Cadmium and other elements in tissues from four ungulate species from the Mackenzie Mountain region of the Northwest Territories, Canada.

Tissue samples from four ungulate species from the south Mackenzie Mountain region of the Northwest Territories (NT), Canada, were analysed for stable and radioactive elements and (15)N and (13)C stable isotopes. Elevated Cd concentrations in moose (Alces americanus) kidney have been observed in the region and are a health care concern for consumers of traditional foods. This study examined the factors associated with, and potential renal effects from, the accumulation of cadmium, and interactions with other elements in four sympatric ungulate species. Mean renal Cd concentration was highest in moose (48.3mg/kg ww), followed by mountain caribou (Rangifer tarandus caribou) (13.9mg/kg ww) and mountain goat (Oreamnos americanus) (5.78mg/kg ww). No local sources of Cd were evident and the elevated levels in moose are considered to be natural in origin. Conversely, total Hg concentration was significantly higher in mountain caribou kidney (0.21mg/kg ww) than in moose (0.011mg/kg ww). (134)Cs (t½=2.1 y) in mountain goat and Dall's sheep (Ovis dalli) muscle is evidence of deposition from the Fukushima reactor accident in 2011. (137)Cs (t½=30.2 y) in all four ungulates is primarily a remnant of the nuclear weapons tests of the 1960s. The levels of both nuclides are low and the risk to the animals and people consuming them is negligible. Stable isotope δ(15)N and δ(13)C signatures in muscle showed a separation between the mountain caribou, with a lichen-dominated diet, and moose, which browse shrubs and forbs. Isotope signatures for mountain goat and Dall's sheep showed generalist feeding patterns. Differences in elemental and radionuclide levels between species were attributed to relative levels of metal accumulation in the different food items in the diets of the respective species. Kidneys from each species showed minor histological changes in the proximal tubule and glomerulus, although glomerular changes were rare and all changes were rare in mountain goat kidney. Kidney function was not expected to be affected in any species. Provisional Monthly Intake recommendations from the WHO indicate that Cd in moose organs will continue to be a public health care concern. However, traditional foods continue to be an important nutritional component of northern diets, particularly in consideration of the shift towards store-bought food.

Effectiveness of Protective Activities for Rehabilitation of the Forage Lands in Russia and Belarus Contaminated as a Result of the Chernobyl Accident.

Regularities of changes in the content of (137)Cs in green fodder during the remote period after the CNPP accident depending on application of agro-technical and agrochemical activities are analyzed. It is revealed that the use of mineral fertilizers reduces receipt of (137)Cs from the soil to forage and further to a food chain. It is also established that agrochemical activities are more effective than agro-technical ones.

Copper Ferrocyanide-Functionalized Magnetic Nanoparticles for the Selective Removal of Radioactive Cesium.

Copper ferrocyanide-functionalized magnetite nanoparticles (Cu-FC-MNPs) were successfully synthesized by immobilizing copper and ferrocyanide on the surfaces of [1-(2 amino-ethyl)-3-aminopropyl] trimethoxysilane-modified magnetite nanoparticles. Radioactive cesium (Cs) adsorption tests were conducted to investigate the effectiveness of the Cu-FC-MNPS toward the removal of radioactive Cs. The Cu-FC-MNPs showed excellent separation properties using an external magnet in an aqueous solution.

[Dynamics of Radioecological State of the Fresh-Water Ecosystems Affected by a Long-Term Impact from Nuclear Power Plant in the Frontiers of the Zone under Observation].

The results of radioecological studies of six small rivers situated in the surveillance zone of the Beloyarskaya NPP (BNPP) and around the cooling pond of the power plant are presented. 21 radionuclides and the total α- and ß-activity were studied in the main components of the aquatic ecosystems. It is shown that after the 1st and 2nd BN PP blocks decommissioning the content of 60Co and 137Cs in the Beloyarskoye storage pond water, sediments, fish fauna and macrophytes dropped tens and hundreds of times. The fundamental importance of this fact is that in a large range of time the aquatic ecosystem mechanism of self-purification from radionuclides is working due to radioactive substances decay as well as redistribution of radionuclides from water to other components, primarily to the sediments. Of 6 small rivers the maximum levels of radioactive substances is found in the river Olkhovka, which for several years has been subjected to the low-level radioactive water discharges from Beloyarskaya NPP. The radionuclide content in the main components of the aquatic ecosystems of the other five rivers studied after BNPP 47-year operation period corresponds to the regional background.

