High Levels Of Natural Radioactivity Research Articles

Factors controlling groundwater radioactivity in arid environments: An automated machine learning approach

Groundwater resources in the Kingdom of Saudi Arabia (KSA) have high levels of natural radioactivity. Within the northwestern KSA, gross alpha (α) and gross beta (β) levels exceed national and international drinking-water limits. In this study, we developed and used an automated machine learning (AML) approach to quantify relationships between gross α and gross β activities and different geological, hydrogeological, and geochemical conditions. Two AML model groups (group I for gross α; group II for gross β) were constructed, using water samples collected from 360 irrigation and water supply wells, to define a robust model that explains the spatial variability in gross α and gross β activities, as well as variables that control the gross activities. Each group contained four model families: deep neural network (DNN), gradient boosting machine (GBM), generalized linear model (GLM), and distributed random forest (DRF). Model inputs include chemical compositions as well as geological and hydrogeological conditions. Three performance metrics were used to evaluate the models during training and testing: normalized root mean square error (NRMSE), Pearson's correlation coefficient (r), and Nash-Sutcliff efficiency (NSE) coefficient. Results indicate that (1) the GBM model outperformed (training: NRMSE: 0.37 ± 0.10; r: 0.92 ± 0.05; NSE: 0.85 ± 0.09; testing: NRMSE: 0.71 ± 0.08; r: 0.72 ± 0.08; NSE: 0.49 ± 0.12) the DNN, DRF, and GLM models when modelling gross α activities; (2) gross α activities are controlled by pH, stream density, nitrate, manganese, and vegetation index; (3) the DRF model outperformed (training: NRMSE: 0.41 ± 0.05; r: 0.92 ± 0.02; NSE: 0.83 ± 0.04; testing: NRMSE: 0.67 ± 0.09; r: 0.77 ± 0.07; NSE: 0.54 ± 0.12) the GBM, DNN, and GLM models when modelling gross β activities; (4) input variables that affect the gross β actives are pH, temperature, stream density, lithology, and nitrate; and (5) no single model could be used to model both gross α and gross β activities—instead, a combination of AML models should be used. Our computationally efficient approach provides a framework and insights for using AML techniques in water quality investigations and promotes more and improved use of different geological, hydrogeological, and geochemical datasets by the scientific community and decision makers to develop guidelines for mitigation.

Influence of 2019-nCoV in the increment of external gamma exposure in a uranium deposit area in Brazil

ABSTRACT The new coronavirus pandemic (2019-nCoV) arrived in Brazil in February 2020, where the worsening led to social isolation. The population started to remain entirely in their homes, mainly the elderly, children, and adolescents. The study aimed to determine the impact of radioecological dosimetry within the residences located in the municipality from Espinharas, Paraíba, Brazil, where one of the main uranium deposits in Brazil occurs. A scintillator-type gamma spectrometer with a combined NaI (Tl) and BGO probe, at 1.0 m from the soil surface, was used. A total occupation factor for the pandemic period was considered. The dose-response for the three months ranged from 0.55 to 1.70 mSv, with an average of 0.68 mSv, which characterises an increase of 25% when compared to the same period of the retrospective study in 2014. In the period of one year, the dosimetric response can vary between 2.22 and 6.80 mSv/y, with an average of 2.73 mSv/y. The work portrays the importance of a database for future affirmative actions and the determination of different radiometric conditions in an environment already considered to have a high level of natural radioactivity. The study also provides definitions of extreme exposure conditions and correlations with public health parameters.

Natural radioactivity and radiological hazard for humans: a simple introduction for newbies and students. New perspectives and innovative teaching methods

Pollution due to natural radioactivity is still a poorly known topic among young people. This paper describes the contents for an introductive university course or lecture conceived in a multitask program. Along with a so-called “flipped” configuration, where students are able to receive didactic materials prior to face-to-face lessons, multimedia contents should be shown to the students, who are at first faced with known anthropogenic accidents. Moreover, field and laboratory experimental activities can provide further insight regarding the radiological assessment strategies. Here, the most important principles and effects concerning the radioactive decay of naturally occurring radionuclides are described. The greatest part of natural radioactivity derives from terrestrial radionuclides occurring in soil and rocks. The radionuclides are atoms characterized by an excess of nuclear energy, which makes them unstable giving rise to decay. The radionuclides emit gamma rays, as well as alpha and/or beta particles. People are constantly subjected to indoor and outdoor exposure due to natural radioactivity. The possible sources can be considered as external due to natural sources located outside the human body, and internal provoked by ingestion or inhalation of radionuclides. The indoor exposure from natural sources is mainly related to radiation from building materials and to radon entering buildings from soils and rocks though cracks in walls and floor. The outdoor exposure mainly accounts for the terrestrial gamma radiation that crosses the soil air interface, and for the radon emitted from soils in seismic and volcanic areas. In this regard, there is a strong relationship between health diseases (e.g. cancer, necrosis and DNA and RNA modifications) and high-levels of natural radioactivity. For this reason, the radiological assessment of the most vulnerable areas represents a key point in order to mitigate hazard and risk connected to the human exposure to natural radioactivity.

