137Cs Activity Research Articles

90Sr and 137Cs distribution in Chornobyl forests: 30 years after the nuclear accident.

The primary aim of this study was to quantify patterns in the distribution of 90Sr and 137Cs activity in pine (Pinus sylvestris L.: 18 sites) and birch (Betula pendula Roth.: 2 sites) forests within the Chornobyl exclusion zone, 30 years after the Chornobyl nuclear power plant (NPP) accident (1986). To achieve this, radionuclide activity concentrations were measured in the mineral and organic soil horizons, the green forest floor (grasses, mosses, and lichens), and trunk wood in forest plots dominated by either pine or birch trees.Our results showed that the geometric mean of the 90Sr aggregated transfer factors from mineral soil to the trunk wood of pine trees (Tag) for Scots pines was 24 x 10-3m2kg-1, which is an order of magnitude higher than the IAEA Handbook (2010)reference value (1.7 x 10-3m2kg-1), which were based on studies conducted after the Kyshtym accident (Ural region, Russia) and in the first years following the Chornobyl accident (Ukraine and Belarus). The observations suggest that the above-ground biomass (soil organic layers, green forest floor, and trees) may contribute more to the 90Sr inventory than the mineral soil at the stand level. In contrast, the 137Cs Tag values for pine and birch stands were consistent with those reported in the literature (ranging from 0.1 to 10 and 0.5-1.1 x 10-3m2kg-1, respectively). Both results align with the known bioavailability of radionuclides from previous studies: low for 137Cs, leading to limited soil depth migration (less than 30cm in the mineral horizon), and higher for 90Sr, resulting in greater soil migration (up to 1m in the mineral horizon). This study highlighted significant correlations between the radionuclides' activity concentrations in the litter layers and their content in the trunk wood of pine trees.

Assessment Activity Concentrations of Rice Components (Root, Stem, Leaf, and Grain) and Transfer Factors (TF) from Paddy Soil to Rice Grain of Radionuclides 40K, 226Ra, 232Th, and 137Cs Investigation in Taiwan

This study analyzed the activity concentrations of various radionuclides in irrigation water, rice components, and corresponding soil samples from eleven paddy fields, revealing significant findings with potential environmental and health implications. The soil exhibited high levels of activity concentrations ranging from 350 to 829, 12.4 to 41.2, and 18.5 to 60.3 Bq/kg, with mean values of 609, 31.1, and 45.0 Bq/kg for 40K, 226Ra, and 232Th respectively. Additionally, 12 soil samples from two paddy fields showed 137Cs activity concentrations of 5.6 ± 1.3 Bq/kg. The rice plant roots accumulated the highest percentages of total activity concentrations for 226Ra, 232Th, and 137Cs, ranging from 76–86%, while only 1.1–10.0% were found in the un-hulled grain. For 40K, activity concentrations were distributed among the root (23%), stem (32%), leaf (35%), and un-hulled grain (10%). The mean activity concentrations were 99 ± 12, 0.49 ± 0.09, 0.43 ± 0.12, and 0.10–0.31 Bq/kg for 40K, 226Ra, 232Th, and 137Cs for un-hulled rice grain, respectively. Transfer factors (TFs) from soil to un-hulled rice grain were calculated as (1.21–2.86) × 10−1 for 40K, (0.07–0.11) × 10−1 for 232Th, (0.11–0.29) × 10−1 for 226Ra, and (0.16–0.61) × 10−1 for 137Cs. Notably, significant negative correlations were observed between TFs and soil concentrations for 40K (r = 0.92, p < 0.001, n = 11) and 226Ra (r = 0.98, p = 0.026, n = 4), suggesting that macronutrients in soil solutions may inhibit the linear transfer of natural nuclides from the soil solution to rice plants.

