Global Radioactive Fallout Research Articles

Plutonium isotopes in the ground air layer in southern Poland (2010–2016): Source terms, seasonal variability and correlations with meteorological conditions

In this study, the results of the analysis of Pu-238 and Pu-239 + 240 activity concentrations on aerosol filters collected from 2010 to 2016 in Krakow (Southern Poland) are presented and discussed. For the first time, the temporal variation of Pu-239 + 240 activity concentration in surface air in Poland was studied using Fourier analysis. The analysis clearly showed that the Pu-239 + 240 content in the near-ground air layer is subject to seasonal variations and demonstrates annual periodicity. Pu analyses were performed using alpha spectrometry. The measured values ranged from 1.93∙10−10 Bq/m3 to 1.31∙10−8 Bq/m3 with an average of 2.07∙10−9 Bq/m3 for Pu-239 + 240 and from 9.07∙10−11 Bq/m3 to 1.27∙10−9 Bq/m3 with the average 1.52∙10−10 Bq/m3 for Pu-238. The analysis of the potential sources of plutonium isotopes in the air aerosols samples indicated that only two samples are uniquely characterized by the ratio corresponding to spent nuclear fuel: February 2012 (0.59 ± 0.18) and February 2015 (0.68 ± 0.19). The remaining samples showed mixed origins, with global radioactive fallout appearing to contribute more than spent nuclear fuel. To study the relationship between Pu-239 + 240 and meteorological conditions, Pearson's correlation and circulation pattern analyses were performed. The analyses showed that the Pu-239 + 240 activity concentration depends on air temperature (R = 0.51), the sum of ice and snowfall (R = −0.45), relative humidity (R = −0.54) and mean total cloud cover (R = −0.56). High concentrations of Pu-239 + 240 were positively correlated with air advection from the southern and eastern sectors, whereas low concentrations were observed during dynamic weather conditions with intense circulation from the western sector. In case of Pu-238 no significant correlation was observed.

The Sedimentation Rate in the Crimean Hypersaline Lake Aktashskoye Estimated Using the Post-Chernobyl Artificial Radionuclide 90Sr as a Radiotracer

Artificial 90Sr is one of the most important long-lived radionuclides of global radioactive fallout from the atmosphere after the testing of nuclear weapons and the accident at the Chernobyl Nuclear Power Plant in 1986. In addition to fallout from the atmosphere, secondary radioactive contamination of Crimea was mainly from the Dnieper River and the North Crimean Canal, which occurred until 2014. 90Sr was used as the optimal radiotracer for estimating the rate of sedimentation in the Crimean hypersaline lake. Its vertical distribution in the bottom sediments was assessed. In the core of the bottom sediments, the detectable activity of 90Sr in layers 0–1.5 cm and 16.7–21.9 cm was absent, and it was determined again in the layer of 15.5 cm, which was associated with atmospheric fallout of the radionuclide after the Chernobyl NPP accident. There were well-isolated peaks of specific activity in layers at a depth of 4.6 and 13.3–14.3 cm. The calculated rate of sedimentation varied within 0.5–1.5 cm year−1: the minimum rate corresponded to the period 1971–2017, and the highest rate corresponded to the period 1954–1971.

Multifractal features of activity concentration and stochastic risk assessment of naturally occurring and technogenic radionuclides in the soil of Yerevan, Armenia

