137Cs Activity Concentrations Research Articles

Transfer Factor of Radionuclides from Soil to Leafy Vegetables in Iraq Using Gamma Ray Spectroscopy

The activity concentration of natural radioactivity levels, of artificial cesium and transfer factor from soil to plants in agricultural areas at Al- Yusiefya region were determined by using NaI (Tl) detector spectrometer. Ten species of leafy plants have been selected: Spinach, Parsley, Watercress, Lettuce, Rashad, Radish, Green onion, Turnip green, Green beet and Mint. The mean activity concentrations of 238U, 232Th, 40K and 137Cs in leafy vegetable samples were 12.4±3.8, 14.8±4.7, 283±93 and 1.06±0.99 Bg/kg, and in soil samples were 15.9±4.3, 16.1±5.2, 298.5±3.9, and 1.11±0.37 Bq/kg. The radiation hazard indices were evaluated (radium equivalent, external hazard index, annual effective dose, absorbed dose rate) were within the permissible values except for excess lifetime cancer risk. The mean transfer factor values of 226 Ra, 232Th, 40K, and 137Cs were 0.89±0.2, 0.9±0.2 , 1.02±0.3, and 0.77±0.25. The leafy vegetable are safe for consumption and the studied area does not pose a considerable radiological threat .

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.

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. 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. 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. 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.

Influence of Precipitation on the Spatial Distribution of 210Pb, 7Be, 40K and 137Cs in Moss

Mosses have been widely used as biomonitors of a variety of atmospheric pollutants, including radionuclides. Here we determine the radionuclide activity concentration of 210Pb, 137Cs, 7Be, and 40K in moss tissue (Hylocomium splendens) collected from 24 sites across Ireland and assess the influence of precipitation on radionuclide spatial distribution. Lead-210 was the most abundant radionuclide (range: 226–968 Bq kg–1), followed by 7Be (range: <DL—604 Bq kg–1), 40K (range: <DL—155 Bq kg–1), and 137Cs (range: <DL—41 Bq kg–1). Albeit nearly thirty years since the Chernobyl disaster, 137Cs activity concentration was detected at 67% of the study sites; however, the spatial distribution was not fully consistent with the 1986 Chernobyl deposition pattern. Rather, 137Cs was weakly correlated with rainfall, with higher concentrations along the west coast, suggesting that the 2011 Fukushima Dai-ichi nuclear accident was also a potential source. Average annual rainfall was a significant predictor of 210Pb activity (linear regression, R2 = 0.63, p < 0.001). As such, the highest radionuclide activity was observed for 210Pb (average: 541 Bq kg–1), owing to the high levels of precipitation across the study sites (average: 1585 mm). In contrast, 7Be or 40K were not correlated with precipitation; rather, 40K and 7Be were significantly correlated to each other (rs = 0.7), suggesting that both radionuclides were transferred from the substrate or through soil re-suspension. Precipitation is widely reported as an important factor in the spatial distribution of radionuclides; however, only 210Pb activity concentrations in moss were strongly influenced by precipitation in the current study.

Flow filtration/adsorption and simultaneous monitoring technologies of radiocesium 137Cs in river water

This study develops a method that combines a radiation-grafting fibrous Cs-adsorbent filter of ammonium molybdophosphate (AMP) and a Ce:Gd3Al2Ga3O12 scintillator-based γ-ray detector for in situ measurements of the activity concentrations of 137Cs in a continuous water flow. To ensure adequate performance, the study locations were set along an upper tributary stream of the Ukedo River and a nearby spring-fed stream, approximately 30 km northwest of the Fukushima Daiichi Nuclear Power Plant. In the tributary stream, the activity concentrations of 137Cs slowly decreased from 19 to 1.7 mBq/L between 2018 and 2020 until reaching equilibrium with a few millibecquerels in 10 years after the accident. This equilibrium value is significantly below the admissible radiocesium activity (10 Bq/L) for drinking water. The spring-fed stream rarely included 137Cs. The monitoring results support previous views about the environmental fate of 137Cs in a forest ecosystem at the Abukuma granitic catchments. The major advantage of this method is that utilizing fibrous Cs adsorbents with AMP-loaded graft chains enables the effective accumulation of 137Cs through a large amount of stream water. Therefore, 137Cs γ-rays can be detected simultaneously, and combining these strategies provide a unique monitoring platform for on-site and real-time detection of 137Cs at the trace level.

