Levels Of 137Cs Contamination Research Articles

Peculiarities of the exposure dose formation on the population in the most affected regions of Russia after the Chernobyl NPP accident

The paper presents an analysis of the current radiation situation in the settlements of the Russian Federation located on the most radioactively contaminated territory after the Chernobyl accident. The assessment of 137Cs content in local agricultural (milk, beef, pork, potatoes), natural (mushrooms) foodstuffs, doses of external, and internal irradiation of residents was carried out. 37 years after the Chernobyl NPP accident, 72 settlements with a total number of residents of 63869 remain in the zone of radioactive contamination whose average effective radiation doses exceed 1 mSv/year. All these settlements are located in five southwestern districts of the Bryansk region and are rural except for Novozybkov. In the private sector of settlements, potatoes and pork fully comply with radiological standards for the content of 137Cs. In milk, the content of the radionuclide can exceed the standards up to 3, in beef up to 5, in mushrooms up to 8–17 times. Over the past 30 years, the number of settlements exceeding the legally established standard for the total exposure dose to the population (1 mSv/year) has decreased by 7.5 times. Due to the decrease in the levels of 137Cs contamination of local foodstuffs and the volume of their consumption, the role of internal exposure dose has been decreasing in recent years. It was noted that in addition to a comprehensive assessment of the radiation situation in settlements, agricultural and natural ecosystems, when planning the rehabilitation of settlements with average annual radiation doses of residents above 1 mSv, it is important to take into account the current diets of residents and the real demographic situation in the territories affected by the Chernobyl accident.

The impact of radioactive contamination on tree regeneration and forest development in the Chernobyl Exclusion Zone

AbstractQuestionsNuclear power is under increasing consideration in many countries because it is a low‐carbon strategy to satisfy growing energy demands. Yet, the long‐term environmental impacts of nuclear accidents remain unclear. Here we asked how ionizing radiation affects tree regeneration and forest development after the Chernobyl nuclear accident. We hypothesized that high levels of 137Cs contamination in the soil: (a) inhibit tree establishment; (b) accelerate structural development (i.e., facilitation of an early differentiation of tree sizes); while (c) prolonging the dominance of early‐seral deciduous communities (because of an elevated susceptibility of conifers to ionizing radiation).LocationChernobyl Exclusion Zone, Ukraine.MethodsWe sampled 103 plots on former agricultural lands in the Chernobyl Exclusion Zone that were abandoned after the accident in 1986.ResultsContamination had no significant effect on the stem density of forests established on former agricultural lands (p = 0.769). Structural development was not accelerated by radioactive contamination (p > 0.191), but we did find weak indications that the presence of tree regeneration was reduced by high radiation levels (p = 0.054). Tree species composition did not vary significantly with contamination (p = 0.250). Individual Scots pine trees did, however, experience a considerably higher proportion of deformed stems when contamination levels were high (p = 0.009).ConclusionsOur analyses confirm negative effects of radioactive contamination on the individual tree health of Scots pine, yet early stand development in the Chernobyl Exclusion Zone was largely insensitive to different levels of radiation. As wildfires threaten to remobilize and redistribute radionuclides stored in the growing forests of the Chernobyl Exclusion Zone, our findings have potential implications for human health. We conclude that forest dynamics is a key element for assessing the long‐term risk at nuclear accident sites and requires intensified research and monitoring.

Assessing the natural and anthropogenic radionuclide activities of the Pechora River estuary: Bottom sediments and water (Arctic Ocean Basin)

This paper studies the activity of natural and technogenic radionuclides in bottom sediments and surface water of the Pechora River estuary, which is the largest Arctic river within the European part of Russia. The relevance of conducting radioecological studies of this region is associated with active oil and gas activities in the Pechora basin and the presence of potential sources of radiation hazard. The average activities of 137Cs, 226Ra, 232Th, and 40K in bottom sediments were 0.16, 18.72, 13.36, and 373.59 Bq·kg-1, respectively. The average activity of 226Ra in the bottom sediments of the Pechora delta was two times higher than in other rivers of the Arctic basin of the European part of Russia, which is associated with oil and gas activities that are carried out in the Pechora basin. This is due to the fact that the decay products of uranium are the main by-products of oil and gas production. The specific activity of technogenic 137Cs in bottom sediments of the Pechora River delta was low and did not exceed 2.2 Bq·kg-1. We did not detect any radioactive 90Sr in bottom sediments. The low 137Cs activity in the bottom sediments of the Pechora delta was associated with both the larger granulometric composition of the sediments in comparison with the estuaries of the Siberian rivers, and with low concentrations of 137Cs in the terrigenous material (soil) entering the river from the catchment area. This was due to the low levels of 137Cs contamination in the soil of the Pechora river basin. We did not find any negative radiation effects of the underground nuclear explosion “Pyrite” carried out in the northern part of the delta, since there were no other technogenic radionuclides. The values of the radionuclides 3H, 137Cs, 226Ra, 232Th and 40K, as well as the total alpha activity in the surface waters of the Pechora River delta, turned out to be below the detection limit. In surface waters, we were able to determine only the total beta activity, which varied over a range from 19.6 to 59.6 Bq·m-3 with an average value of 33.9 Bq·m-3, which was significantly lower than the radiation safety standards. The values of the radiation hazard parameters were below the world average levels and were not significantly hazardous to the health of people living in the area of the Pechora River delta. We concluded that at present, in the Pechora River delta, there are pastures for reindeer with low levels of natural and man-made radioactivity. These conducted studies are the source material in a series of comprehensive studies of the current radioecological state of the tundra territories of the European part of Russia.