NORM waste, cements, and concretes. A review

The use of industrial waste and/or by-products as alternative sources of raw materials in building materials has become standard practice. The result, more sustainable construction, is contributing to the institution of a circular economy. Nonetheless, all necessary precautions must be taken to ensure that the inclusion and use of such materials entail no new health hazard for people or their environment. Due to the processes involved in generating industrial waste/by-products, these alternative or secondary materials may be contaminated with heavy metals, other undesirable chemicals or high levels of natural radioactivity that may constrain their use. In-depth and realistic research on such industrial waste is consequently requisite to its deployment in building materials. This paper reviews the basic concepts associated with radioactivity and natural radioactivity, focusing on industrial waste/by-products comprising Naturally Occurring Radioactive Materials (NORM) used in cement and concrete manufacture. Updated radiological data are furnished on such waste (including plant fly ash, iron and steel mill slag, bauxite and phosphogypsum waste) and on other materials such as limestone, gypsum and so on. The paper also presents recent findings on radionuclide activity concentrations in Portland cements and concretes not bearing NORMs. The role of natural aggregate in end concrete radiological behaviour is broached. The radiological behaviour of alternative non-portland cements and concretes, such as alkali-activated materials and geopolymers, is also addressed.

Radiological characterization of the phosphate deposit in Al-Jalamid phosphate mining area, Saudi Arabia

Abstract It is a known fact that phosphate rocks have high levels of natural radioactivity due to the presence of large concentrations of radionuclides. This work aims to estimate radiation exposure and dose levels at Al-Jalamid site in northern Saudi Arabia. Al-Jalamid area is one of the largest reserves of phosphate worldwide. Ma’aden, a Saudi Government public company, owns the mine and is responsible for all mining activities. Phosphate and soil samples collected from Al-Jalamid phosphate mining area have been analysed for their uranium and thorium content by an α-spectrometer using radiochemical techniques. The quantity of radon gas was measured both in groundwater and in the atmosphere (indoor and outdoor) at the site using a portable radiation survey instrument. Groundwater samples collected from wells surrounding the mining area were analysed using a liquid scintillation counter in addition to an α-spectrometer. Finally, it is found that phosphate rock concentrate products cannot be utilized economically based on the standards set by the International Atomic Energy Agency (IAEA), since the average activity concentration does not reach the limit set by IAEA and hence are not commercially feasible.

Geospatial Modeling of Radon-Prone Areas

Methods for identification of potentially radon-prone areas using geospatial analysis in ArcGIS 10.6 software environment and mathematical modeling in SPSS 19.0 on the example of high background radiation area have been developed. High level of natural radioactivity associated with uranium content in environment objects and natural uranium occurrences, and also the spatial density of faults (reliable and unreliable) and lineaments were taken into account as well as the distance from uranium mine located nearby.
 The method of linear discriminant functions was used to make a math model for determining the level of radon hazard. To do this, data on all locations were divided into training and test samples. Determination of predictors of the mathematical model was performed using Fisher's criterion by their sequential inclusion in discriminant equations. Among the considered 13 factors of radon hazard, seven of them turned out to be informative. For them, canonical coefficients were calculated using the least squares method for first- and second-order polynomials. Based on the values of discriminant functions, a territorial map was constructed to assign the new location to a certain level of radon hazard.
 The maps obtained present the correlation of the radon-prone areas with the zones of high spatial density of faults and lineaments, and confirmed by the data of direct indoor radon measurements. In a limited number of measurements, the methods might get a good help in prioritization for round-the-country radon survey. As far as the model for identification of potentially radon-prone areas is mainly based on geological studies, the further research is supposed to be directed to its approbation for a different geological environment of the Ukrainian shield.

