Edaphic factors affecting the vertical distribution of radionuclides in the different soil types of Belgrade, Serbia

The specific activities of natural radionuclides ((40)K, (226)Ra and (232)Th) and Chernobyl-derived (137)Cs were measured in soil profiles representing typical soil types of Belgrade (Serbia): chernozems, fluvisols, humic gleysols, eutric cambisols, vertisols and gleyic fluvisols. The influence of soil properties and content of stable elements on radionuclide distribution down the soil profiles (at 5 cm intervals up to 50 cm depth) was analysed. Correlation analysis identified associations of (40)K, (226)Ra and (137)Cs with fine-grained soil fractions. Significant positive correlations were found between (137)Cs specific activity and both organic matter content and cation exchange capacity. Saturated hydraulic conductivity and specific electrical conductivity were also positively correlated with the specific activity of (137)Cs. The strong positive correlations between (226)Ra and (232)Th specific activities and Fe and Mn indicate an association with oxides of these elements in soil. The correlations observed between (40)K and Cr, Ni, Pb and Zn and also between (137)Cs and Cd, Cr, Pb and Zn could be attributed to their common affinity for clay minerals. These results provide insight into the main factors that affect radionuclide migration in the soil, which contributes to knowledge about radionuclide behaviour in the environment and factors governing their mobility within terrestrial ecosystems.     

Distribution of gamma-ray emitting radionuclides in the marine environment of the Burullus Lake: II. Bottom sediments

The sediment compartment has the ability to trap large amounts of radionuclides and to indicate the radiological impact of pollution. The present work shows the results obtained related to the concentrations of ¹³⁷Cs and natural radionuclides in sediment in the Burullus Lake, Egypt. The average values of ²²⁶Ra, ²³²Th, and ⁴⁰K in the bottom sediments collected from the east of the Burullus Lake ranged from 10.3 to 21.8 Bq/kg, from 11.9 to 34.4 Bq/kg, and from 268 to 401 Bq/kg, respectively. The study has shown that ⁴⁰K concentration is nearly uniform throughout the studied area while ²²⁶Ra and ²³²Th are more concentrated in the northeastern shore. Lake sediments showed contamination with ¹³⁷Cs (2.7–15.9 Bq/kg). The ¹³⁷Cs sediment activities indicated higher concentrations in the off-shore sites. Concentrations of all γ -ray emitting radionuclides except ⁴⁰K in water samples were below the detection limits. The ⁴⁰K sediment–water distribution coefficients of the near-shore samples were higher than the off-shore samples.     

Implementation of Neural Networks for Classification of Moss and Lichen Samples on the Basis of Gamma-Ray Spectrometric Analysis

Mosses and lichens have an important role in biomonitoring. The objective of this study is to develop a neural network model to classify these plants according to geographical origin. A three-layer feed-forward neural network was used. The activities of radionuclides ((226)Ra, (238)U, (235)U, (40)K, (232)Th, (134)Cs, (137)Cs and (7)Be) detected in plant samples by gamma-ray spectrometry were used as inputs for neural network. Five different training algorithms with different number of samples in training sets were tested and compared, in order to find the one with the minimum root mean square error. The best predictive power for the classification of plants from 12 regions was achieved using a network with 5 hidden layer nodes and 3,000 training epochs, using the online back-propagation randomized training algorithm. Implementation of this model to experimental data resulted in satisfactory classification of moss and lichen samples in terms of their geographical origin. The average classification rate obtained in this study was (90.7 +/- 4.8)%.     

2016—2020年云南土壤放射性水平及其变化趋势分析

根据2011—2020年云南辐射环境质量土壤国省控点²³⁸U、²³²Th、²²⁶Ra、⁴⁰K、¹³⁷Cs、⁹⁰Sr的监测结果，给出云南环境土壤放射性水平，得出云南环境土壤放射性水平总体平稳；云南环境土壤国省控点²³⁸U、²³²Th、²²⁶Ra、⁴⁰K的监测结果与云南省环境天然放射性水平调查结果相近，与云南土壤²³⁸U、²³²Th、²²⁶Ra、⁴⁰K分布趋势基本吻合；云南土壤²³⁸U、²³²Th、²²⁶Ra活度浓度略低于全国平均水平；由于大气迁移、沉降作用，早期核试验、核事故释放的核素¹³⁷Cs、⁹⁰Sr在云南环境土壤均有不同程度的检出。云南属伴生放射性矿产资源大省，滇西南某地...     

