Content Of Radionuclides In Soil Research Articles

Assessment of radionuclides in the "soil-plant" chain of uranium mining regions (literature review)

It is well known that as a result of the activities of the mining industry, radionuclides and chemicals with active mutagenic and carcinogenic effects can be extracted to the surface. Disposal products, such as radioactive waste and others, may cause particular danger. In this regard, this requires regular monitoring of radioactive waste storage sites and the degree of migration of radionuclides and heavy metals in environmental objects. This review article considers the uranium ore region’s current data for the content of radionuclides in soil, vegetation, and their migration in the “soil-plant” chain.

Investigation of the radiation situation at the dumps of the mine No. 1 of the LPO "Almaz" five years after recultivation

Introduction. The work was completed on the remediation of dumps located in the area of nine tunnels of mine No. 1 of the Lermontov production association “Almaz” over 2014-2015. The article presents the results of a study of the radiation situation on these dumps five years after the remediation. Materials and methods. During the survey, the methods of pedestrian gamma survey were used using a portable spectrometric complex MKS-01A “Multirad-M” and soil sampling with subsequent measurement of the specific activity of radionuclides using a stationary gamma spectrometer manufactured by CANBERRA. The activity of 210Po and 210Pb was measured using a UMF-2000 radiometric setup after their radiochemical isolation. Results. After the remediation of the dump areas, where gamma ambient dose equivalent rate exceeds 0.5 μSv/h, areas significantly decreased and do not exceed 10% of the total dump area, with the exception of the dumps of tunnel No. 42. On the territory of all surveyed dumps, except for dumps of tunnels No. 10 and No. 26, there are areas where gamma ambient dose equivalent rate exceeds 0.6 μSv/h, which is prohibited in accordance with the adopted remediation criteria. Not all tunnel mouths are isolated. Limitations. It is assumed that comparing the content of radionuclides in soil with the criteria for classifying them as solid radioactive waste 238U and 230Th are in secular equilibrium. Measurements of the total alpha-activity in the soil and comparison with the recultivation criteria for this parameter were not carried out. Conclusion. At present, the radiation situation in some areas of all surveyed reclaimed dumps, except for the dumps of tunnels No. 10 and No. 26, does not meet the requirements established in the remediation project.

Radionuclide contents in soil, sediments and food samples, and incidences of cancer in oil producing localities in Imo State south-east Nigeria

The communities in Ohaji-Egbema and Oguta Local Government Areas (LGAs) are surrounded by about 83 oil wells. Investigations indicated that crude wastes were not properly managed, and there were reported high number of cancer cases in the LGAs. Therefore, assessment of radionuclide contents in environmental and food samples, and incidences of cancer in the LGAs was carried out to determine any possible relationship between natural radionuclides in soil and sediment samples, and farm products, establish any possible relationship between reported cancer incidences and actual environment of the inhabitants, and develop models that could predict committed effective dose equivalents in yam, cassava and fish samples from radioactivity in soil and sediment samples. Soil, yam and cassava samples were collected from farmlands while sediment and fish samples were collected from rivers in the communities. The collected samples were prepared and taken to the laboratory for measurement. A well-calibrated lead-shielded 76 mm × 76 mm NaI (Tl) detector was deployed for the radiological investigation. It had a modest resolution of about 8% at 662 keV. Activity concentration of 214Bi (determined from its 1.760 MeV gamma-ray peak) was chosen to provide an estimate of 226Ra (238U) in the samples, while that of daughter radionuclide 208Tl (determined from its 2.614 MeV gamma-ray peak) was chosen as an indicator of 232Th. Potassium-40 was determined by measuring the 1.460 MeV gamma rays emitted during its decay. Results indicate that mean activity concentrations obtained from Ohaji-Egbema and Oguta are higher than those obtained from the control LGAs for 226Ra and 232Th which may be attributable to the geological variations of the study areas. The absorbed dose rates from Ohaji-Egbema and Oguta are slightly higher than world average value of 51 nGyh−1 while the committed effective dose equivalents from the study areas are less than world average value of 1.1 mSvy−1. The percentage contributions of natural radiation exposures to incidence of cancer in the study areas are less than 7% which implies that cancer incidences in the study areas may not be due to natural radioactivity levels. Hence, natural radioactivity levels may have been elevated in the communities of the oil producing localities but the concentrations are not yet frightening. In future environmental radioactivity studies, the developed models could be very useful.