Vertical distribution of radionuclides in soil at the Semipalatinsk Test Site beyond its test locations.

Data on the vertical distribution of radionuclides in the soil is necessary to fully understand the radioecological situation around ecosystems, give predictive estimates to how safe crop products are and justify a rehabilitation strategy for radioactively contaminated areas. A study was conducted to investigate the vertical distribution of radionuclides in soils of the former Semipalatinsk Test Site (STS) territory beyond its testing sites, that is, in areas in which no nuclear weapons or nuclear effects of radiological warfare agents were tested. Soil was sampled layerwise all over the Semipalatinsk Test Site down to 30 cm deep at a 5-cm spacing. Most of high activity concentrations of radionuclides all over the study area were detected in the 0-5 cm soil layer. Activity concentrations of the major man-made radionuclides were determined in soil samples collected by γ-, β and α-spectrometry. As a result, ranges of activity concentrations of 137Cs, 241Am, 90Sr and 239+240Pu were determined in 0-5, 5-10, 10-15, 15-20, 20-25, 25-30 cm soil layers. In the conventionally 'background' area, the 0-5 cm soil layer, on average, contains (the percentage of total activity concentration across the soil profile depth): 137Cs- 83%, 239+240Pu- 87% and 90Sr- 38%. For the 1953 plume, these values were 92%, 83% and 73%, respectively. Values for the 1951 plume in the 0-5 cm soil layer were: 137Cs- 93%, 239+240Pu- 93% and 90Sr- 59%. The minimum concentration of radionuclides are observed 20-30 cm deep in all areas studied. 90Sr is the most mobile radionuclide from the perspective of its ability to travel deep down the soil. The study found out that the nuclide vertical migration rates downward in soils based on detected activity were as follows (in descending order): 90Sr- 137Cs- 239+240Pu- 241Am. Coefficients that determine the ratio of the activity concentration of the radionuclide in the 0-20 and 0-30 cm soil cover layers to that of this radionuclide in the 0-5 cm topsoil were calculated. These coefficients enable to estimate the radionuclide inventory at each soil sampling point from their activity concentration in the 0-5 cm soil layer.

Factors affecting 137Cs radioactivity and water-to-body concentration ratios of fish in river and pond environments near the Fukushima Dai-ichi Nuclear Power Plant

To elucidate 137Cs contamination levels and mechanisms of fish inhabiting river and pond environments near the Fukushima Dai-ichi Nuclear Power Plant, 137Cs activity concentrations in fish (15 species, n = 164) and water collected from Maeda River (3.3–8.9 km from the plant) and Shimofukazawa Pond (2.9 km) in 2017 were analyzed. Also, an 8-week rearing experiment using Japanese dace Pseudaspius hakonensis fed on non-contaminated pellets and the pond water (mean 137Cs concentration of 2.0 Bq/L) was conducted to evaluate 137Cs accumulation from water to fish. The 137Cs concentrations in Japanese dace, the only species collected throughout five sampling sites from estuarine to upstream areas in Maeda River, were found to be correlated with ambient air dose rates and fish size, exhibiting large variations (16.5–2.6×103 Bq/kg-wet). By contrast, dissolved 137Cs in river waters increased from the upper to lower course (0.025–0.28 Bq/L), which caused large variations of the water-to-body concentration ratio (CR) in Japanese dace (60.0–35700 L/kg-wet). These CRs (geometric mean of 3670 L/kg-wet) were much higher than the steady-state CR of reared fish (9.7 L/kg-wet), indicating that river fish uptake 137Cs mainly from prey items from aquatic and riparian zones, rather than from water. Statistically significant negative correlations between K+ concentrations in water and river fish CRs were detected, resulting in the decreasing trend of CRs from upstream to estuarine areas. These results suggest that the large heterogeneity of air dose rates, K+ concentration, and estuarine processes in brackish water habitats, in association with the feeding habit and size effect in fish, can engender wide variation of 137Cs concentrations and CRs of river fish along a river course. In contrast, 137Cs concentrations in pond fish (4.3–14.6 kBq/kg-wet) were higher than in river fish. The CRs of pond fish were constantly high but the range was smaller (1010–3440 L/kg-wet) with larger values in fish of higher trophic levels. These findings suggest that biomagnification within a pond was inferred as the main cause of 137Cs contamination of pond fish.