[Spatial variability of quasidiffusion coefficients for 137Cs in grey forest soils in the distant zone of contamination from the Chernobyl NPP].

The calculated values of quasidiffusion coefficients for 137Cs for the 15-year period after the Chernobyl fallout in the top mineral thickness of grey forest soils of the Tula region vary within 0.18-0.35 cm2/year, accruing among biogeocenoses: pine forest < oak forest < birch forest < pasture. Correlations are revealed and the equations of linear regression for quasidiffusion coefficients for 137Cs depending on soil properties are constructed. Estimates of the periods of effective residence half-time of 137Cs in grey forest soils are made: for a layer of 0-5 cm - 11-14 years 0-15 cm - 22-25 years, 0-30 cm - 27-28 years. The periods necessary for the decrease in the contents of 137Cs in a 0-5 cm layer of soils to the level of 37 kBq/m2 are considered, taking into account a spatial variation of fallout and heterogeneity of quasidiffusion. Forecasts of the vertical migration of 137Cs on the basis of the diffusive model with spatially distributed soil parameters are submitted.

[The assessment of the content of 137Cs of the global and Chernobyl origin in forest soils and some types of edible fungi].

The article analyzes the density of pollution of the soil by radioisotopes of caesium and the content of 137Cs in fruit bodies of some species of forest mushrooms on the "long" trail of radioactive fallout in the Republic of Belarus in 1994 and 2012. On the basis of the calculated density of pollution of the soil with 134Cs in 1986 the contribution to the total density of pollution with 137Cs of the global radioactive fallout and emissions owing to the accident at the Chernobyl nuclear power plant was defined for the studied territory. It was established that at the density of pollution of the soil by 137Cs of 12-19 kBq/m2 in 1986 about 35% of pollution was caused by the global radioactive fallout. In 1994 and 2012, a specific activity and transfer factor of 137Cs were analyzed for fruit bodies of some species of forest mushrooms. The transfer factors of 137Cs for fruit bodies of Boletus edulis are at level of 10 x 10(-3) m2/kg, Leccinum scabrum and Leccinum aurantiacum - (15-20) x 10(-3) m2/kg, Xerocomus badius--(60-80) x 10(-3) m2/kg.

[Radiological control of silvicultural production in Perm Krai].

Results of the studies carried out in 2009-2012 on the 137Cs content in edible fungi, berries and fruits of wild-growing bushes and the low shrubs growing in forest ecosystems of a number of regions of the Perm Krai are presented. It is shown that the activity of radio caesium in the studied samples does not exceed the maximal allowed levels approved in the Russian Federation.

[Distribution of 137Cs, 90Sr and their chemical analogues in the components of an above-ground part of a pine in a quasi-equilibrium condition].

The additional study of the distribution of radioactive isotopes of caesium and strontium and their chemical analogues in the above-ground components of pine in the remote from the accident period was carried out. The results of the research confirmed the existence of analogy in the distribution of these elements on the components of this type of wood vegetation in the quasi-equilibrium (relatively radionuclides) condition. Also shown is the selective possibility of using the data on the ash content of the components of forest stands of pine and oak as an information analogue.

[Man-made radionuclides and their accumulation by plants of different taxonomic groups from the soils of the eastern ural radioactive trace].

Investigations of the spatial and vertical distribution of 90Sr, 137Cs and 239, 240Pu in the soils of the Eastern Ural Radioactive Trace (EURT) and accumulation of these radionuclides by plants were carried out in 2003-2011. Investigations showed that the spatial distribution of the radionuclides with increasing distances from the epicenter of the accident is satisfactorily approximated by the exponential function. During the post-accidental period the essential amount of radionuclides is located in the 15-20 cm root layer of the soil. Uptake by plants of 90Sr is determined, first of all, by the level of the soil contamination. For 137Cs, reliable differences in its accumulation ability between representatives of the higher plants and lower ones are remained in the whole gradient of contamination.