КОНТРОЛЬ РАДІОАКТИВНОСТІ ЖИТЛА В УКРАЇНІ

The main sources of natural radiation in Ukraine and their location are given. High levels of natural radioactivity were noted. The elements with the greatest influence on the formation of radioactive background in our country are indicated. The content of natural radionuclides in building materials of Ukraine is considered. Listed are organizations that provide services in the manufacture of radiation measurement devices in Ukraine, as well as organizations that provide services for measuring radioactivity. The cases of contamination of houses due to the use of radioactive bricks, as well as several consignments of gas block due to insufficient quality control of products, as well as the desire of the customer to save on "cheap" bricks are indicated. The basics of the methodology for determining the radioactivity of building materials in Ukraine, the preparation of a test sample and the spectrometric measurement of radioactivity of natural radionuclides in samples of building materials are presented. The specified norms of radioactivity of building materials, specific effective activity and class of building materials. Ways to reduce the radioactivity of building materials are suggested.

MEASUREMENT OF URANIUM IN URINE, HAIR AND NAILS IN SUBJECTS OF NISKA BANJA TOWN, A HIGH NATURAL BACKGROUND RADIATION AREA OF SERBIA.

Urine, hair and nail samples were collected from a population of both sex aged from 40 to 87 years in Niška Banja (227 km south of Belgrade, Serbia) with a high level of natural radioactivity (HLNRA). To assess and monitor the public exposure, urine samples for each subject (24 h period) were collected and concentration of uranium (U) was analysed using alpha-particle spectrometry. Human hair and nails considered as bio-indicators of the public exposure to radionuclides over a long period of months or even years and concentration of U was determined using inductively coupled plasma-mass spectrometry. The mean concentrations of U in urine, hair and nail were 123 ng/L, 17 ng/g and 8 ng/g, respectively. There was a large variation and may be due to geological origin.

A comparative study using different resins to determine thorium isotopes

Thorium is a naturally occurring radioactive element that is widely distributed in the crust of the Earth. This element is very common in mineral formations in regions with high levels of natural radioactivity, therefore, its determination in environmental samples is important. Thorium isotopes (228Th, 230Th, and 232Th) were determined in a reference material, the IAEA Soil 327 sample, to validate the two methods, these isotopes were also analyzed in two groups of food samples, employing these different resins. The initial preparation with acid dissolution is the same to both, in the first is used anion exchange resin (DOWEX 1x2) and electrodeposition in silver planchets. And in the second method is used a specific chromatographic resin (TEVA) and cerium fluoride microprecipitation. At the end both analysis are quantified by alpha spectrometry. The two methods the results obtained were satisfactory for the reference material used, with relative error of less than 4% for 228Th, 230Th, and 232Th. The analysis of variance for samples foods analyzed seen to be no significant difference between the methods used for thorium isotopes determination. The main differences found between methods were spectrums resolutions, time and cost of analysis.

Influence of terrestrial radionuclides on environmental gamma exposure in a uranium deposit in Paraíba, Brazil

One of the main natural uranium deposits in Brazil is located in the municipality of Espinharas, in the State of Paraíba. This area may present high levels of natural radioactivity due to the presence of these radionuclides. Since this is a populated area, there is need for a radioecological dosimetry assessment to investigate the possible risks to the population. Based on this problem, the objective of this study was to estimate the environmental effective dose outdoors in inhabited areas influenced by the uranium deposit, using the specific activities of equivalent uranium, equivalent thorium and 40K and conversion factors. The environmental assessment was carried using gamma spectroscopy in sixty-two points within the municipality, with a high-resolution gamma spectrometer with HPGe semiconductor detector and Be window. The results obtained ranged from 0.01 to 19.11 mSv y−1, with an average of 2.64 mSv y−1. These levels are, on average, 23 times higher than UNSCEAR reference levels and up to 273 times the reference value of the earth's crust for primordial radionuclides. Therefore, given the high radioactivity levels found, we conclude that there is need for further investigation to evaluate the levels of radioactivity in indoor environments, which will reflect more closely the risks of the local population.

