Natural Radioactivity Levels Research Articles

Activity concentrations and dose assessment of 226Ra, 228Ra, 232Th, 40K , 222Rn and 220Rn in soil samples from Newmont-Akyem gold mine using gamma-ray spectrometry

In this study 14 soil samples were measured for natural radioactivity levels including radon-222 (222Rn) and radon-220 (220Rn) concentration at Akyem-Gold Mine premises, surrounding communities in Ghana. Both radon and radioactivity concentrations of radium-226 (226Ra), thorium-232 (232Th) and potassium-40 (40K) were determined by means of gamma spectrometry system equipped with high purity germanium detector. The studied samples gave natural radioactivity levels of 28, 12 and 11 Bq/kg, respectively compared to global 226Ra, 232Th, and 40K concentrations of 37, 33 and 400 Bq/kg, respectively, according to UNSCEAR (2000) report. The annual effective dose rate (AED) due to external and internal gamma exposure ranged from 0.060 to 0.18 mSvy-1 with a mean value of 0.11 ± 0.03 mSvy-1 compared to the recommended value of 1 mSvy-1. There is a correlation between 226Ra and 222Rn in soil gas with a good linear coefficient of (R2 =1). The availability of 226Ra and 222Rn shows that there is a source of uranium-238 (238U) and thorium-232 (232Th) bearing minerals within the adjacent geologic units of Akyem. This implies that most of the radon in the soil gas comes from 226Ra. The assessment of radium equivalent activity varied from 19.71 to 69.88 Bq/kg with mean value of 37.53 ± 15.51 Bq/kg lower than the global limit of 370 Bq/kg. The internal hazard index ranged from 0.07 to 0.25 Bq/Kg with a mean value of 0.13 ± 0.05 Bq/Kg, also lower than the accepted value of unity, while external hazard index ranged from 0.05 to 0.19 Bq/Kg with a mean value of 0.10 ± 0.04 Bq/Kg. Key words: Radon, thoron, natural radioactivity, annual effective dose, radium equivalent index, external and internal hazard index.

Natural radioactivity levels and related risk assessment in soil samples from Sakarya, Turkey

An evaluation of the environmental radioactivity levels in soil samples from Sakarya province (Turkey) was undertaken in order to create a comprehensive radiological map of Sakarya. A total of 85 soil samples collected from different parts of the city were analysed using NaI(Tl) γ-ray spectrometry. It was found that the mean activity concentrations of natural radionuclides 226Ra, 232Th and 40K were 23.2 ± 2.5, 21.0 ± 3.4 and 371 ± 25.9 Bqkg−1, respectively, all falling below the worldwide mean values. Accordingly, in order to assess the radiological risk, radium equivalent activity (Ra eq), absorbed gamma dose rate (D), annual effective dose equivalent (AED), and external hazard index (H ex) were estimated and found to have mean values of 30.93 nGyh−1, 37.93 μSvy−1, 64.14 Bqkg−1 and 0.18 Bqkg−1, respectively. Also, the results were statistically analysed to make recommendations for further regulation.

Quantitative elemental analysis and natural radioactivity levels of mud and salt collected from the Dead Sea, Jordan

Mud and salt samples from six different locations have been collected from the eastern shore of the Dead Sea, Jordan. Wavelength dispersive X-ray fluorescence (WDXRF) showed twenty-five elements in the mud and salt samples. Shape and grain size of the studied samples were characterized by Scanning Electron microscopy (SEM). Quantitative phase analysis (QPA) based on X-ray diffraction (XRD) of mud samples revealed that five minerals are dominant namely Quartz, Kaolinite, Calcite, Topaz and Dolomite while the salt samples are mainly composed of Halite. The radiation hazard parameters and the activity concentrations of 226Ra, 232Th, 228Ra, 40K and 137Cs have been quantified by γ-ray spectrometry. Noticeable differences were recognized from location to another but all of the obtained values were within the world activity concentration range.