Spatial patterns and background ranges of naturally occurring radionuclides (NORs) (i.e. U-238, Th-232, K-40) and Cs-137 were studied in the urban soils of Yerevan, the capital city of Armenia. Multifractal Inverse Distance Weighting (MIDW) was used to generate and analyze distribution patterns of radionuclide activities. Based on Fourier transformation of radioactivity data, a spectral analysis was also applied to separate, where possible, background/baseline patterns from local anomalies: two ranges of background values were found to characterise the Yerevan territory.Specifically, in the south and south-east of Yerevan, the lower background ranges of U-238, Th-232 and K-40 comprised in the intervals 2.60–36.42 Bq/kg, 4.04–30.63 Bq/kg and 147.7–396.7 Bq/kg, respectively, were observed in association with the presence of sedimentary formations. In contrast, the higher ones were found, instead, in the central and northern parts of the city where andesite-basalt lavas and ignimbrite tuffs occur. Here, the background values rise to 142.4 Bq/kg, 138.76 Bq/kg and 1502 Bq/kg, respectively.As for the distribution of artificial Cs-137, its baseline levels in Yerevan seem to depend mostly on the global radioactive fallout and some local technogenic sources. Its distribution patterns partially differ from those of NORs.In the framework of this paper, Radium equivalent activity (RaEq), outdoor absorbed dose rate in air (ODRA) and annual effective dose equivalent (AEDEs) were also determined and mapped. They show a good coincidence of their spatial variations with those of NORs.The Monte Carlo simulation was used to assess excess lifetime cancer risk from a stochastic perspective. The related sensitivity analysis revealed that, among NORs, U-238 and Th-232 give the greatest contribution to the total variance (45.7% 42.8%, respectively). In comparison, K-40 has the lowest share (11.3%). Regarding Cs-137, a highly negligible contribution to the onset of health risks (accounting for 0.02%) was observed.

Comprehensive radioecological monitoring of terrestrial ecosystems in the vicinity of the Rooppur nuclear power plant (People’s Republic of Bangladesh)

Terrestrial ecosystems (soil and plants) accumulate artificial radionuclides from emissions of nuclear power plants. In order to control the radiation situation in the vicinity of the Rooppur Nuclear Power Plant (Bangladesh), a system of radioecological monitoring of terrestrial (mainly agricultural) ecosystems has been created. Radioecological studies were carried out in 2014–2017 before the start of operation of the Rooppur Nuclear Power Plant. Assessment of specific activity in soil of natural (40K − 750–855, 226Ra − 44–52, 232Th − 63–75 Bq.kg−1) and artificial (90Sr − 0.5–1.6, 137Cs − 1.2–2.5 Bq.kg−1) radionuclides before the start of operation the Rooppur Nuclear Power Plant has revealed the radioisotope content in the soil being consistent with other areas in Bangladesh. The 137Cs/90Sr ratio in the soil is 1.5–2.8, which is close to the level of global radioactive fallout. Ambient dose equivalent rates in the 30-km zone of influence of the nuclear power plant vary within 0.11–0.15 μSv.h−1 and are determined by the natural background radiation. Agricultural crops of arable land, pastures and orchards accumulate 1.5–2 times more 90Sr compared to 137Cs. The accumulation coefficients of radionuclides by plants are determined by the crops species and soil characteristics. The monitoring system will make it possible to assess long-term changes in the radioecological situation in the zone of influence of the Rooppur Nuclear Power Plant after the start of its operation.

Radiation-hygienic characteristic of the global radionuclide fallout in the arctic regions of Russia (based on the data of the Institute of Radiation Hygiene after professor P.V. Ramzaev)

The recent years are associated with active development of the coastal areas of the Russian arctic regions including a construction of the facilities of the extraction and processing of the hydrocarbons, the civil and military facilities. The nuclear weapon tests, performed by the USSR and other nuclear countries in the second half of the XX century, lead to the global radioactive fallout, including the fallout on costal areas of the arctic regions of the USSR. Five most powerful nuclear munitions were tested on the Novaya Zemlya Test Site in the Arkhangelsk region. The Institute of Radiation Hygiene after professor P.V. Ramzaev (before 1994 — the Leningrad Scientific-Research Institute of Radiation Hygiene) has accumulated a 20-year experience of the radiation-hygienic surveys on the assessment of the consequences of the nuclear weapon tests for the Far-North of the USSR: from the development of the equipment and methods for the extraction, analysis and measurement of the low levels of the radioactive isotopes in humans and environment, to the wide-scale radiation-hygienic surveys of the links in the “northern food chain” — lichen, raindeers and native inhabitants. The obtained data allowed performing a complex assessment of the role of the radiation factor in the health of the public residing on the coastal areas of the Arctic Ocean.