Study of the Biogas Ebullition from Lacustrine Carbonate Enriched and Black Silt Bottom Sediments

The greenhouse effect, which is also promoted by naturally occurring biogas ebullition fluxes (released via bubbles), generated by the decomposition of organic matter in carbonate-enriched and black silt sediments, has been analyzed. This study is based on results obtained using passive gas collectors at different parts of eutrophic Lake Juodis, located in a temperate climate zone in the vicinity of Vilnius (Lithuania). The measured annual biogas (containing about 60% of biomethane) ebullition fluxes from carbonate-enriched sediments and black silt sediments were 16.9–23.0 L/(m2∙y) and 38.5–43.2 L/(m2∙y), respectively. This indicates that the gas fluxes from carbonate sediments were almost twice as low as those from black silt sediments. Oxygen, produced by the photosynthetic activity of green algae in the near-surface water and sediments, helps to retain carbonates in the sediments by preventing their dissolution. In turn, the calcite coating on sediment particles partially preserves organic matter from decomposition, reducing the effective thickness of the sediment layer generating biogas. The characteristic vertical distribution profile of 137Cs activity, with sharp peaks in sediments, suggests that generated biogas bubbles move to the surface of the sediments forming vertical channels by pushing sediment particles asides without noticeably mixing them vertically. This examination showed that factors such as abundance of carbonates in the sediments may result in a significant reduction in biogas generation and emissions from the lake sediments.

Effect of sodium butyrate on kidney and liver mitochondrial dysfunction in a lipopolysaccharide mousemodel.

Sodium butyrate can reduce inflammation, but it is not known if butyrate can improve mitochondrial dysfunction during sepsis. We tested butyrate to prevent or reverse lipopolysaccharide (LPS)-induced mitochondrial dysfunction in murine kidney and liver. C57BL/6 mice were grouped as control (n = 9), intraperitoneal (IP) LPS (n = 8), pretreatment with IP butyrate 600 (n = 3) or 1200 mg/kg (n = 8) followed 2 h later by LPS, posttreatment with IP butyrate 600 (n = 3) or 1200 mg/kg (n = 7) 1 h after LPS, or butyrate 1200 mg/kg only (n = 8). Kidney and liver tissue were collected at 24 h to measure mitochondrial respiration, electron transport system (ETS) complex activity and subunit expression, and content (citrate synthase [CS] activity and mtDNA/nDNA). Kidney mitochondrial respiration was decreased after LPS compared to controls. Pretreatment with butyrate 1200 mg/kg increased kidney OXPHOSCI+II, ETSCI+II, ETSCII, and CIV respiration compared to LPS; posttreatment did not achieve significant increases except for OXPHOSCI. Liver mitochondrial respiration exhibited a similar pattern as in kidney, but differences were not significant. ETS complex and CS activity did not differ between groups, but CI and CII subunit expression trended higher with butyrate in kidney. Changes in mtDNA/nDNA followed a similar pattern as respiration in kidney and liver with a decrease after LPS that was not present with butyrate pretreatment. These data show that butyrate can prevent-but not significantly reverse-the LPS-induced decrease in kidney mitochondrial respiration without a clear effect in liver. Mitochondrial protection was not attributable to changes in ETS complex activity but may reflect maintenance of ETS subunit expression.

Optimizing the volume of drinking water sampling during the radiation and hygienic monitoring around the Belarusian NPP

Drinking water sampling is one of the key stages of radiation hygiene monitoring (RHM), both for planned radiation in the Belarusian NPP observation zone and for existing radiation in the areas affected by the Chernobyl accident. In Belarus, there is no uniform methodological document establishing the quantities of drinking water samples required to determine radiological indicators. The purpose of the paper wasto analyze the results of the radionuclide content study carried out in the Belarusian NPP observation zone and to justify the quantity of samples needed. In the 2017-2022 RHM, water samples from centralized (artesian wells) and non-centralized (wells) drinking water sources were taken in reference settlements located in the NPP's Belarusian observation zone. On the basis of the results of the research, the quantities of drinking water samples required and sufficient from wells have been evaluated. The study found that if the water is characterized by low levels of 137Cs activity (less than 0.01 Bq/l), the sample volume should be at least 100-150 l, and for 90Sr - at least 80 l. The data will allow selecting the required volumes of drinking water samples to determine the volumetric activity of radionuclides, including man-made ones - 137Cs and 90Sr, which will allow assessing the radiation safety of water supply sources and ensuring the reliability of the results of studies conducted within the RGM both in case of the planned irradiation (around the Belarusian NPP), and in areas with different levels of radioactive contamination as a result of the Chernobyl accident.

