Transfer Of Cesium Research Articles

CURRENT RADIOLOGICAL STATUS OF CONTAMINATED MEADOWS AND PASTURES AND ASSESSMENT OF THE POSSIBILITY OF THEIR RETURN TO USE

Meadows and pastures are the fodder base for milk and meat production. The rehabilitation and return to economic use of the radionuclide-contaminated meadows and pastures is an important and urgent national economic task. The criterion of returning radionuclide-contaminated meadows and pastures to economic use may be individual doses to residents who consume milk and meat produced on these lands. Values that determine the doses are the terrestrial density of soil contamination and permissible levels of radionuclides in food products (PL-2006). Considering abandoned agricultural lands, it is necessary to note the time that passed after the accident. The contamination of the territory by 137Cs and 90Sr decreased in more than 2 times due to radioactive decay only. The decreasing due to radioactive decay and self-remediation processes (fixation of radionuclides by soil, their redistribution in the root layer of the soil, etc.) resulted in declining of radioactive contamination of products. This allows us to consider the issue of returning reclaimed lands to use in accordance with the current radiological criteria and existing legal acts. Agricultural lands are a territorial resource and the main means of agricultural production, therefore the rehabilitation of the lands will contribute to the development of both individual producers and settlements as a whole. After the Chornobyl accident, in accordance with the Law of Ukraine "On the Legal Regime of the Territory Exposed to Radioactive Contamination Due the Chornobyl Catastrophe", the territory exposed to radioactive contamination had been divided into zones. However, the belonging of the lands to a zone does not guarantee that the products produced there will meet the requirements of PL-2006. Therefore, in 1998, taking into account the type of soil, the UIAR assessed the maximum permissible levels of soil contamination which ensure the fulfillment of the requirements of PL-2006 in terms of the content of 137Cs in produced products. However, in the 25 years that have passed since the establishment of these levels and the cesium transfer factors into plants have decreased significantly. Therefore, the values of the maximum permissible levels of soil contamination are conservative and their use leads to conservative conclusions. The current radiological state of meadows and pastures contaminated with radionuclides and the possibility of returning them to use were assessed. It is shown that most of the considered abandoned lands actually belong to the third zone of radioactive contamination. Some of the lands belong to the second zone of radioactive contamination - radiation-hazardous lands. It was found that the restrictions set in the recommendations for conducting agriculture in the conditions of radioactive contamination for the production of milk and meat are very conservative. Assessment of the possibility of using contaminated meadows and pastures for milk and meat production requires more precise and targeted forecasting methods.

Effects of cattle manure compost application on crop growth and soil-to-crop transfer of cesium in a physically radionuclide-decontaminated field

Resuming crop production in physically decontaminated fields affected by radiocesium (134Cs and 137Cs) releases is crucial for restoring impacted areas. However, surface soil excavation to reduce radiocesium may lead to lower crop yield due to the loss of fertile topsoil. This study aimed to assess the effects of cattle manure compost (CMC) application on soil properties, crop growth, and 137Cs soil-to-crop transfer in a physically decontaminated field and pot experiment. Field trials were conducted during 2018–2022, with CMC (1 and 2 kg m−2 year−1) applied alongside conventional fertilization (CMC1 and CMC2 plots, respectively) in 2018–2019 and conventional fertilization alone in 2020–2022. Additionally, a pot experiment was used to evaluate the impact of CMC application in soil (1 kg m−2 year−1 for 5 years) on 137Cs transfer. In the field trial during 2018–2019, CMC1 and CMC2 plots exhibited higher soybean shoot dry weight (DW) compared with plots receiving conventional fertilization and additional K fertilizer (+K2O). CMC application also improved soil nutrient content. The transfer factor of 137Cs (TF-137Cs: plant 137Cs activity concentration/soil 137Cs activity concentration) followed the order CMC2 < CMC1 ≈ +K2O < conventional fertilization only (CF) and was negatively correlated with soil exchangeable K (Ex-K). During 2020–2022, when all plots received conventional fertilization alone, grain yields were higher in CMC1 and CMC2 plots than in the +K2O plot, with the lowest TF-137Cs in CMC2 plot followed by CMC1, +K2O, and CF plots. The pot experiment confirmed that CMC soil had a lower TF-137Cs and higher plant DW compared with CF soil with the same Ex-K level. Additionally, the soil exchangeable 137Cs (Ex-137Cs) level was significantly lower in CMC soil than CF soil. These findings demonstrate the potential of CMC application to improve crop growth and reduce 137Cs transfer in physically decontaminated fields.