ACTIVITY CONCENTRATION OF RADIONUCLIDE AND EXTERNAL DOSE RATE IN BOTTOM DEPOSITS OF BRIT LAKE IN THE CHОRNOBYL EXCLUSION ZONE

The profiles of the vertical distribution of the gamma dose rate and activity concentrations of 90Sr, 137Cs, 154Eu, and 241Am in the bottom sediments of Brit Lake were obtained. The lake is located within the dammed section of the Krasnenska floodplain of the Pripyat River in the Chоrnobyl Exclusion Zone (51.44844°; 30.06020°). The values of the dose rate and activity concentration of 137Cs in the sediments reached 23 μGy h−1 and 43 Bq∙cm−3. In the lake Brit radioactive contamination of bottom sediments did not depend on the depth of the lake due to the washing of radionuclides from the water intake. A weak correlation was observed between values of in-situ measured and calculated gamma dose rates in bottom sediments. The average calculated and measured dose rates of gamma radiation in bottom sediments of the lake varied within the range of 1.3-19 μGy h−1 and was compatible with the internal radiation dose to fish (5-15 μGy h−1). Contribution of radionuclide content in water to the gamma dose rate does not exceed 2 nGy h−1. In October 2021, appropriate equipment for acoustic 3-D telemetry and individual dosimetry of various fish species was installed in the lake to reduce uncertainty in estimates of doses of external exposure to aboriginal fish in the lakes

Spatiotemporal patterns in differences between the 137Cs concentrations of forest and stream litters: effect of leaching.

Forest-stream ecotones possess prominent detritus-based food webs, and 137Cs-contaminated litter can influence the contamination levels of animals inhabiting such ecosystems. The effects of leaching on contaminated litter induce greater absolute differences between the 137Cs concentrations of forest and stream litter in more contaminated sites. Because 137Cs concentrations in litter can be attenuated temporally, spatiotemporal patterns in the differences in 137Cs concentrations between forest and stream litter may vary depending on both the amount of 137Cs deposition and the passage of time. To test this hypothesis, we sampled coniferous needle and broad-leaved deciduous litter in forests and streams at seven forested headwater sites affected by the Fukushima nuclear accident 3.24 and 11.24 years after the accident. We found that 137Cs concentrations in the two litter types were one order of magnitude lower 11.24 years after the accident than 3.24 years afterwards. The absolute difference in 137Cs activity concentrations of litter between forest and stream ecosystems was higher at more contaminated sites both 3.24 and 11.24 years after the accident. The spatiotemporal changes in litter contamination provide insight into 137Cs dynamics and complex transfer in the detritus-based food webs of forest-stream ecotones.

<sup>137</sup>Cs IN THE ORGANISMS OF MOUSE-LIKE RODENTS INHABITED THE AREA OF NUCLEAR WEAPON TESTING

The paper presents the results of researching 137Cs radionuclide concentration in the organisms of mouse-like rodents (organisms of jerboa (Allactaga major Kerr and Allactaga saltator Eversmann) and marmots (Citellus erythrogenus Brandt)) living in the field of nuclear-weapon testing at the Semipalatinsk test site and the parameters of 137Cs radionuclide transition to organisms of studied animals. It is revealed that relatively elevated magnitudes of 137Cs activity concentration in organisms of jerboa and marmots are observed on the assumption of their residence in local contamination sites. With venturing from contamination sites at the distance exceeding the radius of animal activity, high values of radionuclides’ activity concentration are not reported. Despite the fact that animals live in the environment which components display high activity concentration of radionuclides, the extremely high concentration of radionuclide in these animals’ organisms has not identified.The midpoint measures (AM±SD) of CRmuscl of 137Cs radionuclide for the muscle tissue of Allactaga saltator Eversmann amounted (2.1±1.3)×10−3 (n-11), for muscle tissue of Allactaga major Kerr – (4.7±2.7)×10−3 (n-9), for the muscle tissue of Citellus Erythrogenus Brandt – (7.0±5.6)×10−3 (n-6).