METHODOLOGY OF RECONSTRUCTION OF INTERNAL DOSES FROM 137Cs AND 134Cs OF RESIDENTS OF RADIOACTIVELY CONTAMINATED SETTLEMENTS IN UKRAINE NOT COVERED BY WBC MONITORING.

Scientific justification of the methodology for calculating radiation internal doses from 137Cs and 134Cs intake for residents of Ukrainian settlements radioactively contaminated as a result of the Chornobyl (Chernobyl) accident in which measurements of incorporated radiocesium isotopes in humans using whole-body counters (WBC) were not carried out. The paper presents a new methodology for reconstructing doses due to internal irradiation from Chornobyl fallout for both surface (in 1986) and root (in 1987-2023) contamination of vegetation with 137Cs and 134Cs and their transfer into the human body. The methodology for calculating the dose due to surface contamination of vegetation was based on the theoretical model of the transfer of radiocesium isotopes through the food chain with further adjustment of this model to the results of WBC measurements carried out between 15 July and 31 December 1986. For root intake, an ecological dosimetric model is used with the parameters determined by the types, quality and completeness of cow's milk and WBC monitoring carried out in radioactively contaminated territories in 1987-2013. In the absence of WBC measurements, the doses were estimated considering the properties and specifics of radioactive contamination of environmental objects in each region: soil type, levels of soil and milk contamination, and milk equivalent. A new methodology for reconstruction of internal doses from radionuclides 137Cs and 134Cs to residents of the territories of Ukraine radioactively contaminated due to the Chernobyl disaster is substantiated. The methodology is based on the analysis of all data obtained as the result of radioecological and dosimetric monitoring carried out in Ukraine after the accident. According to the methodology developed in the work, the calculation of annual internal doses to residents of settlements that were not covered by WBC monitoring is based on the measurements of the 137Cs activity in the milk of private farms, which were carried out in these settlements. In the absence of such measurements, a linear regression model which connect the incorporated in human body 137Cs with four groups of soils in the vicinity of the settlement is used for doses calculation. The doses calculated according to the new methodology agree with the dosesderived directly from the results of WBC measurements.

Circadian clock disruption impairs immune oscillation in chronic endogenous hypercortisolism: a multi-level analysis from a multicentre clinical trial

Glucocorticoids (GC) are potent entrainers of the circadian clock. However, their effects on biological rhythms in chronic human exposure have yet to be studied. Endogenous hypercortisolism (Cushing's Syndrome, CS) is a rare condition in which circadian disruption is sustained by a tumorous source of GC excess, offering the unique opportunity to investigate GC's chronic effects invivo. In a 12-month prospective case-control multicentre trial, the daily fluctuations in the number of circulating peripheral blood mononuclear cells (PBMCs) and the time-specific expression of clock-related genes were analysed in a cohort of 68 subjects, 34 affected by CS and 34 matched controls. Cosinor mixed effects model, rhythmicity algorithms and machine learning techniques were applied to the multi-level dataset. Multiple, 5-point daily sampling revealed profound changes in the levels, amplitude, and rhythmicity of several PBMC populations during active CS, only partially restored after remission. Clock gene analyses in isolated PBMCs showed a significant flattening of circadian oscillation of CLOCK, PER1, PER2, PER3, and TIMELESS expression. In active CS, all methods confirmed a loss of rhythmicity of those genes which were circadian in the PBMCs of controls. Most, but not all, genes regained physiological oscillation after remission. Machine learning revealed that while combined time-course sets of clock genes were highly effective in separating patients from controls, immune profiling was efficient even as single time points. In conclusion, the oscillation of circulating immune cells is profoundly altered in patients with CS, representing a convergence point of circadian rhythm disruption and metabolic and steroid hormone imbalances. Machine learning techniques proved the superiority of immune profiling over parameters such as cortisol, anthropometric and metabolic variables, and circadian gene expression analysis to identify CS activity. The research leading to these results has received funding from the European Union in the context of the National Recovery and Resilience Plan, Investment PE8 - Project Age-It: "Ageing Well in an Ageing Society". This resource was co-financed by the Next Generation EU [DM 1557 11.10.2022], the PRecisiOn Medicine to Target Frailty of Endocrine-metabolic Origin (PROMETEO) project (NET-2018-12365454) by the Italian Ministry of Health, and through internal funding to Sapienza University of Rome.

