Cs Isotopes Research Articles

Current state and trends in the content of 137Cs and 90Sr in abiotic and biotic components of Arctic ecosystems (Barents and Kara Seas case study)

This publication summarizes long-term data on radioactive contaminants in seawater, bottom sediments, and marine fish and describes current patterns in radionuclide distribution using data collected by the Murmansk Marine Biological Institute during cruises to the Barents and Kara Seas in 2015–2017. During the study period, no short-lived artificial radionuclides were found in the Barents and Kara Seas. 137Cs and 90Sr isotopes with a longer half-life are still registered in Atlantic waters that are the main source of radioactive contamination in these Arctic seas. Volumetric activity of 137Cs and 90Sr was compared at different depths. A uniform distribution of 137Cs in the vertical column of water and a tendency to increase the volume activity of 90Sr from surface to bottom were observed in the Barents Sea. Bottom sediments in the Kara Sea contain on average 2 times more 137Cs than the Barents Sea. Atlantic cod is characterized by an extremely low concentration of 137Cs in muscular tissue, about an order of magnitude lower than in the period of maximum contamination of Barents Sea waters observed in 1982. Currently there is a decreasing trend in concentrations of anthropogenic radioisotopes in the environment and biota. Processes of 137Cs and 90Sr removing from biotic and abiotic components are described with exponential functions. Due to natural marine purification processes, the decrease of 137Cs and 90Sr concentrations in the Barents and Kara Seas occur 2–4 times faster than the physical radioactive decay of these radionuclides.

Interdependence of oxidative/antioxidant system indicators and thyroid status under conditions of prolonged exposure to small doses of radiation

We have studied the interdependence of the intensity of oxidative processes/antioxidant level and the thyroid status parameters in a group of students aged 18–24 who lived for a long time in the territory of enhanced radioecological control (density of soil contamination by isotopes (137Cs 3.7 ∙ 104 – 18.5 ∙ 104 Bq/m2). We examined 50 people from relatively environmentally friendly areas (control group) and 50 people from IV radiation zone (experimental group). In the experimental group, there were no individuals with clinical manifestations of thyroid pathology. However, subgroups with signs of hyperthyroidism and hypothyroidism were identified. We evaluated the level of cortisol, thyrotrophic hormone (TSH), triiodothyronine (T3), thyroxine (T4), malonic dialdehyde (MDA), ceruloplasmin (CP), transferrin (Tf), sulfhydryl groups (SH); we calculated the oxidative stress index (OSI). The research was conducted one month before the examination time and also during the exams as a factor in increased emotional stress. A lowered CP level was found in the subgroup with signs of hypothyroidism; SH groups – in all subgroups, separated by thyroid status. The oxidative stress index was higher in all students examined of the experimental group, compared with the control. The growth of MDA level is marked in the experimental group – it is the most strongly pronounced in conditions of additional emotional load in people with signs of hyperthyroidism and hypothyroidism. CP level significantly decreased in the subgroup of hyperthyroidism on the background of T3 decrease. OSI increased in all students examined from the experimental group. In the subgroup of hypothyroidism it became significantly higher than in the subgroup of euthyroidism. A positive correlation between the levels of CP and T3 was found. The highest values of the correlation coefficients were noted for subgroups with signs of hyperthyroidism and hypothyroidism, with the coefficient significance increasing under conditions of emotional stress. The index of oxidative stress in the experimental group positively correlated with the level of TSH – in terms of emotional stress, the statistical significance of the coefficients disappeared. In the subgroups divided by thyroid status, variability of interactions between OSI and T3 was observed but it was not statistically significant. It was found that the participation of thyroid status in supporting redox homeostasis in people aged 18–24 who suffered from chronic small-doze radiation exposure was realized mainly by the influence on the antioxidant system. The ability of thyroid hormones to maintain a proper antioxidant state was suppressed in this group. The unbalanced relationship between thyroid hormones and oxidative stress indicators is strongly manifested under conditions of additional emotional stress.