Application of gamma spectrometry for the characterization and influence of the archeological works of an archaeological site

The purpose of this study was the use of gamma spectrometry to characterize the archaeological site of Molina de Aragón, located in the province of Guadalajara in Spain. To do so, a set of samples with different historical influences have been selected. The samples were analyzed by gamma spectrometry with HPGe detectors, and by X-ray fluorescence, to know their chemical composition. The statistical study of the activity concentration of radionuclides from the natural radioactive series, 40K and 137Cs, was carried out using box-and-whisker plots, cluster analysis and principal component analysis (PCA). Likewise, the in-situ effective dose rates and the ones determined from the activity concentrations obtained by gamma spectrometry were evaluated to verify sampling reproducibility. The results obtained made it possible to classify the areas of Jewish and Christian influence based on the relationships between 232Th and 238U series and the possible influence of the archaeological works carried out in the study area. The least altered areas could also be identified from the activity concentrations of 137Cs and 210Pbex. Activity concentrations and effective dose rates were equivalent to the natural radioactive background of the Iberian Peninsula. PCA showed a correlation between Fe2O3, Al2O3 y ZrO2 and the natural radioactive series of thorium and uranium.

Clean feed as countermeasure to reduce the 90Sr and 137Cs levels in fish from contaminated lakes

Glubokoye Lake situated within the Chernobyl Exclusion Zone is highly contaminated with respect to radioactive caesium and strontium isotopes, which also is reflected in the contaminated fish. To utilize the fish resources in contaminated lakes, the present work presents for the first time the effectiveness of using clean feed to counteract contamination of radionuclides in fish. The study is based on a series of repeated experiments with Prussian carp (Carassius gibelio (Bloch, 1782)) kept in cages in the contaminated Glubokoye Lake during summer 2018–2021. By the addition of clean feed, the activity concentration of 137Cs in fish muscle tissues was lowered with a factor of 2–5 due to biodilution. Surprisingly, additional clean feed did not lead to further decrease in the uptake of 137Cs in fish.In contrast to 137Cs, the addition of clean feed increased the 90Sr activity concentration in fish by a factor of 2–4 compared to fish fed with naturally occurring feed items. Radioactive strontium accumulated mainly in the fish bones and the muscle tissue level was 2 orders of magnitude lower, similar to the distribution observed for stable Sr. By utilizing a new kinetic model describing the dynamics of strontium isotopes in bone tissues of fish, predictions fitted well with site-specific data, taking growth rates and aging into account. Results showed that clean feeding can be used to counteract high activity concentration of 137Cs in fish due to biodilution, but cannot counteract bioaccumulation of 90Sr. Findings highlighted that it is essential to understand underlying factors influencing the uptake pathways for contaminants, as access to clean feed could increase the growth and thereby reduce the body activity concentration of dietary associated radionuclides such as 137Cs (biodilution), as well as increase the transfer of dissolved compounds such as 90Sr directly from water to fish.

The occurrence of 40K and 137Cs radioactivity in mosses during 2015-2019 in the Djerdap National Park (E. Serbia).