Effective Instructional Strategies for the Development of Computational Thinking in Primary Education: A Systematic Literature Review

Abstract This study consists of a 17-year (2006-2021) systematic literature review on the effective instructional strategies for developing Computational Thinking (CT) in primary school students (K-5). The aim of this paper is to identify instructional strategies that have been implemented and evaluated by means of a pre- and post-test, with the aim of developing CT as a thinking process (i.e. going beyond the mere acquisition of CS concepts). The analysis considers the overall pedagogical approach, with the intention of overcoming both the archetypal approaches to coding and the assessment tools used to measure CT acquisition. The results show that there is a strong difference between K-3 and 4-5 classes, the former being more the context for educational robotics or unplugged activities; they also show that a task-based approach is prevalent, whose effectiveness is limited to the first access to CS activities, namely improving self-efficacy and reducing learning anxiety. Nevertheless, this study also identifies some interesting models of problem solving (such as IGGIA or CPS) that go beyond the puzzle-based approach, as well as two significant teaching strategies (IDC and DBL) that try to promote more meaningful learning (typically including elements of constructionism), while enabling curricular learning objectives.

Appreciation of primary preservice teachers about the potential educational use of citizen science in environmental education

PurposeThis study aims to determine prior knowledge regarding the term “citizen science” (CS) and evaluate preservice teachers’ appreciation of the educational potential of CS.Design/methodology/approachFollowing the pedagogical framework of Experiential Learning Theory, a training program was designed for the subject of Environmental Education (EE) of the Primary Teacher Degree, incorporating CS activities. A quasi-experimental research was carried out with 36 primary preservice teachers who participated in this study, with a qualitative approach and without a control group. Two ad hoc surveys were defined for this study, the first one is related to prior knowledge about the term CS and a questionnaire was conducted to assess the educational potential of the CS after the implementation of the training program. The results showed a great initial lack of knowledge about CS but the appreciation of the preservice teachers after the educational intervention reveals the advantages and educational potential of CS.FindingsPreservice teachers consider that CS can and should be incorporated, as part of the course syllabus, into the teaching system and this can be done in scientific-technological subjects or in all subjects with an interdisciplinary and transversal approach, with the majority of responses indicating that the development of generic skills would be the greatest perceived benefit for students.Originality/valueThere has been an increase in CS initiatives and projects in recent decades. However, despite the advantages for the participants and actors involved, its incorporation into higher education curricula is scarce.

Shallow Lake, Strong Shake: Record of Seismically Triggered Lacustrine Sedimentation From the 1959 M7.3 Hebgen Lake Earthquake Within Henrys Lake, Idaho

AbstractWe investigate a shallow lake basin for evidence of a large historic intraplate earthquake in western North America. Henrys Lake, Idaho is an atypical candidate for lacustrine paleoseismic study given its shallow depth (∼7 m) and low relief (≤2° slopes). Here, we test the earthquake‐recording capacity of this basin type by showing sedimentological evidence of the 1959 M7.3 Hebgen Lake earthquake within sediment cores, using anthropogenically produced 137Cs activity to constrain timing. In addition to expanding the morphologic range of basins targeted for lacustrine paleoseismic studies, this work has implications for sediment response in dam‐enhanced basins. Lack of sedimentological evidence for other earthquakes coupled with radiocarbon chronology reveals that the 1959 event is the only clearly recorded earthquake within Henrys Lake since the mid‐Holocene. Henrys Lake offers a proxy for paleo‐earthquake signatures within similar lacustrine environments and underscores the importance of further paleoseismic studies in the region.

