137Cs Activity Research Articles

137Cs Sediment Profiles as a Tracer of Marine Sedimentation Processes in a Semi-Enclosed Bay Affected by Anthropogenic Releases—Example of Kaštela Bay (Adriatic Sea, Croatia)

Kaštela Bay was taken as a model to study sedimentation processes using the vertical sediment profiles of 137Cs massic activities. The aim was to distinguish the sedimentation conditions in different parts of the Bay and to partly determine the pathways of terrigenous input into the Bay. The purpose was to demonstrate that 137Cs profiles are applicable in differentiating sedimentation processes. It was found that mostly continuous, undisturbed sedimentation takes place in the central and south parts of the Bay; the sedimentation conditions in the west part of the Bay are more complicated. The west part is characterised by the extremely slow sedimentation of the coarse-grained sediment or even by erosion and selective resuspension of the fine-grained particles followed by resedimentation in other parts of the Bay. It was also observed that the upper 10 cm of the sediment is the most exposed to homogenisation. The strong influence of the Jadro River and anthropogenic activities in the east part of the Bay are reflected in the higher 137Cs activities, strong sediment mixing, and increased sediment input. This study shows that the 137Cs profiles can provide comprehensive insights for the whole study region when a sophisticated sampling layout is deployed. The results of the study are applicable to other aquatic environments with comparable processes and sedimentary environments.

Topography and land use impact erosion and soil organic carbon burial over decadal timescales

To provide a more accurate assessment of soil organic carbon (SOC) stocks in agroecosystems, sampling strategies should be designed in a way that accounts for topographic variability and soil redistribution via erosion and deposition. While the importance of topography for influencing soil properties is long established, recent advances in digital elevation models (DEMs) permit more rapid assessment of topographic attributes. We determined primary terrain attributes from a 3 m DEM to guide sampling in cultivated fields and nearby grasslands in Southeastern Minnesota, USA. Soil samples were analyzed to quantify SOC stocks and activity of 137Cs, a radioisotope employed to track soil movement over decadal timescales. In addition to soil depth, digital terrain attribute values were important for developing predictive models in both cropland and grassland sites but contributed more to predictions in cropland soils. Profile and planform curvature were significant terms in the regression model for both cropland and grassland soils. Additionally, percent slope was also significant in models for cropland soils. Overall, regression models were able to explain 90% and 73% of variability in SOC stocks observed in grassland and cropland sites, respectively. Soil profile 137Cs inventories were correlated with SOC stocks in both land cover types and show that soil movement can explain SOC variability in upland soils. Soil erosion or deposition rates (based on 137Cs inventories) ranged from 34.8 (erosion) to −70.1 (deposition) t ha−1 yr−1 in cropland sites and from 11.7 to −17.2 t ha−1 yr−1in grassland sites. Results from this study showed that soil redistribution can result in burial of eroded OC-rich surface soil in depositional locations characterized by low slopes and concave curvature in agricultural fields.

DETERMINING THE TRANSFER FACTORS FOR ESTIMATES OF THE RADIATION CONTAMINATION OF AGRICULTURAL CROPS

The study aims to provide a basis for measures reducing the consequences of a nuclear accident in its late phase, when plant contamination occurs mainly through the root system. Samples of the above-ground biomass of crops and soil were taken in 2020 in the vicinity of the Temelín and Dukovany nuclear power plants (Czech Republic). The 137Cs activities were determined using gamma spectrometry, and the 90Sr activities were measured through beta radiation. From the obtained values, the radionuclide transfer factors (TFs) from soil to crop biomass were calculated. The average area activity of 137Cs in the soil around Dukovany and Temelín was 1700 and 2400Bqm-2, respectively. The average area activity of 90Sr around Dukovany and Temelín was 211 and 184Bqm-2, respectively. The TF 137Cs ranged from < 6.3 × 10-6 to 7.9 × 10-3, with a mean of 3.5 × 10-4m2kg-1, and the TF 90Sr ranged from 2.7 × 10-4 to 6 × 10-2, with a mean of 1.7 × 10-2m2kg-1.

