Investigation and assessment of natural radioactivity in commercial animal feeds in Texas

Commercial animal feed in Texas was characterized by determining natural gamma emitters including 40K,137Cs, and Uranium (235U and 238U) and Thorium (232Th) series to obtain basic radioactivity values. The measured activity concentration of natural radionuclides in animal feed was low enough for safe consumption by animal and largely depended on the type of animal feed.40K was the predominant radionuclide showing the highest activity concentration in animal feed. The radioactivity concentration of 214 Bi and 214Pb in 238U decay series was 1.39 and 1.33 Bq/kg in corn, respectively, lower than in other animal feed types. On the other hand, the vitamin/mineral mix samples showed higher concentrations of 214 Bi (9.04 Bq/kg) and 214Pb (10.19 Bq/kg). Beef cattle feed, poultry feed, and vitamin/mineral mix exhibited higher activity concentration of 228Ac and 212Pb in 232Th decay series. Gamma radionuclides appeared to be highly and significantly correlated within each decay series. 235U was present at low levels in all feed samples while the anthropogenic radionuclide of 137Cs was not detected irrespective of the type of animal feed. This study highlights an importance of establishing a current baseline of radioactivity concentration in animal feed in Texas in which the largest animal feed consumption in the US exists.

PREVENTION OF REPRODUCTIVE LOSSES ASSOCIATED WITH INTRAPLANTAR ACCUMULATION OF RADIONUCLIDES

The materials of the article are based on the results of our past studies of morphological and immunohistochemical features of placental damage due to 137Cs incorporation.

OBJECTIVE

to determine the effectiveness of radioprotective therapy in preventing reproductive losses and perinatal consequences associated with the incorporation of radionuclides in the placenta.

MATERIALS AND METHODS

According to the research design, the first group consisted of 153 women with reproductive losses in anamnesis and signs of termination of the current pregnancy. The control consisted of 30 women with a physiological pregnancy and an uncomplicated history. Based on the fact that one of the causes of premature termination of pregnancy is the vulnerable effect of 137Cs incorporated in the placenta, «Apple Pectin Antioxidant» (the «APA») with a high sorption potential was included in preventive measures regarding reproductive losses and perinatal consequences. The effectiveness of therapy with the inclusion of «Apple Pectin Antioxidant» was evaluated based on indicators of the fetoplacental complex and pregnancy scenarios. The results were compared with the effectiveness of standard treatment for habitual miscarriage of pregnancy.

RESULTS

It was established that the destructive effect of incorporated 137Cs leads to placental dysfunction and fetal distress. Therapy with the inclusion of «APA» more significantly than standard treatment increases the progesterone-synthesizing function of the placenta, microcirculation, adaptation potential, and antioxidant protection of cells with the efficiency of 7.5 %, 10.7 %, 17.7 %, and 43.4 %, respectively. «APA» has a positive effect on the scenarios of pregnancy. «APA» in the composition of therapy to preserve pregnancy contributed to a decrease in the frequency of premature births by 11.4 % and an extension of their term to 34 weeks of gestation. Extending the gestational age of preterm birth reduced the frequency of severe asphyxia by 18.7 %, hypoxic-ischemic central nervous system injury by 13.5 %, respiratory distress by 17.3 %, and intraventricular hemorrhage 2nd and 3rd degrees by 12.7 %.All children were born alive due to the preservation of the compensatory ability of the placenta.

CONCLUSIONS

Termination of pregnancy is a universal reaction of the mother and the fetus to negative exogenous and endogenous influences. Placental dysfunction is the most frequent cause of reproductive losses. Incorporated 137Cs is one of the factors that disturb the architecture of the placenta. Extreme effects depend on the number of incorporated 137Cs and the compensatory capacity of the placenta. Today, the possibility of internal exposure to 137Cs is associated due to consumption of agricultural products. Unfortunately, the level of food contamination with radionuclides remains higher than permissible. Living in an area with a standard radiation background does not guarantee a person the radiation safety of agricultural products. The confirmation is the accumulation of 137Cs in the placentas of women from different regions of Ukraine. The high efficiency of therapy with «APA» is associated with the removal of radionuclides and the minimization of the effect of internal irradiation, which made it possible to reduce the frequency of termination of pregnancy by 28.0 % due to the reduction of cases of premature births (-11.4 %), spontaneous abortions (-11.0 %), termination of pregnancy (-5.5 %). The «APA» is advisable to prescribe from pregravid and during pregnancy to all women, regardless of the region of residence.

Levels of caesium-137 in food of animal origin in Poland

Introduction

Radioactive contamination of the environment is one of the greatest threats after a nuclear accident due to released radionuclides. From a radiotoxicological point of view, the most important radionuclide is caesium-137. Formed mainly during nuclear explosions, caesium-137 can persist in the soil for many years, from where it constantly enters the food chain. One of the elements of ensuring food safety is the monitoring of its radioactive contamination, mainly with radioactive caesium isotopes. The aim of the study was to determine the content of caesium-137 in food of animal origin.

Material and Methods

A total of 1,416 muscle samples from cattle, sheep, pigs, game and fish, as well as chicken eggs and dairy products were examined using gamma-ray spectrometry.

Results

Caesium-137 activities ranged from below the minimum detectable activity concentration (MDC) to over 4,000 Bq/kg wet weight (w.w.). Most often, the values did not exceed the MDC or were in a range below 100 Bq/kg. The exception was the muscle tissue of game animals, especially wild boar, where a significant activity of caesium-137 was recorded, the highest of which was 4,136.8 ± 238 Bq/kg w.w. Committed effective doses determined for each matrix ranged from 0.01 to 0.83 µSv/kg, with the highest value determined for wild boar.

Conclusion

The calculated exposure doses with values well below the accepted low radiation dose (100 mSv) did not indicate any significant amounts of ionising radiation from the food consumed.

The spatiotemporal variation, background, and baseline activities of radionuclides in the soil of Aragats Massif (Armenia)

The present study was performed to reveal the distribution patterns and spatiotemporal changes of radionuclides in the soil of the highest mountain of Armenia: Aragats Massif. In this regard, two surveys were implemented in 2016-2018 and 2021 with an altitudinal sampling strategy. The activities of radionuclides were determined by gamma spectrometry system with HPGe detector (CANBERRA). Correlation and linear regression analysis were applied to determine the dependence of radionuclides' distribution from altitude. Classical and robust statistical methods were used to assess the local background and baseline values. In two sampling profiles, the spatiotemporal variation of radionuclides was studied. A significant correlation was revealed between ¹³⁷Cs and altitude pointing to global atmospheric migration as a primary source of ¹³⁷Cs in Armenian environment. The predicted values of regression model revealed a 0.08-Bq/kg and 0.03-Bq/kg increase of ¹³⁷Cs in each m on average, for the old and new survey, respectively. The assessment of background activities of NOR (naturally occurring radionuclides) enables setting the local background for ²²⁶Ra, ²³²Th, and ⁴⁰ K in soils of Aragats Massif: 831.3 ± 20.2 Bq/kg and 540.6 ± 18.3 Bq/kg for ⁴⁰ K, 85.5 ± 3.1 Bq/kg and 27.7 ± 2.6 Bq/kg for ²²⁶Ra, and 66.8 ± 3.2 and 46.4 ± 3.0 Bq/kg for ²³²Th, respectively, for the years of 2016-2018 and 2021. ¹³⁷Cs baseline activity was estimated by altitude: 350 ± 3.7 Bq/kg and 108 ± 2.5 Bq/kg, respectively, for the years of 2016-2018 and 2021.

Natural and artificial radioactive pollution in sediment and soil samples of the Bosphorus, Istanbul

This study focused on the determination of natural (²³⁸U, ²³²Th, and ⁴⁰K) and artificial (¹³⁷Cs) radionuclide concentrations both in 55 sediment samples collected from various depths in the Bosphorus and 5 soil samples from the coastline of the Bosphorus, Istanbul, using gamma-ray spectrometry with an HPGe detector. The mean activity concentrations of natural ²³⁸U, ²³²Th, and ⁴⁰K and anthropogenic ¹³⁷Cs were determined to be 11.41 ± 0.21 Bq kg^-1, 6.87 ± 0.16 Bq kg^-1, 369.61 ± 3.41 Bq kg^-1, and 6.54 ± 0.11 Bq kg^-1, respectively, in the sediment samples. The average activity concentrations of ²³⁸U, ²³²Th, ⁴⁰K, and ¹³⁷Cs radionuclides in the soil samples were also measured to be 11.65 ± 0.18 Bq kg^-1, 9.55 ± 0.15 Bq kg^-1, 369.43 ± 3.09 Bq kg^-1, and 4.57 ± 0.09 Bq kg^-1, respectively. Radiological contour maps based on the activity concentrations of natural and artificial radionuclides in the sediment samples for the Bosphorus, Istanbul, were created. The total annual effective doses due to soil samples were calculated to be 34.58 μSv y^-1.