Analysis of the natural activities of radionuclides, heavy metals, and other poisonous elements in lead-free Sn–6.5Zn solders with different alloying elements

Problem statementSn–Zn solders are candidate alternatives to Sn–Pb-based solder alloys. With the increasing requirement for lead-free solders, the reliability of successor solders in microelectronics assemblies is in high demand. The elimination of radionuclides, heavy metals, and other poisonous elements in lead-free Sn–6.5Zn solders in the microelectronics industry is a worldwide goal. As a result, it is useful to identify the natural concentrations of radioactive nuclides, heavy metals and other poisonous trace elements (both macro- and micro-element contents), such as Au-196, Th-227, Ag-110M, Fe-59, Zn-65, Rb-89, Rh-106M, Bi-207, Cs-137, Eu-154, Sb-126, Eu-152, Co-56, Co-58, Co-60 and K-40. If this lead-free solder contains high concentrations of natural radioactive nuclides, then workers handling it might be exposed to significant levels of radiation. Therefore, it is important to determine the levels of radioactive nuclides in this solder to protect workers; these levels provide background for the safety rules and precautions that should be applied for those working in this field. ApproachThe levels of natural radionuclides (238U, 232Th, and 40K) and their daughter products contained in Sn–6.5Zn solders have been estimated via gamma-ray spectrometry using a 100% Hyper-Pure Germanium (HPGe) detector. ResultsThe mean activities due to radionuclides, heavy metals, and other poisonous elements were measured, and the results are summarised in tables. ConclusionThe results of this assessment obtained by gamma-ray spectroscopic analysis indicated the presence of high levels of natural radioactivity, heavy metals and other poisonous elements. This result implies that a comprehensive study should be conducted to protect workers from high doses of hazardous substances.

Natural radioactivity can explain clinal variation in the expression of melanin-based traits

A recent study shows that the expression of pheomelanin-based coloration in barn owls follows a continuous gradient across Europe as a result of local adaptation. The selective pressures that promote local adaptation remain, however, unknown. Here we hypothesize and test that natural radioactivity levels follow a similar spatial gradient to that of pheomelanin-based color in Europe and thus represents a potential selective pressure. The rationale is that the production of pheomelanin consumes glutathione (GSH), a key intracellular antioxidant, and that GSH is particularly susceptible to ionizing radiation, which depletes antioxidants. As predicted, the intensity of pheomelanin-based coloration in 18 populations of barn owls was negatively associated with terrestrial γ-dose rates across Europe. Therefore, we propose that natural selection acts against barn owls that present the molecular basis to produce large amounts of pheomelanin in those populations that are exposed to high levels of natural radioactivity, as in these populations individuals would require higher antioxidant resources to combat oxidative stress. This is the first time that natural radioactivity levels are related to the expression of a phenotypic trait.

High levels of natural radioactivity in biota from deep-sea hydrothermal vents: a preliminary communication

Hydrothermal deep-sea vent fauna is naturally exposed to a peculiar environment enriched in potentially toxic species such as sulphides, heavy metals and natural radionuclides. It is now well established that some of the organisms present in such an environment accumulate metals during their lifespan. Though only few radionuclide measurements are available, it seems likely that hydrothermal vent communities are exposed to high natural radiation doses. Various archived biological samples collected on the East Pacific Rise and the Mid-Atlantic Ridge in 1996, 2001 and 2002 were analysed by ICP-MS in order to determine their uranium contents ( 238U, 235U and 234U). In addition 210Po–Pb were determined in 2 samples collected in 2002. Vent organisms are characterized by high U, and Po–Pb levels compared to what is generally encountered in organisms from outside hydrothermal vent ecosystems. Though the number of data is low, the results reveal various trends in relation to the site, the location within the mixing zone and/or the organisms' trophic regime.

Risk assessment after internal exposure to black sand from Camargue: uptake and prospective dose calculation

Some beaches in the south of France present high levels of natural radioactivity mainly due to thorium (Th) and uranium (U) present in the sand. Risk assessment after internal exposure of members of the public by either inhalation or ingestion of black sand of Camargue was performed. This evaluation required some information on the human bioavailability of U and Th from this sand. In vitro assays to determine the solubility of U, Th and their progeny were performed either in simulated lung fluid, with the inhalable fraction of sand, or in both simulated gastric and intestinal fluids with a sample of the whole sand. The experimental data show that the bioavailability of these radionuclides from Camargue sand is low in the conditions of the study. Prospective dose assessment for both routes of intake show low risk after internal exposure to this sand.

226Ra concentration in the teeth of habitants of areas with high level of natural radioactivity in Ramsar

The level of natural radiation in some regions of Ramsar, a northern coastal city of Iran, is known to be among the highest levels of natural radiation in the world. 226Ra existing in high concentrations in the soil of this region is washed by underground water and transferred to the surface. In this way, 226Ra enters the food chain of residents and substitutes within the hard body tissues of humans. 226Ra is one of the so-called bone seekers as its metabolic processes in the human body are similar to calcium and remains in hard tissues of body because of its long half-life, and being an α emitter causes dangerous effects on human health. The purpose of this study is to determine the concentration of 226Ra in the teeth of residents of these high-level natural radiation areas, compared with a control group. Thirteen teeth in five groups were studied as the case group and thirteen teeth in five corresponding control groups were inspected. The mean values of the activity of 226Ra in the case group and in the control group were 0.32 and 0.18 mBq g −1, respectively.

