137Cs Activity Concentrations Research Articles

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.

Species-specific trends of plutonium, radiocesium, and potassium-40 levels in three fish species of the Yenisei river (Siberia, Russia)

The Yenisei is the largest river in the Northern Hemisphere receiving controlled radioactive discharges from nuclear facilities. The paper presents a comparative study of temporal trends of artificial radionuclides plutonium (239,240Pu) and radiocesium (137Cs), and a natural isotope of the essential macronutrient potassium (40K) in samples of three commercial fish species (Northern pike, Baikal grayling, and Siberian dace) occupying different positions in a trophic network in the Yenisei River (Siberia, Russia). Samples of fish were caught in the Yenisei in 2011–2020 during a period of significant changes in controlled radioactive releases into the river. The study has shown no increase in plutonium concentration in fish samples within two years after the upsurge in controlled Pu discharge into the river (2018–2020). Average activity concentration of 239,240Pu (mBq∙kg−1 d.w., range, mean ± sd) in muscle of grayling (0.6–31.8, 10.9 ± 8.6) was higher (p < 0.01) than in muscle of dace (1.0–4.4, 2.4 ± 1.2) and pike (1.1–11, 3.8 ± 2.9). This can be attributed to the feeding of grayling on benthic invertebrates rich in Pu. The concentration of Pu tended to increase in muscle of pike with the increasing size of the fish. Average activity concentration of 137Cs (Bq∙kg−1 d.w., range, mean ± sd) in muscle of pike, a piscivorous fish (1.8–23.4, 7.7 ± 5.1), was significantly higher (p < 0.001) than the average activity concentration of 137Cs in muscle of dace (0.7–5.7, 2.7 ± 1.6) and grayling (1.3–7.2, 2.5 ± 1.7). A similar effect was revealed for 40K. This can be attributed to biomagnification of 137Cs and 40K in food chains. The results will draw a baseline for assessment of dose-dependent ecological risks for wild fish itself and fish consumers, add field-based facts to the fundamental knowledge of behavior of artificial radionuclides in freshwater food chains, and suggests a hypothesis for consequent experimental studies.

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.

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 &lt;sup&gt;137&lt;/sup&gt;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.

Radioecological characteristics of Siberian roe deer (Capreolus pygargus Pal., 1771) inhabiting locations of nuclear weapon tests.

This paper reports the activity concentrations of 137Cs, 90Sr, 239+240Pu, 241Am, and 3Н in the form of tritiated water (НТО) and organically bound tritium (ОBТ) in the tissues and organs of roe deer (Capreolus pygargus Pal., 1771) that inhabit the 'Degelen' test location of the Semipalatinsk Test Site. Tissues and organs were sampled from six deer by killing. The activity concentrations of specific radionuclides in the samples were measured using γ-, α-, and β-spectrometry. The radionuclide activity concentrations in the tissues and organs showed considerable variation, for example, 0.6-170 Bq kg-1 for 137Cs and 0.3-2.8×103 Bq kg-1 for 90Sr. The activity concentrations of radionuclides in animal muscular tissue did not exceed permissible values for the meat of wild animals. The tissues and organs in the roe deer were arranged as follows in descending order of their ability to accumulate 137Cs and 90Sr: for 137Cs, muscular tissue-kidneys-lungs-spleen-heart-liver-bone tissue; for 90Sr, bone tissue-liver-lungs-muscular tissue-spleen-heart-kidneys. The activity concentrations of 241Am and 239+240Pu did not exceed the minimum detectable activity. Therefore, no quantitative values could be determined for 241Am, and the 239+240Pu activity concentration could be derived for only one sample: 0.5±0.1 Bq kg-1 (liver). The distribution pattern of these radionuclides in the tissues and organs of the roe deer could not be determined because of insufficient data. The HTO volumetric activity in the tissues and organs of the examined animals ranged from 2.6×10-2 to 77 kBq l-1; activity concentration of OBT, 3.0×10-2 to 16 kBq kg-1; and OBT-to-HTO ratios, 2.0×10-3 to 5.3×102. This ratio can serve as an indicator of how long the examined animals stay in radioactively contaminated ecosystems. Within the 'Degelen' site, the activity concentrations of 90Sr and tritium, in the form of HTO and OBT, are expected to be high in the bone tissues, soft tissues, and organs, respectively.