Prospects for fungal bioremediation of unburied waste packages from the Goiânia radiological accident

Goiânia, the Goiás State capital, starred in 1987, where one of the largest radiological accidents in the world happened. A teletherapy machine was subtracted from a derelict radiotherapy clinic and disassembled by scavengers who distributed fragments of the 50 TBq ¹³⁷CsCl source among relatives and acquaintances, enchanted by the blue shine of the substance. During the 15 days before the accident was acknowledged, contaminated recycling materials were delivered to recycling factories in four cities in the state of São Paulo, Brazil, in the form of recycling paper bales. The contaminated bales were spotted, collected, and stored in fifty 1.6 m³ steel boxes at the interim storage facility of the Nuclear and Energy Research Institute (IPEN). In 2017, a check of the content was performed in a few boxes and the presence of high moisture content was observed even though the bales were dry when conditioned and the packages were kept sealed since then. The main objective of this work was to report the fungi found in the radioactive waste after they evolved for 30 years in isolation inside the waste boxes and their role in the decay of the waste. Examination of the microbiome showed the presence of nematodes and fungal communities. The fungi species isolated were Aspergillus quadricinctus, Fusarium oxysporum, Lecanicillium coprophilumi, Scedosporium boydii, Scytalidium lignicola, Xenoacremonium recifei, and Pleurostoma richardsiae. These microorganisms showed a significant capacity to digest cellulose in our trials, which could be one of the ways they survive in such a harsh environment, reducing the volume of radioactive paper waste. These metabolic abilities give us a future perspective of using these fungi in biotechnology to remediate radioactively contaminated materials, particularly cellulose-based waste.

Levels, sources, variations, and human health risk assessment of 90Sr and 137Cs in water and food around Sanmen Nuclear Power Plant (China) from 2011 to 2020

Objectives

Radioactivity monitoring around nuclear facilities is crucial to provide important baseline data for effective detection of radioactive leakage to the environment. We aim to establish a baseline study for monitoring radioactive levels of ⁹⁰Sr and ¹³⁷Cs around Sammen Nuclear Power Plant (SNPP) and to assess their associated health impact on surrounding residents.

Methods

In this study, we collected water and food samples around the SNPP from 2011 to 2020 and determined for ⁹⁰Sr and ¹³⁷Cs activity concentrations. We statistically analyzed the temporal trends of ⁹⁰Sr and ¹³⁷Cs and evaluated their radiation exposure to the local residents.

Results

During this period, the activity concentrations of ⁹⁰Sr and ¹³⁷Cs varied within 1.2-9.9 mBq/L and 0.10-7.6 mBq/L in water, and 0.037-1.3 Bq/kg and 0.011-0.45 Bq/kg in food, respectively, with no significant seasonal variation trend.

Conclusions

All reported activity concentrations of ⁹⁰Sr and ¹³⁷Cs were significantly lower than the recommended value of WHO and Chinese national standards. There is no indication of notable radioactive release into the study area due to the operation of SNPP during 2018-2020. The annual effective doses (AEDs) from the ingestion of ⁹⁰Sr and ¹³⁷Cs in water and food were well below the international permissible limits, indicating the radiation exposure around SNPP during 2011-2020 was kept at a safe level.

MORPHOLOGICAL AND IMMUNOHISTOCHEMICAL FEATURES OF PLACENTAL DAMAGE DUE TO THE INCORPORATION OF 137Cs

OBJECTIVE

to investigate the morphological and immunohistochemical features of placental damage due to theincorporation of 137Cs depending on the scenario of pregnancy completion.

MATERIALS AND METHODS

The study material consisted of placentas from 60 women with reproductive losses inanamnesis and signs of termination of the current pregnancy (first group) and placental samples from 30 women with an uncomplicated gestation and an unencumbered anamnesis (control group). The detailed study required the distribution of placental samples from the first group into subgroups. Subgroup 1a included 38 placentas from women who gave birth at 37-40 weeks, despite signs of termination of the current pregnancy. Subgroup 1b - placentas of 13 women who gave birth at a gestation period of 28-36 weeks + 6 days. Subgroup 1c - 9 placental samples from women who gave birth at a gestation period of 22-27 weeks + 6 days. The volumetric activity of the 137Cs in the placentas was measured using β-spectrometer. The histology of the placenta was studied using a standard technique. The following expressions were studied in placenta: CD31 / PECAM-1, CD45 / T200 / LCA, CD56 / NCAM-1, CEA / CD66e Ab-2, Vimentin, using indirect streptavidin peroxidase detection method.

RESULTS

Placentas accumulate 137Cs. The different volumetric activity of the isotope correlates with scenarios of pregnancy. Due to the action of incorporated 137Cs with a specific mass of more than 1.1 Bq/kg, placental dysfunction develops. The consequences of placental dysfunction depend on the volumetric activity of the 137Cs and the preservation of adaptive and compensatory reactions in the placenta. Morphological and immunohistochemical features of placental damage to incorporated 137Cs were established, depending on the scenario of completion of pregnancy. A marker of unfavorable completion of pregnancy is the expression of a carcinoembryonic antigen (CEA) in the placenta.

CONCLUSIONS

Premature termination of pregnancy (PTP) is a multifactorial pathology associated with pathological changes in immune and neuroendocrine regulation and hereditary, infectious, and environmental factors that disrupt the adaptation mechanisms in the mother-placenta-fetus system. Intraplacental irradiation of 137Cs is one of the factors in the multifactorial nature of reproductive losses. As a result of intraplacental irradiation of 137Cs, the architecture of the placenta is disturbed, the activity of pro-inflammatory cytokines CD45 and CD56 increases, and the coagulation cascade is activated. Extreme effects depend on the volumetric activity of the isotope incorporated in the placenta and the organ's compensatory capacity. Accumulation of up to 1.0 Bq/kg 137Cs does not affect the course of gestation. Internal irradiation with an activity of 4.5-10.4 Bq/kg 137Cs triggers late preterm labor. The nature of the damages corresponds to the category of «lesion of the maternal stroma» of the placenta. The volumetric activity of 137Cs over 10.4 Bq/kg is a probable cause of early preterm labor and antenatal fetal death. At the same time, the maternal and fetal structures of the placenta suffer damage. Expression of vimentin is a marker of placental destruction due to internal irradiation of 137Cs with a specific gravity of more than 4.5 Bq/kg. Expression of CEA in the structures of the placenta of women with PTP is a unique find and marker of premature birth and antenatal fetal death with intraplacental irradiation of 137Cs with an activity of more than 4.5 Bq/kg.

Sedimentary conditions based on the vertical distribution of radionuclides in small dystrophic lakes: a case study of Toporowe Stawy Lakes (Tatra Mountains, Poland)

The aim of this work was to prove the use of radionuclides deposited in sediment core taken from an overgrowing dystrophic lakes surrounded by marsh-peat vegetation to estimate sedimentary conditions. Sediment core samples were taken from the Toporowe Stawy Lakes (Niżni (TSN) and Wyżni (TSW); Tatra Mountains). The sampling was done using a Limnos corer. After the physical sample preparations, gamma measurements were performed. Radiochemical analysis was applied with the aim of determining ²¹⁰Pb radioactivity by means of ²¹⁰Po. The mean values for TSN lake are as follows: ¹³⁷Cs ~ 123 Bq∙kg^-1, ⁴⁰ K ~ 389 Bq∙kg^-1, ²²⁸Th ~ 55 Bq∙kg^-1, ²²⁶Ra ~ 86 Bq∙kg^-1, ²⁴¹Am ~ 5 Bq∙kg^-1, and ²¹⁰Pb_uns ~ 180 Bq∙kg^-1. For TSW lake, the radioactivity levels of ²²⁶Ra and ²⁴¹Am are comparable to the TSN. The mean values of ¹³⁷Cs, ⁴⁰ K, and ²²⁸Th are almost twice as high as in TSN. The level of ²¹⁰Pb in uppermost layer of TSN is higher than in TSW. Sediments were dated by use of ²¹⁰Pb method, and the rate of sedimentation of each layer was also estimated. Basic chemometric tools were used to confirm the way of deposition of radionuclide, find the correlations between variables, and compare analyzed lakes. It was concluded that the presented type of lakes are a valuable source of information and the vertical distribution of radionuclide can be used to interpret the source of material supply and factors that influence the sedimentation process in recent 150-200 years.

Comment on "Development of a gamma ray dose rate calculation and mapping tool for Lagrangian marine nuclear emergency response models" by Little et al

Care must be taken when calculating the sum of released amounts to the environment for different radionuclides of whose physical and chemical characteristics are quite different and the radiological impact of the radionuclides are also quite different. In this comment, the mishandling of summation in "Development of a gamma ray dose rate calculation and mapping tool for Lagrangian marine nuclear emergency response models by Little et al." is pointed out and the correct way is suggested.

Determination, Separation and Application of 137Cs: A Review

In the context of the rapid development of the world's nuclear power industry, it is necessary to establish background data on radionuclides of different samples from different regions, and the premise of obtaining such basic data is to have a series of good sample processing and detection methods. The radiochemical analysis methods of low-level radionuclides ¹³⁷Cs (Cesium) in environmental and biological samples are introduced and reviewed in detail. The latest research progress is reviewed from the five aspects of sample pretreatment, determination, separation, calculation, application of radioactive cesium and the future is proposed.