Removal of radioactive Cs from gravel conglomerate using water containing air bubbles.

Remediation of sites contaminated with radioactive material such as Cs is important because of the risk posed to human health. Here, we report the effectiveness of water containing air bubbles with a diameter around 100 nm (nanobubbled water, NB water) for the removal of radioactive Cs. Laboratory experiments confirmed that NB water is more effective than purified water and as effective as water with neutral detergent in the removal of Cs-137 from gravel. Moreover, NB water retains its effectiveness even after storage for 7 d. Finally, NB water produced onsite from tap water was found to be effective for removal of radioactive Cs from gravel conglomerate in Fukushima, Japan.

[Forecasting model of transfer of 137Cs to the plants].

The forecasting model of the concentration ratio (CR) of 137Cs in the plants taking into consideration organic carbon, pH, mobile and total content of potassium in soil has been developed on the basis of the radioecological investigations in the valleys of the Resseta and Vytebet rivers. The type of functional dependence of CR from soil characteristics can be used for an estimation of the content of radionuclides in various species and productive parts of plants.

[Prognosis of dynamics and risk of exceeding permissible levels of 137Cs and 90Sr contents in fish in the Kiev Reservoir at the late phase of the Chernobyl accident].

On the basis of the radionuclide specific activity measurements made on 832 samples of fish in 2009-2011 and taking into account literature data, the parameters of the stochastic model have been derived to describe the 137Cs and 90Sr contents in typical commercial fish species in the Kiev Reservoir at the late phase of the Chernobyl accident, including: statistical variability, seasonal changes and monotonous long-term trends. At any fixed moment of the year the standard deviations of logarithms of the 137Cs and 90Sr specific activities in carnivorous and benthophage fish species do not reliably differ, making up at average 0.4. The maximum vari- ation of the 137Cs specific activity (a four-fold decrease from April to November) was observed in pike. The obtained values of the ecological half-life periods for 137Cs and 90Sr (1.3-14 years) in fish of the Kiev reservoir in 2002-2012 were significantly lower than both the radioactive decay periods and the estimates of the IAEA Chernobyl Forum. Based on the obtained model parameters, the dynamics of the 137Cs and 90Sr specific ac- tivities in main commercial fish of the Kiev reservoir has been described and the risk of exceeding the permis- sible levels of these radionuclides in fish at the late phase of the Chernobyl accident has been estimated. Now the risk of catching fish with the specific activities of 137Cs and 90Sr above the permissible levels (150 Bq/kg and 35 Bq/kg, respectively) does not exceed 10% (except perch in the spring spawning period that is banned for fishing in Ukraine). Corresponding risks for roach, white bream and rudd are less than 0.1%.

Practical removal of radioactivity from sediment mud in a swimming pool in Fukushima, Japan by immobilized photosynthetic bacteria.

About 90% of the radioactive Cs in the sediment mud of a school's swimming pool in Fukushima, Japan was removed by treatment for 3 d using the alginate immobilized photosynthetic bacterium Rhodobcater sphaeroides SSI. Even though batch treatment was carried out 3 times repeatedly, the activity of immobilized cells in removing Cs was maintained at levels of about 84% (second batch) and 78% (third batch). Cs was strongly attached to the sediment mud because, even with HNO(3) treatment at pH of 2.00-1.60 for 24 h, it was not eluted into the water. Furthermore, more than 75% of the Cs could be removed without solubilization with HNO(3). This suggests that the Cs attached to the sediment mud was transformed into immobilized cells via the Cs(+) ion by the negative charge of the immobilized cell surface and/or the potassium transport system of the photosynthetic bacterium.

Practical removal of radioactivity from soil in Fukushima using immobilized photosynthetic bacteria combined with anaerobic digestion and lactic acid fermentation as pre-treatment.

