Radioisotopes 137Cs Research Articles

The spatio-temporal distribution of elements in the bottom sediments of Lake Onego and small lakes located on the catchment area of Onego Ice Lake

The work presents the results of a comprehensive mineralogical and geochemical study of Late Pleistocene-Holocene bottom sediments of Lake Onego and small lakes located in the territory belonging to Onego Ice Lake. Methods of ICP-MS, atomic absorption spectrometry, X-ray fluorescence analysis, X-ray phase method (XRD), scanning electron microscopy (SEM), and gamma-spectrometric method were used. The geochemical composition of the terrigenous fraction reflects the mineral composition and is permanent for the all bottom sediments cores of Lake Onego and small lakes during time interval about 12,000 years. For the first time, detailed mineralogical studies of sediments have shown that the composition of mineral associations of the terrigenous fraction is similar in the bottom sediment cores of Lake Onego and small lakes. The association of authigenic minerals in bottom sediments is distinguished by the presence of pyrite framboids in small lakes, and crystalline aggregates of Fe-phosphate, ferruginous illites and chlorites in Lake Onego. Sedimentation rates established by the study of correlations the indicator technogenic radioisotope 137Cs and atmospheric 210Pb. In the bottom sediments of small lakes, sedimentation rates vary from lake to lake, as well as in various areas of Lake Onego in the range from 0.05 cm/year to 0.30 cm/year.

Synthesis and Evaluation of Cd-MOFs Materials for Adsorption of Simulated Radioisotopes 137Cs and 90Sr

Synthesis and Evaluation of Cd-MOFs Materials for Adsorption of Simulated Radioisotopes 137Cs and 90Sr

Phytoremediation of 137Cs: factors and consequences in the environment.

Radionuclide contamination is a concerning threat due to unexpected nuclear disasters and authorized discharge of radioactive elements, both in the past and in present times. Use of atomic power for energy generation is associated with unresolved issues concerning storage of residues and contaminants. For example, the nuclear accidents in Chernobyl 1986 and Fukushima 2011 resulted in considerable deposition of cesium (Cs) in soil, along with other radionuclides. Among Cs radioactive variants, the anthropogenic radioisotope 137Cs (t½ = 30.16 years) is of serious environmental concern, owing to its rapid incorporation into biological systems and emission of β and γ radiation during the decaying process. To remediate contaminated areas, mostly conventional techniques are applied that are not eco-friendly. Hence, an alternative green technology, i.e., phytoremediation, should in future be considered and implemented. This sustainable technology generates limited secondary waste and its objectives are to utilize hyper-accumulating plants to extract, stabilize, degrade, and filter the radionuclides. The review highlights plant mechanisms for up-taking radionuclides and influences of different environmental factors involved in the process, while considering its long-term effects.

Study of Naturally Occurring Radioactive Material Present in Deep Soil of the Malwa Region of Punjab State of India Using Low Level Background Gamma-Ray Spectrometry

Background: Epidemiological observations such as mental retardation, physical deformities, etc., in children besides different types of cancer in the adult population of the Malwa region have been reported. The present study is designed to get insight into the role of naturally occurring radioactive material (NORM) in causing detrimental health effects observed in the general population of this region.Materials and Methods: Deep soil samples were collected from different locations in the Malwa region. Their activity concentrations were determined using low-level background gammaray spectrometry. High efficiency and high purity germanium detector capped in a lead-shielded chamber having a resolution of 1.8 keV at 1,173 keV and 2.0 keV at the 1,332 keV line of 60Co was used in the present work. Data were evaluated with Genie-2000 software.Results and Discussion: Mean activity concentrations of 238U, 232Th, and 40K in deep soil were found to be 101.3 Bq/kg, 65.8 Bq/kg, and 688.6 Bq/kg, respectively. The mean activity concentration of 238U was found to be three and half times higher than the global average prescribed by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). It was further observed that the activity concentration of 232Th and 40K has a magnitude that is nearly one and half times higher than the global average prescribed by UNSCEAR. In addition, the radioisotope 137Cs which is likely to have its origin in radiation fallout was also observed. It is postulated that the NORM present in high quantity in deep soil somehow get mobilized into the water aquifers used by the general population and thereby causing harmful health problems.Conclusion: It can be stated that the present work has been able to demonstrate the use of low background gamma-ray spectrometry to understand the role of NORM in causing health-related effects in a general population of the Malwa region of Punjab, India.