Doses from external irradiation and ingestion of 134Cs, 137Cs and 90Sr of the population of Belarus accumulated over 35 years after the Chernobyl accident

This study considers the exposure of the population of the most contaminated Gomel and Mogilev Oblasts in Belarus to prolonged sources of irradiation resulting from the Chernobyl accident. Dose reconstruction methods were developed and applied in this study to estimate the red bone-marrow doses (RBMs) from (i) external irradiation from gamma-emitting radionuclides deposited on the ground and (ii) ¹³⁴Cs, ¹³⁷Cs and ⁹⁰Sr ingestion with locally produced foodstuffs. The mean population-weighted RBM doses accumulated during 35 years after the Chernobyl accident were 12 and 5.7 mGy for adult residents in Gomel and Mogilev Oblasts, respectively, while doses for youngest age groups were 20-40% lower. The highest mean area-specific RBM doses for adults accumulated in 1986-2021 were 63, 56 and 46 mGy in Narovlya, Vetka and Korma raions in Gomel Oblast, respectively. For most areas, external irradiation was the predominant pathway of exposure (60-70% from the total dose), except for areas with an extremely high aggregated ¹³⁷Cs soil to cow's milk transfer coefficient (≥ 5.0 Bq L^-1 per kBq m^-2), where the contribution of ¹³⁴Cs and ¹³⁷Cs ingestion to the total RBM dose was more than 70%. The contribution of ⁹⁰Sr intake to the total RBM dose did not exceed 4% for adults and 10% for newborns in most raion in Gomel and Mogilev Oblasts. The validity of the doses estimated in this study was assessed by comparison with doses obtained from measurements by thermoluminescence dosimeters and whole-body counters done in 1987-2015. The methodology developed in this study can be used to calculate doses to target organs other than RBM such as thyroid and breast doses. The age-dependent and population-weighted doses estimated in this study are useful for ecological epidemiological studies, for projection of radiation risk, and for justification of analytical epidemiological studies in populations exposed to Chernobyl fallout.

Phytoremediation of 137Cs: factors and consequences in the environment

Radionuclide contamination is a concerning threat due to unexpected nuclear disasters and authorized discharge of radioactive elements, both in the past and in present times. Use of atomic power for energy generation is associated with unresolved issues concerning storage of residues and contaminants. For example, the nuclear accidents in Chernobyl 1986 and Fukushima 2011 resulted in considerable deposition of cesium (Cs) in soil, along with other radionuclides. Among Cs radioactive variants, the anthropogenic radioisotope ¹³⁷Cs (t_½ = 30.16 years) is of serious environmental concern, owing to its rapid incorporation into biological systems and emission of β and γ radiation during the decaying process. To remediate contaminated areas, mostly conventional techniques are applied that are not eco-friendly. Hence, an alternative green technology, i.e., phytoremediation, should in future be considered and implemented. This sustainable technology generates limited secondary waste and its objectives are to utilize hyper-accumulating plants to extract, stabilize, degrade, and filter the radionuclides. The review highlights plant mechanisms for up-taking radionuclides and influences of different environmental factors involved in the process, while considering its long-term effects.

Updated soil to fruit concentration ratios for radiocaesium compiled under the IAEA MODARIA II Programme

Under the International Atomic Energy Agency (IAEA) Modelling and Data for Radiological Impact Assessments (MODARIA II) Programme, Working Group 4 activities included collating radionuclide transfer data from Japan following the Fukushima Daiichi Nuclear Power Plant accident and separately collating concentration ratio (CR) data for root uptake of radionuclides by crops grown in tropical and arid climates. In this paper, the newly compiled radiocaesium CR data for fruit from Japan, tropical and arid climates have been combined with the data originally compiled for the IAEA Technical Reports Series No. 472 (TRS 472) and additional data identified from the literature to produce an enhanced MODARIA II dataset of fruit radiocaesium CR values. Statistical analysis of the MODARIA II dataset by climate class (based on the Köppen-Geiger climate classification) indicated that the CR values for tropical climates were significantly higher (p< 0.05) than those for arid, temperate and cold climates. Statistical analysis of the MODARIA II dataset by soil group (based on soil texture) indicated that the CR values for coral sand soil (tropical climates only) and organic soil (temperate climates only) were significantly higher (p< 0.05) than those for the clay, loam and sand soil groups. Statistical analysis of the MODARIA II dataset by plant group (based on plant morphology) indicated that the CR values for non-woody trees (tropical climate bias) were significantly higher (p< 0.05) than those for herbaceous plants, shrubs and woody trees. Comparison of the MODARIA II dataset with original TRS 472 values showed only small changes in the fruit radiocaesium CR values for herbaceous plants and shrubs in temperate climates. There was a decrease in the CR values for woody trees in temperate climate across all soil groups. There was also a decrease in the CR values for tropical climates for all comparable soil groups.

On the ordered nature of redistribution of technogenic elements in undisturbed elementary landscape-geochemical systems of the temperate zone on the example of the Chernobyl 137Cs fallout

The study is aimed at identifying patterns in distribution of pollutants in the elementary landscape-geochemical systems (ELGS) of the temperate zone. The study used ¹³⁷Cs as a tracer, which allows a highly detailed analysis of the nature of the heterogeneity of secondary migration in the toposequence: summit-slope-closing depression, treated as the elementary landscape-geochemical system. The study site was located in the Bryansk region in the Chernobyl abandoned area with an initial level of ¹³⁷Cs contamination exceeding 1480 kBq/m² (40 Ci/km²). An original technique of repeated ¹³⁷Cs measurements along cross-sections accompanied by topographic survey and soil cores sampling has been applied. The obtained results showed a complete absence of constant increase of ¹³⁷Cs concentration downslope but revealed a steady regular variability of ¹³⁷Cs activity of a cyclical type. Given uniformity of the initial ¹³⁷Cs fallout within a small-sized plot, variation of ¹³⁷Cs due to its secondary distribution in ELGS was 2-2.7-fold according to field gamma-spectrometry data which corresponded to the radionuclide contamination density of the top 20-cm layer of the soil containing 96-99% of the total radionuclide amount (correlation between the parameters equaled to r0.01 = 0.782, n = 20). A specifically regular structure obviously formed under the set of radionuclide water migration processes seems to be inherent in all systems of the studied type. The results obtained are believed to be of both theoretical and practical importance, since they can contribute to making decisions on the precise monitoring of zones of technogenic accumulation, as well as solving fundamental problems of soil formation and its restoration after technogenic pollution.

Radiological impact of an active quarry in the Papuk Nature Park, Croatia

Papuk Nature Park, unlike most similar parks and preserves in the world, contains active quarries. Quarries dig stone from the ground, creating dust and exposing deeper, potentially more radioactive layers. Since the forest trails in the Park lead right up to the quarries, we believed it was important to determine the radiological impact of the quarries on the Park environment. We measured ambient dose rate equivalent H*(10) and sampled moss at 26 Park locations along two of four quarries, along the road between them, and near Lake Orahovac, a very popular tourist destination close to the quarries. Moss is a standard bioindicator of exposure to heavy metals, including radionuclides. Using-gamma ray spectrometry we determined the activity concentration of ¹³⁷Cs and of representative naturally occurring radionuclides – ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²³²Th, and ⁴⁰K – in sampled moss. H*(10) at selected locations was similar to the background H*(10) measured continuously all over Croatia. The ranges of measured activity concentrations of ¹³⁷Cs and naturally occurring radionuclides in moss did not differ significantly from other parts of Croatia and nearby countries.

Radiocaesium retention in bog meadows: an analysis based on soil properties

The vertical distribution of ¹³⁷Cs in peat bog soils in the remote period after the Chernobyl Nuclear Power Plant accident (ChNPP, 1986) was investigated. The study was conducted on bog meadows in the Bryansk region of Russia. Soil samples were taken at 4 locations: 2 sites on lowland bogs and 2 sites on transitional bogs. Fifteen years after the accident, analysis of soils showed that the peak of ¹³⁷Cs activity was still in the upper 10-cm layer. The highest percentage of the initial ¹³⁷Cs deposition (92%) has been observed in the top 10-cm layer in the drained transitional bog. The lowest part of the initial ¹³⁷Cs deposition (40%) has been found in 0-10-cm horizon in lowland bog with the deep peat layer. The findings revealed that elevated soil moisture promotes ¹³⁷Cs downward migration. It was shown that ammonium has a major impact on mobility of ¹³⁷Cs in bog soils. On average, the soil solution NH₄⁺ concentrations exceeded the K⁺ concentrations by about a factor 5. A significant linear relationship was found between the rates of ¹³⁷Cs removal from the top layers with the soil solution NH₄⁺ concentrations.

In situgamma spectrometry using a portable HPGe detector. Radiological characterisation and environmental surveillance around an operating nuclear power plant. Possibilities and limits

The in situtechnique for measuring radionuclides in the soil using a portable Ge detector is a highly versatile tool for both the radiological characterisation and for the monitoring of operating nuclear power plants. The main disadvantage of this technique is related to the lack of knowledge of the geometry of the source whose activity concentration is to be determined. However, its greatest advantage is the high spatial representability of the samples and the reduced time and resource consumption compared to gamma spectrometry laboratory measurements. In this study, the possibilities and limits offered byin situgamma spectrometry with a high-resolution gamma portable detector in two common uses are shown. First, the radiological background characterisation and its relationship with the geology of an area of 2700 km²are assessed. Second, its potential for monitoring man-made activity concentration in soils located around an operating nuclear power plant in Spain for surveillance purposes is evaluated. Finally, high-accuracy radiation maps were prepared from the measurements that were carried out. These radiation maps are essential tools to know the radioactive background of an area, especially useful to assess artificial radioactive deposits produced after a nuclear accident or incident.