Effects of 137Cs contamination after the TEPCO Fukushima Dai-ichi Nuclear Power Station accident on food and habitat of wild boar in Fukushima Prefecture

After the Tokyo Electric Power Company Fukushima Dai-ichi Nuclear Power Station accident, wild boar was found to have greater radiocesium (137Cs) activity concentrations in their bodies than other wild animals in Japan; however, the reason for this remains unknown. To understand the mechanism of 137Cs transfer from the environment to wild boar, and the factors that affect variation in 137Cs contamination in wild boar, we sampled muscle and stomach contents from wild boar captured in Fukushima Prefecture and analyzed the relationships among 137Cs concentrations in muscle tissue and in the stomach contents, 137Cs ground deposition at capture sites, and wild boar food habits. Significant positive relationships were observed among 137Cs activity concentrations in muscle and stomach contents, as well as 137Cs deposition density at capture sites. These results suggest that 137Cs is transferred from the environment to plant and animal materials consumed by wild boar, and then from these foods to the bodies of wild boar through digestion. However, no correlation was observed between 137Cs concentrations in stomach contents and the presence of any particular food item in stomachs of wild boar, including mushrooms. These findings suggest mushrooms and underground food items, which were found to affect 137Cs concentrations in wild animals in Europe, were not important contributors to high levels of 137Cs contamination in Japanese wild animals.

The wildfire problem in areas contaminated by the Chernobyl disaster

This paper examines the issue of radionuclide resuspension from wildland fires in areas contaminated by the Chernobyl Nuclear Power Plant explosion in 1986. This work originated from a scientific exchange among scientists from the USDA Forest Service, Ukraine and Belarus that was organized to assess science and technology gaps related to wildfire risk management. A wildfire risk modeling system was developed to predict likely hotspots for large fires and where wildfire ignitions will most likely result in significant radionuclide (Cesium, 137Cs) resuspension. The system was also designed to examine the effect of fuel breaks in terms of reducing both burn probability and resuspension. Results showed substantial spatial variation in fire likelihood, size, intensity, and potential resuspension within the contaminated areas. The potential for a large wildfire and resuspension was highest in the Belorussian Polesie Reserve, but the likelihood of such an event was higher in the Ukrainian Chernobyl Exclusion Zone due to a higher predicted probability of ignition. Fuel breaks were most effective in terms of reducing potential resuspension when located near areas that had both high ignition probability and high levels of 137Cs contamination. Simulation outputs highlighted how human activities shape the fire regime and likelihood of a large fire in the contaminated areas. We discuss how the results can be used to develop a fire management strategy that integrates ignition prevention, detection, effective suppression response, and fuel breaks. Specifically, the modeling system can now be used to explore a wide range of fire management scenarios for the contaminated areas and contribute to a comprehensive fire management strategy that targets specific drivers of fire by leveraging multiple tools including fire prevention and long-term fuel management. Wildfire-caused emissions of radionuclides in Belarus, Ukraine, and Russia are a socio-ecological problem that will require defragmenting existing risk management systems and leveraging multiple short- and long-term mitigation measures.

In situ measurement of cesium-137 contamination in fruits from the northern Marshall Islands

Radioactive contamination of fruits in the northern Marshall Islands, resulting from the US nuclear weapons testing program in the 1940s and 1950s, is still a human health concern, in particular pertaining to island population resettlement and the economic benefit from farming. Over 200 fruits, primarily coconuts and pandanus, were collected on 11 islands from four atolls in the northern Marshall Islands in 2017. The energy spectra from nuclear gamma decays were measured on a research vessel for each fruit in situ. From these recordings, the level of cesium-137 (137Cs) contamination was determined for individual fruits. Comparisons of the results are made to past studies and international food safety standards. There is a broad distribution of values, ranging from below detectable radiation levels to relatively high levels; safety concerns are largest for Bikini Island. A noticeable fraction of fruits from Bikini have significantly higher levels of 137Cs contamination compared with those from all other measured islands.