Forty-year evolution of radioactive groundwater contamination at the site of radioactive waste storage (St. Petersburg region, Russian Federation)

Evolution of tritium and beta contamination plumes resulted from radioactive waste leakage in the 1990s has been studied based on 40-year-long monitoring data at the site of radioactive waste (RW) storage. Localand regional-scale hydrodynamics are found to be the main features controlling the spreading of tritium contamination in the aquifer system, while spatial distribution of beta-activity plume is strongly restricted by sorption of 90Sr и 137Cs isotopes onto rock matrix. The study performed proves that groundwater system at the site is actually in the stage of rehabilitation from the «historical» contamination. Special complex investigation program aimed on examination of water accumulated in repository buildings and its interconnection with groundwater, demonstrated good isolation of the buildings from the surrounding aquifers and no evidence of RW release to the subsurface environment nowadays.

Graphene/semi-insulating single crystal CdTe Schottky-type heterojunction X- and \u03b3-Ray Radiation Detectors

We developed a new concept of X- and γ-ray radiation semiconductor detectors based on a large area graphene/semi-insulating single crystal CdTe Schottky-type heterojunction. These two terminal electronic devices can be easily fabricated by forming a Van der Waals contact between large area chemical vapor deposited graphene and CdTe substrates in air and at room temperature. This approach significantly reduces the fabrication cost and improves the reproducibility and stability of electrical properties. A detailed analysis of their AC and DC electrical properties was carried out in order to determine the width of the space charge region and dominant charge transport mechanisms at reverse bias. The unoptimized graphene/CdTe heterojunction detectors exhibited a promising spectral resolution of 241Am (59 keV) and 137Cs (662 keV) isotope radiation at room temperature.

Sources and accumulation of 7Be, 210Pb and 137Cs isotopes in the annual needles of larch and cedar in Novy Urengoy region (Arctic part of Western Siberia)

Annual needles of larch and cedar were sampled in the tundra zone of the Arctic part of Western Siberia in order to determine 7Be, 210Pb and 137Cs specific activities. Higher concentrations of 137Cs in the needles of cedar relative to the needles of larch can be associated with a clear difference in the properties of accumulation and translocation of caesium among these species. Higher concentrations of 7Be and 210Pb in the needles of larch relative to cedar needles and close isotopic ratios (7Be/210Pb) are probably due to more efficient aerosol deposition on vegetative canopies of larch.

Theoretical study on the ability of bicyclic cryptands to separate alkali-metal isotopes by ion exchange

Cryptand [2.2.2] collects heavier isotope137Cs more readily than [3.2.2] that gives a potential minimum atd=de.

SOURCES OF THE BASIN COMPONENT OF THE SEDIMENT YIELD ON THE SMALL RIVER IN THE FOOTHILL-LOWLAND ZONE OF THE BLACK SEA COAST OF THE CAUCASUS (USING THE EXAMPLE OF THE TSANYK RIVER)

Тhis study aims to evaluate features of the formation and sources of the basin component of the sediment yield during flash floods. Measuring campaigns were conducted in the weakly disturbed section of the Tsanyk River basin, located in the Greater Sochi area in the foothill-lowland zone of the Caucasus Black Sea coast. We used a set of field and calculation methods, including sediment dating with application of 137Cs, pin method, Yang's method, erosion modeling and others techniques for determining the rate of denudation and deposition processes. We investigated the processes of local and long-distance sediment movement. It was established that the rate of creep is 2-2.2 cm/year, the intensity of scree processes varies depending on the rock types in the range 1-3.5 cm/year. The processes of sheet erosion and linear erosion contribute to the movement of part of the eroded material from the catchment area to the river channel. Four types of slopes and slope catchments are distinguished according to the features of a sediment delivery from the catchment area to the river channel. The average annual sedimentation rate in the gully fan is amounted to 2.3 cm/year since 1986. At the same time, on the basis of studying the accumulative deposits of the gully fan, including the content of the 137Cs isotope in the different layers, it was established that the main sources of sediments are material produced by gully erosion, scree processes and slopes settling. 5-6 episodes of catastrophic sediment removal occurred in this particular slope catchment for 30-year period. The ratio between a sediment removal from the slope catchments to the river channel and the measured sediment yield in the Tsanyk River during the rain floods of low repeatability makes it possible to state that the basin component of sediment yield is at least 75% of the total. Information about the ratio of slopes and slope catchments of various types within the small river basins of the subtropical belt of the Black Sea coast of the Caucasus should be taken into account when calculating engineering structures for protecting infrastructure facilities from the impact of flash floods or mudflows.