Natural radioactivity and chemical concentrations in Egyptian groundwater

Measurements of natural radioactivity in drinking water have been performed in many parts of the world, mostly for assessment of the doses and risk resulting from consuming water. A study of the radionuclide and chemical components in groundwater from Beni Suef Governate, Egypt has been carried out. Fifty water samples were analyzed by gamma ray spectroscopy to determine the ²²⁶Ra, ²³²Th, and ⁴⁰K concentrations; major elements, pH, alkalinity, and conductivity were also measured. The specific activity values ranged from 0.008 to 0.040 Bq/l for ²²⁶Ra, from 0.003 to 0.019 Bq/l for ²³²Th, and from 0.025 to 0.344 Bq/l for ⁴⁰K. The annual ingestions of these radionuclides, using local consumption rates (average over the whole population) of 1.5 l day^???1, were estimated to be 8.59, 4.86, and 83.47 Bq year^???1 for ²²⁶Ra, ²³²Th, and ⁴⁰K, respectively. The estimated values and weighted means of these radionuclides compare well with the world average. The estimated effective doses from drinking water were found to be 2.4 ??Sv year^???1 (²²⁶Ra), 1.1 ??Sv year^???1 (²³²Th), and 0.51 ??Sv year^???1 (⁴⁰K). Contribution of these radionuclides to the committed effective dose from 1 year consumption of drinking water is estimated to be only 4%.     

Outdoor 220Rn, 222Rn and terrestrial gamma radiation levels: investigation study in the thorium rich Fen Complex, Norway

The present study was done in the Fen Complex, a Norwegian area rich in naturally occurring radionuclides, especially in thorium ((232)Th). Measurement of radioactivity levels was conducted at the decommissioned iron (Fe) and niobium (Nb) mining sites (TENORM) as well as at the undisturbed wooded sites (NORM), all open for free public access. The soil activity concentrations of (232)Th (3280-8395 Bq kg(-1)) were significantly higher than the world and the Norwegian average values and exceeded the Norwegian screening level (1000 Bq kg(-1)) for radioactive waste, while radium ((226)Ra) was present at slightly elevated levels (89-171 Bq kg(-1)). Terrestrial gamma dose rates were also elevated, ranging 2.6-4.4 μGy h(-1). Based on long-term surveys, the air concentrations of thoron ((220)Rn) and radon ((222)Rn) reached 1786 and 82 Bq m(-3), respectively. Seasonal variation in the outdoor gamma dose rates and Rn concentrations was confirmed. Correlation analyses showed a linear relationship between air radiation levels and the abundance of (232)Th in soil. The annual outdoor effective radiation doses for humans (occupancy 5 h day(-1)) were estimated to be in the range of 3.0-7.7 mSv, comparable or higher than the total average (summarized indoor and outdoor) exposure dose for the Norwegian population (2.9 mSv year(-1)). On the basis of all obtained results, this Norwegian area should be considered as enhanced natural radiation area (ENRA).     

