Distribution Of Natural Radionuclides Research Articles

Simultaneous recycling of both desalination reject brine water and phosphogypsum waste in manufacturing K2Mg(SO4)2·6H2O fertilizer

The purpose of this paper is twofold. The first is to convert phosphogypsum (PG) waste, mainly composed by gypsum (CaSO4·2H2O), into potassium sulfate (K2SO4) compound, which help to reduce the environmental impact and open new ways and valuable chain for the industrial manufacturing of phosphoric acid. The second is to recover MgSO4·7H2O from desalination reject brine water (RBW), thereby minimizing its associated environmental impact. The novelty of the current study is to simultaneously use the recovered salts K2SO4 and MgSO4·7H2O to produce K2Mg(SO4)2.6H2O (K2MgS6), considered as a double fertilizer. Additionally, Solid–Liquid Equilibria (SLE) are frequently applied to several industry domains. SLE are an interesting outline to visualize the precipitation, separation, and purification of a solid phase and the pathways by which crystallization can occur. The SLE of the ternary phase diagrams K2SO4-MgSO4-H2O at 25 °C and 0 °C were especially used to successfully determine the operating conditions and the design of a crystallization process during the PG/RBW conversion into K2MgS6. Several characterization techniques (i.e., XRD, DTA/DTG, SEM/EDS, FTIR) were employed to identify the solids formed during this process. An analysis on the distribution of natural radionuclides and heavy metals was carried out to confirm the effectiveness of the developed process. The main conclusion of this study was that K2MgS6 fertilizer can be manufactured by combining PG and RBW from desalination plants. Furthermore, the formed fertilizer, K2MgS6, is highly recommended for many applications in the agriculture sector.

Bioaccumulation and translocation of radionuclides heavy metals in Cynodon dactylon: A phytoremediation approach in Al-Dora refinery

Oil extraction methods such as fracking and drilling can disperse radioactive elements into the environment, posing potential hazards. Certain plants like Bermuda grass can combat this through rhizodegradation, a process that breaks down pollutants into harmless substances. The efficiency of this process varies by location and is influenced by factors such as soil compatibility and the presence of beneficial microbes. A study showed that Bermuda grass roots absorbed high levels of radioactive elements, especially Uranium in the soil. The distribution and concentration of these isotopes in Bermuda grass varied across different sites. For instance, Cesium-137 showed higher activity in leaves than in soil. These findings highlight the varied accumulation patterns of elements in Bermuda grass and the influence of natural radionuclide distribution on the environment. Approaches like soil amendments, microbial assistance, and genetically modified Bermuda grass can enhance rhizoremediation efficiency. Strategic planning and species selection are key to overcoming rhizoremediation challenges and enhancing its effectiveness. In addition, soil samples from the AL-Dora Refinery showed a high degree of contamination by heavy metals, with the emission from burning fuel and crude oil being the main sources. This indicates the high contamination of soil by these heavy metals. Overall, the text discusses the potential of Bermuda grass in mitigating the environmental impacts of oil extraction through rhizoremediation, and the challenges and strategies in enhancing its effectiveness. It also highlights the issue of soil contamination by heavy metals due to oil refinery emissions. This research examines the levels of heavy metal contamination in the soil of the Al-Dora refinery area, situated in central Iraq. The contamination factor (Cf) was employed to ascertain the contamination status, revealing a significant to extremely high degree of contamination by various heavy metals. The study further investigates the bioaccumulation and translocation of these heavy metals from the soil to the roots and leaves of Cynodon dactylon plants. Two methodologies were utilized to assess the role of Cynodon dactylon in soil phytoremediation: a comparison of heavy metal concentrations in plant parts with global standards, and the application of the Bioconcentration factor (BCF). The findings suggest a high potential for Cynodon dactylon to be employed in the clean-up and phytoremediation process of the contaminated soil. This presents a promising strategy towards environmental remediation in areas contaminated with heavy metals.

