Concentrations Of Primordial Radionuclides Research Articles

Assessment of natural radioactivity levels and hazard indicators in Tarakeshwor Municipality, Nepal through in-situ technique and multivariate analysis

The evaluation of primordial radionuclide concentrations in rapidly urbanized and concrete-laden areas through the importation of construction materials from various regions of Nepal is both important and essential. This study utilized a portable gamma-ray spectrometer (PGIS 2) to analyze the distribution of three natural radionuclides: uranium (238U), thorium (232Th), and potassium (40K) in Tarakeshwor Municipality, Kathmandu, Nepal. The measured dose rates ranged from 70.22 nSv hr−1 to 163.66 nSv hr−1, with an average of 124.65±20.29 nSv hr−1, surpassing the global average of 59 nSv hr−1. The activity concentrations of 40K, 238U, and 232Th exceeded global averages, indicating relatively higher natural radioactivity concentrations in the region. Specifically, the average values for 40K, 238U, and 232Th were 935.26±172.30 Bq kg−1, 80.47±15.53 Bq kg−1, and 80.44±18.58 Bq kg−1, respectively. The calculated radium equivalent (Raeq) ranged from 132.26 to 351.22 Bq kg−1, and the annual gonadal equivalent dose (AGED) varied from 372.61 to 1028.81 μSv yr−1. The annual effective dose rates for indoor and outdoor environments were 0.54±0.09 mSv yr−1 and 0.15±0.03 mSv yr−1, respectively, both exceeding the global average. The representative level index (RLI) within the study area averaged 1.96±0.32, indicating an elevated radiation risk. The excess lifetime cancer risk (ELCR) values for outdoor and indoor environments were 0.52×10−3 ±0.09 ×10−3 and 1.87 ×10−3 ±0.31×10−3, respectively, surpassing the world average. Additionally, external hazard indices (Hex) ranged from 0.36 to 0.59, while internal hazard indices (Hin) ranged from 0.38 to 1.20, both indicating values higher than UNSCEAR recommendations. These findings underscore the necessity for further experimental analysis employing ex-situ equipment. The data generated in this study can provide a valuable baseline for future assessments and interventions in radiation risk management guidelines within the country.

Using radial basis artificial neural networks to predict radiation hazard indices in geological materials.

The estimation of exposures to humans from the various sources of radiation is important. Radiation hazard indices are computed using procedures described in the literature for evaluating the combined effects of the activity concentrations of primordial radionuclides, namely, 238U, 232Th, and 40K. The computed indices are then compared to the allowed limits defined by International Radiation Protection Organizations to determine any radiation hazard associated with the geological materials. In this paper, four distinct radial basis function artificial neural network (RBF-ANN) models were developed to predict radiation hazard indices, namely, external gamma dose rates, annual effective dose, radium equivalent activity, and external hazard index. To make RBF-ANN models, 348 different geological materials' gamma spectrometry data were acquired from the literature. Radiation hazards indices predicted from each RBF-ANN model were compared to the radiation hazards calculated using gamma spectrum analysis. The predicted hazard indices values of each RBF-ANN model were found to precisely align with the calculated values. To validate the accuracy and the adaptability of each RBF-ANN model, statistical tests (determination coefficient (R2), relative absolute error (RAE), root mean square error (RMSE), Nash-Sutcliffe Efficiency (NSE)), and significance tests (F-test and Student's t-test) were performed to analyze the relationship between calculated and predicted hazard indices. Low RAE and RMSE values as well as high R2, NSE, and p-values greater than 0.95, 0.71, and 0.05, respectively, were found for RBF-ANN models. The statistical tests' results show that all RBF-ANN models created exhibit precise performance, indicating their applicability and efficiency in forecasting the radiation hazard indices of geological materials. All the RBF-ANN models can be used to predict radiation hazard indices of geological materials quite efficiently, according to the performance level attained.