Influence of relief characteristics and landscape connectivity on sediment redistribution in small agricultural catchments in the forest-steppe landscape zone of the Russian Plain within European Russia

Sheet, rill and gully erosion occurring in the snowmelt period (March–April) and rainfall season (May–September) is the main factor of soil degradation and mobilized hillslope sediment redistribution within cultivated lands of the Russian Plain. The evaluation of sediment redistribution for the period since 1986 within catchment sediment cascades was done based on an integrated approach for some representative dry valley catchments located in the western (the Plava River basin, Tula Oblast, Russian Federation) and eastern (the Temeva Rechka Creek catchment, the Myosha River basin, Republic of Tatarstan, Russian Federation) sectors of the forest-steppe landscape zone of the Russian Plain. All the catchments studied are characterized by a high proportion (within the range of 60–80%) of cultivated lands. The modified version of the Universal Soil Loss Equation (USLE), the Russian State Hydrological Institute's erosion model, and the LandSoil erosion model were applied to calculate soil losses within the cultivated lands. The morphological classification of interfluve slopes and hollow slope catchments, in combination with the sediment delivery ratio (SDR) assessment for slopes and hollow slope catchments of different configuration, were used to assess sediment transfer from the cultivated lands. The Chernobyl-derived 137Cs isotope was applied as a chronomarker for sediment dating in different sediment sinks located along pathways from cultivated slopes to river valley bottoms. We found that the morphological features of the dry valley catchments, including a pattern of the dry valleys of different Hortonian orders, dry valley and hollow density, dry valley incision depth, and proportion of slopes and hollow slope catchments of different configurations are the main parameters that determined a proportional input of the different sediment sinks to the sediment interception along the pathways from the cultivated slopes to the river valley bottoms. The land use/cover features are mostly responsible for the pattern of buffer zones within the interfluve parts of the catchments. The quantitative assessment of the sediment budget allowed us to conclude that the mean SDR coefficients for the dry valley catchments of second, third, and fourth Hortonian orders are 0.56, 0.33, and 0.07 respectively. The extrapolation of the study results of sediment redistribution evaluation, obtained from the studied catchments located within the Plava River basin, to the entire basin of the river also allowed us to evaluate the mean value of hillslope-to-river-valley-bottom SDR = 0.27.

Measurement of 137Cs in Ice Core Samples from Antarctica

Three different ice core samples from Antarctica were analyzed to identify activity concentrations of radioactive isotopes. Tracking migration of radioactive isotopes to Antarctica can provide a key clue to understand global environmental changes caused by radiation exposures because the Antarctic ice cores can preserve unique characteristics of various environmental conditions. We are particularly interested in the 137Cs nucleus, because it is closely related to radiation exposure from nuclear power plant accidents and nuclear bomb tests. With its half life of 30.17±0.03 years, 137Cs can also be used to assess the age of sedimentation occurring after around the year 1945. We selected three ice core samples, called Tarn8, Styx27, and H25, from different time periods; the Tarn8 sample is known to be from earlier than ~ 1000 AD, the Styx27 sample is approximately from the year 1945, and the H25 sample is from the year 2012. Radioactive isotope measurements of the ice core samples were performed using a 100% HPGe detector at Cheongpyeong Underground Radiation Laboratory (CURL). We measured the activity of 137Cs in the H25 sample to be 0.98 ± 0.82 mBq/kg. Although the activity has a large uncertainty mainly due to the limited sample quantity, the 137Cs isotopes in the Antarctic ice core were measured for the first time in Korea.

Analysis of complex gamma-ray spectra using particle swarm optimization

Analysis of gamma-ray spectra is an important step for identification and quantification of radionuclides in a sample. In this paper a new gamma-ray spectra analysis algorithm based on Particle Swarm Optimization (PSO) is developed to identify different isotopes of a mixed gamma-ray source and determine their fractional abundances. PSO is an iterative algorithm that imitates the social behaviors observed in nature to solve complex optimization problems. The PSO method is used for complex fitting to the response of a 3 × 3 inch NaI (Tl) scintillation detector and the fitting process is controlled by a test for significance of abundance and computation of Theil coefficient. To test the developed algorithm, a number of experimentally measured gamma-ray spectra related to a mixed gamma-ray source including different combinations of 60Co, 137Cs, 22Na, 152Eu and 241Am isotopes are analyzed using information of whole spectrum. The performance of the developed PSO algorithm is compared to the multiple linear regression (MLR) method as well. The results of the developed PSO algorithm show a better match with the real fractional abundances than that of MLR method.