Assessment of Concentrations and Distributions of Natural Radionuclides in Soils of Abandoned Mine Sites of Jos South and Barkin Ladi in Plateau State Nigeria

Barkin Ladi and Jos South Local Government Area of Plateau State is situated in the central part of Northern Nigeria, on a rugged terrain of lowlands. It is the principal centre of tin and columbite mineralization, which forms the focal area of younger granites. The work was aimed at assessing the concentration and distribution of radionuclides in soils of abandoned tin mines and the soil’s physicochemical properties. The samples were collected in July, from five different locations in both Barkin Ladi and Jos South where mining activities were predominant. The samples were analyzed using a gamma-ray spectrometer. The result obtained reveals a range of the concentrations of 40K as 116.76 ± 0.21 to 250.15 ±0.,42 Bq/kg, 226Ra from 24.37 ± 0.31 to 90.45 ± 0.86 Bq/kg, and 232Th from 15.74 ± 0.71 to 88.43 ± 0.14 Bq/kg. The result of the physicochemical properties of the soil analyzed ranges from pH (3.12 to 6.81); organic carbon (0.01 to 1.62%); organic matter (0.22 to 3.01 %), cation exchange capacity (1.01 to 4,21Cmol/kg); clay (9.72 to 40.82 %); silt (8.32 to 40.32% and sand (32.42 to 75.38%) respectively. All the 40K results analyzed in all the sampling sites were lower than the recommended limits of 412Bq/kg, whereas most of the results of 226Ra and 232Th were above the 33Bq/kg and 45Bq/kg recommended safe limits. Exposure to elevated levels of naturally occurring radionuclides in soil can pose potential health risks to nearby populations. The physicochemical properties of the soil varied across the sampling sites. Most of the sampling sites are polluted with radionuclides and migrations of the radionuclides from the ex-mining sites to other parts of the environment were noticed from the studies conducted.

Natural radionuclides and radiological risk assessment in the stream and river sediments of a high background natural radiation area Kanyakumari, India.

The Kanyakumari coast is known to be a high background natural radiation area due to the placer deposits of heavy minerals such as ilmenite, monazite, and rutile. The Kanyakumari river sediments that could be the source of the elevated amounts of natural radionuclides in the coastal sands have been studied in this paper. The activity concentrations of primordial radionuclides 226Ra, 232Th, and 40K were determined using high-purity germanium (HPGe) gamma-ray spectrometry. The mean activity concentrations of 226Ra, 232Th, and 40K were found to be 75Bqkg-1, 565Bqkg-1, and 360Bqkg-1, respectively. The mean absorbed dose rate was 395 nGy h-1. Radiological hazard parameters were studied and compared with the world average values. The contribution of 232Th to the total dose rate was found to be higher than that of the two other radionuclides. The high mean ratio of 232Th/226Ra suggested an enrichment of 232Th and the occurrence of 226Ra leaching due to an oxidizing environment. Principal component analysis (PCA) was carried out for the radionuclides in order to discriminate the source of the sediments. This study provides new insights into the distribution of natural radionuclides in sediments of rivers and streams.

Accumulation of Technogenic and Natural Radionuclides in the Don Delta Sediments

The study of current sedimentation processes and radioactive contamination in the total area of the Don Delta is the research goal. The presented paper contains data analysis of radioecological and lithologic studies on bottom sediments, sampled in the northern part of the Don Delta in 2022. Based on the research results obtained, the authors provide the characteristics of the current conditions of sedimentation and specific activity of artificial and natural radionuclides in fluvial deposits, as well as indicate that similar in characteristics sandy-silty aleurites and sandy aleurite-clayish silts with inclusions of plant and shell detritus compose the bottom sediments of numerous braided channels. The authors determined the zonal accumulation character of both 137Cs technogenic and 226Ra, 40K, and 232Th natural radionuclides which conditions their accumulation and content increase from the lower delta to the upper delta areas. The velocity of currents in the braided channels (bayous) and related sedimentation conditions of suspended matter, as well as the lithotype of the bottom ground determine the indicated regularity. We assume that unlike 137Cs the distribution of natural radionuclides (40K, 226Ra, and 232Th) mainly depends on the mineral content of sediments entering the delta with the river runoff. Relatively low indices – on average ca. 9 Bq/kg of dry weight (d.w.) – characterise the current range of 137Cs radioisotope concentrations in the sediments of the Northern Don Delta. Such a level of specific activity is of no danger to the regional ecosystem.