Radioactivity level in relation to geological substrate: dynamics of natural and artificial radionuclides on Teucrium montanum L. (Lamiaceae) habitats

There are no results of comparative ecological studies of the radionuclide activity concentration in the plants and soil in relation to geological substrate. Presented research encompasses the comparative analysis of the concentration of four radionuclides, three natural (⁴⁰K, ²²⁶Ra, ²³²Th) and one artificial (¹³⁷Cs) in soil samples and aerial plant parts of Teucrium montanum from different natural habitats on serpentinite and calcareous geological substrate. The activity concentrations of radionuclides were measured with high purity germanium (HPGe) detector and expressed as Bq kg^-1. The calculated activity concentrations of ⁴⁰K, ²²⁶Ra, ²³²Th, and ¹³⁷Cs in soil samples from serpentinite/calcareous habitats are in range 39.6-91.0/59.3-1018.8, 1.7-5.5/4.3-52.4, 2.4-10.9/5.9-72.9, and 57.2-844.9/29.6-701.5 Bq kg^-1, respectively. The activity concentrations of ⁴⁰K, ²²⁶Ra, ²³²Th, and ¹³⁷Cs in plant samples are in range 152.9-445.9/228.0-521.4, n.d.-1.2/0.6-5.6, n.d./0.2-0.9, and 1.0-46.4/1.7-7.0 Bq kg^-1, respectively. The obtained results showed that the quantities of ¹³⁷Cs are greater in the soil and plant material from the serpentinite habitats, while quantities of ⁴⁰K, ²²⁶Ra, and ²³²Th are greater in the soil and plant material from calcareous habitats. In general, the level of radioactivity in plants and soil depends on the type of the geological substrate. The content of radionuclides in plants is correlated with the radionuclide content in the soil. In addition to other specifics in physical and chemical properties, serpentinite habitats are characterized by an increased amount of Cs in the soil, which causes an increased amount of this radionuclide in plants such as Teucrium montanum.

Validity of the source term for the Fukushima Dai-ichi Nuclear Power Station accident estimated using local-scale atmospheric dispersion simulations to reproduce the large-scale atmospheric dispersion of 137Cs

The source term of ¹³⁷Cs from the Fukushima Dai-ichi Nuclear Power Station (FDNPS) accident was estimated from the results of local-scale atmospheric dispersion simulations and measurements. To confirm the source term's validity for reproducing the large-scale atmospheric dispersion of ¹³⁷Cs, this study conducted hemispheric-scale atmospheric and oceanic dispersion simulations. In the dispersion simulations, the atmospheric-dispersion database system Worldwide version of System for Prediction of Environmental Emergency Dose Information (WSPEEDI)-DB and oceanic dispersion model SEA-GEARN-FDM that were developed by the Japan Atomic Energy Agency were used. Compared with the air concentrations of ¹³⁷Cs measured by the Comprehensive Nuclear-Test-Ban Treaty Organization, overall, the WSPEEDI-DB simulations well reproduced the measurements, whereas the simulation results partly overestimated some measurements. Furthermore, the validity of the deposition of ¹³⁷Cs by WSPEEDI-DB was investigated using SEA-GEARN-FDM and concentrations of ¹³⁷Cs in seawater sampled from the North Pacific. Seawater concentrations of ¹³⁷Cs by the oceanic dispersion simulation, in which the deposition flux of ¹³⁷Cs by WSPEEDI-DB was used as input from the atmosphere to oceans, were statistically consistent to the measurement. However, the simulated seawater concentrations of ¹³⁷Cs were underestimated regionally in the North Pacific. Both the overestimation of air concentrations and underestimation of seawater concentrations could be attributed to the less amounts of ¹³⁷Cs deposition by less precipitation over the North Pacific. The overestimation and underestimation could be improved without contradiction between the air and seawater concentrations of ¹³⁷Cs using more realistic precipitation in atmospheric dispersion simulations. This shows that the source term validated in this study could reproduce the spatiotemporal distribution of ¹³⁷Cs from the FDNPS accident in both local and large-scale atmospheric dispersion simulations.

Evolution of radioecology in Armenia: a short review

PURPOSE

The article generalizes the evolution of radioecological studies conducted by female scientists in Armenia in the period of 1950-2020. Radioecological studies were launched in 1958, prior to the construction of the ANPP and major nuclear disasters.

CONCLUSION

The obtained results allowed the revealing peculiarities of distribution and accumulation of naturally occurring radioactive materials (NORM) and artificial radionuclides in the natural environment, urban sites and industrial centers. Series of national environmental monitoring programs were designed in order to reveal the main migration pathways of NORM and artificial radionuclides, as well as the assessment of exposure to natural and induced radiation.

Monitoring and assessment of 137Cs and 90Sr radioactive isotopes in the 'soil - rhizosphere - sedge' system of the Yenisei River floodplain (near impact zone of Krasnoyarsk MCC, Russia)

Radiocaesium and radiostrontium contamination in the 'soil - rhizosphere - plants (aerial parts)' system was monitored in the floodplain ecosystem of the Yenisei River in the near impact zone of the Krasnoyarsk Mining and Chemical Combine (MCC). The monitored system included soil, rhizosphere, and sedge vegetation on islands and the river's east bank. The ¹³⁷Cs and ⁹⁰Sr specific activities displayed intricate space and time patterns controlled by the river water level, including the time and duration of floods and their correlation with the sedge vegetation season. The specific activities of both radionuclides, especially ¹³⁷Cs, were above the background in all years of observation, except in a few cases. The soil-to-plant transfer factor (TF) patterns showed continuous ¹³⁷Cs and ⁹⁰Sr influx into the system and annual variations in the shares of their bioavailable and fixed forms, especially for ⁹⁰Sr. The ⁹⁰Sr distribution in the 'soil - rhizosphere - plants' system observed in 2014-2016 provides evidence for possible local fallout.

Rapid HPGe well detector gamma bioassay of 137Cs, 60Co, and 192Ir method

CDC designed a rapid HPGe Bioassay Method for ¹³⁷Cs, ⁶⁰Co, and ¹⁹²Ir that is suitable for a public health response to a radiological incident where people may ingest or inhale radionuclides. The method uses a short count time, small sample volume, and a large volume detector and well size. It measures a patient's urine sample collected post-incident. The levels of concern are directly related to the Clinical Decision Guide levels recommended in the National Council of Radiation Protection 161.

Radionuclides in sediments of the Aare and Rhine river system: Fallouts, discharges, depth-age relations, mass accumulation rates and transport along the river

The Aare-Rhine river system with its four nuclear power plants on the banks of these rivers and with its intermediate lakes and reservoirs provide the unique chance to analyze the input of radioactivity into the system thereby furnishing information on the sources, to analyze the transport within the sediment and along the rivers, and to refine unsupported ²¹⁰Pb dating validated by known discharge maxima. At three locations (Lake Biel, Klingnau Reservoir, old branch of the Rhine) in the Aare and Rhine rivers system downstream of the older nuclear power plants (NPPs) Mühleberg and Beznau, the vertical distributions of ¹³⁷Cs, ²¹⁰Pb, ²¹⁴Pb, ²¹⁴Bi, ⁴⁰K, ⁷Be, ²³⁹Pu, ²⁴⁰Pu, ²⁴¹Am, and ²³⁷Np in sediment cores were determined. Depth-age relations using the excess 210 Pb were established with the raw and with the piecewise Constant Rate Supply (CRS) models. A comparison of the piecewise CRS method with the imprints of known discharges showed differences of up to two years. Besides typical ¹³⁷Cs signals (about 100 Bq∙kg^-1) from the atmospheric nuclear weapons testing (NWT) and the Chernobyl fallouts, imprints of known ¹³⁷Cs discharges (10-70 Bq∙kg^-1) from the NPPs were found in the sediments. The ²³⁷Np distributions (6-10 Bq∙kg^-1) essentially follow the ¹³⁷Cs NWT distributions. In the sediment downstream the NPP Mühleberg (Lake Biel) a²³⁹Pu distribution (<3 Bq∙kg^-1) was found, which was solely due to the NWT fallout. Downstream the NPP Beznau (Klingnau Reservoir and an old branch of the Rhine), besides the NWT distribution, also imprints of ²³⁹Pu discharges (up to 7 Bq∙kg^-1) were found within the time interval 1963 to 1986.²⁴⁰Pu/²³⁹Pu ratios revealed that the burn-up times of the nuclear fuel in the NPP (²³⁵U enrichment of 3.5%), from which the discharges stem, should be about 1 year or less. A comparison between the calculated and the measured ¹³⁷Cs/²³⁹Pu ratio revealed no large discrepancies for the Lake Biel and Rhine positions, but in the Klingnau distribution, the calculated ¹³⁷Cs/²³⁹Pu ratio is one order of magnitude larger than the measured one. The reason could be either a natural uranium research reactor as the source, or strong, short-range ²³⁹Pu precipitation after the discharge from the Beznau NPP. The largest ²³⁹Pu peak in the Rhine sediment (1968/70) corresponds to no major peak in the Klingnau sediment. For the NPP Mühleberg discharge of 1982 the ratio of the ¹³⁷Cs deposition in sediments from Lake Biel, Klingnau Reservoir and the Rhine river is about 1 : 0.5 : 2.9. For the 1977/78 ²³⁹Pu deposition the ratio is 1 : 0.02, for the Klingnau Reservoir and the Rhine sediments, respectively. These numbers indicate a long-range transport of Cs and a rather short-range transport of Pu.

