Spatial Distribution Of Natural Radionuclides Research Articles

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.

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.

Assessment of Natural Radioactivity and Radiological Risks in River Sediments from Calabria (Southern Italy)

This study was developed to carry out a comprehensive radiological assessment of natural radioactivity for river sediment samples from Calabria, southern Italy, and to define a baseline background for the area on a radiation map. In the studied area, elevated levels of natural radionuclides are expected, due to the outcropping acidic intrusive and metamorphic rocks from which the radioactive elements derive. To identify and quantify the natural radioisotopes, ninety river sediment samples from nine selected coastal sampling points (ten samples for each point) were collected as representative of the Ionian and the Tyrrhenian coastline of Calabria. The samples were analyzed using a gamma ray spectrometer equipped with a high-purity germanium (HPGe) detector. The values of mean activity concentrations of 226Ra, 232Th and 40K measured for the studied samples are (21.3 ± 6.3) Bq kg−1, (30.3 ± 4.5) Bq kg−1 and (849 ± 79) Bq kg−1, respectively. The calculated radiological hazard indices showed average values of 63 nGy h−1 (absorbed dose rate), 0.078 mSv y−1 (effective dose outdoors), 0.111 mSv y−1 (effective dose indoors), 63 Bq kg−1 (radium equivalent), 0.35 (Hex), 0.41 (Hin), 0.50 (activity concentration index) and 458 µSv y−1 (Annual Gonadal Equivalent Dose, AGED). In order to delineate the spatial distribution of natural radionuclides on the radiological map and to identify the areas with low, medium and high radioactivity values, the Surfer 10 software was employed. Finally, the multivariate statistical analysis was performed to deduce the interdependency and any existing relationships between the radiological indices and the concentrations of the radionuclides. The results of this study, also compared with values of other locations of the Italian Peninsula characterized by similar local geological conditions, can be used as a baseline for future investigations about radioactivity background in the investigated area.

Ecological impacts of Assuit fertiliser factory in Upper Egypt: environmental implications and spatial distribution of natural radionuclides

ABSTRACT In the present work, radioactivity level in 15 collected soil samples from the area around fertiliser factory in Upper Egypt has been measured using gamma ray Spectrometry due to radionuclides occurred naturally namely 226Ra, 232Th and 40K to study the concentrations of these nuclides in this soil and determine the effect of Assuit fertiliser factory exhaust on radiological contents of surrounding Soil Samples in Assuit Province, Egypt. Activity concentrations of 226Ra, 232Th and 40K for soil samples were measured by scintillation detector NaI (Tl), has recorded average values 49.45 ± 5.04, 59.113 ± 2.96 and 137.85 ± 6.89 Bq/kg, respectively. On the other hand the average value of radiological hazards affected on farmers and populations were 150.32 Bq/kg, 64.3 nG/h, 0.257, 0.544, 1.006, 0.246, 0.315 and 0.0788 mSv/y for radium equivalent activity, absorbed gamma dose, external and internal hazard indices, gamma index, indoor and outdoor effective dose, respectively. The absorbed dose, gamma index and the annual gonadal dose equivalent the radiological hazards were found higher than permissible level.

Assessment of potential radiological risks due to natural gamma radiations in some selected rock samples using y-ray spectrometry

One of the sources of radiation risk in dwellings made of rocks is primordial radionuclides. It is imperative to assess the levels of radioactivity due to gamma rays from these materials and consequently to determine the dose rate from these materials. Fourteen samples of rock were collected from various sites of Aurangabad-India and the level of radioactivity and elemental compositions of samples have been measured utilizing y-ray spectroscopy and EDXRF technique. The findings showed that the mean activity concentrations of the 226Ra, 232Th, and 40K were 6.883, 10.841 and 128.616 Bq/kg, lower than the global average values of 35, 30, and 400 Bq/kg. The obtained results were compared with the worldwide average as well as with similar studies. The ratios among the detected radioisotopes in rocks were computed for the spatial distribution of natural radionuclides in the studied area. The radiological risk parameters were estimated and compared with internationally recommended values. The Pearson correlation was used to determine the relationship between the radionuclide concentration and radioactive variables, as well as with the elemental compositions. EDXRF results indicate that SiO2, Al2O3, K2O, CaO, TiO2, Na2O, MgO, P2O5, MnO, and Fe2O3 are the major oxides present in the samples. Moreover, heavy metals such as V, Cr, Co, Ni, Cu, Zn, As, Ba, Cd, Hg, and Pb with varying concentrations were detected. The radiological assessment indicated that the rocks of the study area are radiologically safe and may be used for construction without causing any threat to human health.