Перспективи вирощування біоенергетичних культур на осушуваних торфових ґрунтах Західного Полісся в умовах кліматичних змін

Goal. To identify the most promising types of bioenergy crops, and explore the potential of their productivity on drained peat soils of Western Polissia in climate change. Methods. Field — to monitor the growth and development of plants, the formation of their yields, laboratory — to determine the quantitative and qualitative characteristics of agrochemical and physicochemical properties of peat soils, measuring and weighing — to determine yields, soil water regime, gamma-spectrometric – to determine the content of radionuclides in soil and crop products, calculation and comparison — to determine the energy efficiency of growing bioenergy crops on drained peat soils of Western Polissia. Results. The productivity potential of the most common species of woody, annual and perennial herbaceous bioenergy crops in the conditions of drained peat soils of Western Polissia was determined. The possibility of obtaining the own seed and planting material of the main types of bioenergy crops in the area of Western Polissia was studied. Conclusions. It is proved that the most promising and technological wood bioenergy crop for growing on drained lands of Polissia is a violet willow of Swedish selection, which under optimal conditions can provide up to 28–30 t/ha of wood biomass annually, which is 10–14 times higher than traditional productivity of forest plantations. Among herbaceous perennial bioenergy crops, the most promising ones are miscanthus and sedge, which provide up to 25 t/ha of dry biomass, and among herbaceous annual crops — sugar sorghum, broom sorghum, and corn, which provide up to 20 t/ha of dry tables. It is proved that on the drained peat soils of Western Polissia, with proper agricultural techniques, it is possible to successfully engage in seed production of most of the studied bioenergy crops, including heat-loving ones such as corn, sugar sorghum, broom sorghum, Sudan sorghum, paise. Due to the high rate of seed propagation, these crops can be quickly introduced into production in a certain area.

Radioactivity of soil in Croatia I: naturally occurring decay chains.

The assessment of environmental radioactivity much relies on radionuclide content in soil. This stems from the significant contribution of soil to both external and internal exposure to ionising radiation via direct emission of gamma radiation and soil-to-plant radionuclide transfer, respectively. This motivated us to carry out a systematic research on the radioactivity of soil in Croatia to obtain relevant data that can be used as a basis for understanding the related effects of geomorphological, biogeographical, and climatological properties of the environment. We collected samples of the surface layer of uncultivated soil (0–10 cm) at 138 sites from all over the country and measured them for radionuclide activity concentrations by means of high-resolution gamma-ray spectrometry. This resulted in radioactivity maps containing data on activity concentrations of representative radionuclides in the environment. In this paper, which is the first in our two-part presentation, we focus on the naturally occurring 232Th and 238U decay chains and their correlations with the diversity of Croatian regions. For both of the chains, activity concentrations were the highest in the Dinaric region, the lowest in the Pannonian region, and intermediate in the Adriatic region. Relatively high concentrations of 226Ra in the soil of the Dinaric region implied a possibility of an enhanced emanation of its progeny 222Rn into the air. Activity concentrations of 210Pb were additionally elevated in areas with dense vegetation, most probably due to an atmospheric deposition of airborne 210Pb onto the surface of plants and their eventual decomposition on the ground.

Комплексные организационные и методические подходы к выводу из эксплуатации хранилищ РАО