The radiation status of the national park (NP) Djerdap (Eastern Serbia) is characterized using bioindicators (mosses). Mosses (16 species, 156 samples) were collected randomly within the area of NP Djerdap during the month of June, periodically from 2015 to 2019. Samples were collected in the regions of Dobra, Donji Milanovac, and Tekija. Within the mosses, the presence of 40K and 137Cs is regarded as a good indicator of radionuclides present in the environment due to their easy interchangeability with 39K highly present in living moss organisms. The activity concentrations of gamma ray-emmiting radionuclides in samples were determined using high-resolution gamma ray spectrometry, an HPGe-ORTEC/Ametek detector. The determining activity concentrations of 40K and 137Cs in collected samples were as follows: for 40K from 31.4 to 721Bqkg-1and for 137Cs varied from 2.6 to 908Bqkg-1. The average activity concentrations of 40K and 137Cs (Bq kg-1) in mosses in the period 2015-2019 were the lowest in moss samples collected in the Dobra region, and the highest in the area of Donji Milanovac. The most prevalent collected moss species within the Djerdap National Park was Hypnum cupressiforme. The determined activity concentrations in H. cupressiforme of 137Cs for the whole region of NP Djerdap for all 5years was 78.1 ± 70.3Bqkg-1 and of 40K was 181 ± 86.1Bqkg-1.

Estimation of soil radioactivity-depth profiles using Bayesian inversion of borehole gamma spectrometry data

Inversion of in situ borehole gamma spectrometry data is a faster and relatively less laborious method for calculating the vertical distribution of radioactivity in soil than conventional soil sampling method. However, the efficiency calculation of a detector for such measurements is a challenging task due to spatial and temporal variation of the soil properties and other measurement parameters. In this study, the sensitivity of different soil characteristics and measurement parameters on simulated efficiencies for a 662 keV photon peak were investigated. In addition, a Bayesian data inversion with a Gaussian process model was used to calculate the activity concentration of 137Cs and its uncertainty considering the sources of uncertainty identified during the sensitivity analysis, including soil density, borehole radius, and the uncertainty in detector position in the borehole. Several soil samples were also collected from the borehole and surrounding area, and 137Cs activity concentration was measured to compare with the inversion results. The calculated 137Cs activity concentrations agree well with those obtained from soil samples. Therefore, it can be concluded that the vertical radioactivity distribution can be calculated using the probabilistic method using in situ gamma spectrometric measurements.

Recent 137Cs Distribution in the Aegean Sea, Greece

Recent spatial and vertical distributions of 137Cs activity concentration in the Aegean Sea are presented almost 30 years after the Chernobyl accident. The study aims to provide the current radioactivity levels of 137Cs in the Aegean Sea and to combine the 137Cs activity concentration with typical oceanographic parameters (T, S) in order to utilize them as tracers to identify/validate the different water masses that are present in the Aegean Sea. This work was performed in the frame of the “KRIPIS” project in 2017 for continuous investigations of the deep basins from all over the Aegean Sea and includes samplings from the water column layers of seven stations. The 137Cs activity concentrations were determined via lab-based gamma ray spectroscopy after appropriate chemical pre-concentration of 137Cs, while the salinity and temperature of the water column were obtained by in-situ measurements. The activity concentration values of 137Cs varied from 1.6 to 5.5 Bq m−3. Clear distinction of the Black Sea and Levantine Waters was obtained based on the combination of temperature and salinity values with 137Cs activity concentration. Furthermore, including 137Cs as a supplementary tracer, the Transitional Subsurface Aegean Waters were identified at the Myrtoan and Antikythera Straits, combining the salinity, temperature and 137Cs activity concentration.

Vegetation induced distinctions between radionuclide distribution in soils (Austria)

In 2019 and 2020, the layers - down to a maximum depth of 30 cm - of 43 soil samples from different regions in Austria were measured gamma-spectrometrically to determine their activity concentration (in Bq/kg and Bq/m³) of 234Th, 214Pb, 214Bi, 210Pb, 228Ac and 40K. 137Cs activity concentration (in Bq/m³) will be found in the supplementary data file only. A basic statistical analysis was carried out and explained variances for distinctions primarily between meadows and forests. Ternary diagrams were applied to represent equilibrium status of inventories and layer activities between 238U-equivalent, 226Ra-equivalent and 210Pb. A method using ternary diagrams for identifying of element-specific dampening effects in remote sensing is presented in the report (ternary “adjustment” diagrams).The tendencies between forest and meadows sites are heterogeneous, but distinctions between coniferous and deciduous forest are extremely likely. Geological settings dominate the distributions, slightly altered by anthropogenic influence, which includes the kind of vegetation. Focusing on top soil layers (first and/or second layer) facilitates discrimination according to vegetation. At some sites changes of activities in the grass root layer (at 15 cm) were observed.

