of Internal Dose Conversion factors in case of fish animals will be: Cs-137> Th-232 > U-238. Conclusion RESRAD code’s results showed that the arrangement of the bioaccumulation and Dose Conversion factors were depend on the type of marine living organism. RESRAD code also showed that there are increments of the calculated external risk factor values which resulted from the adult than all the infants (5,10 and 15 ages) ages this may be related to the continuous replacement of new human’s body cells during the growth stages. The study results showed that, environmental bioaccumulation impacts of the artificial Cs-137 were very effective in both marine living organisms and human as this will support the relation between the ingestion Cs-137 in the body(inside the soft tissues), and the probability of the human cancer risk. On the other hand, study results showed the importance of using RESRAD BIOA code for the EIA's ecological and radiological studies which should be done for any future industrial coastal .projects.

Natural radioactivity of residues from groundwater treatment facilities in Finland

The accumulation of naturally occurring radionuclides in solid residues was investigated from groundwater treatment facilities (GTFs) in Finland. Natural radionuclides U-238, Ra-226, Pb-210 and Ra-228 were found in various precipitates, sludges and filters at concentrations exceeding the general clearance level of 1 kBq kg−1 used for solid materials in the European directive 2013/59/Euratom. The accumulation of natural radionuclides in different solid residues was observed even when the activity concentrations in the untreated groundwater were relatively low, and when there was no measurable change in the concentrations between raw and treated groundwater within analytical uncertainties. Based on mass and activity balance considerations this is thought to be due to the large volumes of treated water per year. The exposure of workers to natural radiation from solid residues in the regular use of a groundwater facility was found not to be likely to exceed 0.3 mSv a−1 if the activity concentrations are <10 kBq kg−1 for U-238, Ra-226, Pb-210 and Ra-228. The worker exposure from solid residues is therefore likely to remain below the reference level of 1 mSv a−1, and indoor radon is more of a concern for the radiation protection of workers at GTFs. However, the natural radionuclide content in the different solid residues from groundwater treatment needs to be characterised properly to be able to ensure safety in the final use of the residues with respect to the potential exposure of the public.

Radiological Impact Assessment of Natural Radionuclides and Heavy Metal Contamination in Industrial Tin-Tailing Processing Effluent

This study investigates the radiological hazard and heavy metal contamination of water effluents from Malaysian tin-tailing processing plants. Samples were collected from retention ponds in seven separate tin tailing processing plants scattered throughout the state of Perak, Malaysia. Samples were analysed for radioactivity and heavy metal concentration using Gamma-ray Spectrometry System and Inductively Coupled Plasma-Mass Spectrometry, respectively. The analysis indicates that the concentration of Radium-226 (226Ra), Radium-228 (228Ra), and Potassium-40 (40K) in samples ranged from 2.4 - 34.9 Bq/l, 0.8 - 14.7 Bq/l, and 19.5 - 299.4 Bq/l, respectively. These levels surpassed the control limits (5 Bq/l and 10 Bq/l for 226Ra and 228Ra) set by the regulatory authority. The analysis of the heavy metal contamination showed that the concentration of Arsenic (As) and Lead (Pb) werehigher than the Maximum Concentration Level (MCL) of 0.01 and 0.015 mg/L, respectively. Further evaluation of radiological impact showed that the average Annual Effective Doses (AED) by water ingestion and AED for external exposure are 1.43±0.67 mSv/y and 1.71±0.79 mSv/y, respectively. While for non-carcinogenic and carcinogenic risk assessments, the value of hazard index and lifetime cancer risk is 2.1×10-10 and 1.2×10-7, respectively. These research findings suggest that effective treatment of the effluent should be implemented before discharge into the drainage system to prevent the accumulation of radionuclides and heavy metals in the environment, which may pose a risk to public health.

New liposome-radionuclide-chelate combination for tumor targeting and rapid healthy tissue clearance