Assessment of Activity Concentrations and Soil-to-Plant Transfer Factors of Natural Radioactivity in Rice Plant Components grown in Kano State, Nigeria

Transfer Factor (TF) depicts the percentage or fraction of natural radioactivity in the soil that is absorbed by different parts of a plant which are eventually transferred, directly or indirectly, to man during ingestion. Activity concentrations of primordial radionuclides were determined in farm soil and rice plant components (root, stem, leaf and seed) in six Local Government Areas (Bagwai, Bunkure, Dambatta, Garko, Kura and Wudil) renowned for production of rice in Kano State, Nigeria, using gamma-ray spectrometry method with sodium iodide scintillation detector. The mean activity concentrations of 40K, 238U and 232Th were: 509.51, 27.75, and 12.26 Bq.kg-1 correspondently in soil; 227.40, 14.24, and 5.19 Bq.kg-1 correspondingly in seed; 935.53, 32.73, and 7.29 Bq.kg-1 accordingly in leaf; 803.65, 16.72, and 6.76 Bq.kg-1 respectively in stem; and, 408.91, 30.03, and 10.31 Bq.kg-1 correspondingly in root. The mean concentrations of 40K reported in soil were greater than the world average of 400 Bq.kg-1, while those of 238U and 232Th were less than the world mean values of 35 Bq.kg-1 and 30 Bq.kg-1 respectively. The estimated mean of TFs of 40K, 238U and 232Th were: 0.52, 0.61, and 0.43 respectively in the seed; 1.95, 1.45, and 0.69 respectively in leaf; 1.72, 0.75, and 0.64 correspondingly in the stem; and, 0.85, 1.27, and 0.76 accordingly in the root. Except for a few plant samples where BDL were recorded for 238U and 232Th, all values of TFs were greater than the recommended values of 4.9 x 10-3 and 2.1 x10-4 given for 238U and 232Th...

Assessment of radioactivity level and associated radiological hazard in fertilizer from Dhaka.

Miners, factory workers, traders, end-users, and foodstuff consumers all run the risk of encountering health hazards derived from the presence of elevated levels of radiation in fertilizers, as these groups often come into direct or indirect contact with fertilizers as well as raw materials throughout various linked processes such as mineral extractions, fertilizer production, agricultural practices. A total of 30 samples of various kinds of fertilizer produced in different factories in Dhaka megacity were analyzed to quantify the concentrations of primordial radionuclides using HPGe detector. Among the analyzed samples, average (range) concentration of 40K was found to be 9920 ± 1091 (8700 ± 957-11,500 ± 1265), 9100 ± 1001 (8600 ± 946-9600 ± 1056), 2565 ± 282 (2540 ± 279-2590 ± 285), and 3560 ± 392 (2620 ± 288-4500 ± 495) Bq/kg in the samples of Muriate of Potash Fertilizer, Sulphate of Potash Fertilizer, Humic Acid Fertilizer, and NPKS Fertilizer, respectively. Elevated concentration of 226Ra was found in Triple Super Phosphate Fertilizer with a mean (range) of 335 ± 37 (290 ± 32-380 ± 42) Bq/kg. The higher activity of 40K can be linked to the greater levels of elemental potassium in phosphate fertilizer. Elevated concentrations of radionuclides may also result from variations in chemical processes as well as the local geology of the mining areas where the raw materials were extracted for fertilizer production. Numerous fertilizer brands surpass prescribed limits for various hazardous parameters, presenting significant health risks to factory workers, farmers, and consumers of agricultural products. This study provides baseline information on the radioactivity of fertilizers, which could be used to develop mitigation methods, establish national fertilizer usage limits, justify regulatory frameworks, and raise public awareness of fertilizer overuse. The findings of the study could potentially help to explore the impact of fertilizer on the food chain.

Assessment of gamma absorbed doses and radiological risk indexes from soil radioactivity around the phosphate area in south Tunisia.

Human beings are constantly exposed to the radiations coming from the environment. This work assesses the radiological hazards of natural radioactivity in soil samples taken at four locations around the phosphate area in south Tunisia. Concentrations of primordial radionuclides were measured by gamma spectrometer using an HPGe detector. The overall mean values of 40K, 226Ra and 232Th concentrations were 264, 27 and 13Bqkg-1, respectively. From the radioactivity measurements, radiation hazard indices specified by the United Nation Scientific Committee on the Effect of Atomic Radiation such as radium equivalent activity (Raeq), absorbed dose rates ($ {\dot{\text D}} $) and annual effective dose (AED) to the population for outdoor environment were determined. The mean values for the abovementioned parameters were 64Bqkg-1, 33 nGy h-1 and 40μSv y-1, respectively.