Diffusion of tritium, technetium, cesium, and uranium from phosphate glass leachates in pore solution of clay materials

The through diffusion method at room temperature was used to study the migration of radionuclides (3H, 99Tc, 137Cs, 233U) in compacted samples of clay materials during pore diffusion from a model leachate of the RW phosphate matrix with a total salt content of about 400 mg/L. Based on the results of the experiments, the effective diffusion coeffcients and coeffcients of the sorption distribution of radionuclides for the studied barrier clay materials were determined. Regularities of the diffusion transfer of tritium, cesium and uranium depending on the structure, mineral composition of clay materials and the content of radionuclides in the pore solution are revealed. Numerical modeles are proposed for calculating the effective pore di usion coeffcients of these radionuclides. There are still insuffcient data to analyze the factors affecting the diffusion of technetium.

Cesium transfer to millet and mustard as a function of Cs availability in soils

137Cs is one of the most persistent radioactive contaminants in soil after a nuclear accident. It can be taken up by plants and enter the human food chain generating a potential human health hazard. Although a large amount of literature has highlighted the role of the different processes involved in Cs uptake by plants, there is still no simple way to predict its transfer for a specific plant from a particular soil. Based on the assumption that the concentration ratio (CR) of Cs can be predicted from one plant taxon if the CR of another taxon is known and taken as reference, whatever the supporting soils, a series of plant/soil Cs transfer experiments were performed on Rhizotest during 21 days using three soils with different textures, clay and organic matter contents and two plants (millet and mustard) with potentially contrasting Cs uptake capacity based on their phylogeny. CRs of each plant varied by 2–3 orders of magnitude depending on the soil and contrary to expectations, the CRs of mustard were either higher (for clay soil), equal (for clay-loam soil) or lower (for sandy soil) than the one of millet. Considering Cs availability in soils and defining a new CR based on the amount of Cs available in the soil (CRavail) decreased the range of variation in CR between the different soil types for a given plant by one order of magnitude. Differences in Cs (and K) translocation to shoots, possibly specific to millet within Poales, could partly explain the relative CRs of millet and mustard as a function of soils.

Comparative study of radioactive cesium transfer from soil to peanut and soybean

ABSTRACT Low transfer of radioactive cesium (radiocesium) from soil to grains of agricultural crops is desirable to ensure food safety for humans and animals. Although the transfer of radiocesium from soil to grains is higher in upland crops such as soybean (Glycine max L.) than in paddy rice (Oryza sativa L.), little information related to the specific difference in radiocesium accumulation among leguminous crops is available, or for the relation between soil conditions and radiocesium accumulation in leguminous crops. This study compared the pattern of radiocesium transfer from soil to grains between peanut (Arachis hypogaea L.) and soybean to elucidate the diversity of radiocesium accumulation in leguminous crops growing with different potassium levels in soil. Pot and field experiments with radiocesium-contaminated soil showed that the radiocesium concentration in grains was lower in peanut than in soybean plants. For peanut, radiocesium absorption was mainly from roots instead of gynophores and fruits formed in the soil. Radiocesium absorption and translocation from roots to shoots were lower in peanut than in soybean plants. Among shoot parts, radiocesium transfers from stems to leaves, shells, and grains were lower in peanut than in soybean plants. Potassium application to the soil decreased the radiocesium transfer from soil to grains in both crops. The radiocesium accumulation was lower in peanut than in soybean under both potassium applied and non-applied conditions. These results underscored the variation in radiocesium transfer from soil to grains in leguminous crops, and demonstrated that peanut plants had lower potential of radiocesium accumulation than soybean plants.