Radionuclide imaging and therapy are promising methods for controlling systemic cancers; however, their clinical application has been limited by excessive radionuclide accumulation in healthy tissues. To minimize radionuclide accumulation in non-cancerous tissues while ensuring sufficient build up in tumors, we aimed to develop a method that controlled the in vivo dynamics of radionuclides post-administration. To this end, we describe a novel strategy that combines liposomes, a potent carrier system for drug delivery, with unique radionuclide-ligand complexes based on 111In-ethylenedicysteine.Conventional 111In-ligand-complexes-carrying liposomes delivered substantial amounts of radionuclides to tumors; however, they also accumulated in the liver and spleen. In contrast, 111In-ethylenedicysteine-carrying liposomes greatly reduced non-specific accumulation, while being retained selectively at high doses within tumors. Liposomes were rapidly broken down in the liver, releasing encapsulated 111In-ligand complexes. Among the chelates used, only 111In-ethylenedicysteine could escape from the liver and be excreted in the urine. Instead, most liposomes remained intact in tumors, retaining the radionuclide-ligand complexes within them. Therefore, high tumor accumulation was obtained regardless of the type of 111In-ligand complexes in the liposomes. In vivo single photon emission computed tomography/computed tomography imaging with 111In-ethylenedicysteine-carrying liposomes accurately revealed tumor-selective radionuclide retention with little background. Hence, our new strategy could greatly enhance tumor-to-healthy tissue ratios, improve diagnostic imaging, boost therapeutic efficacy, reduce toxicity to healthy tissues, and facilitate radionuclide imaging and therapy.

Self-Aggregated Nanoscale Metal-Organic Framework for Targeted Pulmonary Decorporation of Uranium.

The limited availability of effective agents for removing actinides from the lungs significantly restricts the effectiveness of medical treatments for nuclear emergencies. Inhalation is the primary route of internal contamination in 44.3% of actinide-related accidents, leading to the accumulation of radionuclides in the lungs and resulting in infections and potential tumor formation (tumorigenesis). This study focuses on the synthesis of a nanometal-organic framework (nMOF) material called ZIF-71-COOH, which is achieved by post-synthetic carboxyl functionalization of ZIF-71. The material demonstrates high and selective adsorption of uranyl, while also exhibiting increased particle size (≈2100nm) when it aggregates in the blood, enabling passive targeting of the lungs through mechanical filtration. This unique property facilitates the rapid enrichment and selective recognition of uranyl, making nano ZIF-71-COOH highly effective in removing uranylfrom the lungs. The findings of this study highlight the potential of self-aggregated nMOFs as a promising drug delivery system for targeted uranium decorporation in the lungs.

Modeling Radionuclide Transfer from Pasture to Milk in Kisoro, South-western Uganda

Determination of radionuclide transfer from animal feeds to animal products and ingestion transfer rates is important in assessing internal radiation risk to humans who consume the animal products. Seventy-nine (79) pasture samples and milk samples were collected from cattle farms in seven sub-counties. Activity concentrations of radionuclides in the samples were determined using gamma spectroscopy. Transfer ratios of radionuclides to from pasture to milk were calculated. Ingestion transfer rates of radionuclide from pasture to cow were also determined. Radionuclide accumulation to the body of the cow was modeled. Contributions to radiological effects due to accumulation of radionuclides in the body were estimated. Transfer ratios of uranium and thorium from pasture to milk varied from 0.07 to 0.17, and 0.05 to 0.17, respectively. The ingestion transfer rates of uranium varied from 3.110-6 to 7.6 10-6 y l-1 while for thorium, the ingestion transfer rates varied from 2.2 10-6 to 7.5 10-6 y l-1. The contribution to radium equivalent (Bq l-1), annual effective dose equivalent (mSv y l-1), and excess lifetime cancer Risk due to the radionuclide transfer were 0.074, 0.002, and 0.0061 10-3, respectively. Comparing with the safe values of annual effective dose equivalent in foodstuffs of 0.14 mSv y l-1 which translates to excess cancer risk of 0.42 10-3, these contributions to radiological effects only account for about 1.5% of the total safe value of excess lifetime cancer risk, therefore, radionuclide transfer from pasture to milk causes a minimal radiation hazard to the milk consumers in Kisoro District.

Global variability and controls on the accumulation of fallout radionuclides in cryoconite