A facility for production and laser cooling of cesium isotopes and isomers

We report on the design, installation, and test of an experimental facility for the production of ultra-cold atomic isotopes and isomers of cesium. The setup covers a broad span of mass numbers and nuclear isomers, allowing one to directly compare chains of isotopes and isotope/isomer pairs. Cesium nuclei are produced by fission or fusion-evaporation reactions using primary proton beams from a 130 MeV cyclotron impinging upon a suitable target. The species of interest is ejected from the target in ionic form, electrostatically accelerated, mass separated, and routed to a science chamber. Here, ions are neutralized by implantation in a thin foil, and extracted by thermal diffusion. A neutral vapor at room temperature is thus formed and trapped in a magneto-optical trap. Real-time fluorescence imaging and destructive absorption imaging provide information on the number of trapped atoms, their density, and their temperature. Tests with a dedicated beam of 133Cs+ ions at 30 KeV energy confirm neutralization, evaporation, and laser cooling to 150 μK, with an average atomic density of 1010 cm−3. Availability of cold and dense atomic samples of Cs isotopes and isomers opens new avenues for high-precision measurements of isotopic and isomeric shifts thereby gaining deeper insight into the nuclear structure, as well as for sensitive measurements of isotopes’ concentration ratios in trace quantities. The facility also constitutes the core for future experiments of many-body physics with nuclear isomers.

Migration path and isotope tracing of 137Cs and 239 + 240Pu in estuary sediments: a case study of Liao River estuary in China

Currently, the distribution characteristics and transport processes of the radionuclides 137Cs and 239 + 240Pu in the sediments of estuaries are still a controversial issue. Thus, in the present study, we investigated the distribution characteristics, sources and migration path of 137Cs and 239 + 240Pu in sediment cores of the Liao River estuary (LRE), China, and evaluated the relative contributions of the Pacific Proving Grounds (PPG) and riverine sources of Pu for the sediments in this area. We used 137Cs and Pu isotopes for dating the sediments and estimated the sedimentation rates by the two radionuclides in the LRE. Seven sediment samples were collected using a box corer from the Liao River estuarine wetland and tidal flat in the LRE in October 2012 and April 2015, respectively. The activities of 137Cs in the various samples were determined by γ spectrometry using HP-Ge detectors with 60% relative counting efficiency. Approximately 2–5 g of sediment were spiked with 242Pu (ca. 1 mBq) as a chemical yield tracer for Pu isotopic analysis at the School of Radiation Medicine and Protection, Soochow University. The measurement of Pu isotopes (239Pu, 240Pu, 242Pu) was performed by a sector field ICP-MS. In order to quantitatively differentiate the relative proportions of global fallout and PPG, we employed a two-end member mixing model to estimate their contributions. The average values of 137Cs, 239 + 240Pu activity concentrations, and 240Pu/239Pu atom ratios in the surface sediment samples of the LRE were 6.727 ± 0.251 mBq g−1, 0.294 ± 0.024 mBq g−1, and 0.188 ± 0.049 (1σ), respectively. The average 240Pu/239Pu atom ratios ranged from 0.180 ± 0.034 to 0.199 ± 0.021 in sediment cores from the east and west sides of the LRE. For core LT-2 values for 137Cs and 239 + 240Pu concentrations were from below the detection limit: 3.380 ± 0.414 and 0.036 ± 0.007 to 0.105 ± 0.007 mBq g−1. The mean 240Pu/239Pu atom ratio 0.217 ± 0.050 (1σ) in sediment core LT-2 lies between the global fallout and PPG close-in fallout. We found that atmospheric fallout is the main source of Pu in sediment cores from the east and west sides of the LRE. For core LT-2, atmospheric fallout and riverine input (~ 73.4%) are the major sources of Pu with the source of the rest of Pu (~ 26.6%) attributed to the PPG via the Tsushima Warm Current and the coastal water of the East China Sea. The sedimentation rates (means 0.62–0.8 cm year−1) estimated by the two radionuclides were in good agreement and without any statistically significant difference.