Factors affecting the cesium transfer factor to shiitake (Lentinula edodes) cultivated in sawdust medium

The transfer factor (TF) of radioactive cesium-137 (137Cs) to shiitake (Lentinula edodes) cultivated on bed logs varies greatly. Therefore, the present study investigated which factors affect the TF using stable cesium-133 (133Cs) and sawdust medium with 5% rice bran as a model, which had similar 133Cs TFs to bed-log cultivation. It was found that the Cs concentration and nutrient concentration (represented by the nitrogen concentration) concerned with the TF in the model sawdust medium. In addition, the TFs calculated using total 137Cs and 133Cs concentrations differed in both bed-log cultivation and the model sawdust medium cultivation, while the TFs calculated using exchangeable 137Cs and 133Cs concentrations were the same in sawdust medium cultivation, indicating that exchangeable Cs in the medium is the source of Cs for the fruiting body and the former difference was due to the presence of other chemical speciation of Cs that could not be absorbed. One purpose of the TF on the mushroom farm is to determine the fruiting body 137Cs concentration at the start of bed-log cultivation, therefore the prediction method of TF are discussed considering the future changes of 137Cs concentrations in trees.

Variations in radioactive cesium accumulation in wheat germplasm from fields affected by the 2011 Fukushima nuclear power plant accident

Decreasing the transfer of radioactive cesium (RCs) from soil to crops has been important since the deposition of RCs in agricultural soil owing to the Fukushima nuclear power plant accident of 2011. We investigated the genotypic variation in RCs accumulation in 234 and 198 hexaploid wheat (Triticum spp.) varieties in an affected field in 2012 and 2013, respectively. The effects of soil exchangeable potassium (ExK) content to RCs accumulation in wheat varieties were also evaluated. A test field showed fourfold differences in soil ExK contents based on location, and the wheat varieties grown in areas with lower soil ExK contents tended to have higher grain RCs concentrations. RCs concentrations of shoots, when corrected by the soil ExK content, were positively significantly correlated between years, and RCs concentrations of shoots were significantly correlated with the grain RCs concentration corrected by the soil ExK content. These results indicated that there were genotypic variations in RCs accumulation. The grain to shoot ratio of RCs also showed significant genotypic variation. Wheat varieties with low RCs accumulations were identified. They could contribute to the research and breeding of low RCs accumulating wheat and to agricultural production in the area affected by RCs deposition.

Study on paddy soil in Fukushima using Mössbauer spectroscopy

One of the four neighboring fields tended to show slightly higher contamination of radioactive cesium in rice grain soon after Fukushima Daiichi Nuclear Power Plant accident. In order to understand the reason, the oxidative/reductive atmosphere in the paddy field was investigated using 57Fe Mӧssbauer spectroscopy. The iron concentration variation was also investigated based on soil size distribution. It was suggested that the oxidative/reductive condition of iron state may reflect the features of the soils and then affect the solubility of potassium and radioactive cesium in the field. Oxidative atmosphere and in particular more abundant iron in larger size soil may affect the transfer of radioactive cesium from soil to rice grain.

Evaluation of the potential for caesium transfer from contaminated soil to the food chain as a consequence of uptake by edible vegetables

This paper analyzes the effect of caesium (Cs) concentration on seed germination, seedling growth, root uptake, and leaf uptake of Lactuca sativa to understand the potential transfer of the metal from contaminated soil to humans through the food chain.The results of germination experiments show that seed germination and seedling growth strongly depend on increasing Cs concentration, with a decrease in the number of germinated seeds compared to the control up to 13.6% and a reduction in seedling growth up to 10.3% at the highest Cs tested concentration (15 mM).Uptake experiments indicate a low transfer of Cs from soil to leaves and roots of the plants, ranging between 0.06% and 2.2%. The transfer is found to be a not-monotone function of soil potassium (K) content, with highest values corresponding to 1–2 mM K2SO4. Increasing concentrations of K lead to lower translocation of Cs from roots to leaves. Values above the average amount applied (20 and 40 mM K2SO4) almost stop the translocation, suggesting the use of a high amount of K2SO4 protects the food chain from Cs contamination.