Environmental radioactivity, radiological hazards, and trace elements assessment of nearshore sediment in the Bay of Bengal

The current study focuses on the environmental radioactivity and multi-risk assessment of nearshore sediment as a source of marine pollution along the Bay of Bengal. The study examines the distribution of primordial radionuclide concentrations using a thallium-activated sodium iodide (NaI(Tl)) detector-based gamma-ray spectrometer and Potentially Toxic Elements (PTE) through atomic adsorption analysis. The data also were used to characterize ecological threats, radiological risks, and the geospatial distribution of toxic compounds in nearshore sediment as a proxy for marine pollution. The active concentration of primordial radionuclides such as uranium-238 (238U), thorium-232 (232Th), and potassium-40 (40K) was found in the range from ≤ 3 to 68 (11.4), ≤ 9.5 to 142.7 (41.2), and 85.2 to 603.4 (362) Bq/kg, and the results show that the average radioactive concentration of the average radionuclides was less than suggested by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) ranges. Potentially toxic elements iron (Fe), chromium (Cr), nickel (Ni), lead (Pb), and zinc (Zn) were higher in deeper water depths. The current study reveals that mud distribution primarily controls such elements. A decreasing order has been seen as follows by the ecological risk index of individual elements: copper (Cu) > lead (Pb) > nickel (Ni) > chromium (Cr) > zinc (Zn). The significant Pb, Cu, and Zn concentrations indicated high pollution at most stations, possibly resulting from regional and terrestrial sources such as industrial activity, urban drainage, manufacturing, and farming. The migration of contaminated soil from the industrial and transportation sectors may be the source of the increased levels of hazardous elements and naturally occurring radionuclides in the sediment transported into the coastal ecosystems of Bay of Bengal.

Monitoring of outdoor natural gamma absorbed dose rate in air in Hyderabad, Telangana, India.

The Indian Environmental Radiation Monitoring Network continuously monitors the outdoor natural gamma absorbed dose rate in air at different locations throughout India by employing Geiger-Mueller (GM) detector-based field-installed environmental radiation monitors (ERMs). Hyderabad, Telangana, India is known to have high natural background radiation levels due to the presence of high concentrations of primordial radionuclides in its granitic rocks. There are a total of 59 ERMs installed at various locations across Hyderabad. Long-term monitoring data of these locations are presented in this paper. The mean values of outdoor natural gamma absorbed dose rate in air at the monitoring locations were found to vary in the range of 104-258 nGy.h-1 with a mean of 193±40 nGy.h-1. The mean annual effective dose due to outdoor natural gamma radiation was estimated to be 0.24±0.05mSv.y-1. Analysis of the long-term seasonal variation of outdoor natural gamma absorbed dose rate in air showed that the same was lowest during monsoons.

Evaluation of radiological risk associated with local building materials commonly used in Northwestern Nigeria

In this study, potential radiological risk due to the activity concentrations of primordial radionuclides (226Ra, 232Th, and 40K) in commonly used local building materials (sand, clay, kaolin and gypsum) in Northwestern Nigeria were assessed using NaI (Tl) detector. The measured activity concentrations ranged from 47 to 63 Bq kg−1 for 226Ra, 24–32 Bq kg−1 for 232Th, and 219–257 Bq kg−1 for 40K respectively. The mean values of 232Th, and 40K for all samples were below the respective world averages of 45 and 420 Bq kg−1 with that of 226Ra for all the samples higher than the world average value of 32 Bq kg−1. The potential radiological risks were assessed by determining radium equivalent activity (Raeq), internal and external hazard indices (Hin and Hex), absorbed gamma dose rates (DR), internal annual effective dose rates (IAED), and annual gonadal dose equivalent (AGDE) and activity utilization index (AUI). The assessed parameters were found to range between 104 and 125 Bq kg−1, 0.99 to 1.15, 0.28 to 0.34, 48 to 58 nGyh−1, 0.76 to 0.86 mSvy−1, and 0.78 to 0.96 respectively. The Raeq and DR for all the analyzed samples were found to be within International recommended limits of 370 Bq kg−1 and 59 nGy h−1 as recommended by UNSCEAR.