The accumulation of fallout radionuclides (FRNs) from nuclear weapons testing and nuclear accidents has been evaluated for over half a century in natural environments; however, until recently their distribution and abundance within glaciers have been poorly understood. Following a series of individual studies of FRNs, specifically 137Cs, 241Am and 210Pb, deposited on the surface of glaciers, we now understand that cryoconite, a material commonly found in the supraglacial environment, is a highly efficient accumulator of FRNs, both artificial and natural. However, the variability of FRN activity concentrations in cryoconite across the global cryosphere has never been assessed. This study thus aims to both synthesize current knowledge on FRNs in cryoconite and assess the controls on variability of activity concentrations. We present a global database of new and previously published data based on gamma spectrometry of cryoconite and proglacial sediments, and assess the extent to which a suite of environmental and physical factors can explain spatial variability in FRN activity concentrations in cryoconite. We show that FRNs are not only found in cryoconite on glaciers within close proximity to specific sources of radioactivity, but across the global cryosphere, and at activity concentrations up to three orders of magnitude higher than those found in soils and sediments in the surrounding environment. We also show that the organic content of cryoconite exerts a strong control on accumulation of FRNs, and that activity concentrations in cryoconite are some of the highest ever described in environmental matrices outside of nuclear exclusion zones, occasionally in excess of 10,000 Bq kg−1. These findings highlight a need for significant improvements in the understanding of the fate of legacy contaminants within glaciated catchments. Future interdisciplinary research is required on the mechanisms governing their accumulation, storage, and mobility, and their potential to create time-dependent impacts on downstream water quality and ecosystem sustainability.

Radiological Hazard Assessment of High-Level Natural Radionuclides in Surface Sediments Along Red River, Vietnam.

The Red River is one of the largest rivers that plays an important role in the economic development of North Vietnam. There are many radionuclides bearing rare earth, uranium ore mines, mining industrial zones and magma intrusive formations along this river. The contamination and accumulation of radionuclides could exist at high concentration in surface sediments of this river. Thus, the present investigation aims to study the activity concentrations of 226Ra, 232Th (228Ra), 40K, and 137Cs in Red River surface sediments. Thirty sediment samples were collected, and their activity concentration was calculated using high-purity germanium gamma-ray detector. The observed results ranged from 51.0 ± 2.1 to 73.6 ± 3.7 for 226Ra, 71.4 ± 3.6 to 103 ± 5.2 for 232Th, 507 ± 24.0 to 846 ± 42.3 for 40K, and ND (not detected) to 1.33 ± 0.06Bq/kg for 137Cs, respectively. In general, the natural radionuclides concentration of 226Ra, 232Th (228Ra), and 40K is higher than the average world average values. This indicated that the natural radionuclides could contribute from similar and principal sources surrounding the upstream of Lao Cai where distributed uranium ore mines, radionuclide bearing rare earth mines, mining industrial zones and intrusive formations. Regarding the radiological hazard assessment, results of the indices computed such as absorbed gamma dose rate (D), the excess lifetime cancer risk (ELCR), and the annual effective dose equivalent (AEDE) were nearly two times higher than world average values.

Accumulation and distribution of nutrients, radionuclides and metals by roots, stems and leaves of plants

In the process of growth and development, plants not only absorb essential nutritional elements, but also absorb radioactive and non-essential elements from the environment, and their distribution varies in different parts of the plant. In this study, neutron activation analysis and gamma spectrometry were performed on stems, roots, and leaves of vegetables. The results indicate that the accumulation of radionuclides and multi-elements depends on the plant type and plant parts. Activity concentrations of 226Ra and 232Th in plants were accumulated in the following order: Roots > Stems > Leaves. The highest concentrations of 40K and 210Pb were observed in the stems and leaves of plants, respectively. Essential nutrient requirements of plants are in the following order: K > Ca > Mg > Fe > Zn > Mn. Among the non-essential metals, the concentration of Na in the vegetable sample was much greater than those of the other elements. The K/Na ratio in the plant depends on the type of plant and the translocation within the plant.

Hygienic assessment of 90Sr and 137Cs contamination of water and fish in the lakes of the head part of the peripheral zone of the East Ural radioactive trace