Calibration of forest 137Cs cycling model ”FoRothCs” via approximate Bayesian computation based on 6-year observations from plantation forests in Fukushima

Predicting the environmental fate of 137Cs in forest ecosystems along with the concentrations of 137Cs in tree parts are important for the managements of radioactively contaminated forests. In this study, we calibrate the Forest RothC and Cs model (FoRothCs), a forest ecosystem 137Cs dynamics model, using observational data obtained over six years from four forest sites with different levels of 137Cs contamination from Fukushima Prefecture. To this end, we applied an approximate Bayesian computation (ABC) technique based on the observed 137Cs concentrations (Bq kg−1) of five compartments (leaf, branch, stem, litter, and soil) in a Japanese cedar plantation. The environmental decay (increment) constants of the five compartments were used as the summary statistics (i.e., the metric for model performance) to infer the five parameters related to 137Cs transfer processes in FoRothCs. The ABC technique successfully reconciled the model outputs with the observed trends in 137Cs concentrations at all sites during the study period. Furthermore, the estimated parameters are in agreement with the literature values (e.g., the root uptake rates of 137Cs). Our study demonstrates that model calibration with ABC based on the trends in 137Cs concentrations of multi compartments is useful for reducing the prediction uncertainty of 137Cs dynamics in forest ecosystems.

Remote sensing the radionuclide contaminated Belarusian landscape: a potential for imaging spectrometry?

The 1986 Chernobyl accident resulted in radionuclide contamination (dominated by 137Cs) across large areas of Belarus. Consequences of this accident continue to affect Belarus long after initial contamination, which in turn has placed strain upon social, economic and political infrastructures. One method to reduce this strain and remediate contamination is to return areas of land no longer posing a risk, back to an appropriate use. As a method of remediation, this requires regular and accurate monitoring of the landscape at which existing ground based techniques have not been entirely well‐suited. Remote sensing, specifically the use of imaging spectrometry offers the potential to monitor the Belarusian landscape at opportune spatial and temporal resolutions. Vegetation has been shown to be an important agent in the cycling of radioactive isotopes in the environment and therefore a useful indicator of radionuclide contamination. This pilot research has focused on assessing the spectral response from Pinus sylvestris (dominant on the Belarusian landscape) at differing ages and with varying levels of 137Cs contamination. Continuum removal was applied to the spectra showing that for older forests (c. 35 years) significant spectral differences between low and high contaminated sites exist at wavelengths that are causally related to foliar biochemicals. This was not the case for young forests (c. 15 years) where no significant differences were found. The results signify the potential to infer contamination levels from spectra of forests, partitioned by age, thus indicating the possibility of using imaging spectrometry to monitor radionuclide contamination, a possibility warranting further investigation.

Root uptake of 137Cs by natural and semi-natural grasses as a function of texture and moisture of soils

This work studies the dependence of 137Cs root uptake on the structure of landscape, especially on texture and moisture of soils, under natural conditions, on abandoned radiopolluted lands in Northern Ukraine. Researches were carried out on a wide range of landscape conditions, at various levels of 137Cs contamination (from 20 up to 5000 kBq m −2), with different types of soils (approx. 20 soil varieties), which differ in texture, granulometric composition, degrees of gleyization and water regime, and anthropogenic transformation. The results showed that transfer factor (TF) values of 137Cs differ 50 times for the natural grassy coenoses and 8 times for the semi-natural ones. The lowest 137Cs TF values were measured in the herbages of dry meadows at automorphous loamy soils, while the highest were observed in wetland meadows at organic soils. Finally, the correlation between 137Cs TF values and granulometric composition of soil was determined for both automorphic and hydromorphic mineral soils.