Estimating geothermal and background radiation hotspots from primordial radionuclide concentrations in geology of South Africa

Naturally occurring radionuclides are the main generator of geothermal energy in the Earth's crust and mantle. The generated energy is consequently directly proportional to the concentrations of the three main naturally occurring radionuclides (uranium, thorium and potassium), which are primordial in origin. Concentrations of these naturally occurring radionuclides were extracted for all the different geological rock units in South Africa. The radionuclide concentrations were then mapped and integrated by using QGIS. The results were used to estimate and map the geothermal energy production rates for the rock units. The radionuclide concentrations in the rock units were also used to identify regions with high radiation background. These radiation hotspots were plotted and investigated. The estimated geothermal energy and background radiation hotspots were compared to measurements and projections of other studies and good corelations were found.

Geochemometrics of primordial radionuclides and their potential radiological risk in coastal sediments of Southeast Coast of India

In recent years, the contamination of the earth's materials with radioactive elements as naturally occurring radioactive material has been a source of concern. This study is aimed at the environmental radioactivity of beach sediments and the gamma dose levels along the south-eastern coastal region of the Indian subcontinent, from the Palar River mouth (Kadalur Kuppam) to the Pulicat Lake or Pazhaverkadu coast. Furthermore, to analyze the gamma dosage level, as well as the spatial variation of the activity concentrations of 238U, 232Th, and 4 K, as well as the acid-leachable trace elements Ni, Pb, Mn, Zn, Cu, Co, Fe, and Cr in coastal sediments. In addition, radiological risk and hazard indices are assessed in the study domain. The MiniTRACE CSDF survey meter was used to determine the ambient gamma dose level and the activity concentration of primordial radionuclides (238U, 232Th, and 4 K) was quantified using gamma-ray spectroscopy with a NaI (Tl) detector, as well as trace elements studied in atomic absorption spectroscopy. The primordial radionuclides activity concentration (238U, 232Th, and 4 K) in collected coastal sediments of the proposed region were found in the range of ≤3–1953, ≤3–1180, and 41–753 Bq/kg, respectively. The annual effective dose rate was found in the order of 4 K > 232Th > 238U. Based on the geochemometric approach, the data collected for various radiological parameters were combined with radiological risk indices, and trace element concentrations were compared on a regional and global scale. The current study could provide a new research pathway in the areas of coastal monitoring, environmental health, and radiation safety measures.

Assessment of Radioactivity in Textile Sludge Incorporated Bricks

Textile sludge generated from the textile industry is potentially reused in manufacturing bricks. Radiological hazard to the environment while using any kind of new material in the construction industry needs to be predicted to ensure its safety for domestic use. This paper reports the effect of radiation from textile sludge-incorporated bricks. Primordial radionuclides such as Uranium- 238 (238U), Thorium- 232 (232Th), and Potassium- 40 (40K)., are present in raw materials used in the manufacturing of various building materials. In the present investigation, textile sludge-incorporated bricks were studied. It was observed that the content of 238U was less than 20.6 Bq/kg (Becquerel per kg), 232Th was less than 38.3 Bq/kg, and 40K less than 168 Bq/kg compared to the permissible limit of 32 Bq/kg, 45 Bq/kg and 420 Bq/kg respectively, as prescribed by UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation). The activity concentration of primordial radionuclides ranged between 48 Ba/kg to 88 Ba/kg, which was also well below the permissible limit of 370 Bq/kg. Parameters like internal and external hazards index, radium equivalent activity (Raeq), annual effective dose rates, and absorbed dose rates were investigated. The results of all these parameters obtained for sludge-incorporated bricks were found to be less than unity, the permissible limit declared by the UNSCEAR. The study concludes that the sludgeincorporated bricks do not pose any radiation hazard and are suitable for use as construction material.