Yerevan soil radioactivity: Radiological and geochemical assessment

Spatial pattern of naturally occurring radionuclides (NOR): 226Ra, 232Th, 40K, and artificial 137Cs was studied using soil samples of the multipurpose geochemical survey of the city of Yerevan, capital of Armenia. High purity Ge detector-based gamma spectrometry system was used for the determination of radionuclides activity concentrations in urban soils. A combination of compositional data analysis, geochemical mapping and radiological assessment were applied to reveal potential factors of technologically enhanced natural radioactivity and excess lifetime cancer risk for Yerevan’s population due to NOR and artificial 137Cs in the urban environment. Statistical methods with the geochemical mapping revealed the great contribution of soil-forming rocks to NOR distribution in urban soils. The spatial distribution of calculated radiological indices and dose rates levels follows the distribution patterns of NOR. The activity concentration of fallout radionuclide 137Cs was within the range typical for the studied altitudes. Above baseline activity of 137Cs was observed in the north-western and western part of the city that is in typical ranges of 137Cs content in soil derived from global radioactive fallout. Urban soils of Yerevan were found radiologically safe, however, igneous rock derived soils are a sink of NOR and the main environmental source of continuous exposure to the residents. Values of excess lifetime cancer risk were higher than mean global value.

Scientific legacy of professor Pavel Vasilyevich Ramzaev

The article describes the main areas of scientific and administrative activities of professor P.V. Ramzaev during his work in the Research Institute of Radiation Hygiene. In particular, the results of a study of global radioactive fallout in the Far North of the USSR, as well as a study of the radiation situation and an assessment of the doses to the public after the accident at the Chernobyl NPP, are presented in a systematic way. The leading role of P.V. Ramzaev in the development of hygienic regulation and in the development of the theory of health is shown. The activities of P.V. Ramzaev in the International Commission on Radiological Protection are discussed in detail. The role of P.V. Ramzaev in the development of the law «On Radiation Safety of the Population» is shown.

Variations of plutonium isotopic ratios in Antarctic ecosystems

The aim of the article was to verify the hypothesis concerning the diversification of plutonium sources in the natural environment of Antarctica. Plutonium activity and atom ratios were analyzed in two groups of biological samples: terrestrial and marine. Both isotopic ratios in the terrestrial set were consistent with global radioactive fallout ratios. The average activity ratio in the marine ecosystem was lower than global radioactive fallout. At the same time mass ratio values in this group turned out to be surprisingly varied. Analysis of the results showed statistically significant differences between the marine and terrestrial ecosystems.

HYGIENIC EVALUATION OF EXPOSURE DOSES FOR THE VORONEZH REGION POPULATION FROM THE NATURAL AND TECHNOGENOUSLY MODIFIED BACKGROUND

The purpose of the study was to estimate the doses to the Voronezh region population from natural sources of ionizing radiation and the technologically altered background in the territory of Voronezh Region. The data of forms of state statistical observation No. 4-DOZ “Information on the doses of population exposure due to natural and technologically altered background” for 20102017 and the radiation and hygienic passport of the territory of the Voronezh Region were used. The average annual per caput effective dose due to all types of ionizing radiation remains stable with a slight upward trend and lies in the range from 2.925 (2010) to 3.656 mSv (2017). Natural sources are the main dose-forming factors for the population. Their annual contribution to the annual effective dose ranges from 74.96 to 83.65%. The leading contribution to the total dose from natural sources is the exposure due to the inhalation of radon isotopes: it ranges from 37.6 to 51.1%. In second place,there is the share of external exposure from sources of terrigenous origin, which ranges from 21.2 to 28.9% of the total dose. The average annual effective dose of natural exposure to humans varies from 2,355 to 2,980 mSv / year, the exposure from radon – from 0,83 to 1,65 mSv / year. The dose from technogenic-altered radiation background, including global radioactive fallout due to atmospheric nuclear tests and due to past radiation accidents are insignificant (0,062 mSv / year). Its annual contribution to the total dose is less than 2%. Based on the results of the assessment of the indicators characterizing the level of exposure of sources of ionizing radiation to natural and technogenic-altered radiation background, no excess of radiation safety standards has been recorded. The situation associated with exposure to ionizing radiation sources in the Voronezh region has been described as safe for the last 8 years.