Impacts of radiation exposure on the bacterial and fungal microbiome of small mammals in the Chernobyl Exclusion Zone

Environmental impacts of the 1986 Chernobyl Nuclear Power Plant accident are much debated, but the effects of radiation on host microbiomes have received little attention to date. We present the first analysis of small mammal gut microbiomes from the Chernobyl Exclusion Zone in relation to total absorbed dose rate, including both caecum and faeces samples. We provide novel evidence that host species determines fungal community composition, and that associations between microbiome (both bacterial and fungal) communities and radiation exposure vary between host species. Using ambient versus total weighted absorbed dose rates in analyses produced different results, with the latter more robust for interpreting microbiome changes at the individual level. We found considerable variation between results for faecal and gut samples of bank voles, suggesting faecal samples are not an accurate indicator of gut composition. Associations between radiation exposure and microbiome composition of gut samples were not robust against geographical variation, although we identified families of bacteria (Lachnospiraceae and Muribaculaceae) and fungi (Steccherinaceae and Strophariaceae) in the guts of bank voles that may serve as biomarkers of radiation exposure. Further studies considering a range of small mammal species are needed to establish the robustness of these potential biomarkers.

Increased cancer risk in male hunters compared to the general male population in Northern Sweden after the Chernobyl Nuclear Power Plant accident?

Male hunters in Swedish counties with high fallout of ¹³⁷Cs after the Chernobyl Nuclear Power Plant (NPP) accident have higher radiation exposure due to higher consumption of game compared with the general population.

Methods

Cancer incidence in Sweden was studied in 9 counties with different ¹³⁷Cs fallout after the Chernobyl NPP accident in 1986. In total, 9,267 cancer cases occurred in hunters and 138,909 cancer cases in non-hunters to 31 December 2015. Incidence rate ratios (IRR) with 95% confidence intervals (CI) were calculated using unexposed hunters, or non-hunters, as reference to study internal radiation exposure or hunter life style, respectively.

Results

Directly age standardized total cancer incidence showed an increasing trend in non-hunters. For hunters, the total cancer incidence was significantly lower up to 2001 when the total cancer incidence crossed over the weaker non-hunter trend and remained higher for the following 15 years. IRRs for total cancer in hunters versus non-hunters for each county did not show any clear exposure response pattern. IRRs for hunters versus non-hunters were higher regardless of rural/non-rural status with slightly higher risk estimates for the rural settings. The IRR for hunters was 1.06 (95% CI 1.04-1.08) 1986-2015, representing an excess of 531 cancer cases in hunters.

Conclusion

An increased total incidence of cancer was identified for male hunters compared with male non-hunters. No obvious association between cancer and ¹³⁷Cs from the Chernobyl NPP accident could be identified, although the exposure classification was too crude to exclude such an association.

Assessment of erosion: use of nuclear techniques and conventional methods-case of the Fergoug watershed, Algeria

The importance of the soil degradation in the Mediterranean area, more particularly in Algeria, has revealed the need for a diagnosis of the erosion processes' dynamism. In this context, the present work discusses the results obtained by different approaches (conventional methods, Revised Universal Soil Loss Equation (RUSLE), and fallout radionuclides (use of FRNs)). The use of nuclear techniques (FRNs) such as Cesium-137, Lead-210, and Beryllium-7 as tracers can provide an invaluable amount of information on rates of soil loss that is associated with sheet and rill erosion as well as on the redistribution and transfer of that sediment within the landscape. This work mainly presents the results obtained by the application of nuclear isotopes. In the Fergoug watershed study, the use of conventional and nuclear methods has led to converging results. The latter can be summarized as follows: sheet erosion from 1.5 to 10 t·ha^-1·year^-1 for bare soil and 0.1 to 4 t·ha^-1·year^-1 for cultivated soil. The use of the RUSLE method has shown that erosion is medium to very high (1 to 33 t·ha^-1·year^-1). Estimates of erosion by Cesium-137 (¹³⁷Cs) provided a good understanding of the distribution of the isotope at the slope level and therefore of erosion. The erosion rate is from 26 to 42 t·ha^-1·year^-1, depending on the models used. On the other hand, sedimentation reached 35 and 55 t·ha^-1·year^-1 downstream of the slopes. The variation of ¹³⁷Cs between transects and along the same transect is linked to erosion. The ¹³⁷Cs method has provided a great deal of information and thus constitutes, by its accuracy and speed, an effective and valuable tool for assessing erosion for medium term (50 years) and monitoring the impacts of land use. It can enable one to overcome the various constraints and limits encountered in the various conventional approaches. It thus appears to be an essential alternative or an effective tool to supplement the conventional methods.

Combination of 137Cs and 210Pb Radioactive Atmospheric Fallouts to Estimate Soil Erosion for the Same Time Scale

Naturally occurring ²¹⁰Pb and artificial ¹³⁷Cs fallouts are widely used as radioactive tracers for the determination of water-induced soil erosion for different time scales equal to 50 and 100 years, respectively. There exist several calibration models useful to convert the variation of the inventory of these radiotracers in cultivated soil compared to its value on non-disturbed soil to a soil erosion rate. The most comprehensive calibration models are based on a mass balance approach. In the present work, a new calibration model is proposed. It consists on the generalization of the mass balance approach to a cultivated soil subject to two successive and continuous periods of cultivation. The proposed model combines ²¹⁰Pb and ¹³⁷Cs fallouts for the same time scale by relaxing the constraint on ²¹⁰Pb fallout from being used for 100 years’ time scale. The model was applied successfully to hypothetical cases and can be used to measure soil erosion rates for practical cases. It is important to note that the proposed model has two main advantages. First, the complementarity between ²¹⁰Pb and ¹³⁷Cs fallouts is for the same time scale and not for different time scales, as usually considered and believed in this field. Second, ²¹⁰Pb fallout is used for time scales less than 100 years. This makes the model useful to estimate soil erosion rates for two successive periods of cultivation. To the best knowledge of the authors, the combination of ²¹⁰Pb and ¹³⁷Cs fallouts for the determination of soil erosion rate variation due to change in cultivation practices for the same time scale has never been developed or applied in the past.

Evaluation of soil erosion and sediment deposition rates by the 137Cs fingerprinting technique at different hillslope positions on a catchment

Assessment of the variation of soil erosion and sediment mobilization at different hillslope positions using the ¹³⁷Cs tracing technique has been carried out for the Dapotou closed watershed, a representative depression in the karst gabin basin in Southwest China. The results showed that the annual soil erosion rates in the shoulders, backslopes, and footslopes were 0.87, 0.35 and 0.49 cm year^-1, respectively, while the soil sediment deposition rate in the depression bottom was 2.68 cm year^-1. The average annual soil erosion modulus of the complete hillslope was 632 t km^-2year^-1, which confirmed the seriousness of erosion according to the gradation of the karst soil erosion standards. For the whole catchment, the sediment delivery ratio was estimated as 0.82. To identify which factor could play the most important role in influencing the estimates using ¹³⁷Cs, a linear correlation and principal component analysis were conducted. The results showed that ¹³⁷Cs concentrations at different soil depths of the different hillslope positions were significantly correlated with soil organic matter and total nitrogen (P < 0.05). As this watershed is a typical karst geomorphological type, these findings are expected to provide data support for larger watershed soil erosion management and ecological restoration in fragile karst ecosystems.

Elution of Radioactive Cesium from Tofu by Water Soaking

Elution of cesium-137 (¹³⁷Cs) from tofu into water was investigated to know the behavior of ¹³⁷Cs during preservation and cooking. The food processing retention factor (Fr) reached 0.55 when tofu was soaked in water at a ratio of 1:2 w/w for 24 h at 4°C. Doubling the amount of water did not further significantly decrease Fr. When tofu was held in water at a ration of 1:2 w/w at a temperature of 80℃ for 50 min, Fr was 0.72. Increasing the amount of water to 10 times the tofu weight did not further reduce Fr significantly. Cesium-137 is mostly bound to tofu and does not freely diffuse into water. Tofu was then soaked in water at a ratio of 1:2 w/w at 4℃ for 24 h, placed in new water at a ratio of 1:2 w/w, and held at 80℃ for 50 min, resulting in an Fr 0.33. This value is close to an estimated Fr calculated by multiplying the Fr of 0.55 from soaking at 4°C by the Fr of 0.72 from the hot water treatment. The calculated Fr from soybeans sequentially processing into tofu, soaking tofu at 4°C for 24 h and in hot water at 80°C for 50 min was about 0.1, indicating 90% removal of ¹³⁷Cs. Degree of decrease in ¹³⁷Cs during preservation and cooking of tofu demonstrated in this study will be useful for exposure assessment of ¹³⁷Cs through oral intake of contaminated soybeans after processing and cooking.

210Pb dating of recent sediments from the continental shelf of western India: factors influencing sedimentation rates

Several cores from the continental shelf of the Arabian Sea along the Indian Coast were investigated for change in sedimentation rates duly constrained for chronology based on ²¹⁰Pb and ¹³⁷Cs dating techniques. The emphasis was to look for spatial and temporal variation in the sedimentation rate along the continental shelf of eastern Arabian Sea between Goa to Kochi for water depth ≤ 150 m. This study showed varying sedimentation rates in coastal and distant sediment cores. Both ²¹⁰Pb and ¹³⁷Cs dating techniques showed comparable sedimentation rate in most sediment cores. The sedimentation in the continental shelf region of the coastal Arabian Sea is primarily controlled by discharge of sediments from rivers during Indian summer monsoon. Increased sedimentation rate from the north (off Goa) to the south (off Kochi) was triggered by high riverine flux and longshore sediment transport.