Contribution of climate and land cover changes to reduction in soil erosion rates within small cultivated catchments in the eastern part of the Russian Plain during the last 60 years

The eastern part of the Russian Plain is an important agricultural region of European Russia with high proportion of cultivated lands in the steppe, forest-steppe and forest (southern part) landscape zones. Soil erosion is the main process of land degradation and surface water contamination there. Climate and land cover changes have been observed in this region during the last 30 years. However, field quantitative assessments of soil erosion rates are not available for the eastern part of European Russia due to the lack of monitoring data as well as the evaluation of erosion/deposition processes in cultivated catchments using other field methods. Three representative small cultivated catchments with high (> 80%) proportion of cultivated lands were selected in the forest (southern part), forest-steppe and steppe zones of the study region to evaluate sedimentation rates in dry valley bottoms of the catchments for two-time intervals (1963–1986 and 1987–2016) based on the application of the bomb-derived and Chernobyl-derived 137Cs isotope for sediment dating. The 3–4 depth 137Cs profiles were used to assess the sedimentation rates within the each investigated catchment. It was established that the sedimentation rates have considerably decreased (at least 2–3 times) over the last 30 years compared to 1963–1986 in all the investigated catchments. This is in agreement with results of erosion rate calculations using erosion models for the forest zone, however not consistent with erosion rates assessments for the forest-steppe and steppe zones. According to the model calculations, erosion rates show a slight decrease in the forest-steppe zone and increase in the steppe zone. The reduction in surface runoff during snowmelt period is one of the reasons for decrease in erosion rates within cultivated slopes for all the investigated catchments. The increase in proportion of perennial grasses in the regional crop rotation is another important reason for the decrease in erosion rates for the catchment located in the south of the forest zone. The importance of land cover changes in a major decrease of soil losses from the cultivated fields of the investigated catchments located in the forest-steppe and steppe zones cannot be identified due to the lack detailed information about crop rotation for those particular sites. However, available regional information about crop rotation changes for the two-time intervals (1960–1980 and 1996–2012) do not explain very high reduction in sedimentation rates in the dry valley bottoms after 1986.

Cellular level in planta analysis of radial movement of artificially injected caesium in Cryptomeria japonica xylem

Ray parenchyma cells represent the main pathway for mineral radial movement from sapwood towards intermediate wood, based on direct cryo-scanning electron microscopy/energy dispersive X-ray spectroscopy analysis. Ray parenchyma cells are considered to be associated with the radial movement of some elements from sapwood to heartwood in tree trunks. However, this function has not yet been experimentally confirmed. In this study, we analysed the radial movement of caesium (Cs), as a tracer of minerals, through the xylem at the cellular level in standing trees. A solution containing a stable Cs isotope diluted in aqueous acid fuchsin was injected into the outer sapwood of Japanese cedar trees for 3 h, 1, or 4 days. After the injection, the trunk (including the injection points) was freeze-fixed with liquid nitrogen. Subsequently, the trees were felled. The red colour from acid fuchsin was detected in the outer sapwood and did not move passively in the radial direction with free water. For detailed analysis of the Cs distribution in the radial direction (from the red-coloured sapwood towards the pith), we performed cryo-scanning electron microscopy/energy-dispersive X-ray spectroscopy point analysis of the frozen-hydrated samples to analyse the Cs distribution by detecting the characteristic Cs-Lα X-ray peak. In the outer sapwood, Cs was detected in all cell structures at all injection periods. In the inner xylem tissue, Cs was detected in the cell wall and lumen of ray parenchyma cells at 4-day injection, but not at 3-h and 1-day injection. These results suggest that ray parenchyma cells represent the main pathway whereby Cs can move radially from sapwood towards intermediate wood in standing Japanese cedar trees.