Potential effect of natural radionuclides in riverbed sediments: a statistical approach based on granulometric and magnetic mineral differences

South India is one of the regions in the world that has the highest background radiation levels. In this region, river sediments are used in large quantities as building material. Therefore, the knowledge of the radionuclides distribution in such sediments is important for assessing their potential adverse effects on humans residing in buildings made of sediment material. For this goal, we focus on the determination of the natural radioactivity levels and magnetic properties in sediment samples collected from 33 locations along the southwestern Bharathapuzha river originating from the Anamalai hills. The sediment samples were subdivided into two categories according to particle size. It is observed that the average activity concentrations of 226Ra, 232Th, and 40K in sediment samples varied greatly with granulometric and geological differences. The average values of 226Ra, 232Th, and 40K and its associated radiological hazard parameters for category II samples (particle size between 149 μm and 2 mm) were lower than category I sediment samples (bulk samples). Moreover, the average radionuclide activity concentrations (except for 40K) and the calculated radiation hazard parameters are higher in the lowland region compared to the highland and the midland regions. The mass-specific magnetic susceptibility values ranged widely along the river, as well as between physiographic regions, e.g., average values for category I sediment samples were 950.2 × 10−8, 351.1 × 10−8 and 131.8 × 10−8 m3 kg−1 (for high-, mid- and lowland regions, respectively). Differences between physiographic regions and sediment fractions from both radioactivity determinations and magnetic parameters were analyzed with statistical tests and multivariate analysis, which showed the advantages of using both independent techniques.

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.

Natural radioactivity levels and associated health hazards from the terrestrial ecosystem in Rosetta branch of the River Nile, Egypt

ABSTRACTTwenty soil and 25 sediment samples were collected from the banks and bottom of the River Nile in the surroundings of biggest cities located close to it. Natural radioactivity concentrations of 226Ra, 232Th and 40K have been evaluated for all samples by means of γ spectrometric analysis. The radioactivity levels of soil and sediment samples fall within the internationally recommended values. Nevertheless, high natural background radiation zones are detected in the Kafr El-Zayat region due to the presence of a fertilizer factory, and in the Rosetta region due to the presence of black sand deposits. The absorbed dose rate, the γ index and excess life time cancer risk are calculated. High values for some of the radiation health parameters are detected in the Kafr El-Zayat and Rosetta regions representing a serious problem to public health because the soil and sediment are used as constructing material for buildings. Furthermore, the isotope analysis of uranium for representative collected sediment samples via α spectrometry showed average specific activities of 18.7 ± 3.6, 0.087 ± 0.0038 and 18.6 ± 3.8 Bq kg–1 for 234U, 235U and 238U, respectively. In general, these values confirm the balance in the isotopic abundance of U isotopes.

Geochemistry of uranium and thorium and natural radioactivity levels of the western Anatolian plutons, Turkey

Seventy samples from major plutons (mainly granitic) of Western Anatolia (Turkey) have been analyzed by γ-ray spectrometry to determine the specific activities of 238U, 226Ra, 232Th and 40K (Bq/kg). Τhe natural radioactivity ranged up to 264 Bq/kg for 238U, 229.62 Bq/kg for 226Ra, up to 207.32 Bq/kg for 232Th and up to 2541.95 Bq/kg for 40K. Any possible relationship between the specific activities of 226Ra, 238U, 232Th and 40K and some characteristics of the studied samples (age, rock-type, colour, grain size, occurrence, chemical and mineralogical composition) was investigated. Age, major and trace element geochemistry, color, pluton location and mineralogical composition are likely to affect the concentrations of the measured radionuclides. The range of the Th/U ratio was large (0.003–11.374). The latter, along with 226Ra/238U radioactive secular disequilibrium, is also discussed and explained by magmatic processes during differentiation.