A new approach to extracting biofilm from environmental plastics using ultrasound-assisted syringe treatment for isotopic analyses

Plastics are one of the ubiquitous and artificial types of substrates for microbial colonization and biofilm development in the aquatic environment. Characterizing plastic-associated biofilms is key to the better understanding of organic material and mineral cycling in the “Plastisphere”—the thin layer of microbial life on plastics. In this study, we propose a new method to extract biofilms from environmental plastics, in order to evaluate the properties of biofilm-derived organic matter through stable carbon (δ13C) and nitrogen (δ15N) isotope signatures and their interactions with radionuclides especially radiocesium (137Cs). The extraction method is simple and cost-effective, requiring only an ultrasonic bath, disposable plastic syringes, and a freeze drier. After ultrasound-assisted separation from the plastics, biofilm samples were successfully collected via a sequence of syringe treatments, with less contamination from plastics and other mineral particles. Effective removal of small microplastics from the experimental suspension was satisfactorily achieved using the method with syringe treatments. Biofilm-derived organic matter samples (14.5–65.4 mg) from four river mouths in Japan showed 137Cs activity concentrations of <75 to 820 Bq·kg−1 biofilm (dw), providing evidence that environmental plastics, mediated by developed biofilms, serve as a carrier for 137Cs in the coastal riverine environment. Significant differences in the δ13C and δ15N signatures were also obtained for the biofilms, indicating the different sources, pathways, and development processes of biofilms on plastics. We demonstrate here a straightforward method for extracting biofilms from environmental plastics; the results obtained with this method could provide useful insights into the plastic-associated nutrient cycling in the environment.

Accumulation of 137Cs by Thallus of Epiphytic Lichen Hypogymnia physodes (L.) Nyl on Different Trunk Height in Pine Stands

Lichens are considered by researchers as bioindicators of environmental pollution by artificial radionuclides, including 137Cs. One of these bioindicator species is epiphytic lichen Hypogymnia physodes (L.) Nyl, the use of which for radioecological monitoring can be modified by several factors: tree species, placement on the tree (branches – trunk), height of sampling, etc. The purpose of this study was to investigate the specific activity of 137Cs in thalli of hypogymnia in pine stands: on trunks of Pinus sylvestris L. and Betula pendula Roth at different heights of sampling in 3 height ranges: 0–65, 65–130, and 130–195 cm, and to analyse the intensity of radionuclide accumulation in the “lichen thallus – tree bark” link for both tree species in all height ranges. The study was conducted in August 2021 in the Korosten district of the Zhytomyr Oblast, Zhytomyr Polissia, on 4 test plots, in the Drevlianskyi nature reserve, mainly in middle-aged pine stands with an admixture of birch, where 130 samples of soil, tree bark, and lichen were taken. Specific activity of 137Cs in the samples was measured using a SEG-001 “AKP-s”-150 gamma-ray spectrometer with a BDEG-20R2 scintillation detector (NaI(Tl). It was demonstrated that the content of 137Сs in the thalli of Hypogymnia physodes at different altitude ranges did not differ statistically significantly at the 95% confidence level in all test plots on pine. A preliminary conclusion was made on the possibility of sampling Hypogymnia physodes thalli on pine trunks in the height range of 0–195 cm; however, for the convenience of sampling, it is recommended to perform sampling within 130–195 cm. It has been proven that both the specific activity of 137Сs in Hypogymnia physodes thalli and the intensity of 137Сs accumulation in the chain “Hypogymnia physodes - tree bark” are approximately 2 times higher on pine compared to birch. It was found that on a birch, the content of 137Сs in lichen between the height ranges of 0–65 and 65–130 cm, and 0–65 and 130–195 cm differs significantly at the 95% confidence level; therefore, it is recommended to sample Hypogymnia physodes on a birch in the range of 65–130 cm.