Introduction. The article presents the results of studies of the specific activity of 90Sr and 137Cs in the water and fish of the Irtyash and Kazhakul lakes located in the peripheral zone of the head of the East Ural Radioactive trace in 2014-2017.&#x0D; Materials and methods. Determination of the levels of specific 90Sr and 137Cs in the water and the body of the resource-forming species of Siberian roach (soroga, chebak) Rutilus rutilus lacustris (Linnaeus, 1758) from the studied lakes was carried out over the period of 2012–2017. The measurements were carried out using standardized methods adopted in in the Federal State Budgetary Institution of Health “Central Medical and Sanitary Unit No. 71 of the Federal Medical and Biological Agency of Russia” (FGBUZ TsMSCH No. 71 of the Federal Medical and Biological Agency of Russia) and the Southern Ural.&#x0D; Results. The research was carried out over 2014 to 2017. Since the accident at the Mayak enterprise in the fall of 1957, the specific radioactivity of the water in the studied lakes was found to decrease. The concentration of 90Sr in the water of Irtyash lake was 0.019±0.008, and 137Cs – 0.028±0.009, and in Lake Kazhakul – 0.19±0.06 and 0.14±0.06, respectively. These values are much lower than the level of intervention according to NRB-99/2009. &#x0D; The water of the lakes is used to meet household needs. The water of Lake Irtyash is used for drinking water supply of the city of Ozersk. The specific activity of the raw mass of a roach carcass from the Irtyash and Kazhakul lakes for the accumulation of 90Sr is 2.7± 1.7 and 64.5±19 and 137Cs – 1.68± 0.8 and 38±33.5Bq/kg, respectively. All the samples studied separately according to 90Sr and 137Cs had levels of radioactive contamination at or below the regulatory compliance indicator (SanPiN 2.3.2.1078–01). At the same time, taking into account the absolute extended uncertainty (with a coverage factor of k = 2) roach from Kazhakul lake has a significant excess of the limit level of radioactive contamination.&#x0D; Limitations. Hydrochemical parameters of the aquatic environment in various reservoirs can vary significantly over time and affect the accumulation of radionuclides by hydrobionts. Therefore, the research results are relevant only for the research period. To obtain more reliable results, long-term comprehensive monitoring is necessary.&#x0D; Conclusion. Over the past 60 years after the accident at the Mayak enterprise in 1957, the levels of radioactive contamination of water and fish in the studied lakes Irtyash and Kozhakul have decreased by more than 10 times. Calculation of doses of ionizing radiation for certain groups of the population of areas contaminated as a result of accidents, living near lakes, is a complex task, for which additional research is needed.

Soil radioactivity in the highest volcanic region of Northern Andes

This work studied the spatial pattern of four natural radionuclides (226Ra, 228Ra, 228Th and 40K) as well as one artificial one (137Cs) in soils in the Chimborazo province (Ecuador), which belongs to the North Andes of South America. Soil samples were collected considering the Ecuador geological map. Statistical analyses showed that activity concentrations of 226Ra, 228Ra, 228Th do not exceed the worldwide average, while one geological unit exceeds the worldwide average for 40K. These high activity concentrations are attributed to radionuclide accumulation in plutonic and metamorphic rocks and also in ash resulting from eruptions of the Sangay volcano. The inverse distance weighted interpolation method was used to develop corresponding radioactivity maps where the highest activity concentrations are in the central-east of the studied area. In addition, a distribution pattern of 226Ra and 40K is observed in the geologies influenced by the presence of Chimborazo, Igualata, Tungurahua and Altar volcanoes. Spearman's nonparametric test shows positive correlations suggesting the presence of very homogeneous lithologies and that volcanic activities can influence the distribution of radionuclides in our environment. In seven of the samples, 137Cs was detected.

Evaluation of current natural and anthropogenic radionuclide activity in coastal area bottom sediments of the Barents Sea (North of the Kola Peninsula)

This article is devoted to the study of the activity of technogenic 137Cs and 90Sr, as well as natural radionuclides 40K, 232Th and 226Ra in bottom sediments of the Kola coast of the Barents Sea, where a significant number of radiation objects are concentrated. In order to characterize and assess the accumulation of radioactivity in the bottom sediments, we studied the particle size distribution and some physicochemical parameters, such as the content of organic matter, carbonates and ash components. The average activities of natural radionuclides 226Ra, 232Th and 40K were 325.0, 25.1 and 466.7 Bq·kg−1, respectively. Levels of natural radionuclides in the coastal zone of the Kola Peninsula are within the range of marine sediments worldwide. Still, they are slightly higher than those observed in the central areas of the Barents Sea, most likely due to the formation of coastal bottom sediments as a result of the destruction of the natural radionuclide-enriched crystalline basement rocks that make up the Kola coast. The average activities of technogenic 90Sr and 137Cs in the bottom sediments of the Kola coast of the Barents Sea are 3.5 and 5.5 Bq·kg−1, respectively. The highest activities of 90Sr and 137Cs were found in the bays of the Kola coast, while they remain below detection limits in the open parts of the Barents Sea. Despite the presence of potential sources of radiation pollution in the coastal zone of the Barents Sea, we did not find any short-lived radionuclides in the bottom sediments, which indicates the absence of a significant influence of local sources on the transformation of the technogenic radiation background. The study of particle size distribution and physicochemical parameters showed that the accumulation of natural radionuclides is largely related to the content of organic matter and carbonates, while the accumulation of technogenic isotopes occurs in the composition of organic matter and the smallest fractions of bottom sediments.