Inhibition Effects of Industrial Waste-based Sorption Materials on Cesium Transfer From Contaminated Soil to Vegetation and Penetrated Water

Inhibition Effects of Industrial Waste-based Sorption Materials on Cesium Transfer From Contaminated Soil to Vegetation and Penetrated Water

Impact of effective microorganisms on the transfer of radioactive cesium into lettuce and barley biomass

Soil microorganisms play an important role in determining the physical and chemical properties of soils. Soil microorganisms have both direct and indirect effects on the physical and chemical states of radionuclides and their availability for uptake by plant roots. Controlling the soil microorganisms to immobilize radionuclides is a promising strategy to reduce the content of radionuclides in the food chain. In this study, we evaluated the impact of effective microorganisms (EM) comprising lactic-acid bacteria, photosynthetic bacteria, and yeast on the transfer of 137Cs into the aboveground biomass of barley and lettuce. The application of EM or fermented organic fertilizer (bokashi) alone to sod-podzolic sandy-loam soil significantly reduced the aggregated transfer factor of 137Cs in barley by 37% and 44%, respectively. The combination of EM with bokashi or potassium fertilizer produced the largest reductions in 137Cs transfer into barley biomass (50% and 63%, respectively). EM had a stronger effect on 137Cs transfer into barley compared to lettuce. Laboratory experiments suggested that the effect of microorganisms on 137Cs uptake can be attributed to a reduction in the proportion of bioavailable physicochemical forms of 137Cs in the soils treated with EM and bokashi. This study, to the best of our knowledge, is the first to report the mechanism by which microbial fertilizers reduce the transfer of 137Cs into plants.

Determination of cesium transfer factors by instrumental neutron activation analysis

Food-chain models are used to predict radionuclide ingestion after fallout deposition. These models include those transfer processes (soil-to-plant transfer factor(s) [TF], plant-to-animal transfer coefficient(s) [TC] and concentration ratio [CR]) that are likely to be important for radiological assessment. The range of variability for transfer factors for the same plant groups is great, about 4–5 orders of magnitude, which limits their applicability. A better way to determine the best estimate the factors for radiocaesium and other important radionuclides is if the site-specific data are available. Soil, plant and animal samples were collected from a pasture area in Hungary during the vegetation period in 2016. Stable 133Cs concentration was analysed by comparative method with neutron activation analysis (NAA). The comparator and the samples were irradiated in thermal neutron flux 2.55 × 1012 ncm−2s−1 for 2 h (soil) and 6 h (vegetation, animal samples) in the TRIGA Mark II research reactor at the Nuclear Engineering Teaching Laboratory. After an appropriate decay time (12 days) the samples were measured by gamma-spectrometry and analysed. The observed stable caesium TCpm (0.48–0.53) and CRpm (0.41–0.45) were very close to 137Cs factors in the IAEA 2009 Report of 0.49 and 0.54, respectively. This methodology is particularly suitable for the simultaneous study of natural caesium in ecosystem compartments. Consequently, the transfer of stable caesium in a pasture field may be regarded as a useful analogy in predicting the long-term changes of 137Cs affected by site-specific environmental factors.

Potassium behavior and clay mineral composition in the soil with low effectiveness of potassium application

ABSTRACT Increasing exchangeable potassium (ExK) content in soil to an appropriate level is important to mitigate the transfer of radioactive cesium to crops. We focused on a buckwheat (Fagopyrum esculentum Moench) field with a low ExK content, despite the application of K, in Fukushima Prefecture, Japan (Field A), following the Tokyo Electric Power Company Fukushima Dai-ichi (No. 1) Nuclear Power Plant accident in March 2011. We examined the relationship between K concentration and clay mineral composition in the soil of Field A and compared the findings with another field in Fukushima Prefecture (Field B) to clarify whether K applied to the soil was leached or remaining fixed. Pot experiments showed that K concentration in water seepage from pots following irrigation was significantly lower in pots from Field A than in those from Field B. Soil ExK content after soybean cultivation was lower in soils of Field A than those of Field B. These results indicate that K applied to Field A was fixed in the soil. Analysis of clay mineral composition confirmed the distinctive vermiculitic nature of Field A soils. This clay mineralogy would be associated with the higher K fixation ability of Field A than Field B soils. This study demonstrated that K fixation in vermiculite was a factor preventing the increase in ExK content from K application to Field A.