Radiation monitoring of foodstuffs and drinking water in the vicinity of the Rooppur Nuclear Power Plant (People’s Republic of Bangladesh)

The system of radiation monitoring of local foodstuffs and drinking water in the settlements of the area of the Rooppur Nuclear Power Plant was developed. An analysis of the results of a 4-year (2014–2017) cycle of studies on the assessment of the specific activity of natural (40K, 226Ra, 232Th) and artificial (90Sr, 137Cs) radionuclides in the components of the diet of the population of the 30-km zone of influence of the nuclear power plant is presented. Thus, the specific activity of the most radiologically significant 137Cs in cow's milk averages 0.05 Bq.L−1, beef − 0.14, poultry − 0.09, and fish − 0.15 Bq.kg−1. In cereals, the 137Cs content varies in the range 0.2–0.6, vegetables 0.03–0.11, fruits 0.05–0.1 Bq.kg−1 and is determined by the species characteristics of crops. It was noted that 90Sr accumulates in food products to a greater extent than 137Cs. In livestock production, this difference is 1.2–6.8 times, fish 1.5 times, grain 1.2–4.2, vegetables 1.5–8.2, fruits 1.8–5.8 times. In drinking water, the specific activity of 137Cs is at the level of 0.05, 90Sr − 0.03, 3H − 1.3 Bq.L−1. The coefficients of accumulation of 90Sr and 137Cs in foodstuffs of animal and plant origin have been calculated.

Activity concentration of 137Cs in undisturbed attic dust collected from Salgótarján and Ózd (northern Hungary)

Due to the Chernobyl nuclear power plant accident, contaminated air masses, containing 137Cs, were widely propagated across all of Europe. Cesium-137 is easily adsorbed on aerosol particles as it returns to the lithosphere/pedosphere/via wet and dry deposition in the form of a radioactive fallout component. Following the nuclear accident, primary attention was paid to agricultural areas and less to urban environments. Our 137Cs activity study using undisturbed attic dust samples has been carried out from two residential areas (city of Salgótarján and Ózd) in northern Hungary, approx. 1000 km away from Chernobyl. A total of 61 attic dust samples were collected in 2016 and 2018 from houses (>30 years) functioning as family house, kindergarten, blockhouse and church. Activity concentration of 137Cs was determined for 1–2 g homogenized (<125 μm) attic dust samples in a low background iron chamber with a well-type HPGe detector. The mean 137Cs activity concentrations in attic dust samples are 88.5 ± 5.1 Bq kg−1 and 87.8 ± 4.5 Bq kg−1 in Salgótarján and Ózd, respectively. The dependence between 137Cs activities and the age of the houses was found to be significant (p=0.02), which could be explained by Chernobyl nuclear accident-causing elevated activity concentrations in location built prior to the accident. Three outliers in Ózd (>223 Bq kg−1), are probably related to the first rainfall event after the Chernobyl accident. Isotopic landscapes (isoscapes) of 137Cs were derived for both cities by means of kriging interpolation. In Salgótarján the 137Cs activity concentrations were higher than in Ózd which might have been due to redistribution loadings and local topographical features. We concluded that components of attic dust are highly useful indicators of home exposure to pollution events and remain detectable after several decades.

Aerobic training increases mitochondrial respiratory capacity in human skeletal muscle stem cells from sedentary individuals.