Results of modern radiation-hygienic surveys of settlements of Bryansk Oblast of the Russian Federation bordering the Republic of Belarus. Part 3: Radionuclide content in agricultural food products

The third article in a series of publications devoted to the results of studying the current radiation situation in the territories of the Bryansk region bordering the Republic of Belarus presents results of studies of the content of radionuclides (137Cs and 90Sr) in samples of agricultural food products produced in the personal subsidiary plots of the population. The regularities of changing 137Cs and 90Sr content in samples of cow’s milk and potatoes depending on the level of radioactive contamination of the territory were studied; the present values of the quantities characterizing the distribution of the ratio of the activity concentration of radionuclides in agricultural food products to the density of radioactive contamination of the soil of the territory were deter -mined. The ratios of average values of 137Cs activity concentration in milk from stalled and grazing periods for cattle were analyzed. The results of the study show that some dairy product samples (less than 1%) do not meet the radiological safety criterion. Exceedances of the hygienic standards were not found in the studied samples of potatoes, vegetables, and meat of farm animals.

Uncertainty analysis of 137Cs measured by shipborne device for radioactive monitoring

Uncertainty is a crucial indicator of the performance of monitoring devices. Analyzing and calculating uncertainty is a necessary prerequisite for accurately presenting the results of radioactive monitoring for seawater. This paper evaluates the uncertainty involved in the measurement process of the developed radioactive monitoring device. By measuring the different activity concentrations of 137Cs in seawater samples from around a nuclear power plant, and comparing these measurements with radiochemical analysis results. The results show that the main factors affecting the uncertainty of the device are the uncertainty of the γ count rate of seawater sample, the γ count rate and volume of the standard source, with the uncertainty of the γ count rate of seawater sample being the most significant contributor.

Distribution of some natural and artificial radionuclides in soil from the city of Bitola (Macedonia) and its environs.

The aim of the study is a thorough investigation of the radioactivity level in soils of the town of Bitola (Macedonia) and its environs. Topsoil samples collected from 58 locations within a 5×5 km grid were analysed. Serving as a screening, gross alpha and beta activity measurements were performed using gas-flow proportional counter. Gamma-spectrometric measurements revealed the presence of three natural (40K, 226Ra, 232Th) and one artificial radionuclide (137Cs) in the samples. The activity concentrations of these radionuclides were consistent with the results of similar studies in neighbouring areas. Spatial distribution maps and factor analyses have revealed that the activity concentrations of the natural radionuclides are strongly influenced by geology and have no significant influence from human activities. A correlation of 137Cs activity concentrations with terrain elevation was also observed. The aim of the study is a thorough investigation of the radioactivity level in soils of the town of Bitola (Macedonia) and its environs. Topsoil samples collected from 58 locations within a 5×5 km grid were analysed. Serving as a screening, gross alpha and beta activity measurements were performed using gas-flow proportional counter. Gamma-spectrometric measurements revealed the presence of three natural (40K, 226Ra, 232Th) and one artificial radionuclide (137Cs) in the samples. The activity concentrations of these radionuclides were consistent with the results of similar studies in neighbouring areas. Spatial distribution maps and factor analyses have revealed that the activity concentrations of the natural radionuclides are strongly influenced by geology and have no significant influence from human activities. A correlation of 137Cs activity concentrations with terrain elevation was also observed.