Purpose: Development of comprehensive organizational and methodical approaches to decommissioning of shallow radwaste (RW) repositories.
 Material and methods: The following researches were conducted during assessment of radiation and hygiene situation:
 - assessing the state of physical barriers of repositories (tanks) of solid and liquid RW;
 - assessing radiation situation at the repository site before and after remediation;
 - measuring specific activity of 90Sr and 137Cs in ground and subsurface water, core sample, soils, building structures.
 Methods: on foot gamma survey; gamma-ray spectrometric measurement of radionuclides in environmental samples using a stationary spectrometer; radiochemical extraction of radionuclides and their radiometry.
 Results: The surveys were performed in 2014–2016. They delivered data on gamma dose rate at the RW repository site, specific activity of 90Sr and 137Cs in ground and subsurface water, core sample, soils, building structures.
 The surveys showed that content of 90Sr in subsurface water varied from 0.25 to 0.4 Bq/kg, while content of 137Cs was below the detection threshold (0.01 Bq per sample). It was founded that distribution of 90Sr and 137Cs in soil (core sample) forming the top layer of the area is highly uneven. In some cases specific activity of soil exceeded 1000 Bq/kg (C-23 well at the depth of 2.75 m and C-24 well at the depth of 5 m). In all other cases specific activity of the core sample did not exceed 10 Bq/kg, and specific activity of soil was up to 50 Bq/kg which is over background values. The ambient dose equivalent rate at the site varied from 0.1 to 0.3 µSv/h.
 After remediation activities content of radionuclides in soil and subsurface water was at the levels of background values.
 More than 6700 measurements were performed (more than 2400 measurements of the ambient dose equivalent rate, more than 4100 measurements of beta-contamination of work surfaces and equipment, and more than 200 measurements of specific and volumetric activity of environmental samples). 
 Conclusions: This work allowed to substantiate technical solutions, procedure of RW accounting and control, using of shelters and mobile systems for radiation safety of the personnel and environmental protection.
 It was demonstrated that average external radiation doses for the workers involved in decommissioning activities did not exceed 0.7 mSv (variation from 0.16 to 1.7 mSv), while internal radiation doses varied from 0.35 to 3.3 µSv. 
 Density of beta-contamination of the site did not exceed 38 beta-particles/(cm2∙min) which corresponds to background values. The ambient dose equivalent rate of the site was within 0.09-0.15 µSv/h after the work has been done.

THE ENVIRONMENTAL IMPACT OF RADIONUCLIDES FROM SOIL AND CLAY MATERIAL FOUND IN "ZBEGOVI" DEPOSIT IN DONJE CRNILJEVO

The paper presents the results of testing radionuclide content in soil and clay samples on the surface mine "Zbegovi" in Donje Crniljevo, Serbia. The results of the study show that the activity of clay samples and surrounding soil derives mainly from natural radionuclides: 232Th, 238U and 40K. The radioactivity of the samples was determined by the gamma spectrometric method using HPGe detector with relative efficiency of 56.2%. The obtained results show that the tested samples can be used as material for brick and ceramic products, cosmetics as well as the fact that the tested clay deposit does not have a negative impact on humans, plants and animals.

Radiation hazards associated with radionuclides and theoretical evaluation of indoor radon concentration from soil exhalation of Udhampur District, Jammu and Kashmir State, India

Soil is the prime source of radon and thoron concentrations in the household dwellings. The presence of radioactive gases in the environment is mainly due to the presence of radionuclide content in soil, rocks, and building materials. So, it is necessary to estimate the radionuclide content in the living environment. The annual effective dose has been assessed from the radionuclide content, and an effort has been made to correlate the concentration of these radionuclides with exhalation rates of their daughter products, i.e., radon and thoron. Theoretically determined indoor radon concentration has also been compared with experimentally observed results. Scintillation-based Smart RnDuo monitor (SRM) and gamma spectrometry (NaI(Tl)) have been utilized for the estimation of exhalation rates and radionuclide (226Ra, 232Th, and 40K) contents in soil samples. The range of radon mass and thoron surface exhalation rate in soil samples are found to vary from 11.57 to 65.62 mBq kg−1 h−1 with an average of 28.20 mBq kg−1 h−1 and from 52 to 930 mBq m−2 s−1 with an average of 312 mBq m−2 s−1, respectively. The average activity concentrations of 226Ra, 232Th, and 40K are 24.52 Bq kg−1, 41.15 Bq kg−1, and 343 Bq kg−1, respectively. The average values of 226Ra, 232Th, and 40K are well within the safe range recommended by the United Nations Scientific Committee on the Effects of Atomic Radiations. The calculated annual effective dose and radiation hazard risks have been found to be well below the recommended levels. Results obtained from theoretical evaluation are compared with experimentally obtained results and are in good agreement with each other. Different occupancy factors have also been analyzed according to the populace indoor occupancy.