Radiological risk assessment in the terrestrial ecosystem: comparative study of two software tools used for dose rate calculations

In this study, two software tools, namely the ERICA Assessment Tool and the RESRAD-BIOTA code, are used for the calculation of the radiological exposure of non-human organisms. For the purposes of the analysis, data retrieved from field studies are used. The site-specific measurements were performed on organisms (mammals-sheep and goats of Bovidae spp.) collected from free-ranged grazing regions in Greece. Plants (grass) of Poaceae spp. and soil samples were also collected from these regions. Natural radionuclides (²²⁶Ra, ²²⁸Ra, and ²²⁸Th) of lithogenic origin and ¹³⁷Cs, resulted from human activities (Chernobyl and Fukushima nuclear power plant accidents and global fallout), were detected in all samples. The measured activity concentrations were used as input to the two software tools, the ERICA Assessment Tool and the RESRAD-BIOTA code. The results of the simulations provided the external, internal, and total dose rates received by the organisms due to the exposure to the radionuclides. The assessments indicated that out of all detected radionuclides, ²²⁸Th is the main contributor to the external dose and ²²⁶Ra and ²²⁸Ra are the main contributors to the internal dose. The comparative analysis of the two tools revealed significant differences in the calculated doses. In fact, external and internal doses calculated by RESRAD-BIOTA are higher than the values calculated by the ERICA Tool, due to the dose conversion coefficients (DCCs) used for the dose calculation. RESRAD-BIOTA provides more conservative values, but ERICA Tool provides lower uncertainty due to the higher flexibility in the design of the phantom organism. On a risk assessment basis, there is no significant impact, due to organisms' exposure to radioactivity. However, further consideration of the exposure levels is required due to the potential effects of protracted low-level ionizing radiation on the various levels of life's organization.

Application of agronomical approaches to rehabilitating territories of the Republic of Belarus affected by the Chernobyl disaster

The environmental radiation pollution resulting from the Chernobyl nuclear disaster in 1986 is one of the main factors limiting agriculture in the eastern regions of Belarus. In the first decade after the accident, the need to mitigate the effects of radiation had a key role in the implementation of countermeasures. As a result, there are widespread areas of high soil fertility potential in the contaminated zone. Today there is a possibility to include new crops (e.g. sugar beet [Beta vulgaris L.]) into regular crop rotation to increase the effectiveness of agriculture and to use the accumulated soil fertility potential. The article discusses a possible agronomic approach to estimating specific fields (working plots) at the scale of agricultural enterprises for placement of sugar beet. The territory of the Mahilyow region of the Republic of Belarus was examined from the perspective of soil suitability to the cultivation of sugar beet. Along with estimating radionuclide accumulation by sugar beet roots, the areas of soils suitable for sugar beet within agricultural enterprises were calculated for selected districts. It was revealed that sugar beet has low ability to absorb radiocaesium and radiostrontium from soils. The contamination density does not restrict the possibility for placement of sugar beet. Instead, soil fertility, specifically content of plant-available phosphorus and boron, was the limiting factor in that. Based on data from field experiments and soil fertility data, a number of enterprises were selected where sugar beet could be included into crop rotations to high economic effect.

Temporal distribution of Fukushima-derived 137Cs in coniferous forest soil evaluated based on compartment-exponential model

Based on the compartment and exponential models, the distribution of Fukushima-derived ¹³⁷Cs was evaluated at four sampling dates in undisturbed coniferous forest soil. The compartment model was employed to evaluate the dynamic of ¹³⁷Cs in the three sub-sections of the forest floor (FF), namely undergrowth (UG), litter layer (OL), and fragmented litter layer (OF), while the exponential model was administrated to describe its distribution below the FF. According to the compartment model, the derived ecological half-life of ¹³⁷Cs in the UG, OL, and OF layers was 0.97, 1.1, and 4.9 years, respectively, indicating ¹³⁷Cs resides much longer in the OF layer. Hence, this soil section remains a potential source of radiation dose mainly due to its high ¹³⁷Cs content associated with low attenuation effect. Below the OF layer, the ¹³⁷Cs distribution was well described by exponential model and its derived relaxation lengths were in the range of 0.8-1.4 cm, implying the migration of ¹³⁷Cs in mineral soil is very slow and almost intact during the observation time. Collectively, our results highlighted that the compartment model for the FF and the exponential model for the soil below the FF are adequate enough to generate essential information. Thus, the potential decontamination measures should have to be chosen on their effect on the FF's ¹³⁷Cs. Graphical abstract.

Childhood leukemia in Ukraine after the Chornobyl accident

This population-based ecological study analyzes the prevalence of childhood leukemia in Ukraine before and after the Chornobyl nuclear power plant accident, based on the contamination status of the territory, time period, gender, and age. Three regions-Zhytomyr, Kyiv (except Kyiv city), and Chernihiv were included as areas contaminated by radioactive ¹³⁷Cs from 1 to 15 Ci/km² with annual effective doses exceeding 1.0 mSv, and Sumy region as the control (non-contaminated) area with ¹³⁷Cs contamination less than 1 Ci/km² and effective doses less than 0.5 mSv per year. The integrated database of the National Research Centre for Radiation Medicine used in the present study included 1085 childhood leukemia cases. Two aggregated periods were used for analysis: 1980-1986 (pre-accident) and 1987-2000 (post-accident). ICD-9 codes for leukemia (204-208.9) were used to perform analyses according to the extent of leukemic cells maturity (acute, chronic, and maturity unspecified leukemia), leukemic cell lineage (lymphoid, myeloid and lineage unspecified leukemia) and all leukemia cases in different age subgroups (1-4, 5-9, 10-14, and 15-19 years). Standard methods of descriptive epidemiology were used to calculate the prevalence of disease and frequency ratio in regression models. A statistically significant increase in frequency ratio for acute leukemia (1.44; 95% confidence interval (CI), 1.22-1.71), myeloid leukemia (2.93; 95% CI, 1.71-5.40), cell lineage unspecified leukemia (II) (1.48; 95% CI, 1.18-1.87) and all forms of leukemia (1.59; 95% CI, 1.36-1.86) was found for the post-accident period in highly contaminated areas. The results indicate that the frequency of childhood leukemia (and of some of its types) increased in contaminated areas during the post-accident period, suggesting that radiation exposure after the Chornobyl accident might be the cause of the increase. However, further analytical studies, with individual or at least group dose estimates, are needed to confirm a link between childhood leukemia and the Chornobyl accident.

Efficient sampling of shiitake-inoculated oak logs to determine the log-to-mushroom transfer factor of stable cesium

Background

Stable cesium (¹³³Cs) naturally exists in the environment whereas recently deposited radionuclides (e.g., ¹³⁷Cs) are not at equilibrium. Stable cesium has been used to understand the long-term behavior of radionuclides in plants, trees and mushrooms. We are interested in using ¹³³Cs to predict the future transfer factor (TF) of radiocesium from contaminated logs to shiitake mushrooms in Eastern Japan. However, the current methodology to obtain a representative wood sample for ¹³³Cs analysis involves mechanically breaking and milling the entire log (excluding bark) to a powder prior to analysis. In the current study, we investigated if sawdust obtained from cutting a log along its length at eight points is as robust but a faster alternative to provide a representative wood sample to determine the TF of ¹³³Cs between logs and shiitake.

Methods

Oak logs with ready-to-harvest shiitake fruiting bodies were cut into nine 10-cm discs and each disc was separated into bark, sapwood and heartwood and the concentration of ¹³³Cs was measured in the bark, sapwood, heartwood, sawdust (generated from cutting each disc) and fruiting bodies (collected separately from each disc), and the wood-to-shiitake TF was calculated.

Results

We found that the sawdust-to-shiitake TF of ¹³³Cs did not differ (P = 0.223) compared to either the sapwood-to-shiitake TF or heartwood-to-shiitake TF, but bark did have a higher concentration of ¹³³Cs (P < 0.05) compared to sapwood and heartwood. Stable cesium concentration in sawdust and fruiting bodies collected along the length of the logs did not differ (P > 0.05).

Discussion

Sawdust can be used as an alternative to determine the log-to-shiitake TF of ¹³³Cs. To satisfy the goals of different studies and professionals, we have described two sampling methodologies (Methods I and II) in this paper. In Method I, a composite of eight sawdust samples collected from a log can be used to provide a representative whole-log sample (i.e., wood and bark), whereas Method II allows for the simultaneous sampling of two sets of sawdust samples—one set representing the whole log and the other representing wood only. Both methodologies can greatly reduce the time required for sample collection and preparation.