Investigation of radioactivity concentrations and soil-to-plant transfer factors in soil samples taken from different distance zones to the Metsamor nuclear power plant

Abstract Monitoring radioactivity around nuclear power plants is important to avoid the risks of radiation. This study provides an overview of the radioactive emission impact on the near surroundings of the Metsamor nuclear power plant in Armenia. In this context, 29 soil samples were collected from the 40, 80, 120, 160 km radius areas determined in the direction of Iğdır province by accepting the Metsamor nuclear power plant as the center. The activity concentrations of 226Ra, 232Th, 40K and 137Cs in soil samples ranged from 7.90 to 23.44, 7.11 to 33.55, 132.54 to 502.69 and 0.33 to 17.61 Bq/kg, respectively. In addition, the radioactivity concentrations in some agricultural products and the transfer factors from soil to plant were determined. As a result, there is no significant radiological risk in terms of studied radioisotopes for people living in this region.

Investigation of sorption behavior of 137Cs in a river–sea system boundary area after the Fukushima Dai-ichi nuclear power plant accident

The radiocesium (137Cs) distribution between dissolved and particulate phases was examined in river water and coastal seawater as a function of the 137Cs sorption behavior on suspended particles. Dissolved 137Cs activity concentrations in the Tomioka River (salinity <0.1), about 10 km south of Fukushima Dai-ichi Nuclear Power Plant, and in coastal seawater at Tomioka fishery port (salinity >30), Fukushima Prefecture, from June 2019 to October 2021 were 3.6–20 Bq/m3 (geometric mean 11 Bq/m3) and 2.4–86 Bq/m3 (13 Bq/m3), respectively. Although the suspended particle concentration was lower in the river than in seawater, the mean 137Cs activity on suspended particles was 11,000 Bq/kg-dry in the river versus 3200 Bq/kg-dry in seawater. Proportions of ion-exchangeable, organically bound, and refractory fractions of 137Cs on suspended particles were determined by sequential extraction. The ion-exchangeable fraction accounted for 0.3–2.0% (average: 1.2%) and 0.4–1.3% (0.8%) at the river and port sites, respectively. The organically bound fraction accounted for 0.3–4.8% (1.8%) and 0.1–5.5% (2.1%) at the river and port sites, respectively. In both areas, the refractory fraction accounted for >90% of 137Cs. Therefore, the small labile 137Cs fraction on suspended particles in coastal seawater indicates that the mobility of 137Cs to marine biota is quite low. SynopsisThis study is the first to examine radiocesium sorption forms on suspended particles in coastal seawater near the Fukushima Dai-ichi Nuclear Power Plant. It suggests immobility of 137Cs in suspended particles being incorporated to marine biota.

Migration mechanisms of 90Sr and 137Cs on terraces

In order to investigate the impact of environmental conditions on the distribution and migration of 90Sr in the Longji terrace environment, the activity concentrations of 90Sr and 137Cs were determined. The activity concentration ranges of 90Sr and 137Cs in surface soil were 0.15–1.04 Bq/kg and 2.16–6.94 Bq/kg, respectively. These results showed that there was a similar trend between the activity concentration of 90Sr and 137Cs in the surface soil along the runoff path and their activity concentration were influenced by the slope of the terraced terrain. On the other hand, the activity ranges of 90Sr and 137Cs in soil cores were 0.01–2.74 Bq/kg and 0.43–7.19 Bq/kg, respectively. These results indicate that the migration mechanism of 90Sr is different from that of 137Cs. As compared with 137Cs, 90Sr is significantly influenced by the moisture content. In addition, high span of 137Cs/90Sr activity ratios were found in this study, which were attributed to the characteristics of cultivated land and frequent artificial disturbances that intensified the migration of 90Sr.