The impact of aerobic training on human skeletal muscle cell (HSkMC) mitochondrial metabolism is a significant research gap, critical to understanding the mechanisms by which exercise augments skeletal muscle metabolism. We therefore assessed mitochondrial content and capacity in fully differentiated CD56+ HSkMCs from lean active (LA) and sedentary individuals with obesity (OS) at baseline, as well as lean/overweight sedentary individuals (LOS) at baseline and following an 18-day aerobic training intervention. Participants had in vivo skeletal muscle PCr recovery rate by 31P-MRS (mitochondrial oxidative kinetics) and cardiorespiratory fitness (V̇o2max) assessed at baseline. Biopsies of the vastus lateralis were performed for the isolation of skeletal muscle stem cells. LOS individuals repeated all assessments posttraining. HSkMCs were evaluated for mitochondrial respiratory capacity by high-resolution respirometry. Data were normalized to two indices of mitochondrial content (CS activity and OXPHOS protein expression) and a marker of total cell count (quantity of DNA). LA individuals had significantly higher V̇o2max than OS and LOS-Pre training; however, no differences were observed in skeletal muscle mitochondrial capacity, nor in carbohydrate- or fatty acid-supported HSkMC respiratory capacity. Aerobic training robustly increased in vivo skeletal muscle mitochondrial capacity of LOS individuals, as well as carbohydrate-supported HSkMC respiratory capacity. Indices of mitochondrial content and total cell count were similar among the groups and did not change with aerobic training. Our findings demonstrate that bioenergetic changes induced with aerobic training in skeletal muscle in vivo are retained in HSkMCs in vitro without impacting mitochondrial content, suggesting that training improves intrinsic skeletal muscle mitochondrial capacity.

Decadal trends in 137Cs concentrations in the bark and wood of trees contaminated by the Fukushima nuclear accident

Understanding the actual situation of radiocesium (137Cs) contamination of trees caused by the Fukushima nuclear accident is essential for predicting the future contamination of wood. Particularly important is determining whether the 137Cs dynamics within forests and trees have reached apparent steady state. We conducted a monitoring survey of four major tree species (Japanese cedar, Japanese cypress, konara oak, and Japanese red pine) at multiple sites. Using a dynamic linear model, we analyzed the temporal trends in 137Cs activity concentrations in the bark (whole), outer bark, inner bark, wood (whole), sapwood, and heartwood during the 2011–2020 period. The activity concentrations were decay-corrected to September 1, 2020, to exclude the decrease due to the radioactive decay. The 137Cs concentrations in the whole and outer bark samples showed an exponential decrease in most plots but a flat trend in one plot, where 137Cs root uptake is considered to be high. The 137Cs concentration ratio (CR) of inner bark/sapwood showed a flat trend but the CR of heartwood/sapwood increased in many plots, indicating that the 137Cs dynamics reached apparent steady state within one year in the biologically active parts (inner bark and sapwood) and after several to more than 10 years in the inactive part (heartwood). The 137Cs concentration in the whole wood showed an increasing trend in six plots. In four of these plots, the increasing trend shifted to a flat or decreasing trend. Overall, the results show that the 137Cs dynamics within forests and trees have reached apparent steady state in many plots, although the amount of 137Cs root uptake in some plots is possibly still increasing 10 years after the accident. Clarifying the mechanisms and key factors determining the amount of 137Cs root uptake will be crucial for predicting wood contamination.