Dragonflies (Odonata) as bioindicators of radioactivity

ABSTRACT Bioindicators are living organisms that are successfully used for monitoring changes in the environmental health due to natural and/or anthropogenic influences. Dragonflies (Odonata) are considered to be good indicators of water quality; however, research on dragonflies as potential indicators of radioactivity is scarce. The aim of this study was to evaluate dragonflies as potential biological indicators of ionising radiation in nature by measuring 137Cs activity concentrations in the dragonfly and river water samples. Altogether, 11 collective samples of dragonflies were collected from the bank of the Mura–Drava–Danube Biosphere Reserve, in the area of Virovitica–Podravina County. Following the initial sample preparation, the gamma spectrometry technique, employing an ORTEC HPGe detector system, was utilised to determine the activity concentrations of 137Cs. The results show that the activity concentrations of 137Cs in the river water were in the range from 4 to 13 Bq/m3. The results of dragonfly samples showed that 137Cs was in the range from 1.7 to 3 Bq/kg. This was more than a hundred times higher than in the river Drava water. According to the obtained results, we conclude that dragonflies could be used as potential bioindicators of radioactivity.

Long-Term Investigation (1968–2023) of 137Cs in Apples

Due to the consequences of nuclear and/or radiological accidents in the past (Chernobyl, Fukushima, etc.), and potential future events of that kind, the constant monitoring of environmental radioactivity is important. There are different pathways of the transfer of radionuclides from environment to humans (ingestion, inhalation and external). Food ingestion greatly contributes to the total effective dose; hence, it is of great importance to investigate exposure to radionuclides through food. This paper presents the results of a long-term investigation of 137Cs activity concentration in apples in northwestern Croatia for the period 1968–2023. The highest 137Cs activity concentration in apples was measured in 1986, decreasing exponentially ever since. The Fukushima-Daiichi accident in 2011 did not cause a significant increase in 137Cs activity concentration, although the presence of the consequent fallout was detected via the appearance of 134Cs in some parts of the environment. The observed residence time for 137Cs in apples was estimated to be 4.5 and 3.9 years for the pre-Chernobyl and post-Chernobyl periods, respectively. The correlation between 137Cs in fallout and apples is very good, the correlation coefficients being 0.99, which indicates that fallout is the main source of contamination. The estimated effective dose received by adult members of the Croatian public due to intake of radiocaesium from apples over the overall observed period is 6.4 µSv. Therefore, the consumption of apples was not a critical pathway for the transfer of radiocaesium to humans.

A Novel Anthropometric Phantom for Rapid Radiological Triage: A Quick Sort Triage Solution.

Rapidly identifying individuals who have received internal radiation exposure above action guidelines is crucial for mitigating health risks and addressing public concerns immediately following a radiological event involving the dispersal of radioactive materials. This study describes a novel triage method using a conventional Geiger-Mueller (GM) detector to select those individuals from the large group of persons who may have received an intake of radioactive material at levels corresponding to one Clinical Decision Guide (CDG). The triage method involves placing a portable GM detector against the lower anterior torso of a sitting person as they bend over to surround the detector with their body. The response of the GM detector is evaluated using a new, specially designed anthropometric phantom that simulates combined tissues of the lower thorax and gastrointestinal (GI) tract and is fabricated with a tissue substitute material that matches the overall radiological properties of human tissue present in this body region. The phantom has four separate layers of tissue substitute material with ports to accommodate a single GM detector at the center and one or more sealed radioactive sources that can be arranged to characterize the detector response for a variety of source distributions, including a "hot spot." In this study, the response of a Ludlum Model 133-4 GM detector was evaluated using sealed sources of 232Th and 137Cs to determine the measurement efficiency for a quantity of activity present in the abdomen within a few hours post-intake equivalent to 1 CDG. Results demonstrate that the Quick Sort triage procedure using a single GM detector placed against the abdomen of a person can reliably detect internal deposition resulting from an intake equivalent to 1 CDG for 232Th or a significantly lower activity of 137Cs within a few hours following a radiological incident. The evaluation was performed over a wide range of photon energies, so the Quick Sort triage procedure is expected to be suitable for most fission products distributed uniformly within the abdomen or as a single "hot spot."