Accumulation of natural and anthropogenic radionuclides in body profiles of Bryidae, a subgroup of mosses

Mosses can be used as biomonitors to monitor radionuclide deposition and heavy metal pollution in cities, forests, and grasslands. The aims of this work were to determine the activity concentrations of natural (²¹⁰Po, ²¹⁰Pb or ²¹⁰Pb_ex (excess ²¹⁰Pb is defined as the activity of ²¹⁰Pb minus the activity of ²²⁶Ra), ⁷Be, ⁴⁰K, ²²⁶Ra, ²³⁸U, and ²³²Th) and anthropogenic radionuclides (¹³⁷Cs) in moss body profiles and in situ underlying soils of moss samples and to assess/determine the distribution features and accumulation of these radionuclides. Activity concentrations of radionuclides in the samples were measured using a low-background gamma spectrometer and a low-background alpha spectrometer. Consistent with their source, the studied radionuclides in the moss samples and underlying soils were divided according to the principal component analysis (PCA) results into an airborne group (²¹⁰Po, ²¹⁰Pb (²¹⁰Pb_ex), ⁷Be, and ¹³⁷Cs) and a terrestrial group (⁴⁰K, ²³⁸U, ²²⁶Ra, and ²³²Th). The activity concentrations of ²¹⁰Po and ²¹⁰Pb_ex in moss body profiles were mainly concentrated in the stems-rhizoid parts, in which we measured some of the highest ²¹⁰Po and ²¹⁰Pb_ex levels compared to the results in the literature. ⁷Be mainly accumulated in the leaves-stem parts. Different positive correlations were observed between ²¹⁰Po and ²¹⁰Pb and between ⁷Be and ²¹⁰Pb, which indicated that the uptake mechanisms of ²¹⁰Po, ²¹⁰Pb, and ⁷Be by moss plants were different, to some extent. ¹³⁷Cs was detected only in some moss samples, and the fraction of ¹³⁷Cs in the underlying soils was much lower than that in the moss, suggesting that mosses were protecting the underlying soils from further pollution. Except for ⁴⁰K, the terrestrial radionuclide (²³⁸U, ²²⁶Ra, and ²³²Th) content in mosses was predominantly at low levels, which indicated not only the inability of mosses to use those elements for metabolic purposes but also the rather poor capability of mosses to directly mobilize, absorb, and transport elements (U, Ra, or Th) not dissolved in water.

Effect of hillslope aspect on landform characteristics and erosion rates

Understanding the effect of aspect on landform characteristics and erosion rates is an important prerequisite for soil and water conservation in hilly areas. In a cultivated area of the Chinese Loess Plateau, hillslope length, gradient and aspect (east, west, south, and north) were measured on two typical Mao (round loess hill), and net soil loss and location (upper, middle and lower positions) were studied using the ¹³⁷Cs tracing loss ratio. Hillslope length on different aspects was in the order, north > west > east >south, but gradient changes were inconsistent and more complicated. Southern slopes were shorter and steeper, while on northern slopes, it was the opposite. Erosion rate on hillslopes with different aspects ranged from 1440 to 2631 t/km² · a, and on northern slopes they were c.24-81% larger than on southern slopes. Upper and middle hillslope positions usually had higher erosion rates than lower positions. The greatest erosion rates were at upper positions on northern slopes, and upper positions on south slopes had relatively lower erosion rates. For hillslope positions influenced by wind erosion in winter and spring, the ¹³⁷Cs loss ratio could be > 80%, while for the same positions on south slopes without wind erosion, it was < 80%. Our findings demonstrate that aspect is a key driver of landform characteristics and erosion rates on hillslopes, and they could be usefully employed for the prevention and control of soil erosion in this region.

Determination of TG-43 Dosimetric Parameters for Photon Emitting Brachytherapy Sources

Objective:

Brachytherapy sources are widely used for the treatment of cancer. The report of Task Group No. 43 (TG-43) of American Association of Physicists in Medicine is known as the most common method for the determination of dosimetric parameters for brachytherapy sources. The aim of this study is to obtain TG-43 dosimetric parameters for ⁶⁰Co, ¹³⁷Cs, ¹⁹²Ir and ¹⁰³Pd brachytherapy sources by Monte Carlo simulation.

Methods:

In this study, ⁶⁰Co (model Co0.A86), ¹³⁷Cs (model 6520-67), ¹⁹²Ir (model BEBIG) and ¹⁰³Pd (model OptiSeed) brachytherapy sources were simulated using MCNPX Monte Carlo code. To simulate the sources, the exact geometric characterization of each source was defined in Monte Carlo input programs. Dosimetric parameters including air kerma strength, dose rate constant, radial dose function and anisotropy function were calculated for each source. Each input program was run with sufficient number of particle histories. The maximum type A statistical uncertainty in the simulation of the ⁶⁰Co, ¹³⁷Cs, ¹⁹²Ir and ¹⁰³Pd sources, were equal to 4%, 4%, 3.19% and 6.50%, respectively.

Results:

The results for dosimetry parameters of dose rate constant, radial dose function and anisotropy function for the ⁶⁰Co, ¹³⁷Cs, ¹⁹²Ir and ¹⁰³Pd sources in this study demonstrated good agreement with other studies.

Conclusion:

Based on the good agreement between the results of this study and other studies, the TG-43 results for Co0.A86 ⁶⁰Co, 67-65200 ¹³⁷Cs, BEBIG ¹⁹²Ir and OptiSeed ¹⁰³Pd sources are validated and can be used as input data in treatment planning systems (TPSs) and to validate the TPS calculations.

Discussions on the driving mechanism of postdepositional migration of 241Am and 137Cs in organomineral sediments (Lake Krugloe, Tomsk region, Russia)

A core of bottom sediments from Lake Krugloe located within the 30 km influence zone of the Siberian Chemical Plant (located in the city of Seversk "Tomsk-7") was studied to determine scales and rates of migration of artificial radionuclides ¹³⁷Cs and ²⁴¹Am in organomineral sediment. It was found that the main portion of ¹³⁷Cs and ²⁴¹Am was contained in the sediment interval above 10 cm. This means that the horizon of 10 cm corresponds to 1950-the time of the start of widespread tests of nuclear weapons. The ²¹⁰Pb_ex dates also confirm that this particular horizon was formed in the 1950s. Pore waters in the core above the 10 cm horizon are in oxidizing conditions. The depth of the oxidized/reduced boundary was determined from the distribution of redox-sensitive elements Fe and U dissolved in the pore solution. The core distribution of ¹³⁷Cs is a slightly sloping step, with the lower edge at the 10 cm level. The smearing of the lower boundary of this distribution showing the scale of ¹³⁷Cs migration made it possible to estimate the diffusion mobility of ¹³⁷Cs. Its diffusion coefficient turned out to be of the order of 10^-8 cm² s^-1. As shown by measurements, the scale of migration of ²⁴¹Am and the scale of migration of ¹³⁷Cs have similar values. Theoretical analysis carried out in this work shows that the most probable mechanism of ¹³⁷Cs and ²⁴¹Am migration in the pore solution of lake sediment is the migration of colloidal particles to which these radionuclides are strongly bound. Calculation of the diameter of such particles by the Stokes-Einstein formula shows that they have submicron dimensions (d ≈ 400 nm). No evidence was found that the change in redox conditions in the sediment had an effect on migration of Am ions in pore solution.

Nuclear contamination sources in surface air of Finnish Lapland in 1965-2011 studied by means of 137Cs, 90Sr, and total beta activity

Radionuclides ¹³⁷Cs and ⁹⁰Sr and total beta activity were determined from air filters collected in Rovaniemi (Finnish Lapland) in 1965-2011. Nuclear contamination sources present in the air filter samples as well as temporal changes in radionuclide concentrations were examined. Ozone observations and meteorological modeling were used in combination with radionuclide analyses to study the reasons behind the observed seasonal concentration variation. In general, the magnitude and variation in activity concentrations of ¹³⁷Cs and ⁹⁰Sr and total beta activity in the surface air of Rovaniemi in 1965-2011 corresponded well with values from other countries. However, the obtained results prove in practice that hardly any refractory or intermediate radionuclides from the destroyed Chernobyl reactor fuel were introduced to Finnish Lapland. The main source of ¹³⁷Cs and ⁹⁰Sr and total beta activity in the surface air of Rovaniemi in 1965-2011 has been intense atmospheric nuclear weapon testing in 1950s-1960s and later tests performed in 1965-1980, as well as leakages from underground nuclear tests in Semipalatinsk, 1966, and Novaya Zemlya, 1987. For ¹³⁷Cs and total beta activity, the influence of Chernobyl and Fukushima accidents was detected.

Evaluation of the 2016 ENV57 MetroERM measurement comparison on 137Cs, 134Cs and 131I in air filters

In 2016, the European Commission's Joint Research Centre organised an interlaboratory comparison exercise on the measurement of ¹³⁷Cs, ¹³⁴Cs and ¹³¹I in air filters. The exercise was conducted in the frame of the MetroERM EMRP project with code ENV57. This paper describes the context of the interlaboratory measurement comparison, the technical implementation, the air filter measurements performed by the participating laboratories and finally the evaluation of the comparison results. The intercomparison exercise results are such that 56 out of the 67 laboratories (i.e. 84%) reported values within the ±20% range of the reference value for both the ¹³⁷Cs and ¹³⁴Cs. The evaluation of the performance of the laboratories on ¹³¹I was complicated and the details are explained. Nevertheless, 20 (30%) laboratories reported results for ¹³¹I with a percentage difference from the reference value within the ±20% range.