Assessment of radiological parameters of soil in Kogi State, Nigeria

ABSTRACTThe natural radioactivity levels of soil samples collected from four local government areas in Kogi State, Nigeria were measured using a hyper-pure germanium detector, and the radiological hazard parameters associated with them were estimated. The measured concentration ranged from 7.82 ± 0.63 to 82.22 ± 1.99 Bq kg−1 for 238U, 11.05 ± 1.10 to 114.86 ± 4.72 Bq kg−1 for 232Th, and 3.38 ± 0.50 to 1272.20 ± 23.36 Bq kg−1 for 40K. Omala local government was found to have the highest concentrations of 238U (44.31 Bq kg−1) and 232Th (52.13 Bq kg−1), while Ajaokuta has the highest concentration of 40K (711.72 Bq kg−1). The lowest activity concentrations of 238U and 232Th were measured from soil samples collected from Ankpa local government area and 40K from Dekina local government area. It was noted that the activity concentrations of 40K were generally low for all the areas investigated except for Ajaokuta areas. The radium equivalents calculated for all the locations were observed to be lower than the radiation protection regulatory body reference value of 370 Bq kg−1. The radiological parameters estimated for most of the locations compared well with world average values, except for Odogba-okaba, Salem University, Forest, Nepa, Gerugu, Niger Bridge, Igaliwu, Ijeke-ogane, Bagana, and Abegikolo villages, whose values exceeded the recommended limit. This may suggest that those living or working in these areas may be exposed to higher radiation burden from the natural radionuclides.

Natural radioactivity investigation in Dam sediments of northeast Algeria using gamma spectroscopy

Current research paper intends to estimate the natural radioactivity levels in sediments samples collected from Beni Haroun Dam in the northeast Algeria, using high resolution HPGe detector. The mean activity concentrations values measured for the radionuclides 232Th, 226Ra and 40K are 18.9 ± 1.9, 37.3 ± 2.7 and 149.9 ± 5.5 Bq/kg, respectively. The 137Cs anthropogenic radionuclide has been observed with maximum activity concentration value of 0.8 ± 0.4 Bq/kg, which is considered an insignificant amount. In order to assess the radiological threat of gamma radiations emitted by these radionuclides on the health of the population, absorbed dose rate, annual effective dose equivalent and radiation hazard indices were had been calculated. The obtained values are compared with the world wide average ones.

The Experimental Gamma Radiation Dose Rate for Radiation Hazard into Adhesive Building Materials in Saudi Arabia

The primary aim of this work was clearly to apply the norms of radiation protection to building residents against natural radioactivity. This was done through measurement of natural radioactivity in adhesive building materials using HPGe gamma ray spectrometer. The radium equivalent activity (Raeq), indoor gamma absorbed dose rate (DR), and annual effective dose (HR) associated with natural radioactivity were computed to assess the radiation hazards in adhesive building materials. The obtained specific activities of these natural radionuclides and the calculated radiation hazard indexes were compared with the international recommended values. The findings in this work of natural radioactivity levels were below the acceptable limits. Therefore, it was found the adhesive building materials were safe to be used as construction materials. Also, as a minor work, previous unpublished data of heavy metals in the same study adhesive materials were investigated by ICP-MS to figure out the correlation between heavy metal presence and natural radioactivity. The findings showed insignificant correlations between heavy metals and radioactivity.

The hydrocarbon source rocks of the Pliensbachian (Early Jurassic) in the Asturian Basin (Northern Spain): Their relationship with the palaeoclimatic oscillations and gamma-ray response.