MACROMYCETES AS BIOINDICATORS OF RADIONUCLIDE CONTAMINATION IN FOREST ECOSYSTEMS

The aim of the paper is to determine the specific activity of radionuclides in macromycetes in Ulyanovsk region forest ecosystems exposed to radiation after the Chernobyl accident.&#x0D; Materials and Methods. The fruiting bodies of macromycetes (soil and wood-destroying fungi) gathered in the radioactive contaminated territories served as the material for the research. The authors determined the specific activity of Cs-137, K-40, Ra-226, Th-232 radionuclides. The study was conducted during the growing season in the Ulyanovsk region forests (Inza and Karsun districts). For comparison, fungi samples (control) were also gathered in the Novospassky region, where the excess background radiation was not observed. Trial sites with similar forest growth conditions were selected. The specific activity of radionuclides in the fungi fruiting bodies was determined according to Guidelines 2.6.1.1194–03.&#x0D; Results. In soil fungi, the highest average Cs-137 specific activity was found in the fruiting bodies of Leccinum scabrum, K-40 and Ra-226 specific activity – in the fruiting bodies of Suillus luteus, and Th-232 specific activity – in the fruiting bodies of Macrolepiota procera.&#x0D; In wood-destroying fungi, the highest average Cs-137, K-40 and Ra-226 specific activity was observed in the fruiting bodies of Fomitopsis pinicola, and the highest Th-232 specific radioactivity – in the fruiting bodies of Coriolus versicolor. The average specific activity of all radionuclides in the mushrooms from the radioactive contamination territories (Inza and Karsun districts) was mainly higher than in the control (Novospassky district). In the studied samples of soil and wood-destroying fungi, excess radioactive concentrations were not found.&#x0D; Conclusion. Forest mycobiota can be used as a bioindicator of radioactive environmental pollution.

Spatial and vertical distribution of 137Cs activity concentrations in lake sediments of Turawa Lake (Poland).

The main objective of this research was to study the spatial and vertical distribution of 137Cs activity concentrations in the bottom sediments of Turawa Lake 32years after the Chernobyl fallout to investigate possible factors responsible for the post-fallout migration and accumulation of 137Cs in the selected reservoir. The results demonstrated a strong relationship between the increasing 137Cs and 40K activity concentrations and the decreasing grain size of sediments. Significant amounts of 137Cs were detected in the bottom sediments deposited in the deeper parts of the reservoir (especially near the dam). Therefore, this research showed that Turawa Lake can be an important trap for sediments polluted with 137Cs. Moreover, disturbed vertical distribution of 137Cs activity concentrations in the sediment columns collected from the littoral zone of this lake was observed, which is probably related to the bottom erosion intensified by wind-wave action, bioturbations, and water-level fluctuations. In the profundal zone, the vertical distribution of 137Cs activity concentrations was undisturbed, which indicates stable sedimentation conditions in this part of Turawa Lake.

Gamma-ray absorbing characteristic of obsidian rocks as a potential material for radiation protection

In this study, natural radionuclide levels and mass absorption coefficients of obsidian samples were examined to determine their gamma radiation properties. Fourteen obsidian samples were collected from 7 different locations in Rize province, İkizdere region, Turkey. X-ray fluorescence measurements of the samples revealed the silica structure and comparable elemental structure with slight differences in atomic ratios. Radionuclide analysis showed that the 137Cs activity was below the detection limit, and the mean activities of 238U, 232Th and 40K were 93 ± 9, 67 ± 7, 1027 ± 19 Bq.kg−1, respectively. The average experimental mass absorption coefficients at 81.0 keV, 302.9 keV, 356.0 keV and 661.7 keV were found to be 0.216, 0.108, 0.098 and 0.080 cm2 g−1, respectively. In the <100 keV region which the photoelectric effect is dominant, differences among the absorption coefficients were more pronounced, while it was relatively much smaller in the intermediate energy region. Also, it was seen that the absorption coefficients of the samples were higher than many materials, especially in the low energy region. The average half-value thicknesses showed that obsidian between 1.43 cm and 3.84 cm depending on the photon energy should be used to halve the radiation intensity. In addition, it was determined that the thicknesses in the range of 4.75 cm–12.76 cm were sufficient to reduce the intensity to one tenth. Considering all the analysis results, it can be said that obsidian is a potential material in radiation protection and its absorption properties can be improved by processes such as elemental doping.