2D inversion of in situ gamma-ray spectrometric measurements of 137Cs for site characterization

Environmental contamination by radioactive materials can be characterized by in situ gamma surface measurements. During such measurements, the field of view of a gamma detector can be tens of meters wide, resulting in a count rate that integrates the signal over a large measurement support volume/area. The contribution of a specific point to the signal depends on various parameters, such as the height of the detector above the ground surface, the gamma energy and the detector properties, etc. To improve the spatial resolution of the activity concentration, contributions of a radionuclide from nearby areas to the count rate of a single measurement should be disentangled. The experiments described in this paper, deployed 2D inversion of in situ gamma spectrometric measurements using a non-negative least squares-based Tikhonov regularization method. Data were acquired using a portable LaBr3 gamma detector. The detector response as a function of the distance of the radioactive source, required for the inversion process, was simulated using the Monte Carlo N-Particle (MCNP) transport code. The uncertainty on activity concentration was calculated using the Monte Carlo error propagation method. The 2D inversion methodology was first satisfactorily assessed for 133Ba and 137Cs source activity distributions using reference pads. Secondly, this method was applied on a 137Cs contaminated site, making use of above-ground in-situ gamma spectrometry measurements, conducted on a regular grid. The inversion process results were compared with the results from in-situ borehole measurements and laboratory analyses of soil samples. The calculated 137Cs activity concentration levels were compared against the activity concentration value for exemption or clearance of materials which can be applied by default to any amount and any type of solid material. Using the 2D inversion and the Monte Carlo error propagation method, a high spatial resolution classification of the site, in terms of exceeding the exemption limit, could be made. The 137Cs activity concentrations obtained using the inversion process agreed well with the results from the in-situ borehole measurements and those from the soil samples, showing that the 2D inversion is a convenient approach to deconvolute the contribution of radioactive sources from nearby areas within a detector's field of view, and increases the resolution of spatial contamination mapping.

ASSESSMENT OF DOSES FROM INGESTION OF RADIONUCLIDES 40K, 137CS, 226RA AND 232TH IN EDIBLE COMMERCIAL MUSHROOMS FROM TAIWAN.

This study analyzed activity concentration and annual effective dose of radionuclides 40K, 137Cs, 226Ra and 232Th of 44 mushrooms collected from local markets in Taiwan. The 40K activity concentrations were 1570±150Bq/kg-dw (Agaricus bisporus)>1084±183Bq/kg-dw (Flammulina velutipe)>736±150Bq/kg-dw (Lentinula edodes). The activity concentrations of 226Ra were 5.04±2.43, 4.00±2.40 and 3.43±2.69Bq/kg-dw, and 232Th were 3.96±2.18, 3.86±1.43 and 2.90±1.99Bq/kg-dw for F. velutipe, L. edodes and A. bisporus, respectively. In seven of the 44 samples, 137Cs activity concentrations were detected, and the samples had an average of 1.55±1.75Bq/kg-dw. The total annual effective dose ranged from 0.90 to 3.50μSv/y, with an average of 1.94±0.62μSv/y at an ingestion rate of 0.235kg-dw/y.