Graphene-prussian blue nanocomposite impregnated in alginate for efficient removal of cesium from aquatic environment

Simple hydrothermal reaction followed by displacement reaction was used for preparation of prussian blue graphene oxide alginate (PB-GO-Alg) composite in beads form for highly efficient removal of Cs isotopes from aquatic environment. The optimum composition of the beads was 5% loading of PB (Prussian blue)-GO(Graphene Oxide) nanoparticles into 4% Ca-alginate matrix. GO upon functionalization with PB which is a zeolite-like inorganic materials capable of exchange of its K ions for Cs ions. Due to the combined effects of GO, PB and host alginate matrix, the hybrid beads showed excellent removal efficiency (>98%) for Cs isotopes from different aquatic environments. Sorption isotherm followed the Langmuir model (linear regression correlation = 0.95) and the maximum sorption capacity of Cs was calculated to be 290.6 mg g−1. Kinetic study showed that the uptake was following the pseudo second order rate law. The beads were effective at pH5-7 (uptake >98%) for Cs removal and the equilibrium time required was 6 h.Mechanism of sorption was proposed based on the zeta potential values of the GO and PB-GO nanocomposites at different pH. The developed hybrid beads hold great promise to be used in case of any nuclear eventualities to decontaminate Cs contaminated water without disturbing the water quality parameters.

Studying the impact of radioactive charging on the microphysical evolution and transport of radioactive aerosols with the TOMAS-RC v1 framework

Radioactive charging can significantly impact the way radioactive aerosols behave, and as a result their lifetime, but such effects are neglected in predictive model studies of radioactive plumes. The objective of this work is to determine the influence of radioactive charging on the vertical transport of radioactive aerosols in the atmosphere, through its effect on coagulation and deposition, as well as quantifying the impact of this charging on aerosol lifetime. The TwO-Moment Aerosol Sectional (TOMAS) microphysical model was extended to account for radioactive charging effects on coagulation in a computationally efficient way. The expanded model, TOMAS-RC (TOMAS with Radioactive Charging effects), was then used to simulate the microphysical evolution and deposition of radioactive aerosol (containing the isotopes 131I and 137Cs) in a number of idealized atmospheric transport experiments. Results indicate that radioactive charging can facilitate or suppress coagulation of radioactive aerosols, thus influencing the deposition patterns and total amount of radioactive aerosol mass available for long-range transport. Sensitivity simulations to uncertain parameters affirm the potential importance of radioactive charging effects. An important finding is that charging of neutral, coarse mode aerosol from background radiation can reduce coagulation rates and extend its lifetime in the atmosphere by up to a factor of 2.

Removal of cesium through adsorption from aqueous solutions: A systematic review

Cesium radioactive isotopes (134Cs and 137Cs) are dangerous to human health due to their long half-life and high solubility in water. Nuclear experiments, wars, and nuclear plant accidents have been the main sources of Cs release into the environment. In recent years, several methods have been introduced for the elimination of Cs radioactive isotopes from contaminated water. This study provides an overview of the available published articles (2008–2016) regarding the remediation of waters polluted by Cs isotopes. The maximum adsorption capacity (MAC) of Cs isotopes corresponded to natural chabazite (273.24 mg Cs/g adsorbent), hollow Prussian blue (PB) nanoparticles (262 mg Cs/g adsorbent), and Prussian blue implemented non-woven fabric (260 mg Cs/g adsorbent). Using natural chabazite and PB adsorbents, along with another adsorbent (PB graphene oxide hydrogel), Cs radioactive isotopes can be effectively removed from the aqueous solutions.

A double-tracer radioisotope approach to assess simultaneous bioaccumulation of caesium in the olive flounder Paralichthys olivaceus

To better understand bioaccumulation of radiocaesium in the commercially important Japanese flatfish, Paralichthys olivaceus, the uptake and depuration kinetics of caesium via both seawater and food were assessed simultaneously using controlled aquaria. The pre-conditioned fish were exposed to radionuclides via the two different pathways (aqueous versus dietary) concurrently using two isotopes of caesium, 137Cs and 134Cs, respectively. Dissolved caesium uptake was linear and did not reach a steady state over the course of the 8-day exposure period. Consumption of 134Cs-labelled food led to higher bioaccumulation rates of radioactive Cs than via seawater exposure of 137Cs during uptake and following depuration, though the model-derived long-lived biological half-lives of both pathways was approximately 66 d. Further development of this method for assessing multiple radiocaesium bioaccumulation pathways simultaneously could lead to a promising new approach for studying Cs contamination in marine organisms.