Deposition of black shale facies, one of the main contributors for hydrocarbon production, is commonly assumed to be linked to Oceanic Anoxic Events (OAEs), which are supposed to be generated during warm palaeoclimats. This assumption could bias the exploration for hydrocarbon source rocks preferentially towards sediments deposited under warm palaoenvironments, as a preferential guide for hydrocarbon exploration. As a consequence, the establishment of the links between palaeotemperature and the formation of organic-rich deposits is of primary importance to find arguments on this subject. For this purpose, the Upper Sinemurian, Pliensbachian and Lower Toarcian (Lower Jurassic) deposits of the Asturian Basin in Northern Spain, including more than 100 m thick succession containing organic-rich and black shale deposits, has been studied. Correlation between palaeoclimatic data, previously obtained from oxygen isotopes, and the TOC content reveals that black shales and organic-rich sediments were deposited not only during warming intervals but also during a prominent cooling event that occurred at the Late Pliensbachian. This cooling interval has been pointed out as one of the main candidates to have developed ice caps in the poles during the Jurassic. On the contrary, no black shales were generated during the postulated Early Toarcian OAE, which coincides with a superwarming interval. Additionally, the study of the facies cycles and the measurement of gamma-ray in outcrops and its correlation with TOC content provides data on the use of natural radioactivity and sea level changes as a proxy for preliminary organic matter richness evaluation.

The Investigation of Terrestrial Radioactivity in Soil Samples around Pshdar Region in Iraqi-Kurdistan

Measurements of the natural radioactivity levels in soil samples from the Pshdar area in Iraq have been carried out. This survey is considered the first scientific assessment of the radioactivity level in the studied area so far. Soil samples were collected in 22 regions across the landscape over an area of 1,339.13 km2. Gamma ray spectroscopy analysis was carried out using the high purity germanium (HPGe) detector in a low background configuration to detect radioisotopes of natural decay chains (226Ra, 232Th), the long-lived radionuclide 40K in the environment. It was found that the activity concentrations of 226Ra, 232Th and 40K ranged from 7.6±1.0 Bq kg-1 to 23.5±1.7 Bq kg-1, 2.50 Bqkg-1 to 31.8±2.2 Bqkg-1 and 77.6±7.8 Bq kg-1 to 554.5±42.7 Bq kg-1 respectively. The results have been compared with other radioactivity measurements in different countries’ soils. The absorbed dose rate (D), the annual effective dose equivalent (AEDE), the radium equivalent activity (Raeq), the external hazard index (Hex) and the internal hazard index (Hin) in the soil samples were also determined. They were found to have ranges of 7.34 ± 0.78 to 45.01 ± 2.37 nGy h-1 with an average value of 33.26 ± 0.39 nGy h-1, 9.01 ± 0.96 µSvy-1 to 55.20 ± 2.91 µSvy-1 with an average of 40.79 ± 0.48 µSvy-1, 15.72 ± 1.6 to 96.12 ± 4.17 Bq kg-1 with an average of 69.83 ± 0.82 Bq kg-1, 0.06±0.003 to 0.27 ± 0.01 with an average of 0.20 ±0.002, and 0.07 ± 0.002 to 0.31 ± 0.01 with an average of 0.22 ± 0.002 respectively. The results indicate that the radiation hazard from primordial radionuclides in all soil samples from the studied area in the current work is not significant, and the natural background radiation of the area is at normal levels.

Modelling seasonal variations of natural radioactivity in soils: A case study in southern Italy

The activity of natural radionuclides in soil has become an environmental concern for local public and national authorities because of the harmful effects of radiation exposure on human health. In this context, modelling and mapping the activity of natural radionuclides in soil is an important research topic. The study was aimed to model, in a spatial sense, the soil radioactivity in an urban and peri-urban soils area in southern Italy to analyse the seasonal influence on soil radioactivity. Measures of gamma radiation naturally emitted through the decay of radioactive isotopes (potassium, uranium and thorium) were analysed using a geostatistical approach to map the spatial distribution of soil radioactivity. The activity of three radionuclides was measured at 181 locations using a high-resolution ?-ray spectrometry. To take into account the influence of season, the measurements were carried out in summer and in winter. Activity data were analysed by using a geostatistical approach and zones of relatively high or low radioactivity were delineated. Among the main processes which influence natural radioactivity such as geology, geochemical, pedological, and ecological processes, results of this study showed a prominent control of radio-emission measurements by seasonal changes. Low natural radioactivity levels were measured in December associated with winter weather and moist soil conditions (due to high rainfall and low temperature), and higher activity values in July, when the soil was dry and no precipitations occurred.