Practical removal of radioactivity from polluted soil in Fukushima, Japan was done using a photosynthetic bacterium, Rhodobacter sphaeroides SSI, immobilized in alginate beads. The beads were put in a mesh bag and soaked in which soil was suspended (5 kg of soil/10 L of tap water). The radioactivity of the broth decreased by 31% after 15 d of aerobic treatment. When lactic acid bacterial culture broth was added to the suspend broth, about 50% of the radioactivity was transferred to a suspend broth fraction consisting of small particles from the soil after 3 d of fermentation and 20 s of sedimentation. The results suggest that organic matter in the soil was decomposed by anaerobic digestion and lactic acid fermentation simultaneously, and was then transferred into the liquid as small particles. With combined treatment by anaerobic digestion and lactic acid fermentation for 5 d and immobilized bead aerobic treatment for an additional 19 d, the radioactivity of suspend broth decreased by 66%. The radioactivity of the original soil (10.56 µSv/h) ultimately decreased by 67% (3.52 µSv/h) after the combined treatment.

[The forecasting of vertical distribution of 37Cs and 90Sr in the forest soils of the Republic of Belarus].

The study analyzes the distribution of 137Cs and 90Sr in the vertical profile of soil of forest biogeocenoses with different modes of moisture and species composition of woody vegetation on the "long" trail of radioactive fallout in the Republic of Belarus. The parameters of radionuclide migration are calculated for the two component quasi-diffusion equation, also based on this equation, pollution of root zone soil layers is predicted, as well as semi-refined periods and the contribution of migration in this process are defined. The intensity of radionuclide migration in the vertical profile of forest soils is found to increase with the change of the soil moisture regime from automorphic to hydromorphic.

Selective Separation of Radiocesium from Complex Aqueous Matrices Using Dual Solid-Phase Extraction Systems.

The release of radiocesium (r-Cs) into natural aqueous systems is of concern because of its extended solubility as an alkaline metal ion and its facile incorporation into living beings. A technique for the selective separation of Cs from an aqueous matrix using dual solid-phase extraction (SPE) systems in a series is proposed in this paper. The SPEs equipped with chelates (Nobias Chelate-PA1 and Nobias Chelate-PB1), an ion-exchange resin (Nobias Ion SC-1), or macrocycles (MetaSEP AnaLig Cs-01 and MetaSEP AnaLig Cs-02) were evaluated in terms of selectivity and retention/recovery behavior toward Cs and other potentially competing ions (Li, Na, K, Rb, Ba, Ca, Mg, and Sr). The simulated solution of 133Cs, a chemical analog of r-Cs, was used to optimize the separation process. Operating parameters such as pH (3-13), flow rate (0.2-5.0 mL min-1), and elution behavior (HCl, 0.1-5.0 mol L-1) were optimized to ensure maximum removal of Cs from the aqueous matrices. The dual SPE system comprised Nobias Chelate-PB1 that minimized the competing impact of ions, while selective Cs retention was attained with MetaSEP AnaLig Cs-02. The proposed process was verified using real r-Cs-contaminated water from Fukushima, Japan, to observe the quantitative separation and preconcentration of r-Cs from the complex matrices.

Radiocaesium accumulation capacity of epiphytic lichens and adjacent barks collected at the perimeter boundary site of the Fukushima Dai-ichi Nuclear Power Station.

We investigated the radiocaesium content of nine epiphytic foliose lichens species and the adjacent barks of Zelkova serrata (Ulmaceae, "Japanese elm") and Cerasus sp. (Rosaceae, "Cherry tree") at the boundary of the Fukushima Dai-ichi Nuclear Power Station six years after the accident in 2011. Caesium-137 activities per unit area (the 137Cs-inventory) were determined to compare radiocaesium retentions of lichens (65 specimens) and barks (44 specimens) under the same growth conditions. The 137Cs-inventory of lichens collected from Zelkova serrata and Cerasus sp. were respectively 7.9- and 3.8-times greater than the adjacent barks. Furthermore, we examined the radiocaesium distribution within these samples using autoradiography and on the surfaces with an electron probe micro analyzer (EPMA). Autoradiographic results showed strong local spotting and heterogeneous distributions of radioactivity in both the lichen and bark samples, although the intensities were lower in the barks. The electron microscopy analysis demonstrated that particulates with similar sizes and compositions were distributed on the surfaces of the samples. We therefore concluded that the lichens and barks could capture fine particles, including radiocaesium particles. In addition, radioactivity was distributed more towards the inwards of the lichen samples than the peripheries. This suggests that lichen can retain 137Cs that is chemically immobilised in particulates intracellularly, unlike bark.