Assessment of Background Radiation in Ojota Chemical Market, Lagos, Nigeria

The monitoring of radiation levels in human-inhabited environments is imperative to avoid public exposure. The activity concentration of primordial radionuclides at Ojota Chemical Market was measured to determine the in situ activity of 238U, 232Th, and 40K in ambient air using an RS-125 Super SPEC gamma spectrometry with global positioning system. The measured absorbed dose rates ranged from 28.35 to 106.55 nGy/h, giving an average value of 70.46 nGy/h. The estimated absorbed dose rate spanned from 22.25 to 101.03 nGy/h with a mean value of 65.50 nGy/h. The average concentrations of 40K, 238U, and 232Th were 458.55, 30.26, and 54.77 Bq/kg respectively. The outdoor and indoor absorbed doses averaged 80.39 and 132.55 µSv/y, respectively, and the mean value of excess lifetime cancer risk was 0.26 × 10−6 µSv/y. The external and internal hazard index averaged 0.39 and 0.47, respectively, and the mean annual gonadal dose equivalent was 465.14 µSv/y. The radium equivalent dose averaged 143.45 Bq/kg while the gamma representative index averaged 1.05. The absorbed dose rate, mean concentration of 40K and 232Th, the average values of excess lifetime cancer risk, the annual gonadal dose equivalent, and the gamma representative index were above the permissible limit as set by the radiation regulatory agencies. The study concluded that the human activities in Ojota Chemical Market might have increased the radiation burden of the community.

Primordial radionuclides in the dust samples from the educational institutions of central Bangladesh: radiological risk assessment

For the first time, this study presents the radio-activity concentrations of primordial radionuclides in a suite of classroom-dusts collected from 23 schools in central part of Bangladesh. Bulk elemental compositions from instrumental neutron activation analysis (INAA) were transformed into accompanied radio-activity contents (Bq.kg−1). Mean activity contents of 226Ra, 232Th, &40K in dust samples were 86.0, 43.4, and 448 Bq.kg−1, respectively, which were comparatively elevated relative to the relevant world average value. Higher NORMs abundances were due to the surface soil weathering and aerodynamic fractionations. Estimation of typical radiological-risk indices demonstrates human health risks. Bearing in mind that the greater susceptibility of school-going juveniles & children to the ionizing-radiations & the entering of NORMs-comprising dust-particle into human lungs, calculated radiological indices merely represent the least potential risk. However, in actual cases, α-particles from the 238U and 232Th-decay series can create significant radiation-damage to the respiratory-system.

The presence of primordial radionuclides in powdered milk and estimation of the concomitant ingestion dose

Milk and milk-based foodstuffs are considered as a primary source of nutrition to human health. Therefore, monitoring of hazardous material in powdered milk is important for the safety of public health. This study determines the concentrations of primordial radionuclides in powdered milk samples collected from the local markets of Dhaka city in Bangladesh using HPGe γ-ray spectrometry. The mean activity concentrations of 226Ra, 232Th and 40K for infant (9.6 ± 2.10, 9.0 ± 1.5 and 164.5 ± 3.7 Bq kg−1, respectively) were found comparable to the people of all other ages (7.2 ± 3.7, 7.4 ± 1.5 and 143.2 ± 3.9 Bq kg-1, respectively). Based on the typical consumption characteristics of powdered milk, the mean annual effective doses were found below the FAO/WHO (1995) and ICRP (2007) recommended limit of 1 mSv y-1 for public exposure, in all investigated age groups (<2 y - >17 y). On the other hand, the doses for infant show close to the UNSCEAR (2000) reference ingestion dose constraints of 290 μSv y−1, which may indicate a non-negligible concern for the infants’ health. The carcinogenic risks due to the ingestion of radionuclide show to be 6.4 × 10−4 (0–72 years) and 5.4 × 10−4 (>2 years) are significantly less than the ICRP (2006) suggested cancer risk factor of 2.5 × 10−3 based on the annual dose limit of 1 mSv for general public, thus discarded the radiation hazards via the consumption of local or imported powdered milk in Bangladesh. Overall, the measured data may help to establish national rules and regulations on powdered milk relating to radiological protection for the general people of Bangladesh.