Mineralogy and physico-chemical parameters on the behavior of natural radionuclides in the riverine environs of Hemavathi, South India

Systematic studies were carried out to understand the influence of mineralogy and physico-chemical parameters on the behavior of natural radionuclides in the riverine environs of Hemavathi, one of the important rivers of South India. The physico-chemical parameters, granulometric content, magnetic susceptibility and mineral compositions were measured in the soil and sediment samples to understand the factors affecting the activity concentration of radionuclides in the river ecosystem. The mean activity of 226Ra, 232Th, and 40K in the soil was found to be 37.65 Bq kg−1, 36.79 Bq kg−1, and 301.47 Bq kg−1, respectively. The mean activity of 226Ra, 232Th, and 40K in the sediment was 64.26 Bq kg−1, 100.43 Bq kg−1, and 379.02 Bq kg−1, respectively. Elevated level of radionuclide concentration was observed in the sediment samples. In order to trace the source of the radionuclides, the mineral composition of the soil and the sediment was studied using FTIR and extinction coefficient of major minerals were calculated. Multivariate statistical analyses were carried out to determine the possible correlation between radionuclides, Physico-chemical parameters and the minerals. In particular, Magnetic susceptibility shows significant correlation with 226Ra in both soil and sediment. The statistical analyses suggested that quartz and clay mineral kolanite play a major role in enhancing the radionuclide content in soil and sediment.

Radioactivity of Selected Agricultural Soils in Croatia: Effects of Soil Properties, Soil Management, and Geological Parameters

We present a study on the radioactivity of selected Croatian agricultural soils that vary considerably with respect to geological background; physical, chemical, and biological characteristics; soil type; land use; and soil management. Our investigation is focused on the main naturally occurring radionuclides (40K, 238U, 226Ra, 232Th, 235U) and 137Cs as the most threatening long-lived anthropogenic radionuclide. We find that the radioactivity level is not influenced by the application of different soil amendments, at least in moderate quantities, and that no effect of soil management can be detected as well. In contrast, geological and location-specific properties influence radionuclide content in soil, especially regarding the naturally occurring ones. Moreover, physical and chemical soil properties such as texture and soil adsorption complex, respectively, seem to be the main factors regarding fixation of 137Cs in soil. Calculated dose rates for external exposure to the gamma radiation originating from soil have been found to be generally low, except for two locations where they are higher but not at a level that would lead to health problems for workers on the field.

Uptake of radionuclide thorium by twelve native plants grown in uranium mill tailings soils from south part of China

The concentrations of thorium (232Th) in soil from a uranium mill tailings repository in South China were analyzed. The results showed that all the soil samples were acidic and the concentrations of 232Th in all the soil samples were more than the natural radionuclide content in soil of China. Through the field investigation, twelve kinds of dominant plants were discovered. The total quantity of 232Th in the whole plant is highest in rice flat sedge. We also found that Miscanthus floridulus has the greatest transfer factor (TF) for 232Th, rice flat sedge has the greatest bioconcentration factor (BF) for 232Th. At the mean time, M. floridulus has the greatest phytoremediation factor (PF) for 232Th. On the basis of the above conclusions and the definition for hyperaccumulator, rice flat sedge and M. floridulus could be the candidates of phytoremediation for radionuclide 232Th in the soil.