The content and distribution of natural (232Th, 238U, 40K) radionuclides in the model small lakes bottom sediments of different sedimentogenesis types (south of Western Siberia)

The assessment of the content and distribution of natural radionuclides (232Th, 238U, 40K) in stratified bottom sediments cores of the similar composition (silicon class) in model small lakes, taking into account the type of sedimentogenesis (humid, arid, and nival), in consistently changing landscape conditions of the south of Western Siberia, was carried out. In the bottom sediments of the model small lakes (silicon class) of the humid and arid sedimentogenesis type, the average content and distribution of Th, U and K are similar throughout the studied time interval (about 200 years). For bottom sediments in model lakes of the nival sedimentogenesis type, fluctuations in the average composition along the core, as well as generally higher Th and U contents, are observed.

Natural radionuclide distribution and analysis of associated radiological concerns in rock samples from a rocky town (Dutsin-Ma) in the North-Western region of Nigeria

Natural radionuclides in rock samples, especially 226Ra (Radon), 232Th (thorium), and 40K (potassium), are the primary source of exposure to radiation for employees and the public, and their detection is critical for radiation safety. The gamma (γ) radiation from natural radionuclides was quantified using the γ-ray spectrometry method in twenty rock samples obtained from Dutsin-Ma, a rocky town in Nigeria's north-western region. The data obtained were used to estimate the radiological parameters and the excess lifetime cancer risk (ELCR). The results obtained show that the minimum activity concentrations of 40K, 232Th, and 226Ra are respectively 36.7 Bq/kg, 25.99 Bq/kg, and 11.59 Bq/kg, with their maximum values being 73.23 Bq/kg, 92.81 Bq/kg and 100.93 Bq/kg respectively. The average activity of 40K, 232Th, and 226Ra in the rock samples were found to be 73.5781±3.38 Bq/kg, 40.7848±3.32 Bq/kg, and 33.6616±3.58 Bq/kg respectively, which were all below the World average values of (33, 45 and 420) Bq/kg respectively. The ELCR was found to be 0.185±0.01, while the average absorbed dose rate, as well as the mean annual effective dose rate, were calculated to be 43.13±2.7 nGy/h and 0.015±0.003 mSv/y respectively. The outcomes for internal hazard, external hazard, annual absorbed and effective dose equivalent (ABEDE), alpha and gamma index values were below the maximum values allowed limits of 1 mSv/y for ABEDE and 1 for representative alpha & gamma index values, internal and external hazards as recommended by the International Commission on Radiological Protection (ICRP). This study shows that the radiation contamination of rock particles in Dutsin-Ma LGA does not pose much significant risk.

Radioactivity level evaluation in granite building raw material production area in Cenxi, China.

This study was conducted to evaluate the radioactivity level in the granite building raw material production area in Cenxi, China. Natural radionuclide concentrations, γ absorbed dose rates (ADRs) and radon exhalation rates were measured in the area. The spatial distribution of natural radionuclides, γ ADR and radon exhalation rate were mapped with GPS information. The radioactivity levels in the study area were analysed based on the descriptive statistics and frequency distribution of measurement data. According to the Chinese standard, the granite raw materials used for building and decoration in this region were classified based on their radiological hazards. In addition, radiation protection measures were proposed for the mining of local granite building materials products as well as environmental protection around the work area and resident safety.

