Soil radioactivity levels, radiological maps and risk assessment for the state of Kuwait

Health risk assessment for soil radioactivity around Shidaowan nuclear power plant in Shandong, China

Monitoring radioactivity levels in the environment around nuclear power plants is of great significance to assessing environmental safety and impact. Shidaowan nuclear power plant is currently undergoing commissioning; however, the baseline soil radioactivity is unknown. The naturally occurring radionuclides 238U, 232Th, 226Ra and 40K, and artificial radionuclide (AR) 137Cs in soil samples around the Shidaowan nuclear power plant were measured to establish the baseline levels. Human health hazard indices such as external hazard indices (Hex), Radium equivalent (Raeq), outdoor absorbed dose rate (Dout), annual effective dose (AED) and excess lifetime cancer risk (ELCR) were estimated. The average concentration of 232Th, 40K, 137Cs, 238U and 226Ra were 42.6 ± 15, 581 ± 131, 0.68 ± 0.38, 40.13 ± 9.07 and 40.8 ± 12.8 Bq per kg, respectively. The average Hex, Raeq, Dout, AED and ELCR were 0.40, 146 Bq per kg, 68.8 nGy per h, 0.09 mSv per y and 3.29E-04, respectively. These data showed an acceptable level of risk to residents near the nuclear power plant and that the current radioactivity in the soil may not pose immediate harm to residents living close to the nuclear power plant. The observed lower AED and 40 K and 137Cs concentrations were comparable to other studies, whilst ELCR was higher than the world average of 2.9E-04. The commissioning of the Shidaowan nuclear power plant is potentially safe for the surrounding residents; further continuous monitoring is recommended.

Assessing radioactive contaminants in Kathmandu soils: measurement and risk analysis

Soil samples from vegetable farmland in densely populated wards of Nepal were analyzed for natural radionuclide levels, employing a NaI(Tl) 3" [Formula: see text] 3" gamma detector. The study aimed to evaluate the causes of radiation risk, attributing it to soil contamination resulting from the rapid urbanization and concretization that followed the earthquake in 2015. The activity concentration of radium-226, thorium-232, and potassium-40 and the ranges observed are 2.080±0.084-33.675±1.356 Bq kg[Formula: see text], 17.222±0.198-119.949±1.379 Bq kg[Formula: see text], and 11.203 ± 0.325-748.828±21.716 Bq kg[Formula: see text], respectively. The average values obtained for hazard indices are as follows: radium equivalent activity (82.779 Bq kg[Formula: see text]), absorbed dose rate (36.394 nGy h[Formula: see text]), annual effective dose equivalent (0.045 mSv yearr[Formula: see text]), gamma index (0.291), external hazard index (0.224), internal hazard index (0.253), excess lifetime cancer risk (0.159), annual gonadal dose equivalent (243.278 mSv year[Formula: see text]), alpha index (0.054), and activity utilization index (0.716). However, in most places, thorium-232 concentration is greater than those of the world average and recommended values. In specific locations such as Ward 4 in Baluwatar, the soil was found to have concentrations of Ra[Formula: see text] and K[Formula: see text] exceeding recommended limits. Despite this localized concern, the overall analysis of hazard indices across the studied areas revealed that most values were within permissible limits. This suggests that, on a broader scale, radiation exposure may not be a significant concern in the investigated regions. Nonetheless, the study recommends regular monitoring in additional locations to ensure a comprehensive and ongoing assessment of radiation levels.

Soil radioactivity in the highest volcanic region of Northern Andes

This work studied the spatial pattern of four natural radionuclides (²²⁶Ra, ²²⁸Ra, ²²⁸Th and ⁴⁰K) as well as one artificial one (¹³⁷Cs) in soils in the Chimborazo province (Ecuador), which belongs to the North Andes of South America. Soil samples were collected considering the Ecuador geological map. Statistical analyses showed that activity concentrations of ²²⁶Ra, ²²⁸Ra, ²²⁸Th do not exceed the worldwide average, while one geological unit exceeds the worldwide average for ⁴⁰K. These high activity concentrations are attributed to radionuclide accumulation in plutonic and metamorphic rocks and also in ash resulting from eruptions of the Sangay volcano. The inverse distance weighted interpolation method was used to develop corresponding radioactivity maps where the highest activity concentrations are in the central-east of the studied area. In addition, a distribution pattern of ²²⁶Ra and ⁴⁰K is observed in the geologies influenced by the presence of Chimborazo, Igualata, Tungurahua and Altar volcanoes. Spearman's nonparametric test shows positive correlations suggesting the presence of very homogeneous lithologies and that volcanic activities can influence the distribution of radionuclides in our environment. In seven of the samples, ¹³⁷Cs was detected.

Environmental radioactivity assessment of the Brunei Darussalam coastline of the South China Sea

Radioactivity levels of naturally occurring radionuclides at the coast of Brunei Darussalam were evaluated along with their dose rates. Twenty-six berm and intertidal sediment samples were measured using gamma-ray spectrometry. The mean activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in berm sediments were 10.07 ± 1.02 Bq/kg, below the minimum detectable activity, and 21.44 ± 1.23 Bq/kg, respectively, whereas for intertidal sediments they were 7.01 ± 0.87, 1.67 ± 0.15 and 4.99 ± 0.42 Bq/kg, respectively. With respect to the radiological health risk, the average hazard indices, absorbed gamma dose rate, effective dose equivalent, and excess lifetime cancer risk were found to be less than the global average. Calculation of the activity ratio showed that ⁴⁰K is the main source of radiation in the coastal sediments. Furthermore, the difference in radioactivity levels between the berm sediments and intertidal sediments collected at the same location was investigated. Finally, a standard geological terminology of the littoral zone profile is proposed for describing coastal samples for universal communication among researchers.