Transfer factors for natural radioactivity into date palm pits

Palm pits are used in various human and animal feed products. In this study, the natural radioactivity levels from soil and date palm pits of 9 samples collected from major date palm farms in three different regions (Buraidah, Al-Zulfi and Al-Majmaah) of Saudi Arabia were determined by using the high purity germanium (HPGe) gamma-ray spectrometer. The mean activity concentrations of 226Ra, 232Th, 137Cs and 40K in soil samples were 12.8 ± 2.2, 10.2 ± 2.1, 0.28 ± 0.10 and 329 ± 87 Bg kg−1, respectively. Similarly the mean activity concentrations of 226Ra, 232Th, and 40K in date palm pits were 5.6 ± 1.2, 2.8 ± 0.4 and 181 ± 17 Bq kg−1, respectively, whereas 137Cs could not be detected. The geometric mean of TF values (geometric standard deviation in parentheses) of 226Ra, 232Th, and 40K were 0.33 (2.1), 0.22 (1.8) and 0.51 (2.0), respectively.

Application of Fuzzy Decision Making with Multiple Criteria in Ranking Natural Radioactivity Levels of Beach Sediments

Objectives: Fuzzy set theory is a marvelous tool to handle uncertainty associated with vagueness, imprecision and lack of information. The objective of this paper is to solve a Multiple Criteria Decision Making problem (MCDM) in fuzzy environment using LR Fuzzy number with a numerical example. Methods/Statistical Analysis: Decision making is a process of selecting a possible course of action from all available alternatives. The scope of the problem is to rank the natural radioactivity levels of various sites of Kerala beaches from the pre-investigated radioactivity supporting parameters of the beach sites. This can be achieved by using vertex method. The parameters are categorized in to cost and benefit criteria and the basic ranking is based on the performance index which is close to 1. Findings: The data for the current study is collected from a researcher, in which the radioactivity levels are calculated using experimental studies. In this paper, just by considering radioactivity supporting parameters of the beach sites, the sites are ranked. As the samples are collected from first three feet of the sites, the data are taken as LR fuzzy numbers. Using vertex method, performance index is calculated and the sites are ranked. The sites which are mentioned as most hazardous and least hazardous in the pre- investigated study is found to take first and last few ranks in the present study. Finally, the result is analyzed for various risk attitudes and several levels of confidence. Application/Improvements: Any real life problem with multiple criteria can be modeled as fuzzy multi criteria decision making problem using any type of fuzzy number and can be solved by vertex method. The type of fuzzy number is decided depending upon the data.

Natural radioactivity levels in some vegetables and fruits commonly used in Najaf Governorate, Iraq.

Radioactivity in Food may be contaminated with radioactive materials due to the natural and a nuclear emergency. The vegetables and fruits will become radioactive by deposit of radioactive materials falling on that from the air or through rain water. The aims of the present work were to measure the specific activity and annual effective dose as a result of the intake of vegetables and fruits collected from local market in Najaf governorate. Natural radioactivity was measured in samples using gamma ray spectrometer in this study. The results show that the average specific activities in vegetables samples for 238 U, 232 Th and 40 K were 5.21, 4.76, and 186.15 Bq kg -1 , respectively, the average specific activities for 232 Th, 40 K in fruit samples were 2.53, 211.64 Bq kg -1 , while the total average annual effective dose in vegetables samples for adults, children (10 years old) and infants is estimated to be 0.117, 0.122, and 0.179 mSv, respectively, while the total average annual effective dose in fruit samples for adults, children (10 years old) and infants is estimated to be 0.141, 0.295, and 0.388 mSv, respectively. The values found for specific activity and the annual effective dose in all samples in this study were lower than worldwide median values for all groups according to UNSCEAR (2000) and ICRP (1996) respectively; therefore, these values are found to be safe.