Natural radioactivity of granites used as building materials

Sixteen kinds of different granites, used as building materials, imported to Greece mainly from Spain and Brazil, were sampled and their natural radioactivity was measured by gamma-ray spectrometry. The activity concentrations of 238U, 226Ra, 232Th and 40K of granites are presented and compared to those of other building materials as well as other granite types used all over the world. In order to assess the radiological impact from the granites investigated, the absorbed and the effective doses were determined. Although the annual effective dose is higher than the limit of 1 mSv y −1 for some studied granites, they could be used safely as building materials, considering that their contribution in most of the house constructions is very low. An attempt to correlate the relatively high level of natural radioactivity, shown by some of the granites, with their constituent radioactive minerals and their chemical composition, was also made.

Of Stones and Health: Medical Geology in Sri Lanka

Geoscientists are usually known for their studies of rocks and minerals and the distributions of these on Earth, but this group of scientists has been expanding its discipline into surprising new territory by linking geology with human and animal health. Known as medical geology, this emerging specialty is gaining momentum. Chandra Dissanayake, professor of geology at the University of Peradeniya, Sri Lanka, outlines some of the major areas of medical geology in both his homeland and beyond, covering topics such as the link between naturally occurring fluoride in drinking water and a disfiguring tooth condition; global health risks due to iodine deficiency; the widespread practice of eating dirt; the potential for hard water to serve protective roles against cardiovascular disease; and the apparent paradox that people living in regions marked by high levels of natural radioactivity do not seem to suffer adverse health effects from their exposure. Because people must interact with their geological surroundings, discoveries made by medical geologists can have enormous consequences for the well-being of people all over the world. All essays and interactive features appearing in this series can be found online at [www.sciencemag.org/sciext/globalvoices/][1] [1]: http://www.sciencemag.org/sciext/globalvoices/

NATURAL RADIOACTIVITY OF GRANITES USED AS BUILDING MATERIALS IN GREECE

The granites used in Greece as building materials and imported from foreign countries, mainly from Spain and Brazil, are rock types similar with the stony building materials world-wide used. Sixteen kinds of different granites, considered as the most popular, were sampled and their natural radioactivity was measured by gamma spectrometry. The, 226Ra, 232Th and 40K contents of granites were compared to corresponding ones of other building materials as well as other granite types used all over the world. For the reasons of radiological impact from use of granites as building materials, the absorbed dose and the effective dose as well were determined. Although the annual effective dose is higher than the limit of 1 mSv a"1 for some granites examined, they could be used safely as building materials, considering that their contribution in most of the house constructions is very low. An attempt to correlate the relatively high level of natural radioactivity of different kinds of granites with the presence of radioactive minerals and their chemical composition was also made.

Radioactivity in Zirconium Oxide Powders Used in Industrial Applications

Recent work involving the decommissioning of a former ceramic manufacturing facility licensed by the Nuclear Regulatory Commission for activities involving depleted uranium oxide has uncovered the presence of unexpected high levels of natural radioactivity in non-licensed zirconium oxide powders also used in the same facility. A comparison between the levels of source material found in samples of this material and the current regulatory guidance for licensed activities and decommissioning has been conducted. It has been determined that the radioactivity in the zirconium oxide is of a high enough magnitude to raise health physics concerns in the areas of licensing and regulatory compliance, decontamination criteria, and worker health and safety. An examination of these areas has been conducted and the implications associated with our findings are presented.

Mesure de la radioactivité dans des tomates cultivées sur des résidus miniers d'Oka – Communauté minière de niobium

The radioactivity contained in the tailings of a niobium mine in the Oka region, Quebec, was the object of concern for the population of the area in 1979. To find the impact of these tailings on fruit and vegetables grown in this environment, an investigation of the radioactivity found on tomatoes grown in green houses in niobium tailings and in vermiculites was undertaken. The tailings contained a high level of natural radioactivity and a small amount of 137Cs while the vermiculites has a very low level of natural radioactivity and an appreciable amount of 137Cs. Cesium-137 was the only nuclide detected in tomato ashes in measurable quantity. Absence of natural radioactivity is explained by its presence as insoluble minerals.