DISTRIBUTION OF NATURAL RADIONUCLIDES IN ASHES, COLLECTED BY THERMAL POWER PLANTS ELECTROSTATIC PRECIPITATOR

Link for citation: Nazirov R.A., Vede P.Yu., Tarasov I.V., Zhuikov A.V., Sergunicheva E.M., Tolochko O.R. Distribution of natural radionuclides in ashes, collected by thermal power plants electrostatic precipitator. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 177-186. In Rus. Relevance. In the context of the global trend towards sustainable development, there is a problem of utilization of ash and slag waste from thermal power plants. The use of these wastes in the construction industry is of particular importance, due to the resource intensity of the production of building materials. Fly ash in the building materials composition can influence to a large extent the natural radioactivity of structures and increase the background radiation in the buildings. This is due to the fact that when coal combusting, fly ash is enriched with natural radionuclides. Purpose: to study the radioactivity of fly ash deposited on various fields of the electrostatic precipitator. Object: fly ash deposited on the fields of electrostatic precipitators from the combustion of Kansk-Achinsk brown coal in power boilers BKZ-420-140 PT-2. Methods. Content of Ra-226, Th-232 and K-40 was determined by gamma-spectrometric method, the value of the normalized indicator of specific effective activity for fly ash was calculated. The granulometric composition of the studied samples was determined by the method of laser diffraction analysis. Cluster analysis was used for statistical processing of test results. Results. The presence of two clusters in the content of natural radionuclides was established. In the first cluster, which has high radioactivity, the first and second fields of UGZ-4 electrostatic precipitators are combined, and in the second – the third and fourth fields. A correlation dependence was established between the numbers of fields of electrostatic precipitators, the size of ash particles, the content of Ra-226 and specific effective activity was established. No such dependence was found for Th-232. Conclusions. Particle distribution in the fields of electrostatic precipitators is multimodal. The nature of the distribution of each mode approaches the lognormal law. The content of radium and the value of the specific effective activity depend on the size of ash particles and are described by an exponential function. The highest content of Ra-226 is observed in the ashes deposited on the third and fourth fields of electrostatic precipitators, which indicates the enrichment of finer ash particles with this radionuclide. The conclusions obtained correspond to the well-known thesis about the increased radioactivity of ash particles that are not deposited by ash collection systems and enter the atmosphere together with flue gases. The proposed method for studying the distribution of natural radionuclides over the fields of electrostatic precipitators can be used to predict the radioactivity of particles that are not captured by the flue gas cleaning system and released into the environment.

Distribution of natural radionuclides in NORM samples from North Abu Rusheid area, Egypt

The North Abu Rusheid area in Egypt is a well-known high background natural radiation area (HBNRA) due to the existence of naturally occurring radioactive materials (NORMs) in mylonitic rocks. In this study, 27 rock samples were selected for dose estimation studies. 238U and 232Th were measured using inductively coupled plasma mass spectrometry (ICP-MS) and 40K was measured using sodium iodide (thallium) gamma-ray spectroscopy. The ranges of activity concentrations (Bq/kg) of 238U, 232Th and 40K in the samples varied from 270 ± 2 to 2120 ± 29, 350 ± 2 to 1840 ± 27 and 20 ± 2 to 1390 ± 35 with mean values of 980 ± 349, 770 ± 351, and 640 ± 402 Bq/kg, respectively. The radiological hazard parameters were estimated from activity concentrations of 238U, 232Th and 40K and compared to United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) values. The present study revealed that the hazard parameters were several times higher than the worldwide averages. The U/Th concentration ratio ranged from 0.7 to 3 and could be attributed to the presence of kasolite, uranothorite, zircon, and columbite in mylonitic rocks. From the radiological protection viewpoint, it is necessary to monitor natural radionuclides in these rocks prior to their use in residential and commercial construction materials.

Geochemical distributions of natural radionuclides in surface soils and sediments impacted by lead-zinc mining activity

This study investigated the distribution features of uranium-238 (238U), radium-226 (226Ra), thorium-232 (232Th), and potassium-40 (40K) and evaluated the associated environmental radiological hazards of the topsoil and river sediments in the Jinding lead-zinc (Pb-Zn) mine catchment from Southwest China. The activity concentrations of 238U, 226Ra, 232Th, and 40K ranged from 24.0 ± 2.29–60.3 ± 5.26 Bq.kg-1, from 32.5 ± 3.95–69.8 ± 3.39 Bq.kg-1, from 15.3 ± 2.24–58.3 ± 4.92 Bq.kg-1, and from 203 ± 10.2–1140 ± 27.4 Bq.kg-1, respectively. The highest activity concentrations for all these radionuclides were primarily found in the mining areas and decreased with increasing distance from the mining sites. The radiological hazard indices, including radium equivalent activity, absorbed gamma dose rate in the air, outdoor annual effective dose equivalent, annual gonadal dose equivalent, and excess lifetime cancer, revealed that the highest values were observed in the mining area and downstream, specifically in the vicinity of the ore body. These elevated values exceeded the global mean value but remained below the threshold value, suggesting that routine protection measures for Pb-Zn miners during production activities are sufficient. The correlation analysis and cluster analysis revealed strong associations between radionuclides such as 238U, 226Ra, and 232Th, indicating a common source of these radionuclides. The activity ratios of 226Ra/238U, 226Ra/232Th, and 238U/40K varied with distance, suggesting the influence of geological processes and lithological composition on their transport and accumulation. In the mining catchment areas, the variations in these activity ratios increased indicated the impact of limestone material dilution on the levels of 232Th, 40K, and 238U in the upstream region. Moreover, the presence of sulfide minerals in the mining soils contributed to the enrichment of 226Ra and the removal of 238U caused those activity ratios decreased in the mining areas. Therefore, in the Jinding PbZn deposit, the patterns of mining activities and surface runoff processes in the catchment area favored the accumulation of 232Th and 226Ra over 40K and 238U. This study provides the first case study on the geochemical distributions of natural radionuclides in a typical Mississippi Valley-type PbZn mining area and offers fundamental information on radionuclide migration and baseline radiometric data for PbZn deposits worldwide.