137Caesium, 40Potassium and potassium in raw and deep-oil stir-fried mushroom meals from Yunnan in China

A number of wild, edible mushroom species (Baorangia bicolor, Boletus calopus, Boletus obsclereumbrinus, Butyriboletus roseoflavus, Rubroboletus sinicus, Rugiboletus extremiorientalis and Xerocomus sp.) were collected in 2017, from Yunnan (Yuxi prefecture) in SW China. Samples of raw and stir-fried pools of these specimens were analysed for radioisotopes 137Cs (caesium) and 40K (potassium), and for total K concentrations. On a whole (wet) weight (ww) basis, 137Cs activity ranged from < 0.10 to 0.75 Bq kg−1 for raw, and from 0.5 to 4.4 Bq kg-1 in stir-fried mushrooms. Radiopotassium (40K) activity ranged from 57 to 96 Bq kg−1 ww for raw, and 170 to 370 Bq kg−1 ww for stir-fried mushrooms, while the corresponding concentration ranges for total K were 2100–3400 mg kg−1 ww (mean: 2800 ± 3900 mg kg−1 ww), and 6000–13000 mg kg−1 ww-(mean: 8700 ± 2100 mg kg−1 ww), respectively. This data indicates that mushrooms from this region show negligible 137Cs contamination with evidently higher activity levels of 40K. The deep oil stir-frying process results in enrichment in the resulting meals for all three determinants. 100 g meal portions showed 137Cs activity in the range < 0.08 to 0.44 Bq 100 g−1 ww (mean 0.15 ± 0.12 Bq 100 g−1 ww), and 40K activity from 16 to 37 Bq 100 g−1 ww (mean 24 ± 6 Bq 100 g−1 ww). The consequent exposure from 40K contained in a single 100 g serving and weekly (100 g x7) servings was equivalent to radiation doses in the range of 0.099 to 0.23 μSv and 0.68–1.6 μSv per capita (means 0.15 ± 0.04 and 1.1 ± 0.3 μSv). This is equivalent to doses in the range of 0.0017 to 0.0038 μSv kg-1 bm day-1 and 0.011 to 0.027 μSv kg-1 bm week-1 respectively (mean values of 0.0025 ± 0.006 μSv kg-1 bm day-1and 0.018 ± 0.004 μSv kg-1 bm week-1). Analogically to the annual 137Cs radiation exposure resulting from high rates of annual consumption (20–24 kg per capita), the estimated annual dose of radiation from 40K would range from 0.34 up to 0.92 μSv kg-1 bm (mean 0.60 μSv kg-1 bm). Thus in practice, high annual consumption rates of wild, stir-fried mushrooms as seen in Yunnan, would result in negligible internal doses from decay of artificial 137Cs, relative to that from natural 40K. The 100 g servings also contained between 590–1300 mg K making this local food one of the top dietary sources of nutritionally important potassium for local consumers.

Sub-nanomolar detection of cesium with water-gated transistor

Cesium (Cs+) cations are rare in nature, but the β− active radioisotope 137Cs can be released from nuclear accidents and find its way into the water supply, where it is harmful to humans and animals who drink it. We here report a water-gated thin film transistor (WGTFT) that allows the detection of Cs+ in drinking water at very low concentrations. The transistor channel is formed from spray-pyrolyzed tin dioxide, SnO2, which gives WGTFTs with near-zero initial threshold. When the WGTFT is sensitized with a plasticized PVC membrane containing the Cs+-selective zeolite “mordenite,” it displays a threshold shift when exposed to drinking water samples carrying traces of Cs+. The response characteristic is given by the Langmuir adsorption isotherm instead of the Nikolsky-Eisenman law commonly found for ion-sensitive WGTFTs sensitized with organic ionophores. We find a complex stability constant K = (3.9 ± 0.4) × 109 l/mol and a limit of detection (LoD) of 33 pM. Our LoD is far lower than the Cs+ potability limit of 7.5 nM, which cannot be met by organic-sensitized membranes where the LoD is typically in the order of 100 nM or more.