Assessment of environmental radioactivity for Batman, Turkey

The province of Batman, located in southern Anatolia, has a population of approximately 500,000. To our knowledge, there exists no information regarding the environmental radioactivity in this province. Therefore, gamma activity measurements in soil, building materials and water samples and an indoor radon survey have been carried out in the Batman province. The mean activity concentrations of the natural radionuclides (²²⁶Ra, ²³²Th and ⁴⁰K) and a fission product (¹³⁷Cs) were 35 ± 8, 25 ± 10, 274 ± 167 and 12 ± 7 Bq kg^???1, respectively, in the soil samples. The concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in the selected building materials ranged from 18 to 48 Bq kg^???1, 8 to 49 Bq kg^???1 and 68 to 477 Bq kg^???1, respectively. All the calculated radium equivalent (Ra_eq) activity values of the building material samples are lower than the limit of 370 Bq kg^???1, equivalent to a γ-dose of 1.5 mSv year^???1. The activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in tap waters collected from the study area were determined with mean specific activity concentrations of 42 ± 15, 35 ± 9 and 524 ± 190 mBq L^???1, respectively. Indoor radon measurements were made at 95 dwellings in Batman using a CR-39 detector. The radon concentration levels were found to vary from 23 to 145 Bq m^???3. The arithmetic mean of the measured radon concentration levels was found to be 84 Bq m^???3 with a standard deviation value of 23 Bq m^???3. The measurement results obtained in this study did not significantly differ from those taken in other parts of the country. The data generated in this study can be used to determine whether the Batman province is in a normal or high background radiation area and provides a valuable database for future estimations of the impact of radioactive pollution.     

Enhancement of natural radionuclides in the surroundings of the four largest coal-fired power plants in Spain

The production of electricity in coal-fired power plants (CFPP) is considered a NORM (Naturally Occurring Radioactive Materials) activity because the coals they burn can present relatively high contents of the naturally occurring radionuclides. In this study, the main radiological impact pathways into the surrounding environments of the four largest coal-fired power plants in Spain were analyzed. These pathways are, first, atmospheric evacuations and wind resuspension and, second, effluent evacuations to nearby rivers or directly to the sea. The atmospheric releases of radionuclides were evaluated by the analyses of soil profiles in the vicinities of the CFPPs. No significant enhancement of radionuclides in the surface soil was observed at the points of maximum deposition of combustion gases, located from 4.3 to 13 km away depending on the considered CFPP. However, an increase of (40)K, (226)Ra, and (232)Th in the surface soils was observed in the first kilometre from the chimney for two CFPPs. This suggested that these radionuclides were released in particulate form. There was also a net influence of the climate in which the CFPPs were located. This was observed in the two CFPPs that were in dry environments, while no increase was observed in the other two, located in more humid environments. The liquid effluents released usually presented an enhancement of dissolved chemical species regarding the initial intake water. Enrichments of the (234,238)U and (226)Ra contents in the water used in the plants' routine procedures were observed, and of (210)Po in the wastewater of just one of the plants. In any case, this enhancement was below the parametric value for the Total Indicative Dose for the hypothetical human consumption of the released waters. As a consequence of these releases of radionuclides, local products destined for human consumption produced in the vicinity of the facilities might incorporate natural radionuclides by these pathways, finding no significant enhancement of the natural radionuclide contents due to the CFPPs.     

我国内陆流域各类水体中天然放射性核素浓度

1985年～1989年由新疆、甘肃、青海、西藏、内蒙古、陕西、宁夏等省、自治区环境监测站(研究所)对内陆流域各类水体中U、Th、~(226)Ra、~(40)K浓度进行调查,由调查的29条内陆河、23个湖泊、15座水库、55处井泉和34个自来水的统计结果表明,流域内各水体中U和~(40)K浓度的平均值与同期调查的黄河水系同类水体的浓度相近,明显高于长江水系,与全国同类水体相比亦属偏高。Th和~(226)Ra的平均浓度与全国同类水体的浓度相近,甘、新内陆区浓度较低。调查发现,一些咸水湖、井水和自来水中U、~(226)Ra,或~(40)K浓度异常偏高。     

Assessment of public exposure to naturally occurring radioactive materials from mining and mineral processing activities of Tarkwa Goldmine in Ghana

Studies have been carried out in a Goldmine in Ghana to determine the exposure of the public to naturally occurring radioactive materials from processing of gold ore. Direct gamma spectrometry and neutron activation analysis techniques were used to analyse soil, rock, water and dust samples from the mining environment. The mean activity concentrations measured for (238)U, (232)Th and (40)K in the soil/rock samples were 15.2, 26.9 and 157.1 Bq kg(?-?1), respectively. For the water samples, the mean activity concentrations were 0.54 and 0.41 Bq l(?-?1)) and 7.76 Bq l(?-?1) for (226)Ra, (232)Th and (40)K, respectively. The mean activity concentrations measured in the dust samples were 4.90 and 2.75 μBq m(?-?3) for (238)U and (232)Th, respectively. The total annual effective dose to the public was estimated to be 0.69 mSv. The results in this study compared well with typical world average values. The results indicate an insignificant exposure of the public from the activities of the Goldmine.     