Activity Concentrations of <sup>137</sup>Cs and <sup>90</sup>Sr in Seawaters of East Sea, Korea

Background: This study was a long-term evaluation of 137Cs and 90Sr activity concentrations in seawater samples from the East Sea, Korea, in order to establish current activity levels. Results and long-term monitoring trends will be useful in the future monitoring of environmental radioactivity. Materials and Methods: Surface seawater samples were collected quarterly from Guryongpo and Jangho in the East Coast between 1998 and 2010 and the quarterly deep seawater samples were collected from three sites in the sea adjacent to Ulleung-do between 2012 and 2015. The activity concentrations of 137Cs were measured using a gamma-spectrometer. The activity concentrations of 90Sr and 90Y in a radioactive equilibrium state were measured using a gas flow proportional counter. Results and Discussion: We found the annual average activity concentrations of 137Cs in the surface seawater was 1.66-2.89 mBq∙kg-1 in Guryongpo and 1.68-2.43 mBq∙kg-1 in Jangho. The annual average activity concentrations of 90Sr in the surface seawater was 0.83- 1.98 mBq∙kg-1 in Guryongpo and 0.82-1.57 mBq∙kg-1 in Jangho. The annual average activity concentrations of 137Cs in the deep seawater sites were 1.51-1.73 mBq∙kg-1, 1.19-1.60 mBq∙kg-1 and 0.87-1.15 mBq∙kg-1 in TH, JD, and HP. The annual average activity concentrations of 90Sr in the same deep seawater sites were 1.00-1.94 mBq∙kg-1, 0.82-1.26 mBq∙kg-1, and 0.79-1.32 mBq∙kg-1. The effective half-life was calculated by analyzing change over time in the activity concentration in the surface seawater. The effective half-life of 137Cs was 15.3 ± 0.1 years in Guryongpo and 102 ± 3 years in Jangho. The effective half-life of 90Sr was 28.3 ± 4.3 years in Guryongpo and 16.6 ± 0.1 years in Jangho. The ratio of the average activity concentration (137Cs/90Sr) was 1.72 in the surface seawater, which is similar to the reported ratio of the global radioactive fallout. The ratio in the deep seawater was 1.24, which is somewhat low compared to the global ratio (1.6, 1.8). Conclusion: Activity concentrations of 137Cs and 90Sr in the seawaters of the East Sea were similar to the previously reported activity levels in the East Sea and northwestern Pacific as a result of global radioactive fallout following atmospheric nuclear weapon tests.

Migration of global radioactive fallout to the Arctic ocean (on the example of the Ob's river drainage basin)

This article provides an assessment of the impact of global fallout on (137)Cs contamination in the bottom sediments of Kara Sea. The erosiveness of 10th-level river basins was estimated by landscape-geochemical and geomorphological characteristics. All 10th-level basins (n=154) were separated into three groups: mountain, mountain-lowland and plain. Four different types of basins were identified depending on the geochemical conditions of the migration of radiocaesium in the plain and mountain-lowland. Classifications of types were carried out using the geographic information systems-based approach. The Ob River's macroarena covers 3.5 million km(2). Internal drainage basins cover 23 % of the macroarena and accumulate whole radiocaesium from the global fallout. The remaining territory is transitional for the (137)Cs. The field research works performed in the three plain first-level basins allow one to estimate the radiocaesium run-off. The calculations show that 7 % of (137)Cs was removed from the first-level basin in arable land. Accumulation of radiocaesium in the first-level basin under undisturbed forest is 99.8 %. The research shows that (137)Cs transfer from the humid basins is in the range of 6.9-25.5 TBq and for semi-humid basins 5.6-285.5 TBq. The areas of these basins cover 40 and 8 % of the Ob River's macroarena, respectively. Drainage lakes and reservoir drainage basins make up 22 % of the macroarena. Mountainous and semi-arid drainage basins cover 7 % of the macroarena.