Synergy between Zeolite Framework and Encapsulated Sulfur for Enhanced Ion-Exchange Selectivity to Radioactive Cesium

To eliminate the radioisotope 137Cs+ from contaminated water, various inorganic ion-exchange materials have been developed. Many selective ion-exchange materials are relatively expensive and difficult to prepare, whereas conventional materials such as aluminosilicate zeolites lack ion-exchange selectivity in the presence of competing cations. Here, we report a simple but powerful strategy to significantly increase the Cs+ selectivity of conventional zeolites. We demonstrate that encapsulation of elemental sulfur in the micropores of zeolites (NaA, NaX, chabazite, and mordenite) via vacuum sublimation can remarkably increase the selectivity toward Cs+ in the presence of competing ions. It appears that the elemental sulfur does not provide additional adsorption sites for Cs+ ions but increases the ion-exchange selectivity toward Cs+ by providing additional interaction. Various analyses show that sulfur partially donates its electron to the ion-exchanged Cs+ cations in zeolites, indicating significant Lewis ...

Development of a semi-empirical method to determine the efficiency of a gamma radiation detector

In the present work we present the development of a new method to calibrate the Full energy peak (FEP) efficiency of a gamma radiation detector. The method consists of the experimentally determination of the detector efficiency for an energy using a monoenergetic gamma source and from this value to extrapolate constructing the complete detector efficiency curve using the physics of first principles of gamma detection theory. For this reason the proposal method corresponds to a semi-empirical method.In this first work we show the application and the study for the validation of the method by means of simulations based on the Monte Carlo method using FLUKA code. The energies considered in the simulations correspond to those emitted by the radioisotopes 137Cs, for the determination of the efficiency for one energy we will call reference efficiency, and 152Eu, to perform the extrapolation of the intrinsic efficiency from the reference efficiency.So far, we have calibrated the total instrinsic efficiency of a bare cylindrical detector by applying the proposed method. A systematic difference between the expected values of the intrinsic efficiency obtained by statistical count for the 152Eu gamma energies, and those determined by the proposed method is observed. Despite this, the results show a good agreement with relative biases less than 5% in most cases.One of the principal advantages of this method is that it let us obtain a calibration curve with all phenomenology involved in the detection, such as the resonance peaks.

A GEOMORPHOLOGICAL APPROACH TO THE ASSESSMENT OF RADIOACTIVE CONTAMINATION IN SMALL LOWLAND AGRICULTURAL CATCHMENTS

Large fallout of 137Cs caused by the Chernobyl accident resulted in radioactive contamination of vast areas in the East-European Plain. Adsorption of the radionuclide by soil particle makes erosion processes the main driver of 137Cs redistribution in the landscape. In turn, radioisotope 137Cs is widely used to evaluate soil erosion rates and erosion-driven transport of sediments and associated contaminants. The paper presents the overview of more than two-decade long investigations of erosion and associated 137Cs migration in Chernobyl-affected areas in European part of Russia as well as the specific scheme of field data collection required for proper assessment of modern radioecological risks. The main result is that the most part of the transported 137Cs was deposited in the upper reaches of fluvial networks.

Molecular dynamics simulations of cesium adsorption on illite nanoparticles

The charged surfaces of micaceous minerals, especially illite, regulate the mobility of the major radioisotopes of Cs (134Cs, 135Cs, 137Cs) in the geosphere. Despite the long history of Cs adsorption studies, the nature of the illite surface sites remains incompletely understood. To address this problem, we present atomistic simulations of Cs competition with Na for three candidate illite adsorption sites – edge, basal plane, and interlayer. Our simulation results are broadly consistent with affinities and selectivities that have been inferred from surface complexation models. Cation exchange on the basal planes is thermodynamically ideal, but exchange on edge surfaces and within interlayers shows complex, thermodynamically non-ideal behavior. The basal planes are weakly Cs-selective, while edges and interlayers have much higher affinity for Cs. The dynamics of NaCs exchange are rapid for both cations on the basal planes, but considerably slower for Cs localized on edge surfaces. In addition to new insights into Cs adsorption and exchange with Na on illite, we report the development of a methodology capable of simulating fully-flexible clay mineral nanoparticles with stable edge surfaces using a well-tested interatomic potential model.