Total effective dose equivalent assessment after exposure to high-level natural radiation using the RESRAD code

The current work reports the activity concentrations of several natural radionuclides (²²⁶Ra, ²³²Th, and ⁴⁰K) in Khak-Sefid area of Ramsar, Iran. An evaluation of total effective dose equivalent (TEDE) from exposure to high-level natural radiations is also presented. Soil samples were analyzed using a high-purity germanium detector with 80 % relative efficiency. The TEDE was calculated on a land area of 40,000 m² with 1.5-m thickness of contaminated zone for the member of three critical groups of farmer, construction worker, and resident using Residual Radioactive Material Guidelines (RESRAD) modeling program. It was found that the mean activity concentrations (in Bq/kg) were 23,118?±?468, 25.8?±?2.3, and 402.6?±?16.5 for ²²⁶Ra, ²³²Th, and ⁴⁰K, respectively. The maximum calculated TEDE during 1,000 years was 107.1 mSv/year at year 90, 92.42 mSv/year at year 88, and 22.09 mSv/year at year 46 for farmer, resident, and construction worker scenarios, respectively. The maximum TEDE in farmer scenario can be reduced to the level below the dose limit of 1 mSv/year which is safe for public health using soil cover with thickness of 50 cm or more on the contaminated zone. According to RESRAD prediction, the TEDE received by individuals for all exposure scenarios considerably exceed the set dose limit, and it is mainly due to ²²⁶Ra.     

A study of background radioactivity level for Canakkale, Turkey

This study assesses the level of background radiation for Canakkale province of northwestern Turkey. Radon concentrations in indoor air were determined using CR-39 nuclear track detectors and ²²²Rn activity was found to be 167 Bq m^???3 (equivalent to an annual effective dose of 4.2 mSv). Measurements of outdoor gamma radiation (of terrestrial and cosmic origin) in air were performed using plastic scintillators, and the average absorbed gamma dose rate was found to be 66.4 nGy h^???1 (corresponding to an annual effective dose of 81.4 μSv). The radionuclide activity concentrations in soil samples collected from the study area were measured through gamma-ray spectrometry, and the average activities were determined as 94.55, 110.4, and 1,273 Bq kg^???1 for the natural radionuclides ²³⁸U, ²³²Th, and ⁴⁰K, respectively, and 19.39 Bq kg^???1 for the fission product ¹³⁷Cs. The natural radioactivity sources resulted in an annual effective dose of 184 μSv. The radioactivity levels of drinking water samples were measured as 0.0599 Bq l^???1 for gross-alpha activity and 0.0841 Bq l^???1 for gross-beta activity using a low-background counting technique (equivalent to an annual effective dose of 12.25 μSv). The results of this study show that the activity levels of radon in air, radionuclides in soil, and alpha activities in drinking water are higher compared to the data available for other Turkish cities and the world averages. On the other hand, the outdoor gamma dose rates in air and beta activities in drinking water are within natural limits.     

Study on transfers of uranium, thorium and decay products from grain, water and soil to chicken meat and egg contents