Impact of fluvial discharge on 137Cs in the ocean following the Fukushima Daiichi Nuclear Power Station accident

Abstract After the Fukushima Daiichi Nuclear Power Station (F1NPS) accident, 137Cs activity concentrations have not yet decreased to pre-accident levels because of direct release from the site and fluvial discharges of 137Cs deposited on land. It is necessary to consider dispersion processes in the coastal area to understand the impact of multiple river discharges and direct release. To achieve this goal, we carried out oceanic dispersion simulations that considered direct release and fluvial discharges and compared the results with the annual averages of observed data. We assumed that particulate 137Cs discharged from rivers to the ocean quickly resuspended and re-leached after coagulation and precipitation, and that all of the 137Cs was dispersed. The reproducibility of results was improved by considering fluvial discharges of particulate 137Cs at all sites between 2013 and 2016, except near the F1NPS. In other words, particulate 137Cs discharged from rivers was found to influence the results of ocean surface activity concentrations within a relatively short period of time. The impact of direct release was dominant for the observed 137Cs activity concentrations adjacent to the F1NPS, which was used to estimate direct releases.

Assessment of the radionuclide remediation potential of novel miscanthus hybrids

There are few studies related to the radionuclide remediation options, which comply to the demands of the environmentally non-destructive physical remediation methods. So far, most of the research was conducted on the phytoremediation capacity of different energy crops, as well as the established miscanthus hybrids which involved metal and heavy metal contaminants. Hence, the objective of this research was the radioecological characterization of the examined agroecosystem, including the initial source of the radionuclides (soil) as well as different miscanthus hybrids grown on the same soil. The results have shown that the radioactive content of soil was similar to the global averages. All measurements of the activity concentration of 137Cs in miscanthus samples were below the detection limits. There is also an indication that 210Pb is leaching into the lower layers (or is being taken up by miscanthus plant from the upper layers). Moreover, transfer factors (TFs) for radionuclides, as a more precise parameter for evaluating the phytoremediation potential, were calculated; the TFs were found to be very low for 226Ra (≤0.07), TFs for 40K (≤0.39) and for 232Th (≤0.21) were in the lower limits, whereas the TFs for 238U were found to be the highest (≤0.92). For 210Pb, the TFs were not calculated, since the expectation was that a significant part of the measured quantity came from the air, and not through the soil. Having in mind the sustainability and the circularity aspect of the radionuclide phytoremediation system, the appropriate management method should be applied for the disposal and utilization of the biomass contaminated with radionuclides. This research has shown that the radiological content in miscanthus is high enough and the ash content is low enough that miscanthus ash could be considered as a NORM (Naturally Occurring Radioactive Material), and it can be further used for the construction industry (i.e. concrete, tiles), in mixtures with other materials with certain limitations, similar to the utilization of ash from other sources such as coal or wood.

Dynamics of radioactive contamination of lingonberry (Vaccinium vitis-idaea L.) in the forests of Zhytomyr Polissia (Ukraine) since the Chernobyl Nuclear Accident