ОГЛЯД РЕЗУЛЬТАТІВ ДОСЛІДЖЕНЬ ЗАБРУДНЕННЯ КАХОВСЬКОГО ВОДОСХОВИЩА ЦЕЗІЄМ-137 І СТРОНЦІЄМ-90, ЯКІ ПРОВОДИЛИСЬ ПІСЛЯ АВАРІЇ НА ЧОРНОБИЛЬСЬКІЙ АЕС (1986-1921 РР.)

The available data on the state of radioactive contamination of water and bottom sediments of the Kakhovka Reservoir were analyzed in order to assess the possible deterioration of the quality of the environment based on the indicators of radioactive contamination in the zone of influence of the emergency discharge of water due to destruction of the Kakhovka NPP dam by the Russian military. Contamination of the Kakhovka Reservoir with 137Cs occurred mainly through the fallouts of this radionuclide with aerosols on the water surface in May 1986. A much smaller part of this radionuclide transported by water runoff directly from the headwaters of the Dnieper basin. Strontium-90 entered the reservoir exclusively by water pathway starting from October 1986. The steady trends of decreasing activity of both radionuclides in water has been observed since 1987. Approximately to 1996 137Cs activity concentrations had decreased to pre-accident level, 90Sr activity demonstrated a slow decrease and by 2022 remained slightly higher than pre-accidental level. The average levels of contamination of the Kakhovka reservoir bottom with 137Cs and 90Sr turned out to be the lowest compared to the other reservoirs of the Dnieper cascade. It was shown that in 1994 137Cs activity levels were 0.06 Ci/km2(2,2 kBq/m2) on 80% of the bottom surface (submerged former floodplain of the Dnieper) and were lower than on the territory adjacent to the reservoir. In the areas of silt accumulation (former channel of the Dnieper) 137Cs activity was on average three times higher. Balance calculations based on the data of radiation monitoring of water showed that the amount of 137Cs activity in the bottom sediments in the period 1987-2022 halved due to natural radioactive decay, the amount of 90Sr activity decreased by approximately 20%, since activity losses due to natural radioactive decay were partially compensated by the constant supply of this radionuclide with water runoff from the contaminated part of the catchment. After a catastrophic water leak from the reservoir, the Dnieper floodplain had exposed. According to the calculations, the average density of soil contamination of the ехposed areas with 137Cs does not exceed 0.03 Ci/km2 (1,1 kBq/m2), with 90Sr – less than 0.1 Ci/km2 (3,7 kBq/m2). Silt deposits of the former Dnieper channel, which had an increased level of 137Cs contamination, were re-suspended, probably, and carried out into the Dnipro-Bug estuary and further into the Black Sea. However, according to our assumptions, this should not have a negative effect on the radioecological state of the sea, because the 137Cs activity concentrations in the water of north-western part of the Black Sea were always 20-30 times higher than in the Dnieper water.

Phytohormonal balance and differential gene expression in chronically irradiated Scots pine populations from the chernobyl affected zone.