Removal of Cs+ from aqueous solutions by perlite.

Perlite is an abundant mineral that requires minimum processing before use either as raw or expanded perlite, resulting in a low-cost, natural porous material. The application of materials for the removal of radioactive cesium from liquid effluents and contaminated waters is currently of great interest. Perlite has been evaluated in the last years for the sorption of a variety of metals, but it had not been investigated before for removal of Cs+ from contaminated waters. The present work examines the use of perlites from a deposit in Salta, Argentina, for removal of Cs+ from aqueous solutions. The mineral was characterized by means of powder X-ray diffraction, thermal analysis, analysis of specific area, and scanning electron microscopy. The effect of solution pH, presence of concomitant ions, contact time, Cs+ initial concentration, perlite dose, and basic or acidic treatment of the sorbent were studied by batch experiments. Removal increased at high pHs and after treatment with NaOH. Sorption of Cs+ by perlite presented a rapid rise in the first 80min of contact. The selected material (from Pava mine) yielded removal efficiencies of 84 and 89% before and after treatment with NaOH, respectively, for a dose of 30gperlite/L and initial cation concentration of 10mg/L. Our results demonstrate that perlite is a material capable of removing Cs+ from aqueous solutions, even when applied at low doses. These findings are relevant in the context of removal of radioactive Cs isotopes from nuclear effluents and in case of contamination of environmental waters.

Interconnection of the immune system and the intensity of the oxidative processes under conditions of prolonged exposure to small doses of radiation

This research studied the interrelationship between the immune and oxidative-antioxidant systems in a group of individuals who had lived for a long time in areas contaminated with radionuclides after the Chernobyl catastrophe and as a result experienced prolonged exposure to small doses of ionizing radiation. We have examined a group of 100 students aged 18–24, where 50 of them formed the control group and the remaining 50 belonged to the experimental group as they arrived from the territories of enhanced radioecological control (IV radiation zone, density of soil contamination by isotope 137Cs 3.7 x 104 – 18.5 x 104 Bq/m2). Here we determined the level of cortisol, leukocytes and their populations, the levels of lymphocyte subpopulations with phenotypes CD3+, CD5+, CD4+, CD8+, CD16+, CD72+, immunoregulatory index CD4+/CD8+, indicators of phagocytic activity of neutrophils and monocytes, IgG (H), IgM (H), IgA (H), malondialdehyde (MDA), ceruloplasmin (CP), transferrin (Tr), sulfhydryl (SH); and also calculated the oxidative stress index (OSI). We performed the analysis twice: in the absence/presence of additional emotional stress such as an examination session. The studies showed an increase in the oxidative stress index in the group examined from the experimental cluster, especially in terms of emotional stress. At the same time, the neutrophil level increased, but phagocytic activity of neutrophils and monocytes, the relative and absolute number of lymphocytes with phenotypes CD3+, CD5+, CD4+, CD4+/CD8+, and IgG levels decreased. Consequently we revealed the negative correlation between the indexes of oxidative stress in the group of examined (the oxidative stress index (ISO)/the level of malonic dialdehyde (MDA)) and the parameters of phagocytic activity of monocytes, the immunoregulatory index CD4+/CD8+, and the number of lymphocytes with the CD16+ phenotype. In this study we demonstrated the decrease in the participation of ceruloplasmin (CP) as an important antioxidant factor in maintaining the immune homeostasis of the group examined from radiation-contaminated areas compared with control group. The evidence of this is the lack of reliable correlation between ceruloplasmin level and immune system parameters. Moreover we found that radiation-induced intensification of oxidative processes in the experimental group grew in conditions of additional stresses of an emotional nature. Besides, it was accompanied by a significant correlation in the level of oxidative stress and phagocytic activity parameters. Reducing phagocytic activity and the CD4+/CD8+ index on the background of oxidative stress increase can be considered as a sign of immune system ageing, while a decrease in the number of lymphocytes with the CD16+ phenotype is a sign of antitumor defense inhibition. Thus, we draw the conclusion that the inhabitants of the territories of strengthened radioecological control, undergoing exposure to small doses of ionizing radiation from birth, show a significant imbalance of redox homeostasis, which creates the preconditions for immunoreactivity pathology development at the level of both innate and acquired immunity.