Tracing sediment sources in a mountainous forest catchment under road construction in northern Iran: comparison of Bayesian and frequentist approaches

Development and land use change lead to accelerated soil erosion as a serious environmental problem in river catchments in Iran. Reliable information about the sources of sediment in catchments is therefore necessary to design effective control strategies. This study used a composite sediment source tracing procedure to determine the importance of forest road cuttings as a sediment source in a mountainous catchment located in northern Iran. A fallout radionuclide (¹³⁷Cs) and 12 geochemical tracers (Ca, Cu, Fe, K, Mg, Mn, Na, Ni, OC, Pb, Sr and TN) were used to determine the relative contributions of three sediment source types (hillslopes, road cuttings and channel banks) to both suspended and bed sediment samples. Two mixing models based on different mathematical concepts were used to apportion the sediment sources: the mixture sampling importance resampling Bayesian model which incorporates the mass-balance matrix and a distribution model using normal and summed probability of normal distributions. The results of both mixing models indicated that sub-soil erosion from road cuttings and channel banks dominated the sources of river bed and suspended sediment samples, respectively. These results therefore highlight that conservation that works in the study area to remedy the sediment problem should initially focus on stabilisation and rehabilitation of road cuttings and channel banks. This successful application of a composite (radionuclide and geochemical) tracing technique for discriminating source end members characterised by different erosion processes underscores the importance of sub-soil erosion in this case study.

Sedimentary chronology reinterpreted from Changshou Lake of the Three Gorges Reservoir Area reveals natural and anthropogenic controls on sediment production

Sedimentary archives preserved in geomorphic sinks provide records of historical sediment dynamics and its related natural and anthropogenic controls. This study reinterpreted sedimentary processes in Changshou Lake of the Three Gorges Reservoir Area in China by combining a rainfall erosivity index with multiple tracing proxies, and the impacts of natural and anthropogenic drivers on sediment production were also explored. Erosive rainfalls with low frequency and large magnitude in the rainy season contribute to a substantial proportion of annual total rainfall, which thus can be used to infer erosion and sediment yield events. The sedimentary chronology was determined by comparing rainfall erosivity index with depth distribution of ¹³⁷Cs and absolute particle size, which revealed annual sedimentation rates ranging from 1.1 to 2.3 cm a^-1. The multi-proxy dating index and variation of sedimentation rate divided the sediment profile into three major periods. The reference period (1956-1982) displays low variability of TOC, TN, trace metal concentrations, and mean sedimentation rate. In the stressed period (1982-1998), industrial and sewerage discharge led to input and deposition of TOC, TN, and trace metals (e.g., Cd, Co, Cu, Cr, and Ni). The highest annual sediment accumulation rate of 2.3 cm a^-1 may be ascribed to the 1982 big flood event. In the present period (1998-2013), increased TOC, TN and decreased trace metals in the top layers of the sediment core indicated changes in lake ecology. Fish farming promoted algal growth and primary productivity which caused eutrophication until 2004-2005. The reduced mean sedimentation rate of 1.7 cm a^-1 between 1998 and 2004, and thereafter, may be attributed to soil and water conservation and reforestation policies implemented in the Longxi catchment. Human activities such as deforestation, cultural and industrial revolution, and lake eutrophication associated with fish farming since 1989, therefore led to appreciable limnological variations. Overall, the dated sedimentary profile from Changshou Lake displays high consistency with archived historical events and reflects the impact of both natural and anthropogenic controls on sediment production.

Agricultural aspects of radiocontamination induced by the Fukushima nuclear accident - A survey of studies by the Univ. of Tokyo Agricultural Dept. (2011-2016)

Immediately after the Fukushima nuclear power plant accident, a team of 40-50 researchers at the Graduate School of Agricultural and Life Sciences at the University of Tokyo began to analyze the behavior of radioactive materials in the fallout regions. The fallout has remained in situ and become strongly adsorbed within the soil over time. 137Cs was found to bind strongly to the fine clay, weathered biotite, and organic matter in the soil; therefore, it has not mobilized from mountainous regions, even after heavy rainfall. In farmland, the quantity of 137Cs in the soil absorbed by crop plants was small. The downward migration of 137Cs in soil is now estimated at 1-2 mm/year. The intake of 137Cs by trees occurred through the bark and not from the roots. This report summarizes the findings of research across a wide variety of agricultural specialties.

Cesium Uptake by Rice Roots Largely Depends Upon a Single Gene, HAK1, Which Encodes a Potassium Transporter

Incidents at the Fukushima and Chernobyl nuclear power stations have resulted in widespread environmental contamination by radioactive nuclides. Among them, 137cesium has a 30 year half-life, and its persistence in soil raises serious food security issues. It is therefore important to prevent plants, especially crop plants, from absorbing radiocesium. In Arabidopsis thaliana, cesium ions are transported into root cells by several different potassium transporters such as high-affinity K+ transporter 5 (AtHAK5). Therefore, the cesium uptake pathway is thought to be highly redundant, making it difficult to develop plants with low cesium uptake. Here, we isolated rice mutants with low cesium uptake and reveal that the Oryza sativa potassium transporter OsHAK1, which is expressed on the surfaces of roots, is the main route of cesium influx into rice plants, especially in low potassium conditions. During hydroponic cultivation with low to normal potassium concentrations (0-206 µM: the normal potassium level in soil), cesium influx in OsHAK1-knockout lines was no greater than one-eighth that in the wild type. In field experiments, knockout lines of O. sativa HAK1 (OsHAK1) showed dramatically reduced cesium concentrations in grains and shoots, but their potassium uptake was not greatly affected and their grain yields were similar to that of the wild type. Our results demonstrate that, in rice roots, potassium transport systems other than OsHAK1 make little or no contribution to cesium uptake. These results show that low cesium uptake rice lines can be developed for cultivation in radiocesium-contaminated areas.

Cesium Uptake by Rice Roots Largely Depends Upon a Single Gene, HAK1, Which Encodes a Potassium Transporter

Incidents at the Fukushima and Chernobyl nuclear power stations have resulted in widespread environmental contamination by radioactive nuclides. Among them, 137cesium has a 30 year half-life, and its persistence in soil raises serious food security issues. It is therefore important to prevent plants, especially crop plants, from absorbing radiocesium. In Arabidopsis thaliana, cesium ions are transported into root cells by several different potassium transporters such as high-affinity K+ transporter 5 (AtHAK5). Therefore, the cesium uptake pathway is thought to be highly redundant, making it difficult to develop plants with low cesium uptake. Here, we isolated rice mutants with low cesium uptake and reveal that the Oryza sativa potassium transporter OsHAK1, which is expressed on the surfaces of roots, is the main route of cesium influx into rice plants, especially in low potassium conditions. During hydroponic cultivation with low to normal potassium concentrations (0-206 µM: the normal potassium level in soil), cesium influx in OsHAK1-knockout lines was no greater than one-eighth that in the wild type. In field experiments, knockout lines of O. sativa HAK1 (OsHAK1) showed dramatically reduced cesium concentrations in grains and shoots, but their potassium uptake was not greatly affected and their grain yields were similar to that of the wild type. Our results demonstrate that, in rice roots, potassium transport systems other than OsHAK1 make little or no contribution to cesium uptake. These results show that low cesium uptake rice lines can be developed for cultivation in radiocesium-contaminated areas.

Radioactivity in mushrooms from selected locations in the Bohemian Forest, Czech Republic

¹³⁷Cs is one of the most important radionuclides released in the course of atmospheric nuclear weapon tests and during accidents in nuclear power plants such as that in Chernobyl, Ukraine, or Fukushima, Japan. The aim of this study was to compare ¹³⁷Cs and ⁴⁰K concentrations in particular species of mushrooms from selected locations in the Bohemian Forest (Czech: Šumava), Czech Republic, where a considerable contamination from the Chernobyl accident had been measured in 1986. Samples were collected between June and October 2014. Activities of ¹³⁷Cs and ⁴⁰K per dry mass were measured by means of a semiconductor gamma spectrometer. The ¹³⁷Cs values measured range from below detection limit to 4300 ± 20 Bq kg^-1, in the case of ⁴⁰K from 910 ± 80 to 4300 ± 230 Bq kg^-1. Differences were found between individual locations, due to uneven precipitation in the course of the movement of the radioactive cloud after the Chernobyl accident. There are, however, also differences between individual species of mushrooms from identical locations, which inter alia result from different characteristics of the soil and depths of mycelia. The values measured are compared with established limits and exposures from other radiation sources present in the environment. In general, it can be stated that the values measured are relatively low and the effects on the health of the population are negligible compared to other sources of ionizing radiation.

Fat tissue is not a reservoir for radiocesium in wild boars

Meat of wild boars is not only known for high ¹³⁷Cs activity concentrations but also for the remarkable constancy of these levels. Even decades after the Chernobyl accident, the ¹³⁷Cs levels in wild boar meat in Central Europe have not declined but even partly increased. In the present study, we investigated an unusual hypothesis for this very unusual phenomenon: may the boars’ fat tissue act as a reservoir for radiocesium? We investigated fat and muscle tissues of four wild boars in Western Germany and found that the ¹³⁷Cs concentrations in fat were in the range of 10–30% of the respective activities in muscle tissue. Hence, the hypothesis was refuted.

Monitoring and radioecological characteristics of radiocesium in Japanese beef after the Fukushima nuclear accident

After the Fukushima nuclear accident, beef proved to be a problematic food item with several exceedances entering the market. The reason was contaminated rice straw that was fed to cattle. Japanese authorities responded quickly to the exceedances and made beef one of the most-monitored food items after the Fukushima accident with more than a million samples within 5 years. Activity levels dropped quickly and are now considerably below the regulatory limit. No exceedance of the regulatory limit was observed after October 2012. The monitoring campaign focuses on the pre-market to catch any exceedances before they reach the consumer. The analysis also showed that some late beef samples exhibited an unusually high ¹³⁴Cs/¹³⁷Cs activity ratio. The reason for this is unknown.