Radiation doses from global fallout and cancer incidence among reindeer herders and Sami in Northern Finland

ObjectivesPeople in the Arctic regions are one of the most heavily exposed population from the global fallout from atmospheric atomic bomb testing of the 1950s and 1960s due to their...

An alternative radiometric method for calculating the sedimentation rates: Application to an intertidal region (SW of Spain)

A new method using the inventory determined for the activity of the radionuclide (137)Cs, coming from global radioactive fallout has been utilised to calculate the sedimentation rates. The method has been applied in a wide intertidal region in the Bay of Cádiz Natural Park (SW Spain). The sedimentation rates estimated by the (137)Cs inventory method ranged from 0.26 cm/year to 1.72 cm/year. The average value of the sedimentation rate obtained is 0.59 cm/year, and this rate has been compared with those resulting from the application of the (210)Pb dating technique. A good agreement between the two procedures has been found. From the study carried out, it has been possible for the first time, to draw a map of sedimentation rates for this zone where numerous physico-chemical, oceanographic and ecological studies converge, since it is situated in a region of great environmental interest. This area, which is representative of common environmental coastal scenarios, is particularly sensitive to perturbations related to climate change, and the results of the study will allow to make short and medium term evaluations of this change.

Retrospective of radioactive fallout from data on sampled bottom sediments in closed water bodies

A method for identifying past radiation events from dated layers of bottom sediments in stagnant water bodies is described. Results of an experimental study (2005–2006) of the samples of bottom sediments in the pond of the Timiryazev dendropark in Moscow are considered. The sediment layers are dated with 210Pb. The same radionuclide is used as a tracer for calculating the rate of sedimentation in the pond, which is estimated at 0.3–0.4 cm/year. The maximum 137Cs values are detected in the 0–24 cm column at depths of 7 and 13 cm. The 137Cs peak at a depth of 13 cm is dated as 1963, which reflects the maximum global fallout from the atmospheric nuclear weapon tests. A small peak of this radionuclide at 7 cm is dated as 1986. It appears to be attributed to the long-range fallout after the Chernobyl NPP accident. The origin of the 137Cs maximum at a depth of 13–14 cm is confirmed by characteristic ratios of radionuclide pairs available in the global fallout in the Moscow region. The ratios of 90Sr/137Cs = 0.6 and 239,240Pu/137Cs = 0.03 in the 13–14 cm layer are characteristic of the global radioactive fallout from nuclear explosions. In the layers above this maximum, such ratios vary sharply toward the enhanced 137Cs content in the fallout.

Use of lichens and mosses for on-line testing of environmental radioactive contamination

The data on the concentrations of 90Sr and 137Cs in 54 species of lichen and moss with different taxonomic natures, as well as in samples of lichen-moss plant cover, are reported. It is shown that currently (during the period of stabilization of global radioactive fallout) the detected contents of radionuclides in lichens and mosses serve as a background and are crucial for the long-term radioecological monitoring and forecasting.

Plutonium Contamination Level and Isotopic Composition in Soils around St. Petersburg

Plutonium isotopic composition including 238Pu, 239Pu, 240Pu, and 241Pu and the Pu contamination level are determined in soils around St. Petersburg using an advanced procedure involving radiochemical separation stage followed by the α-ray spectrometric and mass spectrometric determination. The Pu specific activity in surface horizons (0-25 cm) ranges from 0.2 to 0.44 Bq kg-1. The mean 238Pu/239,240Pu activity ratio is found to be 0.033±0.007. The Pu contamination level of the surface horizon (0-25 cm) is 62±5 Bq m-2. The 238Pu/239Pu, 240Pu/239Pu, and 241Pu/239Pu isotopic ratios are (2.0±0.5)×10-4, 0.172±0.004, and 0.003±0.002, respectively. These ratios are close to the values typical of plutonium from the global radioactive fallout due to nuclear weapons tests in the atmosphere. The effect of the Chernobyl accident and regional potential contamination sources, including the Leningrad NPP, on the Pu isotopic composition and contamination level in the soil is insignificant.