Four‐year decline in radioactive cesium transfer to perennial Gramineae candidate bioenergy crops in a field polluted by radioactive fallout from the Fukushima Daiichi Nuclear Power Plant in 2011

AbstractThe accident caused at the Tokyo Electric Power Company's Fukushima Daiichi Nuclear Power Plant by the Great East Japan Earthquake of 11 March 2011 resulted in radioactive fallout over a wide area of eastern Japan. Production of bioenergy crops and their conversion to energy may be one way to resume agricultural production at an early date and to put renewable energy to practical use. We examined yearly changes in radioactive cesium concentrations in the harvested parts of six perennial Gramineae candidate bioenergy crops and the distribution of the cesium in plant organs and rhizosphere soil layers under no‐till conditions in an experimental field 112 km from the nuclear power plant. Average radioactivity of the sum of cesium‐134 and cesium‐137 in the harvested parts (foliage) of the six bioenergy crops on the day of harvest declined considerably from 193.3 Bq kg−1 in 2011 to 31.6% of the 2011 level in 2012, 28.8% in 2013 and 28.7% in 2014. Radioactivity was higher in the underground plant parts (subterranean stem and root) than in the aboveground parts (foliage and stubble). In 2014, radioactivity in the untilled rhizosphere soil was higher in the shallow layer (0–5 cm from the soil surface) than in the deeper layers, indicating that rainfall and perennial bioenergy crop cultivation for more than 3 years had a limited effect on the soil distribution of the fallout. These results provide unique and specific information on radioactive cesium transfer to bioenergy crops and could help in the planning of feedstock supplies in radiation‐polluted areas.

Reducing radioactive cesium transfer from sawdust media to Pleurotus ostreatus fruiting bodies

The Fukushima Daiichi nuclear power plant was damaged, and radionuclides such as 137Cs were spread into the environment. Three years have passed since the accident, and ingestion of foods contaminated with radioactive material through the food chain is a health hazard of concern. Mushrooms are known for absorbing radionuclides, and methods for reducing fruiting body radioactivity are needed. We investigated radiocesium transfer activities and methods of reducing radiocesium transfer from sawdust media into fruiting bodies using Pleurotus ostreatus. Fruiting body radiocesium activity increased linearly with increasing media radioactivity. The radiocesium activities of fruiting bodies cultivated in different sawdust media were 0.2–0.9-fold (on wet-weight basis) and 1.3–3.7-fold (on dry-weight basis) higher than those of sawdust media, showing that transfer rates vary with cultivation conditions. From the reducing fruiting body radiocesium activity tests by medium additives, Prussian blue was effective and nanoparticle insoluble Prussian blue was more efficient than soluble Prussian blue. However, nanoparticle insoluble Prussian blue is more expensive than soluble Prussian blue. If mushroom growers use Prussian blue, it will be necessary to determine the type and the additional amounts that correspond to used strains, consumer needs, commercial value and cost.

Returning land contaminated as a result of radiation accidents to farming use

An assessment is given of the possibility of sorbents based on natural aluminosilicates (glauconite and clinoptilolite) being used for remediation of radioactively contaminated land with the aim of returning it to farming use. A comparative study of selectivity and reversibility of radiocaesium and radiostrontium sorption by natural aluminosilicates as well as by modified ferrocyanide sorbents based on these aluminosilicates was made. It was found that surface modification of aluminosilicates by ferrocyanides increases the selectivity of synthesized sorbents to caesium by 100–1000 times, increases sorption capacity and makes caesium sorption almost irreversible, whereas, selectivity of these sorbents to strontium radionuclides remains approximately the same as for natural aluminosilicates. The caesium distribution coefficient for mixed nickel–potassium ferrocyanide on glauconite is 10(5.0±0.6) L kg−1, the static exchange capacity (SEC) is 63 mg g−1; for mixed nickel–potassium ferrocyanide based on clinoptilolite caesium distribution coefficients in various concentration ranges are 10(7.0±1.0), 10(5.7±0.4) and 10(3.2±0.7) L kg−1, total SEC was 500 mg g−1. Caesium leaching by various leaching solutions from saturated mixed nickel–potassium ferrocyanide based on clinoptilolite was lower than 2%; from saturated mixed nickel–potassium ferrocyanide based on glauconite it was 1.5–14.6%. Ferrocyanide sorbents, based on glauconite and clinoptilolite are recommended for remediation of land, contaminated by caesium as a result of the Fukushima accident in Japan. Use of these sorbents should decrease the transfer of caesium to agricultural vegetation up to a factor of 20.