Distribution of Natural Radionuclides and 137Cs in Urban Soil Samples from the City of Novi Sad, Serbia-Radiological Risk Assessment.

This work presents the natural radioactivity distribution of 21 surface soil samples taken in the city of Novi Sad, Serbia. The analysis for radioactivity was performed using a gas low-level proportional counter for gross alpha and gross beta activity, while the specific activities of radionuclides were determined using HPGe detectors. The gross alpha activity of 20 samples was below the minimum detectable concentration (MDC), while in 1 sample it was 243 Bq kg-1; the gross beta activity ranged from the MDC (11 samples) to 566 Bq kg-1. The gamma spectrometry measurements showed naturally occurring radionuclides 226Ra, 232Th, 40K, and 238U in all investigated samples, with average values (Bq kg-1) of 33.9, 36.7, 513.8, and 34.7, respectively. Natural radionuclide 235U was detected in 18 samples with activity concentrations in the range of 1.3-4.1 Bq kg-1, while in the other 3 samples, the values were below the MDC. The artificial 137Cs radionuclide was detected in 90 percent of the samples, with a maximum value of 21 Bq kg-1, while the other artificial radionuclides were not detected. Based on the obtained concentrations of natural radionuclides, hazard indexes were estimated, and radiological health risk was assessed. The results present the absorbed gamma dose rate in the air, annual effective dose, radium equivalent activity, external hazard index, and lifetime cancer risk.

Radiometric mapping of the Berg River estuary

AbstractGeographic Information Systems (GIS) consists of various tools to perform spatial analyses in a wide variety of disciplines, including radiometric analysis to characterize the distribution of natural radionuclide concentrations. Recently, open‐source GIS has become popular among geospatial users because it can be freely used, and powerful tools are constantly developed to enhance software capabilities. Gamma‐ray spectroscopy was used to measure the concentrations of these natural radionuclides by dragging a Delta Underwater Gamma System (DUGS) among the sediment in the Berg River estuary located in Velddrif, South Africa. In this study, QGIS was used to visually illustrate and interpret the distribution of natural radionuclides, that is, potassium (K40), thorium (Th232), and uranium (U238). These concentrations can be used to investigate various geographical and geological phenomena, which include sediment processes. The data were then interpreted to derive sediment characteristics. Various features of tidal estuaries were demonstrated by the results.

Natural Radionuclides in Soils of Natural-Technogenic Landscapes in the Impact Zone of Potassium Salt Mining

This study considers the contents of natural radionuclides (226Ra, 232Th, and 40K) in the soils of natural–technogenic landscapes in the Verkhnekamskoe potassium–magnesium salt deposit (Perm Krai, Russia). The purpose of the study is to assess the lateral activity distribution of natural radionuclides (226Ra, 232Th, and 40K) in the soils of natural–technogenic landscapes of the mining areas on the territory of the Berezniki–Solikamsk industrial hub. Seventy-five soil samples from depths of 0–0.4 m are examined. The specific activities of the natural radionuclides 226Ra, 232Th, and 40K in the soil samples are measured using gamma spectrometry. The average values of the activity concentrations of 226Ra, 232Th, and 40K are 11.78 Bq/kg, 8.11 Bq/kg, and 246.9 Bq/kg, respectively. A gamma survey is conducted using the MKS/SRP-08A search dosimeter–radiometer over a control point framework covering 50,000 hectares. The research shows that the migration of the studied natural radionuclides is limited to a radius of 10 km. The results of the gamma-radiation measurements in the study area fall within a range of 0.06–0.25 µSv/h, which does not exceed the permissible limits. According to the findings, there is an increase in the concentration of natural radionuclides in transit supra-floodplain terrace landscapes and accumulative floodplain landscapes in the area affected by potash mining.