The article presents results of study of levels of radioactive soil contamination and 137Cs activity concentration in the aboveground part of lingonberry (Vaccinium vitis-idaea L.) phytomass and berries on permanent experimental plots in different years since the Chernobyl Nuclear Power Plant accident (forest site type conditions — moist fairly infertile pine site type (B3), soils — soddy-podzolic sandy-loam on fluvioglacial sands). The research was conducted at the Poliskyi Branch of the Ukrainian Research Institute of Forestry and Forest Melioration named after G.M. Vysotsky over the years 1998–2021, utilized methods generally accepted in forest science and radioecology were used. Results were processed using statistical analysis. To substantiate the research, an official reporting data from forestry enterprises of the Volyn, Rivne and Zhytomyr regions were used. An analytical review of the state of research on this problem revealed that at the last 10–15 years there were no scientific publications on the study of 137Cs contamination of lingonberry. It was demonstrated that there was significant reduction in the density of radioactive soil contamination and 137Cs activity concentration in the aboveground part of lingonberry phytomass and berries in the forests of the research region over the observation period. It was found that the main part of the total 137Cs activity is currently located in the upper (10 cm) layer of the mineral part of the soil — 74.7% where root systems of herbaceous and dwarf-shrub species are concentrated in forest ecosystems. It was established that a considerable content of the radionuclide is retained in the aboveground part of lingonberry phytomass even with low density of radioactive soil contamination. It was found that in 1998, at relatively low value of soil 137Cs contamination density (49±5.6 kBq∙m–2), specific activity of 137Cs in aboveground phytomass of lingonberry was 8043±511 Bq∙kg–1, while in 2021 (value of soil 137Cs contamination density 22±0.3 kBq∙m–2) — 1046±182 Bq∙kg–1. The values of radionuclide transfer coefficients in 1998 were quite significant and varied within wide range: in the air-dry aboveground phytomass from 33.4 to 164.1 m2∙kg–1∙10–3 and in the fresh berries, from 9.5 to 26.0 m2∙kg–1∙10–3. Dependencies between density of radioactive soil contamination and the content of 137Cs in the aboveground part of lingonberry phytomass and berries were calculated, which can be applied in the practice of their harvesting. It was found that lingonberry belongs to the group of plants characterized by the high content of 137Cs in the aboveground vegetative phytomass. Harvesting of lingonberry leaves for the production of medicinal products should be restricted in all areas contaminated with 137Cs. Lingonberry fresh berries can be harvested in areas with a radioactive soil contamination density up to 74 kBq∙m–2.

Unique transport paths of 137Cs from the Indian to Southern Oceans

To assess ocean-scale transport systems, we examined the latitudinal cross-sectional distribution of 137Cs activity concentrations in the Indian and Southern Oceans between December 2019 and January 2020 using low-background γ-spectrometry. At 0°–20°S, 137Cs concentrations exhibited a gradual decrease below the mixing layer (1–0.1 mBq/L). However, the concentrations steeply decreased toward the Southern Ocean along a transect of 30°–60°S (from 0.8 to 0.02 mBq/L) with minor vertical variation at each site. For the 137Cs inventories (0–800 m depth) from 15 to 600 Bq/m2, a maximum value was recorded at 30°S, indicating the downwelling of 137Cs as a reservoir for the Subantarctic Mode Water. The significantly low concentrations (0.02 mBq/L) at 60°S suggest minimal transport of 137Cs to the Southern Ocean. These findings assist in understanding 137Cs circulation patterns and provide valuable insights into the transport pathways of soluble contaminants.

EFFECT OF 137CS ON FATTY ACID COMPOSITION IN COW`S MILK

Lipid composition of raw milk is a key factor determining the nutritional value and technological suitability of the milk. Monitoring the level of contamination of cow’s milk is often not available for farmers, living in the zone of radioactive contamination. 137Cs activity concentration was higher than permissible level of 100 Bq/kg in all the studied milk samples from all the experimental groups of animals from the studied settlements. The highest value of the 137Cs activity concentration of 600 Bk/kg in cow’s milk was found in Stare Selo village of Rokytne district. According to our study, local animals have partially adapted to the seasonal increase in background radiation, and the milk of these cows, in accordance with existing quality standards, is conditionally suitable for consumption. The only factor prohibiting the consumption of this milk is the level of cesium-137 contamination. An increase in the 137Cs activity concentration of more than 100 Bq/kg in cow’s milk causes a sharp decrease in the relative content of polyunsaturated fatty acids (mostly of omega-6 fatty acids) and changes in the omega-3/omega-6 ratio downward omega-3 relative content. Relative adaptation of the lactating cows to the contamination was revealed; however, metabolism of lipids in the mammary gland and the level of lipids secretion are found to be sensitive to the level of 137Cs contamination of milk. Thus, a violation of the secretory function of the mammary gland was revealed, in particular, metabolism of lipids with 18 carbon atoms in the chain. Relative content of linoleic acid immediately decreases by several times with the increasing the contamination level. Concentration of the stearic acid immediately exceeds the physiological limits at the value of 137Cs activity concentration in milk about 110–130 Bq/kg. It gradually increases with the increasing the 137Cs activity concentration up to 270–330 Bq/kg. And then it is being plateaued with the increasing the 137Cs activity concentration up to 600 Bq/kg. On the base of the study of effect of 137Cs on fatty acid ratio in cow’s milk, the C18-coefficient is being proposed to be used as the parameter of damage to the mammary gland of cows in response to a high level of 137Cs contamination, which is calculated as follows: C18c = (C18:0–C18:2)/100). Determination of the C18-coefficient indicates the dose-dependent effect of the 137Cs contamination on lipid metabolism in the mammary gland and catabolism of polyunsaturated fatty acids, particularly linoleic acid. Duration of the affecting contamination is obviously decisive factor of damage effect to the mammary gland, defining the level of biochemical transformations and initiating of peroxide processes.