Spatial Variations of the Activity of 137Cs and the Contents of Heavy Metals and Petroleum Products in the Polluted Soils of the City of Elektrostal

The levels of specific activity of 137Cs and the contents of mobile forms (1 M ammonium acetate extraction) of heavy metals (Zn, Cu, Ni, Co, Cr, Pb) and petroleum products were studied in the upper soil horizon of urban landscapes of the city of Elektrostal under conditions of local radioactive and chemical contamination were studied. In the soils within a short radius (0–100 m) around the heavy engineering plant, the specific activity of 137Cs and the contents of mobile forms of Pb, Cu, and Zn were increased. The lognormal distribution law of 137Cs was found in the upper (0–10 cm) soil layer; five years after the radiation accident, the specific activity of 137Cs varied from 6 to 4238 Bq/kg. The coefficients of variation increased with an increase in the degree of soil contamination in the following sequence: Co < Ni < petroleum products < Cr < 137Cs < Zn < Pb < Cu ranging from 50 to 435%. Statistically significant direct correlation was found between the specific activity of 137Cs and the contents of mobile forms of Pb, Cu, and Zn in the upper horizon of urban soils, and this fact indicated the spatial conjugacy of local spots of radioactive and polymetallic contamination in the studied area. It was shown that the specific activity of 137Cs, as well as the content of heavy metals and petroleum products in the upper layer (0–10 cm) of the soils disturbed in the course of decontamination, earthwork and reclamation is reduced.

High-resolution records of cesium, plutonium, americium, and uranium isotopes in sediment cores from Swiss lakes

The Aare river system in Switzerland, with two nuclear power plants on the banks of the river, and its intermediate lakes and reservoirs, provides a unique opportunity to analyze the contribution of different sources to the radioactive contamination. Sediment cores were collected from two lakes and a reservoir, all connected by the river Aare. In order to study the influence of the Chernobyl accident, one sediment core was collected from a lake in the southern part of Switzerland. The sediment cores were sliced and analyzed with gamma ray spectrometry. Plutonium, americium, and uranium were extracted radiochemically, and their concentrations were measured with a sector field ICP-MS. The uranium isotope ratios were further measured with a multi collector ICP-MS. The maximum 137Cs activity from the Chernobyl accident and the Pu and 137Cs activities associated to the 1963 global fallout maximum were well identified in sediments from all three lakes. High-resolution records of plutonium isotopes in the zone of the sediments corresponding to the period of maximum fallout from the atmospheric nuclear weapon testing showed distinct fingerprints, depending on the different test activities. Pu isotope ratios could be used to detect non-global fallout plutonium. The ratio 241Am/241Pu was used to determine the age of the plutonium. Despite of very low 241Pu and 241Am concentrations, the calculated plutonium production dates seemed to be reasonable for the sediment layers corresponding to the NWT tests. The calculated production date of the plutonium in the upper most 15 cm of the sediment core seemed to be younger. The reason for this could be additional non-global fallout plutonium. For the lake sediments, natural ratios for 235U/238U and enriched or depleted ratios for 234U/238U were measured, depending on the lake. A small increase of the 236U/238U ratio could be recognized for the NWT zone in all three lakes and, for Lake Lugano, a further distinct increase in the Chernobyl layer.

Radiocesium-bearing microparticles cause a large variation in 137Cs activity concentration in the aquatic insect Stenopsyche marmorata (Tricoptera: Stenopsychidae) in the Ota River, Fukushima, Japan.

After the Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Plant accident in Japan, freshwater ecosystems near the site remained contaminated by radiocesium (RCs). Clarifying RCs concentrations in aquatic insects is crucial because fishes consume these insects that transfer RCs into freshwater ecosystems. As aquatic insects are usually measured for radioactivity in bulk samples of several tens of insects, variation in RCs concentration among individuals is not captured. In this study, we investigated the variability in 137Cs activity concentration in individual aquatic insects in detritivorous caddisfly (Stenopsyche marmorata) and carnivorous dobsonfly (Protohermes grandis) larvae from the Ota River, Fukushima. Caddisfly larvae showed sporadically higher radioactivity in 4 of the 46 caddisfly larvae, whereas no such outliers were observed in 45 dobsonfly larvae. Autoradiography and scanning electron microscopy analyses confirmed that these caddisfly larvae samples contained radiocesium-bearing microparticles (CsMPs), which are insoluble Cs-bearing silicate glass particles. CsMPs were also found in potential food sources of caddisfly larvae, such as periphyton and drifting particulate organic matter, indicating that larvae may ingest CsMPs along with food particles of similar size. Although CsMP distribution and uptake by organisms in freshwater ecosystems is relatively unknown, our study demonstrates that CsMPs can be taken up by aquatic insects.