137Cs concentration in meat of wild boars ( Sus scrofa) in Croatia a decade and half after the Chernobyl accident

Gamma-spectrometric measurements of 137Cs activities in meat of wild boars collected in Croatia at several locations with different levels of 137Cs contamination are presented. Samples were collected during the period between 2000 and 2002, about 15 years after the Chernobyl accident. 137Cs concentrations ranged over three orders of magnitude: 0.4–611.5 Bq kg −1. On the basis of these results, 137Cs concentrations at researched areas could be categorized into three groups: (i) the area of Slavonski Brod, Lipik and Slunj with 137Cs concentrations in meat of only a few Bq kg −1; (ii) the area of Vrbovsko and Sirac with 137Cs concentrations of a few tens of Bq kg −1; and (iii) the Fužine area with 137Cs values in wild boar meat of a few hundreds of Bq kg −1. In areas with approximately equal contamination level, 137Cs concentrations in wild boar meat varied over two orders of magnitude. This fact suggests that the main reason for high 137Cs values in wild boar meat could be due to food consumed by wild boars, and only secondarily in contamination level of area where they live. Intensive mushroom consumption during autumn months could be one of the factors responsible for high 137Cs values in wild boar meat. An average dose arising from 137Cs due to ingestion of wild boar meat in Croatia is below radiological health concern except in the area of Fužine, and only in cases of high annual wild boar meat intake, probably by hunters or members of their families.

A cost–benefit analysis of long-term management options for forests following contamination with 137Cs

This paper provides a description of a cost–benefit analysis applied to determine the cost effectiveness, or otherwise, of nine management strategies potentially applicable to forests contaminated with 137Cs. The management strategies were considered singly and in a number of likely combinations. A management strategy was considered to be cost effective if it resulted in a lower overall monetary detriment than was incurred if use of the contaminated forest was continued on a ‘business as usual’ basis. Only the banning of mushroom collection and restriction of public access proved to be cost-effective management strategies on the basis of this definition. However, even these strategies only proved cost effective at high levels of 137Cs contamination, at which net savings in detriment in the form of public dose were achieved. Cost-effective savings of doses to forest workers were never achieved at any of the contamination levels considered in this study. It is suggested that novel alternative uses of contaminated forests are required which could provide added value to the standing crop in return for small increases in public and worker doses. One such use might be biofuel production.

Thyroid and Whole-Body Dose Reconstruction in Russia Following the Chernobyl Accident: Review of Progress and Results

The results of direct measurements of radioactive iodine content in the human thyroid gland (in Bryansk and Kaluga regions, Russia) and also available data on 131I and 137Cs contamination of the soil were used for investigation of correlations between the mean thyroid dose for adults in settlements and local levels of 137Cs and/or 131I soil contamination. On the basis of this analysis a model was developed showing how to evaluate retrospectively the thyroid absorbed doses. For individual dose reconstruction using an 'age/milk' scale, special questioning of inhabitants was carried out. Mean dose values in the exposed population of each contaminated Russian settlement were evaluated using the model. The total collective dose due to internal exposure of the thyroid gland by iodine radionuclides equates to 106,500 person.Gy in the population of the most contaminated territories of four Russian regions. The maximum value was found in the Bryansk region (73,000 person.Gy). New data concerning the delay in pasturing in different regions as well as time dependencies of the fallout were taken into account. As a result the dose estimations differ from previous published data. Comparisons between the developed method and the other independent approaches indicate a concordance within a factor 3. For application of the EPR tooth enamel dosimetry on a wide scale, estimation of accumulated external doses are demonstrated and analysed. There were about 2500 tooth samples measured from the contaminated region as well as from the non-contaminated territories of Russia. The investigated factors are: (1) effect of solar light on front teeth; (2) correction for the energy dependence of the EPR response; (3) presence in the enamel of some intrinsic signals; (4) age dependent doses due to natural background radiation. The average values of EPR dose with special account taken of correction factors are presented. The tendency of average doses to grow with the level of 137Cs contamination of settlements was found (the linear regression with the slope equates to 2.4 ± 0.5 mGy per Ci.km-2). This tendency is close to that of analytical calculations.

LIVESTOCK FARMING TECHNOLOGIES IN CASE OF LARGE-SCALE RADIOACTIVE CONTAMINATION (TO 35TH-ANNIVERSARY OF THE CHERNOBYL NPP ACCIDENT)

On the example of the Chernobyl NPP accident, the problems of animal husbandry in case of radioactive contamination of hayfields and pastures are shown. The factors determining the accumulation of radionuclides in milk and meat are presented. It is noted that the excess of radiological standards for the content of 137Cs in livestock products in the southwestern districts of the Bryansk region is long-term and requires continuation of rehabilitation work. A classification of countermeasures and technologies in animal husbandry carried out after the Chernobyl accident is given. It was shown that the most effective was the use of Cs-binding sorbents - hexacyanoferrates for lactating cows and fattening cattle. Farms in the southwestern districts of the Bryansk region have been identified, where until now there is a risk of exceeding the standards for the content of radionuclides in livestock products. For these farms, a scheme for the use of hexacyanoferrates was proposed depending on the levels of 137Cs contamination of grassland.