Dating Sediment in a Fast Sedimentation Reservoir using Cesium‐137 and Lead‐210

More than 10,000 reservoirs have been constructed in agricultural watersheds in the United States since the 1940s to control floods and sediments. Reservoir sedimentation records provide a unique opportunity to retrospectively study the effects of land use changes and climate variations on sediment production if the sediment chronology could be properly determined. The objectives of this study were to: (i) evaluate the applicability of four unsupported 210Pb (210Pbex) models for dating deposited sediments in fast‐sedimentation environments; (ii) estimate the sedimentation rates; and (iii) relate the sedimentation rates to changes in soil conservation measures, land use, and climate. Three sediment profiles were sampled at 5‐cm intervals in a flood control reservoir in the Fort Cobb Reservoir Experimental Watershed in southwestern Oklahoma. Radioactivity was measured with a γ spectrometer for radioisotopes 137Cs and 210Pb. Four 210Pbex dating models were tested. Three models (constant flux–constant sedimentation [CFCS], constant initial concentration [CIC], and constant rate of supply [CRS]), which are widely used in the lacustrine and marine environments under slow‐sedimentation conditions, were not applicable to fast‐sedimentation conditions because of considerable 210Pbex input with the sediment, which is assumed negligible in the models. A modified CRS model that uses 137Cs age markers as references improved determination of the sediment chronology. The average sedimentation rates were three to five times higher during the 1957 to 1963 time period than during the 1964 to 2011 period. The significant sediment reductions coincided with the implementation of numerous conservation measures in the watershed, including check dams, terraces, changing cropping patterns, and progressive adoption of no‐till and conservation tillage systems.

Mechanism of Strong Affinity of Clay Minerals to Radioactive Cesium: First-Principles Calculation Study for Adsorption of Cesium at Frayed Edge Sites in Muscovite

The present first-principles study based on density-functional theory confirms that frayed edge sites (FESs) formed in micaceous clays have a crucial role in the long-term stability of radioisotopes of Cs on the topsoil surface. An FES is modeled according to the weathering scenario of muscovite, and the substitution of originally occupied K with Cs is virtually simulated. The calculation results clearly demonstrate that such a replacement is strongly promoted only when the stack structure is loosely expanded at the clay edges. This is the first atomic-scale confirmation of the strong affinity of FESs to Cs, which may shed new light on the decontamination engineering of soil materials.

First-Principles Calculation Study of Mechanism of Cation Adsorption Selectivity of Zeolites: A Guideline for Effective Removal of Radioactive Cesium

Zeolites have attracted attention in the reprocessing of radioactive nuclear waste because of their high selective affinity for radioisotopes of Cs. Very recently, their useful properties have been widely utilized in decontamination after the accident at the Fukushima Daiichi Nuclear Power Plants. In this study, we study the high selectivity in the Cs adsorption of zeolites using first-principles calculations and clarify the mechanism of the cation selectivity of zeolites. We obtain energy surfaces on all capture locations for Cs/Na ions inside the micropores of a zeolite, “mordenite”, and find three crucial conditions for the highly ion-selective exchange of Na for Cs: i) micropores with a radius of \({\sim}3\) A, ii) a moderate Al/Si ratio, and iii) a uniform distribution of Al atoms around each micropore. These insights suggest a guideline for developing zeolites with high Cs selectivity and for enhancing the cation selectivity in more general situations.

粘土鉱物とゼオライトにおけるセシウムの吸着挙動：第一原理計算から見るその微視的機構

Since large amounts of radioisotopes of Cs was released after the accidents at Fukushima Daiichi nuclear powerplants, a tremendous number of scientists and engineers have faced several issues in terms of decontamination ofradioactive Cs. In this paper, we present our recent two computational works based on density functional theory, one of which is to clarify mechanism of strong adsorption and retention of Cs in clay minerals to establish an effective Cs removal scheme from large amounts of radioactive wastes left by decontamination activities, and the other of which is to reveal why zeolites can selectively catch Cs even in the presence of other minerals and to make a guideline to create a more improved materials to remove Cs as well as other radioactive ions.