The impact of chronic radiation exposure on phytohormone content and expression of phytohormone- and stress-related genes of Scots pine in the zone affected by the Chernobyl accident was studied. Needle samples were collected from three plots with contrasting levels of radioactive contamination in the Polesye State Radiation-Ecological Reserve, Republic of Belarus, and two reference plots in the Kozeluzhsky forest in June 2022. The experimental plots were located within the artificial plantations of Scots pine established in 1982, before the accident in 1986. The activity of radionuclides 137Cs, 90Sr, 241Am, 238Pu, and 239+240Pu in soil and needles ensured dose rates ranging from 3.3 to 87 mGy × year-1, while at the reference plots, the range was 0.7‒0.8 mGy × year-1. Concentrations of plant hormones, including indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), zeatin, and abscisic acid (ABA) in needles were evaluated using high-performance liquid chromatography (HPLC). We demonstrate that chronic radiation exposure is a significant stress factor that affects both phytohormonal balance and the expression of some important phytohormone- and stress-related genes. We found a tendency toward decreased ABA and auxin concentrations in trees from plots contaminated with radionuclides. The ratio (IAA + IBA + zeatin)/ABA was drastically raised at the most contaminated plots Masany and Kulazhin, reflecting the functional rearrangements of cellular metabolism that ensure plant adaptation under chronic radiation exposure. Changes in gene expression indicated modulation of ABA and Ca2+ signalling pathways, decreased potential of zeatin biosynthesis, and activation of heat shock proteins biosynthesis.

Activity concentrations of 60 Co, 137Cs and 241Am in sieved soil and soil inclusions from the «Taiga» peaceful nuclear explosions site

The article presents results of comparative study of 137Cs, 60Co, and 241Am activity concentrations in components of the soil samples collected in 2009 on the territory adjacent to the «Taiga» peaceful nuclear explosions site (the Perm region, Russia). The objective of the study was to identify differences between: 1) non fractionated native soil, 2) the soil passed through a sieve with a mesh size of 1.2 mm, and 3) the screened out coarse components. Measurements of the radionuclides activities in counting samples were performed using a semiconductor gamma spectrometer. Statistically significantly lower activity concentrations of 137Cs (factor of 1.2), 60Co (factor of 2.2) and 241Am (factor of 2.6) were found in the finely dispersed sieved fraction of soil compared to the native soil. On the opposite, in the solid radioactive inclusions selected from the screened out coarse fraction, the activity concentrations of 137Cs, 60Co and 241Am were significantly higher compared to those in the native soil. Especially large differences (up to a factor of 10 and more) between the native soil and radioactive inclusions were observed for the refractory and low-volatile 60Co and 241Am. Presumably, these radionuclides were concentrated predominantly in the glassy substance of the radioactive inclusions. For 137Cs, the unevenness in the contamination of different soil components was less pronounced. The results obtained will be used to standardize methods for assessing radioactive contamination of the territory at the sites of peaceful nuclear explosions

Biofilm-mediated interactions between plastics and radiocesium in coastal environments.

A ubiquitous distribution of plastic debris has been reported in aquatic and terrestrial environments; however, the interactions between plastics and radionuclides and the radioactivity of environmental plastics remain largely unknown. Here, we characterize biofilms developing on the surface of plastic debris to explore the role of plastic-associated biofilms as an interaction medium between plastics and radiocesium (137Cs) in the environment. Biofilm samples were extracted from plastics (1-50mm in size) collected from two contrasting coastal areas in Japan. The radioactivity of plastics was estimated based on the 137Cs activity concentration of the biofilms and compared seasonally with surrounding environmental samples (i.e., sediment and sand). 137Cs traces were detected in biofilms with activity concentrations of 21-1300Bq·kg-1 biofilm (dry weight), corresponding to 0.04-4.5Bq·kg-1 plastic (dry weight). Our results reveal the interaction between 137Cs and plastics and provide evidence that organic and mineral components in biofilms are essential in 137Cs retention in environmental plastics. Given the ubiquitous distribution of plastic debris in the environment, more attention should be directed to bioaccumulation and the radioecological impacts of plastic-associated radionuclides on ecosystems.