渓畔林における樹木から渓流生態系へのセシウム137の移動

東京電力福島第一原子力発電所事故に起因する, 森林から渓流生態系への落葉を介した放射性セシウムの移動を明らかにするために, 福島県伊達郡川俣町の小渓流において, 渓畔域に分布するコナラの生葉, 林床の枯死・脱落葉 (落葉) および渓流 に堆積している落葉に含まれるセシウム 137 (137Cs) 濃度の関係を明らかにした。コナラの葉は, 生葉から落葉となり, 渓流に 堆積して分解される過程で, 137Cs 濃度が減少していた (2013年)。2012 年と 2013 年の落葉期 (11月) に, 林床に落下したコナラ葉と, 各翌年の3月に, 渓流に堆積しているコナラ落葉の137Cs 濃度を比較すると, 渓流のコナラ落葉の方が低くなった。 また, 林床に落下したコナラ落葉, 渓流に堆積しているコナラ落葉および渓流に堆積しているその他の落葉は, それぞれの各年における137Cs 濃度に大きな変化はなく, 今後も長期間, 渓畔林から渓流生態系へ落葉を介して137Csが移動する可能性が示唆された。

Transfer of Cesium and Potassium from Grapes to Wine

The food-processing transfer parameters of radioactive and stable cesium and radioactive potassium were determined from grapes to wine. The concentration of cesium in the pomace was higher than that in juice, as was the case of potassium. During white and rose wine fermentation, cesium concentration did not change significantly and potassium concentration decreased. These results suggest that the absorbance of cesium by yeast is much lower than that of potassium in the winemaking environment. The food-processing retention factors ( Fr , content in wine/content in grape) of radiocesium and stable cesium for red wine were generally higher than those for white wine, reflecting the yields of wine and the extraction of cesium during maceration.

Cesium transfer to Gramineae biofuel crops grown in a field polluted by radioactive fallout and efficiency of trapping the cesium stable isotope in a small‐scale model system for biomass gasification

AbstractThe accident at the Fukushima Daiichi Nuclear Power Plant (Tokyo Electric Power Company, Inc.) caused by the Great East Japan Earthquake of 11 March 2011 resulted in radioactive fallout that caused heavy damage to agricultural production over a wide area of eastern Japan. Production of biofuel crops and their conversion to energy may be one way to resume agricultural production at an early date and to put renewable energy to practical use. This study addressed two concerns relevant to this scenario: (i) the degree of transfer of radioactive cesium from the soil to biofuel crops; and (ii) evaluation of gasification technology from the standpoint of removal of cesium contained in the biomass. Sixteen lines of Gramineae crops grown in an experimental field 112 km from the nuclear power plant contained 143.4–600.4 Bq kg−1 dry matter (DM) of radioactive cesium, the arithmetic average being 285.9 Bq kg−1 DM. The crops included, inter alia, Erianthus arundinaceus (Retz.) Jesw., Miscanthus spp., maize (Zea mays L.) and sorghum (Sorghum bicolor Moench), all of which were cultivated without tillage in 2011. A comparison of Miscanthus spp. that overwintered between 2011 and 2012 revealed that radioactivity decreased from 146.1 to 229.3 Bq kg−1 DM (arithmetic average: 193.3 Bq kg−1 DM) to 53.0–81.0 Bq kg−1 DM (arithmetic average: 66.0 Bq kg−1 DM). A simplified laboratory‐scale experiment revealed that the stable isotope of cesium attached to pulverized biomass of Japanese cedar (Cryptomeria japonica D. Don) and E. arundinaceus was completely trapped in gasification system and gas purification system. This result indicates that cesium was not transferred to the gas that was produced for fuel. Gasification using polluted biomass will be practical after further studies have addressed problems related to issues such as scale‐up, troubleshooting continuous runs and disposal of radioactive wastes.

Micro-PIXE evaluation of radioactive cesium transfer in contaminated soil samples

Micro-PIXE analysis has been performed on two soil samples with high cesium activity concentrations. These soil samples were contaminated by fallout from the accident at Fukushima Daiichi Nuclear Power Plant. One exhibits a radioactive cesium transfer of ∼0.01, and the other shows a radioactive cesium transfer of less than 0.001, even though both samples have high cesium activity concentrations exceeding 10,000Bq/kg. X-ray spectra and elemental images of the soil samples revealed the presence of chlorine, which can react with cesium to produce an inorganic soluble compound, and phosphorus-containing cesium-capturable organic compounds.