Redistribution of the soil 137Cs inventory through litter and sediment transport on a hillslope covered by deciduous forest in Fukushima, Japan

AbstractThe long‐term behaviour of radiocaesium (137Cs) activity concentrations in forest ecosystems and their downstream impacts remain important issues in the deciduous broadleaf forests of Fukushima, Japan following the Fukushima Daiichi Nuclear Power Plant accident. To predict 137Cs cycling and discharge in the forest ecosystem, it is important to understand the spatial dynamics of the 137Cs inventory and transport along hillslopes. Therefore, we observed the spatial distribution of the 137Cs inventory and 137Cs transport via sediment and litter of a deciduous forest hillslope in Fukushima, Japan in 2016 and 2017 and examined how the spatial distribution of 137Cs inventory was formed using a mass balance model. In 2017, the 137Cs activity concentration was significantly greater in the downslope riparian area (455 kBq/m2) than in the upslope ridge area (179 kBq/m2). Annual 137Cs transport within litter and sediment contributed &lt;0.5% to the current 137Cs inventory and cannot explain the current spatial variation of 137Cs inventory on the hillslope. The mass balance model results showed that if the initial 137Cs deposition was distributed uniformly in 2011, the spatial distribution of the hillslope 137Cs inventory was influenced mainly by the movement of leaf litter with a high 137Cs activity concentration.

Veterinary and sanitary assessment of food products on quality and safety indicators in Zhytomyr region

The veterinary and sanitary assessment results of food products according to SLVSE agro-food markets of Zhytomyr and Zhytomyr region and Zhytomyr regional state laboratory of the Service of Ukraine for Food Safety and Consumer Protection for 2021 are presented. In total, 68.151 tons of products were not allowed to be sold, and 8866 positive research results were obtained, including 50 carcasses and 3305 cases of invasive and non-communicable diseases. The main reason for the rejection of offal in 2021 was invasive and non-communicable diseases, which significantly worsened the sanitary indicators of product quality. MAFAnM of the liver, which was cleaned due to fasciolosis, is higher than in the same organ obtained from healthy animals by 86.0 %. The highest percentage of affected samples for E. coli was found in the study of the lungs (50.0 %), in the presence of Klebsiella – the heart (50.0 %.). In terms of quality and safety (the content of toxic elements, pesticides, mycotoxins, antibiotics, radionuclides), the studied 212838 food samples in 47 exceeded the content of 137Cs following the State Hygienic Standards. The most dangerous are the gifts of the forest. Excess was found in 30 samples of fresh mushrooms and 13 – dry. The specific activity of 137Cs in the sample of fresh mushrooms from Popelny exceeded DR-2006 6.9 times, five samples from Lugin – 1.4–2.0 times, nine samples from Narodychi – the maximum exceedance 2.2 times, six samples from Novograd – 1.2–1.8 times, six samples from Ovruch – 1.2–1.7 times. The specific activity on the content of 137Cs in 3 samples of dried mushrooms from Narodychi exceeded DR-2006 by 2.1–6.7 times, two samples from Olevsk – by 1.6 and 5.6 times, 1 sample from Lugin – by 2.6 times, four samples from Ovruch – 1.0–1.6 times, three samples from Yemilchino – 1.0–1.1 times). The system of monitoring sanitary-hazardous pathogens and residual amounts of toxic substances and radionuclides remains the guarantor of food safety in Ukraine. To eliminate the risk of food consumer hazards, it is necessary to improve the control system of raw materials used to manufacture products, safety indicators at all stages of production “from the field – to the table”, and remove substandard products.