РАДИОНУКЛИДЫ В ВЕРХНЕМ СЛОЕ ПОЧВ ОСОБО ОХРАНЯЕМЫХ ПРИРОДНЫХ ТЕРРИТОРИЙ РОСТОВСКОЙ ОБЛАСТИ

The paper is devoted to the assessment of the features of the distribution of natural radionuclides (226Ra, 232Th, 40K) and artificial 137Cs in the upper soil layer of specially protected areas of the Rostov region. The activity concentration of radionuclides in the soil was measured by the gamma spectrometric method. The distribution of the artificial radionuclide 137Cs in the soils of the Rostov region is uneven. The minimum activity concentration of radiocesium is recorded in the Rostov nature reserve. It is shown that the arithmetic mean, median and modal values of the activity concentration of 137Cs are 21.7, 14.2 and 7.5 Bq/kg, respectively, and the arithmetic mean activity concentration of natural radionuclides in the soils of the protected areas of the Rostov region are 26, 9 Bq/kg for 226Ra, 27.0 Bq/kg for 232Th. These values can be used as background (reference) values in assessing the degree of influence of industry and urbanization on soil radioactivity.

Distribution of Natural radionuclides and its Associated Hazards in the Valleys Coastline of the Red Sea, Egypt

Distribution of Natural radionuclides and its Associated Hazards in the Valleys Coastline of the Red Sea, Egypt

Establishing a pre-mining baseline of natural radionuclides distribution and radiation hazard for the Bled El-Hadba sedimentary phosphate deposits (North-Eastern Algeria)

Since the implementation of the phosphate project in Bled El-Hadba (BEH) deposit, western region of Tébessa, no detailed study has been conducted to assess the natural radioactivity distribution and the associated radiological risk parameter for this open-pit mine. For the sake of determining a credible pre-mining reference database for the region of interest, 21 samples were collected from different geological layers of the above-mentioned deposit. Gamma Spectrometry was applied for measuring radioactivity using a high resolution HPGe semiconductor detector. The obtained activity results have shown a significant broad variation in the radioactive contents for the different phosphate samples. The total average concentrations (in Bq·kg−1) for 226Ra,238U,235U,232Th and40K computed for the different type of phosphate layers were found to be 570 ± 169, 788 ± 280, 52 ± 18, 66 ± 6 and 81 ± 18 respectively. The mean activity concentrations of the measured radionuclides were compared to other regional and worldwide deposits. The ratios between the detected radioisotopes have been calculated for spatial distribution of natural radionuclides in the study area. Based on the aforementioned activity concentrations, the corresponding radiation hazard parameters were assessed. Correlations between the obtained parameters were drawn and a multivariate statistical analysis (Pearson Correlation, Cluster and Factor analysis) was carried out in order to identify the existing relationships.

Radiological Hazards and Natural Radionuclide Distribution in Granitic Rocks of Homrit Waggat Area, Central Eastern Desert, Egypt.

Natural radioactivity, radiological hazard, and petrological studies of Homrit Waggat granitic rocks, Central Eastern Desert, Egypt were performed in order to assess their suitability as ornamental stone. On the basis of mineralogical and geochemical compositions, Homrit Waggat granitic rocks can be subdivided into two subclasses. The first class comprises granodiorite and tonalite (I-type) and is ascribed to volcanic arc, whereas the second one includes alkali-feldspar granite, syenogranite, and albitized granite with high-K calc alkaline character, which is related to post-orogenic granites. 238U, 226Ra, 232Th, and 40K activities of natural radionuclides occurring in the examined rocks were measured radiometrically using sodium iodide detector. Furthermore, assessment of the hazard indices—such as: annual effective dose (AED) with mean values (0.11, 0.09, 0.07, 0.05, and 0.03, standard value = 0.07); gamma radiation index (Iγ) with mean values (0.6, 0.5, 0.4, 0.3, and 0.14, standard value = 0.5); internal (Hin) with mean values (0.6, 0.5, 0.4, 0.3, and 0.2, standard value = 1.0); external (Hex) index (0.5, 0.4, 0.3, 0.24, and 0.12, standard value = 1.0); absorbed gamma dose rate (D) with mean values (86.4, 75.9, 53.5, 43.6, and 20.8, standard value = 57); and radium equivalent activity (Raeq) with mean values (180, 154, 106.6, 90.1, and 42.7, standard value = 370)—were evaluated with the knowledge of the natural radionuclides. The result of these indices falls within the acceptable worldwide limits. Therefore, we suggest that these rocks are safe to be used in industrial applications.