Natural radionuclide and <sup>137</sup>Cs activity concentration in soils of the Brazilian State of Sergipe and their correlation with environmental characteristics

Radionuclides occur naturally in the environment, exposing living organisms to ionizing radiation. In addition, human activities have introduced artificial radionuclides such as 137Cs, among others, into the environment. To better understand the occurrence and behaviour of radionuclides in soil, several countries have developed radiological studies and constructed maps. An effort has been made in Brazil to assess the radioactivity in the soils of the country. In this study, the activity concentrations of natural radionuclides 40K, 226Ra and 228Ra, and artificial 137Cs were determined in samples at a depth of 20 cm collected from the soils of the Brazilian State of Sergipe, in a regular grid of 25 km x 25 km. Samples were analysed by gamma-ray spectrometry with the use of hyperpure germanium detectors. The results were correlated with the type of soil, geology, and climate characteristics of the State. The median activity concentrations of 40K, 226Ra, and 228Ra were 210.4 Bq.kg-1, 12.33 Bq.kg-1, and 18.69 Bq.kg-1, respectively. The results are lower than those reported for soils from other Brazilian States in the same region. The activity concentration of 137Cs was lower than the minimum detectable activity. The activity concentration of 40K in young soils of the semi-arid region was higher than that found in most weathered soils of the rainy regions due to the very low pluviometry of the semi-arid area. Higher activity levels of 226Ra were found in Planosol and for 228Ra it was found in the weathered soils (Acrisol) of the coastal zone. Maps of the distribution of the studied radionuclides were designed. The median value of the outdoor absorbed dose rate in air (Dnat) calculated for the soils of the State of Sergipe is lower when compared with other Brazilian States and the UNSCEAR’s worldwide median value.

The study of radionuclide activities in the sediments of deep areas of Skagerrak and Southern Baltic

This study investigates the activities of radionuclides (137Cs, 210Pb, 214Pb, 239,240Pu, and 40K), carbon isotopes (δ13C and 14C), and grain size compositions in surface bottom sediments across the southern Baltic and Skagerrak Strait. Our findings reveal significant connections between these parameters and their dependence on sediment transport dynamics. The distribution patterns of natural and artificial radionuclides were studied to understand the factors influencing their transport to the deep areas. The results show that 137Cs activity in surface bottom sediments (0–5 cm) ranges from 8 to 11 Bq/kg in the Skagerrak area and reaches 220 Bq/kg in the southern Baltic, closer to the vicinity of river discharges. The activity ranges of 239,240Pu are similar between the study areas, but the mean value at the Skagerrak site is higher at 1.6 Bq/kg. The transport of 210Pbex to the bottom is mainly dependent on the number of fine particles (0–20 μm) in the water column, while the transport of 137Cs primarily driven by scavenging by marine organics from the water column. In the southern Baltic, a strong correlation indicates that a significant share of 137Cs most likely originates from fluvial input. The particle size distribution reflects calm conditions in the deep waters, while in the Curonian Lagoon reference areas there are pronounced contrasts between stations with strong and calm hydrodynamic conditions. The δ13C values in the surface bottom sediments decrease towards river discharge areas, reflecting an increased terrestrial component of the organic fraction, and the number of coarse particles also increases.

Трансформация радиоактивного загрязнения донных отложений Калининградского залива в период 2011–2023 гг.

The article presents the data of radioecological research of the bottom sediments in the Russian zone of the Vistula Lagoon in 2011–2023. According to research, the specific activity of 137Cs in the bottom sediments of the Lagoon was in the range of 3,9–165 Bq/m3. 137Cs is the main technogenic radionuclides that makes the greatest contribution to the pollution of the Lagoon. Contamination of the bottom sediments with 137Cs is determined by the redistribution of mainly post-Chernobyl fallout. The 137Cs accumulation was recorded in the northern deep-water part of the Primorskaya Bay. According to observations, the effective half-life of 137Cs activity in the sediments of the Lagoon is 10,4–42 years. The content of natural radionuclides is: 226Ra – from 9,0 to 35,3; 232Th – from 3,8 to 43,2; 40K from 227 to 715 Bq/kg. The NRN specific activity in the sediments of the Lagoon did not exceed 153 Bq/kg, which was significantly lower than the established safe level (370 Bq/kg), allowing their handling without restrictions. The correlations between the content of 40K, 226Ra, 232Th in the bottom sediments of the Lagoon were established with the type of sediment