Radiological hazard parameters of natural radionuclides for neoproterozoic rocks from Wadi Um Huytat in central eastern desert of Egypt

The aim of this study is to evaluate the radioactivity levels and radiological impacts of representative neoproterozoic rocks: monzogranite, dokhan volcanics, syenogranite, granodiorite, gabbro and metabasalt samples collected from Wadi Um Huytat region in central eastern desert of Egypt using HPGe detector and Alpha GUARD. Remotely sensed data (Landsat 8 OLI) also used in order to appear the high reflectance appearance of neoproterozoic rocks which contain high concentration of radioactive elements. Rhyolite rocks have the highest average concentration of radionuclides of 226Ra, 232Th, 40K and 222Rn. Our results aimed to shed more light on the spatial distribution of natural radionuclides in neoproterozoic rocks.

Application of multivariate technique to evaluate spatial distribution of natural radionuclides along Tamil Nadu coastline, east coast of India

The study focuses on the spatial mapping of naturally occurring radionuclides along entire Tamil Nadu coast, which constitute nearly 30% of the east coast of India. In view of this, a total of 37 beach sediment samples are collected, and spectral measurement was carried out by High Purity Germanium detector. The average activity concentrations were found to be in the range of 34.33 ± 32.94 Bq kg−1 for 238U, 51.55 ± 40.39 Bq kg−1 for 238Th and 282.59 ± 84.45 Bq kg−1 for 40K. The contour maps showed the spatial distributions of each radionuclide and were drawn using the kriging method. Box-whisker plot shows the variation of activity concentrations of radionuclides, which follows the order 40K > 232Th > 238U in all the sediment samples. To understand the complex relationships among the radioactive variables and its environmental classifications, a multivariate statistical technique such as correlation matrices, and cluster analysis were applied to the radioactive data sets.

Spatial distribution and lifetime cancer risk due to naturally occurring radionuclides in soils around tar-sand deposit area of Ogun State, southwest Nigeria

Anthropogenically enhanced naturally occurring radionuclides 238U, 232Th and 40K present in the tar-sand soil samples were measured by gamma ray spectrometer using a highly shielded NaI (TI) detector with the aim of evaluating the environmental radiological hazards. Mineralogical analysis and characterization was carried out using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) techniques. The results obtained showed that the average activity concentrations of 238U, 232Th and 40K ranges from BDL↔76.00 ± 12.00, BDL↔204.48 ± 13.02 and BDL↔755.6 ± 40.15 Bqkg−1 respectively. Eleven other radiological and hazard parameters were estimated to know the complete hazardous nature of the samples. The values obtained for radionuclides and all its associated radiological and health hazard parameters were all higher than the world's average set by UNSCEAR. Five different minerals were identified and characterized as major and minor minerals. The mean radionuclides activity concentrations, radium equivalent and dose rate of measured radionuclides were compared with other literature values. RESRAD computer code was used to calculate the probability of excess lifetime cancer incurred by dwellers of the tar-sand deposit site, the level of which was determined to be 2.3 × 10−3(2310000). Spatial distribution of natural radionuclides in the study area was also investigated for radioactivity disequilibrium. Multivariate statistics were applied to establish the effect of mineralogy on radionuclides activity. Therefore, the tar-sand soil samples are considered to pose serious radiological hazard and cancer risk to human through the multiple routes of exposure and significant soil remediation action need to be taken for future use of the soils.

Environmental implications and spatial distribution of natural radionuclides and heavy metals in sediments from four harbours in the Egyptian Red Sea coast

Measurements of natural radionuclides concentrations (226Ra, 232Th and 40K) in sediments collected from sea, rivers or ocean is significant to protect the sea water ecosystem and to human health from radiation. Thirty-three sample of sediment have been collected from four ports in the Red Sea coast, Egypt for investigation by gamma-ray spectrometer using NaI(Tl) detector. The average and range activity concentrations of 226Ra, 232Th and 40K were 26(5–58), 19(4–33) and 458(16–2665)Bqkg−1 in Quseir Harbour, 30(14–53), 20(14–34) and 430(378–511)Bqkg−1 in Abu-Tartour Harbour. However, the average and range activity concentrations were 23(14–35), 21(15–32), and 602(327–821)Bqkg−1 in Touristic Harbour and 14(5–26), 13(2–23) and 489(36–950)Bqkg−1 in Hurghada harbour. These results were compared with reported ranges in the literature from other location in the world. The radiation hazard parameters; radium equivalent activity annual dose, external hazard were also calculated and compared with the recommended levels by UNSCEAR reports. Eight heavy metals (Fe, Mn, Ni, Co, Zn, Cu, Pb and Cd) have been measured and analyzed by atomic absorption spectrometer. The concentration for the investigated heavy metals overtakes the allowable limits recommended by the Canadian Environmental Quality Guidelines. Because there are no existing databases for the natural radioactivity in the sediment samples from Egyptian Red Sea ports, our results are a start to establishing a database for Red Sea harbours environment.