The presence of terrestrial radionuclides in the Karnaphuli and Halda river sediments and concomitant hazards to the dwellers

ABSTRACT The Karnaphuli and Halda rivers play a significant role in the ecological and commercial arena of Bangladesh, but no detailed study on radioactivity in these two rivers sediments is reported elsewhere. The present study measures the concentrations of terrestrial radionuclides in the sediment samples collected from these two rivers by using high-purity germanium (HPGe) γ-ray spectrometry. The concentrations (Bqkg−1) of 226Ra, 232Th and 40K show in the range of 17.63 ± 1.47–38.90 ± 2.50, 27.86 ± 1.76–48.80 ± 2.70 and 324.28 ± 26.83–640.70 ± 42.70, respectively, which is similar to the literature data and world mean value except for four sampling locations (Kalamiabazar, Natun bridge, Rajakhali and Chaktai khal) that shows higher concentrations of primordial radionuclides. These four sampling points are located adjacent to the industrial wastes discharge channels into the Karnaphuli river. In fact, among the thousands of industries located on the bank of the Karnaphuli river, about 200 units were identified as the sources of environmental pollution. To assess human health hazards due to natural radiation, several indicators such as radium equivalent activity (Raeq ), external hazard index (Hex ) and outdoor annual effective dose equivalent were calculated and compared with the recommended limits. The present results serve as an input to prepare the baseline radioactivity in commercially important river sediments prior to the operation of the first nuclear power plant in the country.

Updating of baseline radionuclides concentration in Jakarta Bay

Jakarta Bay receives a variety of pollutants including radioactive substances originating from industry and operating the Serpong nuclear area in South Tangerang. Radionuclide types that have the potential to enter Jakarta Bay are anthropogenic or primordial radionuclides originating from the Serpong nuclear area and factory. Whereas the input of natural radionuclides originating from the use of industrial raw materials and terrestrial run-off. Monitoring is carried out twice a year on the coast of the bay of Jakarta. Monitoring results showed primordial radionuclide concentrations were in normal condition and originated from global fallout. This is shown from the ratio of 226Ra concentration which is the character of the Pacific Ocean before the nuclear accident at Fukushima. On the other hand, artificial radionuclides are in normal conditions and do not exceed the threshold.

Radionuclide concentrations in medicinal florae and committed effective dose through Ayurvedic medicines

Purpose: Ayurveda is one of the oldest systems of medicines in the world being practiced widely in the Indian subcontinent for more than 3000 years, and still remains as one of the important traditional health care systems. The Ayurvedic drugs are derived primarily from various parts of the plants, like root, leaf, flower, fruit or plant as a whole. Plants uptake minerals and other nutrients from the soil through their root system. Along with other minerals radionuclides present in the growing media also reach to the plant parts following the same pathway. Realizing the probable health hazards via the intake of Ayurvedic drugs, it is important to assess the concentration of natural radionuclides in commonly used medicinal plants.Materials and methods: NaI(Tl) scintillator-based gamma-ray spectrometry has been used to determine the activity concentrations of primordial radionuclides (226Ra, 232Th and 40K) in the most commonly used medicinal plant parts as ingredients of Ayurvedic medicines in India.Results and discussion: The average specific activity (Bqkg−1) of 226Ra, 232Th and 40K was found to be 43 ± 18, 36 ± 15 and 230 ± 46, respectively. The estimated annual committed effective doses due to the intake of common Ayurvedic medicines at prescribed dosage was found to be 39 ± 16 µSv y−1, which is quite low as compared with the radiation dose limit of 1 mSvy−1 from all natural sources, reported by the International Commission on Radiological Protection (ICRP-60).Conclusions: It is found categorically that intake of Ayurvedic medicines at normal dosage poses no radiological hazard to the individual. Present results are significant in the wake of myths that many hazardous materials including radioisotopes are present at higher levels. Obtained results also serve as a reference information for the distribution of radionuclides in medicinal plant species.