Understanding problem-solving processes of preschool children in CS unplugged activities

This study aims to explore the influences of the unplugged CS activities in developing problem solving skills of preschool children. Code.org activities were used as an instructional package. The participants were 11 children (4-5 aged) enrolled in a public pre-school. Activity assessment form and clinical interviews were used to understand children’s problem solving processes. In order to determine the problem solving performances, the tasks were divided into the meaningful sub-tasks with regard to problem steps of Nance’ problem solving model. The results indicated that CS unplugged activities positively influenced students’ understanding and planning performances more than doing and evaluation skills. Preschool children developmental characteristics and the nature of the problems somewhat hampered the development of their performances in doing and evaluation steps. It is hoped that the study may provide insights for the efforts on enhancing preschool children’s problem solving processes.

Analysis of natural and artificial radioactive emission pattern in Qarasu River catchment in Gorgan Bay, northern Iran

Knowledge of distribution and emission pattern of natural and artificial radioactive elements and their radiation level in the environment is very important to assess its effects on human health and living organisms. In this study, the specific activity of natural and artificial radioactive elements for 30 soil and sediment samples collected from upstream and the outlet of Qarasu River to Gorgan Bay as well as sediments in the eastern part of Gorgan Bay were measured using High-Purity Germanium detector and their distribution map with using SURFER and GIS software was drawn. Specific activity of 226Ra, 232Th, 40K and 137Cs was obtained from 8.80 to 31.92, from 11.16 to 43.19, from 183.77 to 562.88 and from 0.83 to 12.72 in Bq/kg respectively. Upstream of the Qarasu River, the average concentration of 226Ra, 232Th, 40K and 137Cs in the soil samples beside the Qarasu River was higher than the sediments of the river, which indicates the washing of sediments and the transport of radioactive elements by water flow and transfer of these elements to lower areas. In Qarasu estuary and Gorgan Bay, 232Th and 40K distribution patterns are almost similar and the highest concentrations of 226Ra, 232Th and 40K elements are related to Qarasu estuary sediments. The concentration of 137Cs in the mouth of Qarasu River has the lowest value and increases with its distance from the mouth to the middle parts of Gorgan Bay, which indicates a high mobility and a tendency to sediment in calmer places for 137Cs. The measured values for radiological parameters and risk indices due to nuclear radiation in this study are within the allowable range and the amount of available nuclear radiation does not threaten the health of the inhabitants of the region‎‎‎.‎

Effects of forest litter on dissolved 137Cs concentrations in a highly contaminated mountain river in Fukushima

Study regionThe upper, forested reaches of the Ota River, 24.4 km northwest of the Fukushima Daiichi nuclear power plant, was studied. Study focusThere is concern about the effects of dissolved radiocesium (137Cs) released from forest litter on long-term contamination of aquatic ecosystems caused by the Fukushima nuclear accident. Therefore, hydrology and water quality measurements were performed under base flow and storm flow conditions in a high-dose-rate forest watershed in Fukushima Prefecture, to investigate the involvement of litter in 137Cs release. New hydrological insights for the regionUnder base flow conditions, the dissolved 137Cs activity concentration significantly positively correlated with the dissolved organic carbon and potassium ion concentrations (the main components leached from litter) over the entire study period. Differences in the annual variations in the 137Cs activity concentrations and potassium ion concentrations indicated that litter indirectly increased 137Cs concentrations in river water by releasing potassium ions that caused 137Cs to desorb from river sediment and riparian soil. In each large runoff event, the dissolved 137Cs activity concentration was higher at the time of maximum runoff than at the start of the event. The relationships between the dissolved 137Cs, dissolved organic carbon, and potassium ion concentrations strongly suggested that 137Cs leached from litter in runoff was directly responsible for the increase in the 137Cs activity concentration in river water.