A preliminary study on determination of radioactivity levels and estimation of the annual effective dose in dried fruits consumed in Albania.

This work aimed to support Albania's food safety monitoring regime. In this context, the natural and artificial radioactivity was measured in 20 samples of dried fruits collected randomly in different markets of Tirana. The activity concentration of 40K, 226Ra, 232Th and 137Cs was determined by using the high-purity germanium detector. The maximum values of activity concentration in dried fruits were calculated as 517±22Bqkg-1 for 40K, 11.10±0.93Bqkg-1 for 226Ra, 4.38±0.26Bqkg-1 for 232Th and 0.83±0.14Bqkg-1 for 137Cs. The average values of activity concentration of 40K and 226Ra were 269and 6.05Bqkg-1 and the average effective dose to individuals from the intake of the dried fruits was 44μSv y-1. All average values in this study were lower than recommended values by reports United Nations Scientific Committee on the Effect of Atomic Radiation, World Health Organization and International Commission on Radiological Protection for all age groups. Therefore, all dried fruit samples in this study are safe for consumption with acceptable radiological risk and none of them pose any significant radiological impact. The obtained data in this paper and information for levels of radioactivity and ingestion absorbed dose from dried fruits can be used to be the basic data for future comparative analysis of the other studies.

The records of 239+240Pu and 137Cs of global fallout in Lake East Dongting Sediments and Responses to watershed environmental changes

Plutonium-239 + 240 and 137Cs in the environment can usually be used to track the impact of nuclear activities on the environment, and have become important tools in environmental geochemical studies. In this study, nine sediment cores (E1-E9) in Lake East Dongting were collected and measured for the activity concentration of 239+240Pu, 137Cs and the atomic ratio of 240Pu/239Pu, and then their vertical distribution characteristics were analyzed. The results show that: the activity concentrations of 137Cs and 239+240Pu in Lake East Dongting ranged from 5.26 ± 0.43 to 28.6 ± 2.23 Bq kg−1 and 0.29 ± 0.02 to 1.37 ± 0.09 Bq kg−1, with an average of 7.48 ± 0.68 Bq kg−1 and 0.39 ± 0.03 Bq kg−1, respectively. The atomic ratios of 240Pu/239Pu are 0.168 ± 0.012–0.211 ± 0.015, which are basically consistent with the global atmospheric deposition. The vertical profiles of 137Cs and 239+240Pu in sediment cores show obvious single-peak distribution in E1-E6 and bimodal distribution in E7-E9. The results of sedimentation rates calculated by 137Cs and 239+240Pu method ranged from 0.59 cm y−1 to 1.99 cm y−1 with a mean of 1.18 cm y−1 and 0.61 cm y−1 to 2.18 cm y−1 with a mean of 1.26 cm y−1. The inventories of 137Cs and 239+240Pu in nine sediment cores are 5.87–10.8 kBq m−2 and 307–545 Bq m−2, which are about 8–14 and 9–15 times the inventory in the global average atmospheric deposition at the same latitude respectively. Comparing the results of the sedimentation rates and the inventories from different sampling points indicates that extreme climatic events and human activities have a significant impact on sediment environment of Lake East Dongting.