Radiometric evaluation of excessive lifetime cancer probability due to naturally occurring radionuclides in wastes dumpsites soils in Agbara, Southwest, Nigeria

The concentration and spatial distribution of the gamma ray emitting 238U, 232Th, 40K and 137Cs radionuclides in dumpsite soils in Agbara were analyzed with the aim of evaluating the radiation hazards and excessive lifetime cancer risk using well calibrated HPGe γ-ray spectrometry technique. The ranges of activity concentrations of 238U, 232Th, 40K and 137Cs are 11.5±1.0↔166±40Bqkg−1, 15.6±1.8↔31.4±2.3Bqkg−1, 20.4±1.3↔366±30Bqkg−1 and 0.52±0.1↔8.44±0.2Bqkg−1 respectively. Radiological parameters such as absorbed dose rate, radium equivalent, annual effective dose equivalent, internal and external hazard indices, gamma level index, activity utilization index, annual genetic significant dose equivalent, exposure rate and excessive lifetime cancer risk were calculated to know the complete radiological hazardous nature of the dumpsite soils to the inhabitants of the sites. The calculated radiological parameters were higher than the world average value in two of the sampling points. The ratio of the detected radioisotopes was calculated for spatial distribution of natural radionuclides in the study area. RESRAD computer code was applied to calculate the total effective dose equivalent (TEDE). The code was also used to calculate the probability of excess lifetime cancer incurred by dwellers/inhabitants of the dumpsites, the level of which was determined to be 0.5×10−4 and 2.5×10−5 for Idowale and Ibijola dumpsite soils over a period of 30years respectively. Therefore, the radiological risks to the general populations from waste enhanced naturally occurring radioactive materials (WENORM) from the Idowale dumpsite top soils are considered to be significant.

Measurements of natural gamma radiation in beach sediments of north east coast of Tamilnadu, India by gamma ray spectrometry with multivariate statistical approach

The distribution of natural gamma ray emitting 238U, 232Th and 40K radionuclides in beach sediments along north east coast of Tamilnadu, India has been carried out using a NaI(Tl) gamma ray spectrometric technique. The total average concentrations of radionuclides 238U, 232Th, and 40K were 35.12, 713.16, and 349.60 Bq kg−1, respectively. Correlations made among these radionuclides prove the existence of secular equilibrium in the investigated sediments. The total average absorbed dose rate in the study areas is found to be 504.75 nGyh−1, whereas the annual effective dose rate has an average value of 0.62 mSvy−1. The mean activity concentrations of measured radionuclides were compared with other literature values. The ratios between the detected radioisotopes have been calculated for spatial distribution of natural radionuclides in studied area. Also the radiological hazard of the natural radionuclides content, radium equivalent activity, external hazard index of the sediment samples in the area under consideration were calculated. Multivariate Statistical analyses (Pearson Correlation, Cluster and Factor analysis) were carried out between the parameters obtained from radioactivity to know the existing relations.

Natural radionuclides in the soils of a small agricultural basin in the Canadian prairies and their association with topography, soil properties and erosion

Summary Samples taken from the A and B horizons of the soil at 160 sites in a small (178 ha) cultivated drainage basin in central Saskatchewan were analysed by gamma spectroscopy to determine the concentration of a number of natural radionuclides in the soil. The concentration of 40K, the 238U daughters 226Ra,214Pb, and 214Bi, and the 232Th daughters228Ac, 212Bi, and 208Tl was determined. A variety of soil properties and topographic variables were measured at each sampling site. Earlier studies in the basin provided net soil erosion estimates (i.e. net loss or gain) for each site. The association of isotope activities with topography, soil properties and net erosion was evaluated. Mean isotope activities for the basin were very close to mean values reported earlier for native soils in southern Saskatchewan. Differences in isotope concentrations between the A and B horizons of the soils were related to differences in the degree to which the different isotopes are taken up by plants. Isotope concentrations in the surface soil were inversely correlated with soil particle size. Variation in isotope activities within the basin appeared to be linked to soil redistribution by erosion, but in a complex manner which reflects size sorting of soil particles by erosion processes. Erosion processes seem to be at least as important as leaching processes in determining the spatial distribution of natural radionuclides in the surface soils of the study area.