Natural radionuclides in waste water discharged from coal-fired power plants in Serbia.

Investigation of the natural radioactivity levels in water around power plants, as well as in plants, coal, ash, slag and soil, and to assess the associated radiation hazard is becoming an emerging and interesting topic. This paper is focused on the results of the radioactivity analysis in waste water samples from five coal-fired power plants in Serbia (Nikola Tesla A, Nikola Tesla B, Kolubara, Morava and Kostolac), which were analyzed in the period 2003-2015. River water samples taken upstream and downstream from the power plants, drain water and overflow water were analyzed. In the water samples gamma spectrometry analysis was performed as well as determination of gross alpha and beta activity. Natural radionuclide 40K was detected by gamma spectrometry, while the concentrations of other radionuclides, 226Ra, 235U and 238U, usually were below the minimum detection activity (MDA). 232Th and artificial radionuclide 137Cs were not detected in these samples. Gross alpha and beta activities were determined by the α/β low level proportional counter Thermo Eberline FHT 770 T. In the analyzed samples, gross alpha activity ranged from MDA to 0.47 Bq L-1, while the gross beta activity ranged from MDA to 1.55 Bq L-1.

Assessment of Natural Radioactivity Level and Hazard Index in Cultivation Medium (Peat Moss and Perlite)

Assessment of Natural Radioactivity Level and Hazard Index in Cultivation Medium (Peat Moss and Perlite)

Naturally occurring radionuclides in particulate emission from a coal fired power plant: A potential contamination?

The use of coal as fuel in coal-fired power plant (CFPP) for electricity generation results in emission of particulate which contains trace quantities of naturally occurring radionuclides, namely Uranium-238 (238U), Thorium-232 (232Th) including their decay series and Potassium-40 (40K). These naturally occurring radionuclides may increase their natural radioactivity level in the ambient particulate matter vicinity of the plant resulting from the combustion processes. This paper presents an investigation of radioactivity level of particulate emission and maximum deposition due to natural radioactive emissions from a typical CFPP using standard Gaussian dispersion model approach. The predicted maximum ground level particulate concentration (Cmax) and downwind distance were 55μgm−3 and 1600m away from the source, respectively. The results recorded that the Cmax released from the CFPP was significantly lower than the national and international ambient air quality limits, which means that radiological hazards from inhalation due to particulate emission released from the stack is insignificant. The air dispersion modelling results suggested that this activity does not impose any significant effect to the human population at large and potential contamination at vicinity of CFPP is remote.

Determination of Natural Radioactivity and Associated Radiological Hazard in Excavation Field in Turkey (Oluz Höyük)

The level of natural radioactivity may be varied with the increase in dependence of the depth into the earth. In present study, soil samples from dierent depths were collected in Oluz Hoyuk excavation area. The radionuclide concentrations in soil samples were determined by gamma-ray spectrometer which contains 3” 3” NaI(Tl) detector connected to multichannel analyser. The photopeaks at 1460, 1764, and 2615 keV due to 40 K, 226 Ra and 232 Th, respectively, have been used. The obtained activity concentrations of 40 K, 226 Ra and 232 Th ranged from 656.03 to 1791.85 Bq/kg, 62.39 to 180.93 Bq/kg and 48.31 to 125.43 Bq/kg, respectively. To assess the radiological hazard of the natural radionuclides content in the soil samples of these area, the radium equivalent activities (the minimum value was 181.99 Bq/kg and the maximum value was 497.97 Bq/kg), the absorbed dose rate (the minimum value was 86.83 nGy/h and the maximum value was 237.22 nGy/h), annual eective dose rate (the minimum value was 0.11 mSv/y and the maximum value was 0.29 mSv/y) and external hazard index (the minimum value was 0.49 and the maximum value was 1.35) were calculated using measured activities.