Natural radioactivity levels of great soil groups in Seferihisar Geothermal Region, Turkey

In this study, measurement of natural radioactivity and analyses of physical properties of soil were carried on great soil groups around the Seferihisar Geothermal Region. The radioactivity levels in soils were analyzed using scintillation gamma spectroscopy. The activity concentrations for 226Ra, 232Th, and 40K range from 7.1 to 32.0 Bq kg−1, 15.2 to 35.9 Bq kg−1 and 223.1 to 802.2 Bq kg−1, respectively. Obtained data was compared with average values given by UNSCEAR and the other studies. The radium equivalent activity (Raeq) in soil samples ranges from 42.2 to 144.7 Bq kg−1 which are lower than the suggested maximal admissible value of 370 Bq kg−1 recommended by OECD. In addition, the value of external exposure dose has been determined from the content of natural radionuclides in soil. The absorbed dose rates change between 20.6 and 70.9 nGy h−1 with a mean value of 46.7 nGy h−1 which is lower than the global average value of 55 nGy h−1. The annual effective dose rates varied from 25.2 to 87.0 μSv year−1 with an average value of 57.3 μSv year−1. Obviously, all the calculated values were lower than this value, and therefore the environment of Tuzla Fault can be regarded as an area with normal natural background radiation.

Effect of Radionuclides Present in Lignite Fly Ash on Soil and Crop Produce

AbstractCoal/lignite contains various organic and inorganic substances including trace quantities of radionuclides. The coal releases some natural radioactive elements in the form of their oxides ultimately to the environment during its combustion and redistributes these radioactive elements in the surface soil, which are of human health concern. In view of the current research on fly ash as soil ameliorant, the present study deals with the presence of three natural radionuclides (Ra226, Th232, and K40) in the lignite fly ash and their mobilization through the amendment of lignite fly ash to the soil and crop produce. The study shows the variation in the content of radionuclides in soil, lignite fly ash, and crop produce depending on types of soil and fly ash; mobilization of the radionuclides from soil/fly ash to the plant, and interactions between radionuclides and soil, etc. The content of the radionuclides in the soil, lignite fly ash, and crop produce is within the permissible limits.

Fate of radionuclides present in Indian fly ashes on its application as soil ameliorant

Natural radioactivity depends primarily on the geological and geographical conditions, and appears at different levels in the soils. Coal contains various organic and inorganic substances including trace quantities of the naturally occurring radionuclides, which are of human health concern. The combustion of coals releases natural radioactive elements in the form of their oxides to the environment. In view of the current researches on fly ash (FA) applications as soil ameliorants, the present study deals with the presence of the natural radionuclides ((226)Ra, (232)Th and (40)K) in the coal ash and their mobilisation through the amendment of coal ash to the soil and crop produce. The study shows the variation in the content of radionuclides in soil, FA and crop produce depending on types of soil and FA, mobilisation of the radionuclides from soil/FA to the plant and interactions between radionuclides and soil, etc. The content of the radionuclides in the soil, FA and crop produce is within the permissible limits.

Analysis of radionuclide wash-off from river basins

The concept of the rate of transport of exchange and non-exchange forms of radionuclides over river catchment is introduced. On this basis, a differential transport equation is proposed for finding the radionuclide content in soil and radionuclide flow into a river with nonuniform contamination of the catchment area. The time dependence of the radionuclide wash-off time constant is determined from the measurements. It is found that transport is slow, so that radionuclide decay plays a large role. A large fraction of the radionuclides, aside from the long-lived transuranium nuclides, decays within the catchment area and does not enter the river. The flow into the river is largely determined by the radionuclide content near river edge. Examples of calculations of radionuclide flow into a river and bukhta are presented.

Independent regulatory examination of radiation situation in the areas of spent nuclear fuel and radioactive wastes storage in the Russian far east

This paper describes the findings of the radiation situation analysis on-site near Sysoeva and Razbojnik Bays. The results of radiation monitoring performed by radiological laboratory of DalRAO and studies performed by the experts from the Burnasyan Federal Medical Biophysical Centre have been used in the course of analysis. On the industrial sites, gamma dose rate reaches 60 µSv h(-1), and the specific activities of man-made radionuclides in soil reach 2.5 × 10(4) Bq kg(-1) for (137)Cs, 7.6 × 10(3) Bq kg(-1) for (90)Sr and 2.0 × 10(3) Bq kg(-1) for (60)Co. Beyond the industrial sites, there are three local parts of the area on the coast and in the off-shore water area, contaminated with man-made radionuclides. Gamma dose rate reaches 8 µSv h(-1). The radionuclide contents in soil at this area reach 3.6 × 10(3), 2.8 × 10(3) and 19 Bq kg(-1) for (137)Сs, (90)Sr and (60)Со, respectively. At the remaining part of the area nearby Sysoeva Bay, the radiation situation complies with natural background.