Activity concentrations of the uranium and thorium series radionuclides were determined in chicken meat and eggs as well as in soil, water and other dietary intakes of poultry at five sites of the French territory. These data allow the calculation of transfer coefficients which enrich the database given by the technical report series no. 472 of the IAEA. In egg contents, the highest activity concentrations (in mBq kg(-1) fresh weight) are for (226)Ra, ranging between 136 and 190 and are much lower for uranium (between 0.51 and 1.30 for (238)U). In chicken meat, (238)U activity concentration is higher than in egg contents and ranges between 1.7 and 9.7. Concerning (232)Th, its activity concentration is lower than uranium and ranges between 0.5 and 4.9. Daily ingested activity concentration by the animals was assessed taking into account the activity concentrations measured in the grains, in the soil and in the drinking water. The activity concentration in grains and the daily intakes allow the calculation of concentration ratios and transfer coefficients for chicken meat and egg contents. In chicken meat the transfer coefficients (d kg(-1)) range between 0.0018 and 0.0073 for (238)U and between 0.0008 and 0.0028 for (232)Th. In egg contents they range from 0.00018 to 0.0018 for (238)U and are much higher for radium isotopes (0.10-0.23 for (226)Ra and 0.07-0.11 for (228)Ra).     

Distribution of radionuclides in surface soils, Singhbhum Shear Zone, India and associated dose

Gamma emitters were estimated in surface soils from a mineralized zone in Eastern India using high purity Germanium detector-based high resolution gamma spectrometry system. Activities of ²³⁸U, ²²⁶Ra, ²³²Th, ²³⁵U, ²²⁷Th, ^234mPa, ²¹⁰Pb, ⁴⁰K, and ¹³⁷Cs were 79?±?50, 81?±?53, 65?±?23, 4?±?2, 5?±?4, 92?±?50, 97?±?45, 517?±?201, and 4?±?2 Bq/kg, respectively. Most radionuclides were observed to follow log-normal distribution. The correlation between physicochemical properties of the samples, like pH, organic matter content, particle size, and moisture content were also studied. Activity ratios of ²²⁶Ra/²³⁸U, ²¹⁰Pb/²²⁶Ra, and ²²⁷Th/²³⁵U indicated deviation from secular equilibrium in some samples. The associated annual effective dose ranged from 0.07 to 0.24 mSv and the mean was calculated to be 0.12?±?0.04 mSv for this region, indicating it to be one of normal natural background radiation.     

Measurement of soil radioactivity levels and radiation hazard assessment in southern Rechna interfluvial region, Pakistan

Rechna interfluvial region is one of the main regions of Punjab, Pakistan. It is the area which is lying between River Ravi and River Chenab, alluvial-filled. Radioactivity levels in soil samples, collected from southern Rechna interfluvial region, Pakistan, have been estimated by using gamma-ray spectrometric technique. ²²⁶Ra, ²³²Th, the primordial radionuclide ⁴⁰K, and the artificial radionuclide ¹³⁷Cs have been measured in the soil of the study area. The mean radioactivity levels of ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs were found to be 50.6 ± 1.7, 62.3 ± 3.2, 662.2 ± 32.1, and 3.1 ± 0.3 Bq kg^???1, respectively. The mean radium equivalent activity (Ra_eq), outdoor radiation hazard index (H _out), indoor radiation hazard index (H _in), and terrestrial absorbed dose rate for the area under study were determined as 190.8 ± 8.7 Bq kg^???1, 0.52, 0.65, and 69.8 nGy h^???1, respectively. The annual effective dose to the general public was found to be 0.43 mSv. This value lies well below the limit of 1 mSv for general public as recommended by the International Commission on Radiological Protection. The measured values are comparable with other global radioactivity measurements and are found to be safe for the public and the environment.     

Radium equivalent activity in the light of UNSCEAR report

Radium equivalent activity (Ra ( eq )) has been in practice for the last 40 years for the assessment of radiological hazard of radioactivity in environmental materials. The in-practice model for the calculation of the Ra ( eq ) has been critically reviewed in the light of the UNSCEAR 2000 report. Annual effective dose (E) values of (232)Th and (40)K were found to be not equal to that of (226)Ra derived from the activity concentrations of these radionuclides used in the expression for the Ra ( eq ). Therefore, a modified model has been proposed for the determination of the Ra ( eq ) for outdoor external exposure to gamma rays. The relation between the E and Ra ( eq ) has been explored. It is recommended that while describing the radiological hazard of the materials containing radioactivity, there should be no need to calculate the Ra ( eq ) if the E has already been determined or vice versa.     