Concentrations of long-lived artificial radionuclides in the moss-lichen cover of mountain plant communities

Specific features of90Sr and137Cs accumulation in individual lichen species and in the moss-lichen cover of plant communities were studied in some mountain ranges of the Polar and Northern Urals. The results showed that the amounts of radionuclides in lichens and mosses of mountain plant communities are at the level characteristic of the moss-lichen cover of flat ecosystems, and their accumulation depends on90Sr and137Cs input with the global radioactive fallout. The radionuclide contents in lichens and mosses sampled from different mountain rocks, slopes, and elevations fluctuate around this level. The differences depend both on the structural and functional properties of plants and on the climatic and ecological features of their environment.

A dosimetric determination of 137Cs ingestion from global fallout and the related risks to Japanese.

137Cs released from atmospheric nuclear detonation tests has been transported worldwide in the environment and finally taken up by humans through various pathways. In particular, ingestion pathways are important for evaluating the human health risks caused by the chronic global low-level radioactive contamination. In this research, the mathematical model for the evaluation of the dietary intake of 137Cs and the related risks to Japanese are proposed by coupling the previously published global 137Cs distribution model with the regional models such as various food ingestion models and the model of the domestic and international supply. Predictions from the proposed model were compared with the monitoring data of 137Cs in Japanese total diet as an attempt at validation. The major findings obtained in this research include that the proposed model is promising for evaluating the risk to Japanese health caused by the dietary intake of global radioactive fallout 137Cs, the 137Cs is taken up by Japanese mostly through farm products, the ingestion of 137Cs through imported foods is increasing, the risk to the Japanese health of inducing cancer by 137Cs internal exposure reached a maximum in 1963, gradually decreasing to the lowest present level, and the risk to infants is the highest.

地球規模フォールアウト｀９０´Ｓｒと食品による日本人への移行

Japan imports 70% of her grain needed. Therefore not only 90Sr level in Japanese food but also concentration in imported grains should be taken into account for the estimation of 90Sr intake by Japanese. Mathematical model is developed and examined by the data of Japanese dietary 90Sr intake for past 30 years. The main results obtained in this study under the limited assumptions are as follows: (1) The proposed model is promising for evaluating the Japanese dietary intake of global radioactive fallout 90Sr. (2) Uptake of 90Sr by ingestion depends mainly on agricultural products, especialy on leaf vegetables during high deposition periods of 90Sr and on wheats during low deposition periods. Almost 60% of Japanese dietary 90Sr intake now comes from foreign countries through foods imported. (3) The Japanese dietary intake of 90Sr depends largely on the direct deposition coefficient of 90Sr on crops for high deposition periods, also on the environmental decay coefficient for low deposition. periods, and the root transfer factor of 90Sr for both periods.

Plutonium content of soils in the Soviet Union

Specimens of a number of types of virgin soil in the Soviet Union were collected in July and August of 1982 in open areas down to a depth of 15 cm. The plutonium content was determined by a radiochemical method, using 50-g weights of soil. The radioactivity was measured by means of a low-background alpha flow counter and an ionization chamber containing a circuit with a 500-channel LP-4050 analyzer (counting efficiency 32%, background 9.8.10/sup -3/ pulses per minute at a threshold of 100 keV and a peak of 5 MeV). The detection limit was 1.7.10/sup -3/ Bq. The average specific activity of a Pu 239 and Pu 240 in the soils of the Soviet Union was 1.15 Bq/kg of air-dried mass, or 188 Bq/m/sup 2/. The average and limiting values obtained for the plutonium concentration in the surface levels of USSR soils are close to the data for other Northern-Hemisphere countries. This indicates that the contamination of the soil cover originates in global radioactive fallout.