Radiological impact assessment of soil and groundwater of Himalayan regions in Uttarakhand, India

In this study, we present the results of measurements and radiological impact of natural radioactivity in soil and groundwater of the Himalayan region in the Uttarakhand State of India. The concentrations of primordial radionuclides (226Ra, 232Th and 40K) in soil samples of the study area were determined using gamma-ray spectrometry by employing the NaI(Tl) detector. The concentrations of radon and uranium were also measured in potable groundwater samples using RAD7 and Inductively Coupled Plasma Mass Spectrometry (ICPMS) techniques, respectively. The average specific activities of 226Ra (116 Bq kg−1), 232Th (137 Bq kg−1) and 40K (735 Bq kg−1) in soil were found considerably higher than the corresponding global average values. The average concentrations of radon (35 Bq l−1) and uranium (1.3 µg l−1) in potable groundwater were found well within the safe limits recommended by the World Health Organization. The effects of natural radioactivity in soil and groundwater are discussed in terms of different risk assessment parameters and dose quantities.

Lithological mapping of Ogun State, Southwestern Nigeria, using aeroradiospectrometry

Airborne gamma-ray spectrometric has gained more recognition over decades, since it serves majorly as a geological mapping tool in most areas. This method utilizes the variation in the three primordial radionuclide concentrations, U, K and Th, to study the lithology of different bedrocks. It measures the earth surface natural radionuclides, which enhances the distribution of soil- and rock-type formations. Ogun State, the study area, is bounded by geographical coordinates of easting 3.0°–5.0° and northing 6.2°–7.8° of tropical rainforest region, Southwestern Nigeria. The present study aims at mapping the distribution of radioelements and delineates the anomalies associated with various interpreted radiometric lithological (IRL) units using the three radioelements U (ppm), Th (ppm), K (%) and the total count (TC) in Ur and their ratios, U/K, U/Th and Th/K. The dose rates were also considered in the study. The lithology was described in terms of three formations; basement, basement–sediment and sediment. With the aid of Geosoft software (Oasis montaj) and Golden Surfer 10 software, the contour map was obtained which showed the trend of distribution of radioelements alongside their ratios. The uranium migration index was also carried out to check the regions associated with uranium leaching. The result revealed that uranium is more concentrated in NW and partly NE directions of the study area. This may be due to the presence of shale and possibly phosphate-bearing rock and metamorphozised granitic rocks while thorium has the largest deposit due to quarry activity which is associated with blasting of rocks and deposition from dumpsites. The study also revealed that only 2 out of all the 47 IRL units, A1 and C4, which belong to basement and basement–sediment formations have their mean dose value to be 1.51 mSv/yr and 1.43 mSv/yr which are above the 1 mS/yr recommended limit.

TERRESTRIAL RADIONUCLIDES IN SURFACE (DAM) WATER AND CONCOMITANT DOSE IN METROPOLITAN KUALA LUMPUR.

Batu Dam is of considerable importance to the metropolis of Kuala Lumpur, its existence and the quality assessment of its waters being essential in helping to maintain the lives of a large sector of the Malaysian population. Concerning the level of naturally occurring radioactivity contained within its waters, a well characterised HPGe γ-ray technique has been used in making measurements of the concentrations of primordial radionuclides in samples of surface water from the Dam. Based on the mean individual daily consumption of dam water, estimation has been made of the concomitant radiation dose. Activity concentrations, in units of Bq l-1, have been found to be in the range 2.4-3.2 for 226Ra, 1.1-1.3 for 232Th and 22.7-40.7 for 40K, in line with literature data for surface waters. The total annual ingestion dose for infants (<1 y) and adolescents (12-17 y) are found to be significant and greater than the World Health Organization recommended maximum dose of 0.1 mSv y-1 from the imbibing of drinking water. However, the Dam water does not pose a threat to public health, the Dam water not being used as the sole source of drinking water. Noting that this is the only known study of water from Batu Dam, the reported levels allow for evaluation of future changes in the natural radioactivity profile.