Migration ability of plutonium and americium in the soils of Polessie State Radiation-Ecological Reserve

The physicochemical forms of radionuclides in soils determine the processes of their entry into the soil solutions, redistribution in the soil profile, soil–plant and soil–ground or surface waters transfer as well as spreading outside the contaminated area. The vertical distribution of plutonium and americium and their physicochemical forms in soils of Polessie State Radiation-Ecological Reserve (PSRER) were studied with the aim of establishing the potential for radionuclide migration. Samples of alluvial soddy-podzolic and peaty soils with a low (1–3%) and relatively high (~80% of dry sample mass) content of organic matter have been selected for investigation. A method employing sequential selective extraction has been used for analysis of radionuclide physicochemical forms in the soils. Activity concentrations of 238Pu, 239,240Pu and 241Am in the samples were determined via radiochemical analysis with alpha-spectrometric identification of radionuclides. The results indicate that the main proportion of plutonium and americium remains in the 0–20 cm soil layer. The inventories of mobile and biologically available forms of plutonium and americium, expressed as a percentage of the total radionuclide content in soil, lie in the ranges of 1.1–9.4 and 2.7–29% respectively. Greater proportions of mobile and biologically available forms of radionuclides appear to be associated with mineral soil as compared to organic soil. In both mineral and organic soils, the portion of mobile americium is higher than plutonium. The inventories of mobile forms of plutonium and americium increase with the depth of soils.

Reconstruction of Database on Natural Radionuclide Contents in Soil in China

Based on the limited open data on natural radionuclide contents in soil and the pedological parameters, a digital version of database with about 15,000 sets of naturally occurring 238U, 226Ra, 232Th, and 40K data in soil in China was constructed by manual editing and spatial interpolation. Both the area-weighted averages of the 4 radionuclides contents and their distributions well agree with those published in previous references. This implies that the database has been successfully reconstructed. Furthermore, digital nationwide maps of the radionuclide contents were also created. It is hoped that the reconstructed database would be helpful for further scientific studies in related fields.

Top soil radioactivity assessment in a high natural radiation background area: The case of Vinaninkarena, Antsirabe—Madagascar

The village of Vinaninkarena, Antsirabe, Madagascar (47°02′40″E, 19°57′17″S) is located in a high natural radioactivity area. In order to evaluate the natural radionuclide content in soil, sampling was done on-site by the transect method (85 soil samples) and off-site through transects across and beyond the region (up to a range of 100 km), to determine the natural radioactivity variation within vs. outside the region, and to detect significant differences, taking into account spatial variability.

Natural radiation environment in China

The Ministry of Health, China conducted national survey of natural radiation level in 1980s. The following items are included in the nationwide survey. Cosmic radiation—outdoor average absorbed dose rate from cosmic radiation is 37.4 nGy/h. The highest average absorbed dose rate from cosmic radiation—116.2 nGy/h is found in Tibet. Terrestrial gamma radiation—outdoor average absorbed dose rate from terrestrial gamma radiation is 81.5 nGy/h in China. The highest average absorbed dose rate—188.0 nGy/h is found in Xunwu County, Jiangxi Province. Radionuclide content in soil—average contents of 238U, 226Ra, 232Th and 40K in Chinese soil are 38.5, 37.6, 54.6 and 584 Bq/kg, respectively. Yangjiang County of Guangdong Province has the highest average radionuclide contents in soil for 238U, 226Ra and 232Th. Radon level in air—average indoor radon level in China is 26.2 Bq/m 3. Average outdoor radon level is 13.5 Bq/m 3. Radon content in water—drinking water in some cities—9.04 kBq/m 3; surface water—1.26 kBq/m 3; well water—16.7 kBq/m 3; deep well water—34.9 kBq/m 3; hot spring water—278.9 kBq/m 3. There are some special areas in China, in which natural background radiation is obviously higher than in neighboring regions. Some epidemiological studies are going on in those areas. We hope to have more cooperation with other scientists in these areas.