Non-invasive imaging of radiocesium dynamics in a living animal using a positron-emitting 127Cs tracer.

Visualizing the dynamics of cesium (Cs) is desirable to understand the impact of radiocesium when accidentally ingested or inhaled by humans. However, visualization of radiocesium in vivo is currently limited to plants. Herein, we describe a method for the production and purification of 127Cs and its use in visualizing Cs dynamics in a living animal. The positron-emitting nuclide 127Cs was produced using the 127I (α, 4n) 127Cs reaction, which was induced by irradiation of sodium iodide with a 4He2+ beam from a cyclotron. We excluded sodium ions by using a material that specifically adsorbs Cs as a purification column and successfully eluted 127Cs by flowing a solution of ammonium sulfate into the column. We injected the purified 127Cs tracer solution into living rats and the dynamics of Cs were visualized using positron emission tomography; the distributional images showed the same tendency as the results of previous studies using disruptive methods. Thus, this method is useful for the non-invasive investigation of radiocesium in a living animal.

Radiocesium concentrations in mushrooms collected in Kawauchi Village five to eight years after the Fukushima Daiichi Nuclear Power Plant accident.

Following the Fukushima Daiichi Nuclear Power Plant accident in March 2011, radionuclides such as iodine-131, cesium-134 and cesium-137 were released into environment. In this study, we collected wild mushrooms from the Kawauchi Village of Fukushima Prefecture, located less than 30 km southwest of the Fukushima nuclear power plant, to evaluate their radiocesium (134Cs+137Cs) concentrations and the risk of internal radiation exposure in local residents. 342 mushroom samples were collected from 2016 to 2019. All samples were analysed for radiocesium content by a high-purity germanium detector. Among 342 mushroom samples, 260 mushroom samples (76%) were detected the radiocesium exceeding the regulatory limit of radiocesium (100 Bq/kg for general foods in Japan). The median of committed effective dose from ingestion of wild mushrooms was in the range of 0.015-0.053 mSv in 2016, 0.0025-0.0087 mSv in 2017, 0.029-0.110 mSv in 2018 and 0.011-0.036 mSv in 2019 based on the assumption that Japanese citizens consumed wild mushrooms for 1 year. Thus, our study showed that although radiocesium is still detected in mushrooms collected in Kawauchi village even after 5 to 9 years later, the committed effective dose due to consuming mushrooms was lower than 1 mSv per year. Long-term comprehensive follow-up should monitor radiocesium concentrations in wild mushrooms to support the recovery of the community after the nuclear disaster.

Simulation study on the use of strippable coatings for radiocesium decontamination of concrete.

The contamination and decontamination of concrete by a soluble contaminant (radiocesium) was modeled using the finite element method. The decontamination process relied on the application of a hyper-accumulating strippable polymer (HASP™) [corrected] to sequester contaminant that was transported to the concrete surface. The model accounted for the transport of cesium by diffusion, capillary pressure-driven convection, and equilibrium adsorption of cesium within the concrete substrate and HASP™ [corrected] coating. The influence of HASP™ [corrected] properties (porosity, thickness, and cesium distribution coefficient), and a wide range of operation variables (HASP™ [corrected] contact time, delay time until HASP™ [corrected] decontamination begins, influence of evaporative boundary conditions) on final decontamination efficacy were explored. Transient saturation (moisture content) and cesium concentration profiles were used to understand key factors in the decontamination process, and water wicking experiments were performed to validate the capillary convection model. The results showed that prompt HASP™ [corrected] application after the initial contamination event is critical for high decontamination efficacies. A 30-day HASP™ [corrected] treatment removed about 90% of the contaminant when HASP™ [corrected] was applied within 30min of the initial contamination event, whereas the decontamination process removed less than half as much cesium if months were allowed to elapse months prior to decontamination. Multiple applications of fresh HASP™ [corrected] were also shown to improve decontamination performance under certain circumstances.