診療画像中に発生した黒点の原因となる放射性同位元素の付着部位に関する推定実験

Caused by the accident of nuclear power plants in the Fukushima at 2011, many radioisotopes (RI) were diffused to the environment. As a result, X-ray detectors were stained with RIs and black spots appeared on the medical images. Using the RI of (134)Cs and (137)Cs, black spots which appeared on the photostimulable phosphor plate (X-ray detector) were reproduced experimentally. The aim of this study is the following two points; firstly, to clarify the relationship between long-time irradiations of RI and fading effect, and secondly, to clarify the positional relationship between the RI sources and the X-ray detector based on irradiation times of RI. For the latter experiment, the samples were made by spraying water (containing the RI) in order to reproduce small point sources. Then, the sources were placed on the photostimulable phosphor plate or on the cassette, and corresponding images with different irradiation times were taken. The black spots could be reproduced with the condition, in which sources were directly adhered to the photostimulable phosphor plate. We observed the black spots when sources were placed on the cassette for one week. Based on the result, we summarized that the RI which are directly adhered on the photostimulable phosphor plate may produce the black spots.

Establishment of a radioactive contamination index in seawater from the Gulf and Pacific coasts in Mexico

This paper intends to establish one radioactive contamination index in seawater based on the relation A1/A2, where A1 is the radioactivity due to the contaminant radioisotope 137Cs and A2 is the radioactivity due to the natural radioisotope 40K, both expressed either as Bq/l in seawater or Bq/g in sea salt. At a second step, the same volumes of marine sediments were detected, but in this case results were expressed as Bq/g (dry basis) in order to find an index of radioactive contamination which remains more or less unchanged in seabed. The first results obtained show the adopted units are suitable for proposed contamination index, which might be useful to measure the extent and importance of radioactive contamination in every sea region of the planet. Therefore, it is a proposal for a direct measurement at greater range, which could be compared with punctual results all over the world to avoid the panic.

The regularities of distribution of radionuclides and reare-earth elements in bottom sediments of Siberian lakes

Geochemical studies of the ecosystems of 184 Siberian lakes in three largest zones of northern Asia (humid, arid, and semiarid) and in mountainous area were carried out. The contents of natural radionuclides, radiocesium, and rare-earth elements in conjugate components of the systems and the types of the main sources of the bottom sediment material have been determined. Dating of the bottom sediments was made by the activity of radioisotopes 137Cs and 210Pb, which permitted estimation of the sedimentation rates in lakes in different regions of Siberia: 0.35 cm/year in the south and 0.25–0.3 cm/year in the north. Six main ions have been determined in the waters of the studied lakes: Ca 2+, Mg 2+, Na +, HCO 3 −, SO 4 2−, and Cl −. The distribution of natural radionuclides in the stratified sections of bottom sediments of Siberian lakes evidences the stable sedimentation and characterizes their contents in the soils of water-catchment areas, which can be considered background contents there. Sediments enriched in organic matter have higher concentrations of U and lower ones of Th and K. The Th/K ratio in the studied bottom sediments is the same as in the soils. The Th/U ratios are somewhat lower than those in the soils because U is accumulated by chemogenic and organic components. The overall 137Cs pollution of bottom sediments of Siberian lakes is close to the global background (40 mCi /km 2 in 2000), but in the Altai Territory and Buryatia and Altai Republics it is twice higher. The uneven areal and temporal distribution of residual radiocesium is observed not only in the lacustrine sediments but also in the lake water areas. The REE patterns of bottom sediments of different mineral types are similar to those of continental crust and clays of the Russian Platform, though organogenic and carbonate sediments have higher absolute REE contents than terrigenous ones. Pelitic fraction is the main REE concentrator in the bottom sediments.