Assessment of Natural Radionuclide Distribution Pattern and Radiological Risk from Rocks in Precambrian Oban Massif, Southeastern Nigeria

A gamma spectrometric analysis of rock samples collected from the Precambrian Oban Massif, southeastern Nigeria, was performed to determine some primordial radioelements’ activity concentrations: U-238, Th-232, and K-40, and their associated radiological hazards. The mean activity of the primordial radionuclides was determined to be 1073.06 ± 0.65, 160.74 ± 1.32, and 250.76 ± 0.91 Bq·kg−1 for 40K, 238U, and 232Th, respectively, showing that they are inhomogeneously distributed, with activity changing with the rock type and location. The activity concentrations are highest in biotite garnet schist, quartz diorite, and biotite gneiss rock domains. The mean values of the radiological hazards are 0.08 Bq·kg−1 (alpha index), 2.15 Bq·kg−1(gamma index), 2.06 Bq·kg−1(internal) and 1.63 Bq·kg−1 (external4.30 Bq·kg−1(representative level index6), 602.23 Bq·kg−1, (radium equivalent), 780 nGy·h−1 (total absorbed dose rate), 270.91 nGy·h−1 (indoor), 509.78 nGy·h−1 (outdoor), 624.99, 1329.07 and 1954.06 mSv·yr−1 (outdoor, indoor and total annual effective dose equivalent, respectively), 6448.40 (cumulative excess lifetime cancer risk) and 248.94–3761.47 Bq·kg−1 (annual gonadal dose equivalent). These results are higher than their various permissible limits (except at Ako Community) and suggest that rocks in the area may be unsuitable for constructing dwelling places. It is strongly advised that basic safety standards and precautionary measures recommended by the European Commission should be strictly adhered to while dealing with these rocks.

Evaluation of natural radionuclides distribution in beach sands of Cox’s bazar sea beach, Bangladesh, using multivariate statistical technique

ABSTRACT The distribution of natural series radionuclides 226Ra, 232Th and non-series 40K in the heavy mineral-rich beach sands of highly touristic areas of Cox’s Bazar sea beach has been studied. The study is made to evaluate the gamma radiation exposure to individuals with an aim to establish reference data for the presence of naturally occurring radionuclides. The present study reports the probable first attempt of detail and systematic work in the study areas for estimation of activity concentration in the recent beach sand samples. Radiometric analysis was performed using gamma ray spectroscopy system based on HPGe detector. The mean activity levels of 226Ra, 232Th and 40K in Laboni beach sands were ranged from 255.69±64.57, 336.83±93.96 and 1785.91±89.60 Bq kg-1, respectively. While in Kolatoli beach sands, the respective values were 166.42±35.99, 157.35±35.90 and 1894.42±74.07Bq kg-1, respectively. The mean values of 226Ra and 232Th concentrations in the investigated beach sands were estimated to be very much higher than the corresponding world average values and comparable to those found in high background radiation areas in the world. The heavy minerals seem to control the activity concentrations of 226Ra and 232Th in sand samples, showing some variances based on uranium and thorium bearing minerals. Various radiation health hazard indicators were found to be extremely higher when compared to the recommended values. Hence, heavy mineral-rich sands may pose a significant radiological health risk to the people. The descriptive statistics indicating the radionuclides of 226Ra, 232Th and 40K are uniformly and symmetrically distributed in the Cox’s bazar beach sand. Multivariate statistical analysis showing the radioactivity and estimated radiological parameters are strongly positively correlated with 226Ra and 232Th, while weakly correlated with 40K, signifying that radiological risk is mainly associated and controlled by the radioactivity levels of uranium and thorium series radionuclides.