Assessment of radionuclide and metal contamination in a thorium rich area in Norway

The Fen Central Complex in southern Norway, a geologically well investigated area of magmatic carbonatite rocks, is assumed to be among the world largest natural reservoirs of thorium ((232)Th). These rocks, also rich in iron (Fe), niobium (Nb), uranium ((238)U) and rare earth elements (REE), were mined in several past centuries. Waste locations, giving rise to enhanced levels of both radionuclides and metals, are now situated in the area. Estimation of radionuclide and metal contamination of the environment and radiological risk assessment were done in this study. The average outdoor gamma dose rate measured in Fen, 2.71 μGy h(-1), was significantly higher than the world average dose rate of 0.059 μGy h(-1). The annual exposure dose from terrestrial gamma radiation, related to outdoor occupancy, was in the range 0.18-9.82 mSv. The total activity concentrations of (232)Th and (238)U in soil ranged from 69 to 6581 and from 49 to 130 Bq kg(-1), respectively. Enhanced concentrations were also identified for metals, arsenic (As), lead (Pb), chromium (Cr) and zinc (Zn), in the vicinity of former mining sites. Both radionuclide and heavy metal concentrations suggested leaching, mobilization and distribution from rocks into the soil. Correlation analysis indicated different origins for (232)Th and (238)U, but same or similar for (232)Th and metals As, Cr, Zn, nickel (Ni) and cadmium (Cd). The results from in situ size fractionation of water demonstrated radionuclides predominately present as colloids and low molecular mass (LMM) species, being potentially mobile and available for uptake in aquatic organisms of Norsj? Lake. Transfer factors, calculated for different plant species, showed the highest radionuclide accumulation in mosses and lichens. Uptake in trees was, as expected, lower. Relationship analysis of (232)Th and (238)U concentrations in moss and soil samples showed a significant positive linear correlation.     

Radioactivities related to coal mining

Natural radioactivity concentrations due to the coal mining in Gabal El-Maghara, North Sinai, Egypt, were determined using gamma-ray spectroscopy. Coal, water and soil samples were investigated in this study. The (226)Ra, (232)Th and (40)K activity concentrations in coal before extraction were 18.5 +/- 0.5, 29.5 +/- 1.2 and 149.0 +/- 8.4 Bq kg(-1), respectively. These concentrations were reduced to 18-22% after extraction due to the clay removal of the coal ore. The activity contents of the water and soil samples collected from the surrounding area did not show any evidence of enhancement due to the mining activities. Absorbed dose rate and effective dose equivalent in the mine environment were 29.4 nGy h(-1) and 128.0 microSv a(-1), respectively. The measured activity concentrations in the mine environment and the surrounding areas (5 km away from the mine) are similar to that found in other regions in North and South Sinai. Based on the measurements of gamma-ray emitting radionuclides, the mine activity does not lead to any enhancement in the local area nor represents any human risk.     

226Ra in Tap and Mineral Water and Related Health Risk in the Republic of Croatia

The presence of 226Ra in drinking water may sometimes make important contribution to natural background radiation exposures. The paper describes the study of 226Ra content in drinking water of Croatia: tap water from the public supply system of several major towns and bottled mineral water from two selected mineral water springs. 226Ra was determined by alpha-spectrometric measurement after radiochemical separation. The radiation doses originating from drinking tap water and bottled mineral water were estimated. The annual dose from consumption of bottled mineral water was compared to that received from ingestion of public system tap water. The study showed that 226Ra content for investigated categories of waters is below the levels at which any unacceptable dose due to ingestion would arise.     

Estimation of external gamma radiation dose in the area of Bory Stobrawskie forests (PL)

The study assessed the radiological risks associated with the presence of natural and artificial radionuclides in the Bory Stobrawskie forests (PL). Using the conversion factors given by UNSCEAR and the measurements results of (232)Th series, (238)U series, (40)K, and (137)Cs specific activities in the 10-cm soil layer the values of absorbed dose (D) and the annual effective dose equivalent derived from terrestrial gamma radiation (E) were calculated. The calculated dose was compared with doses directly measured on the area studied.