Dose rate assessment of 137Cs to mussels and pelagic fish from the combined use of field measurements, satellite data and the ERICA Assessment Tool

Cesium-137 (137Cs) is the most important indicator of radioactive pollution in the marine environment due to its half-life (Tph: 30.2 years), its high fission yield, its solubility (70% in ionic form) and its bioavailability (similar to potassium). Soluble radionuclides, like 137Cs, in the seawater are associated with physicogeochemical and biological parameters of the marine environment (e.g. temperature, water density, biota exchange processes, water mass translocation etc.). Considering this characteristic, we investigate the potential relation between 137Cs activity concentration and sea surface temperature (SST). The parameter of SST is selected, as the element of cesium in the seawater is conservative and its horizontal and vertical dispersion depends on the water mass translocation and water currents. Water mass translocation and water currents are processes that are both governed by the SST. SST also influences the uptake of 137Cs in some marine organisms as it makes it more bioavailable and affects the biological retention time and the elimination rate. The study area is the Gulf of Corinth (Greece). Cs-137 in the Gulf of Corinth originates from water runnoff from the land (Chernobyl fallout from 1986) and a small influence exists from the Ionian and Aegean Sea water currents. A total of 17 measurements spanning 2004-2005, of 137Cs activity concentrations were retrieved from the Environmental Radioactivity Laboratory (ERL) database of NCSR “D”. Furthermore, SST measurements issued from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS). Databases of 137Cs activity concentrations and SST are used for regression analysis and definition of a linear model. The estimated 137Cs activity concentrations obtained by the model are then compared with the newest measured values obtained by seawater samples from September and November 2018 (a total of 8 seawater samples). Estimated concentrations present a relative difference of about 9% to the measured values. In order to conduct the risk assessment analysis in the studied area, the dose rates are calculated for marine organisms. The selected marine organisms are mussels and pelagic fish that are abundant in the area and have significant commercial value, with mussels also being an important bioindicator of marine pollution. The total dose rates in these organisms (resulting by both the internal and external exposure) vary from 3.30 × 101 to 5.40 × 101 μGy/year for the mussels and from 2.97 × 10-1 to 4.86 × 10-1 μGy/year for pelagic fish, which are much lower that the intervention levels, indicating low impact due to the 137Cs exposure.

Fukushima and Chernobyl: Similarities and Differences of Radiocesium Behavior in the Soil-Water Environment.

In the wake of Chernobyl and Fukushima accidents, radiocesium has become a radionuclide of most environmental concern. The ease with which this radionuclide moves through the environment and is taken up by plants and animals is governed by its chemical forms and site-specific environmental characteristics. Distinctions in climate and geomorphology, as well as 137Cs speciation in the fallout, result in differences in the migration rates of 137Cs in the environment and rates of its natural attenuation. In Fukushima areas, 137Cs was strongly bound to soil and sediment particles, with its bioavailability being reduced as a result. Up to 80% of the deposited 137Cs on the soil was reported to be incorporated in hot glassy particles (CsMPs) insoluble in water. Disintegration of these particles in the environment is much slower than that of Chernobyl-derived fuel particles. The higher annual precipitation and steep slopes in Fukushima-contaminated areas are conducive to higher erosion and higher total radiocesium wash-off. Among the common features in the 137Cs behavior in Chernobyl and Fukushima are a slow decrease in the 137Cs activity concentration in small, closed, and semi-closed lakes and its particular seasonal variations: increase in the summer and decrease in the winter.

РАДИОНУКЛИДЫ В ВЕРХНЕМ СЛОЕ ПОЧВ ОСОБО ОХРАНЯЕМЫХ ПРИРОДНЫХ ТЕРРИТОРИЙ РОСТОВСКОЙ ОБЛАСТИ

The paper is devoted to the assessment of the features of the distribution of natural radionuclides (226Ra, 232Th, 40K) and artificial 137Cs in the upper soil layer of specially protected areas of the Rostov region. The activity concentration of radionuclides in the soil was measured by the gamma spectrometric method. The distribution of the artificial radionuclide 137Cs in the soils of the Rostov region is uneven. The minimum activity concentration of radiocesium is recorded in the Rostov nature reserve. It is shown that the arithmetic mean, median and modal values of the activity concentration of 137Cs are 21.7, 14.2 and 7.5 Bq/kg, respectively, and the arithmetic mean activity concentration of natural radionuclides in the soils of the protected areas of the Rostov region are 26, 9 Bq/kg for 226Ra, 27.0 Bq/kg for 232Th. These values can be used as background (reference) values in assessing the degree of influence of industry and urbanization on soil radioactivity.