Radioactivity of Tobacco Leaves and Radiation Dose Induced from Smoking

The radioactivity in tobacco leaves collected from 15 different regions of Greece and before cigarette production was studied in order to find out any association between the root uptake of radionuclides from soil ground by the tobacco plants and the effective dose induced to smokers from cigarette tobacco due to the naturally occurring primordial radionuclides, such as 226Ra and 210Pb of the uranium series and 228Ra of the thorium series and/or man-made radionuclides, such as 137Cs of Chernobyl origin. Gamma-ray spectrometry was applied using Ge planar and coaxial type detectors of high resolution and high efficiency. It was concluded that the activities of the radioisotopes of radium, 226Ra and 228Ra in the tobacco leaves reflected their origin from the soil by root uptake rather than fertilizers used in the cultivation of tobacco plants. Lead-210 originated from the air and was deposited onto the tobacco leaves and trapped by the trichomes. Potassium-40 in the tobacco leaves was due to root uptake either from soil or from fertilizer. The cesium radioisotopes 137Cs and 134Cs in tobacco leaves were due to root uptake and not due to deposition onto the leaf foliage as they still remained in soil four years after the Chernobyl reactor accident, but were absent from the atmosphere because of the rain washout (precipitation) and gravitational settling. The annual effective dose due to inhalation for adults (smokers) for 226Ra varied from 42.5 to 178.6 μSv/y (average 79.7 μSv/y), while for 228Ra from 19.3 to 116.0 μSv/y (average 67.1 μSv/y) and for 210Pb from 47.0 to 134.9 μSv/y (average 104.7 μSv/y), that is the same order of magnitude for each radionuclide. The sum of the effective doses of the three radionuclides varied from 151.9 to 401.3 μSv/y (average 251.5 μSv/y). The annual effective dose from 137Cs of Chernobyl origin was three orders of magnitude lower as it varied from 70.4 to 410.4 nSv/y (average 199.3 nSv/y).

Radioactivity level and soil radon measurement of a volcanic area in Cameroon

The radioactivity level of soils in a volcanic area in Cameroon was determined and discussed. Thirty soils samples were collected from Buea and Limbé cities located in the south-western Cameroon. These two regions are known for theirs volcanic grounds due to the presence of Mount Cameroon Mountain. The activity concentrations of natural radionuclides as well as that of the fission product were evaluated by gamma-ray spectrometry using a hyper-purity germanium detector (HPGe). The ranges of concentrations in the surveyed soils were 11–17 Bq kg −1, 22–36 Bq kg −1 and 43–201 Bq kg −1 for 226Ra, 232Th and 40K, respectively. The radioisotope 137Cs was also found but in a very small amount. The outdoor absorbed dose rate 1 m above ground with the corresponding annual effective dose rate, assuming a 20% occupancy factor was estimated. The radium equivalent and the external hazard index were also evaluated and results are compared with available data from other studies and with the world average value [United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), 1988. Sources, Effects and Risks of Ionizing Radiation. Report to the General Assembly on the Effects of Atomic Radiation. United Nations, New York; UNSCEAR, 2000. Sources and Effects of Ionizing Radiations. Report to the General Assembly with Scientific Annexes. United Nations, New York]. A solid state nuclear track detector (SSNTD), LR-115 was used for soil radon measurements at a depth of 50 cm. The ranges of soil radon concentrations were 6.7–10.8 kBq m −3 and 5.5–8.7 kBq m −3 in Buea and Limbé, respectively. A positive correlation was found between concentrations of radium measured with γ-spectrometry and the soil radon concentrations measured with the nitrate cellulose detectors. The results of this study provide the radioactivity level in soil of a volcanic area, which has been found to be within the safety limits. The south-western Cameroon can be considered as having normal natural background radiation.

Determination of the Initial 137Cs Fallout on the Areas Contaminated by Chernobyl Fallout

Determination of the Initial 137Cs Fallout on the Areas Contaminated by Chernobyl Fallout The fallout radioisotope 137Cs is widely used to study rates and patterns of soil redistribution. This method requires the knowledge about the initial fallout of cesium in the study area. This paper describes the method of establishing the initial fallout of cesium for a study area which is contaminated by Chernobyl fallout. The study was carried out on the loess area near the Ujazd village (South-West Poland). The 137Cs activities for reference soil cores varied from 4.41(24) kBq/m2 to 5.97(26) kBq/m2. The average value of the reference inventory of 137Cs for the study area is 5.23(15) kBq/m2. The calculated contribution of the Chernobyl 137Cs fallout in the total cesium is equal 69%. Moreover the annual values of the 137Cs fallout based on the precipitation data were calculated and presented. This study provides the method of calculating the 137Cs fallout connected with the nuclear weapon testing based on the precipitation data. Moreover, this study also indicated that the spatial variability on the highly contaminated by Chernobyl cesium study area is small (RSD about 10%) and thus it is possible to use the cesium method to study soil redistribution.