Estimation of activity concentrations of radionuclides and their hazard indices in coastal plain sand region of Ogun state

Assessment of natural background radionuclides emanating from the subsurface geological features was carried out with the use of gamma-ray spectrometry at various locations at one of the secondary school in Canaan land, Ota, Ogun State. The activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K were revealed to be 12.66 ± 0.76–42.33 ± 1.37, 44.96 ± 1.41–128.70 ± 1.56, 31.30 ± 1.18–453.85 ± 2.43 Bq kg⁻¹ respectively. The mean value of ²³²Th reported higher than the world reference standard of 50 Bq kg⁻¹. Moreover, the stations closest to the school’s laboratory were noticed to be prone to more gamma radiations than the other buildings in the school. Similarly, the results of the radiological parameters estimated varied between 86.04–243.7 Bq kg⁻¹, 40.02–115.4 nGy h⁻¹, 0.049–0.142 mSv y⁻¹ and 0.232–0.658 for Ra_eq, D_(out), AEDE and H_ex, respectively. Although, the results of the radiological parameters did not exceed the world safe limits, higher values of these parameters were reported at some stations closer to the school laboratory. It can be concluded that the school laboratory is prone to more gamma radiation than the class rooms and the administrative block. Therefore, the laboratory instructors and staff, who spend longer time in the laboratory, are more liable to the health risk that could result from years of exposure to gamma radiation in the laboratory.

Assessment of radiological hazards from soil samples in the Northeastern area of Burkina Faso

The activity concentrations of main naturally occurring radionuclides were determined with the aim of assessing the radiation hazards in the Northeastern part of Burkina Faso. Soil samples were taken and analyzed by the gamma-ray spectrometry method. The ranges of specific activity of 238U, 232Th and40K are $$15.25 \pm 2.59 \, \text{Bq} \cdot {\text{kg}^{-1}}$$ 15.25 ± 2.59 Bq · kg - 1 to $$109.57 \pm 3.21 \, \text{Bq} \cdot {\text{kg}^{-1}}$$ 109.57 ± 3.21 Bq · kg - 1 , $$19.56 \pm 1.65 \, \text{Bq} \cdot {\text{kg}^{-1}}$$ 19.56 ± 1.65 Bq · kg - 1 to $$44.88 \pm 2.49 \text{Bq} \cdot {\text{kg}^{-1}}$$ 44.88 ± 2.49 Bq · kg - 1 and $$125.74 \pm 4.40 \, \text{Bq} \cdot {\text{kg}^{-1}}$$ 125.74 ± 4.40 Bq · kg - 1 to $$705.85 \pm 10.79 \, \text{Bq} \cdot {\text{kg}^{-1}}$$ 705.85 ± 10.79 Bq · kg - 1 respectively. Three high background radioactivity areas have been identified for Uranium, Thorium and Potassium on different places in the study area. The radiological hazards indices vary from $$62.87 \, \text{Bq} \cdot {\text{kg}^{-1}}$$ 62.87 Bq · kg - 1 to $$189.47 \, \text{Bq} \cdot {\text{kg}^{-1}}$$ 189.47 Bq · kg - 1 for the Radium equivalent activity ($$Ra_{eq}$$ R a eq ), $$29.5 \, \eta \text{Gy} \cdot {\text{h}^{-1}}$$ 29.5 η Gy · h - 1 to $$86.65 \, \eta \text{Gy} \cdot {\text{h}^{-1}}$$ 86.65 η Gy · h - 1 for the absorbed dose rate ($$D_R$$ D R ), $$0.18 \, \text{mSv} \cdot {\text{y}^{-1}}$$ 0.18 mSv · y - 1 to $$0.53 \, \text{mSv} \cdot {\text{y}^{-1}}$$ 0.53 mSv · y - 1 for the annual effective dose rate (AEDE), 0.21 to 0.81 for the internal hazard index ($$H_{in}$$ H in ), 0.17 to 0.51 for the external hazard index ($$H_{ex}$$ H ex ), $$1.27 \times 10^{-4}$$ 1.27 × 10 - 4 to $$3.73 \times 10^{-4}$$ 3.73 × 10 - 4 for the Excess Lifetime Cancer Risk (ELCR) and $$209.01{\mkern 1mu} \mu \, 0.18{\mkern 1mu} Sv \cdot y^{{ - 1}}$$ 209.01 μ 0.18 S v · y - 1 to $$594.21 \, \mu \text{Sv} \cdot {\text{y}^{-1}}$$ 594.21 μ Sv · y - 1 for the annual gonadal dose equivalent. The average values of indices are well below their permissible limit. However, at Niapsi the obtained values for absorbed dose rate, annual effective dose rate and excess lifetime cancer risk are little above their permissible limit.

The activity concentrations of radionuclides 226Ra, 232Th and 40K of soil samples in the case of Metekel Zone, Ethiopia

In this paper, we have studied the concentration levels and corresponding radiological hazard indices of natural radioactive elements such as radium-226, thorium-232, and potassium-40 in soil samples collected from Metekel Zone, Ethiopia. We have determined the concentration levels with the help of gamma ray spectrometry. Accordingly, we obtained the average values for radioactive concentrations of radium, thorium, and potassium to be 64 Bq/kg, 70 Bq/kg, and 330 Bq/kg, respectively. The radiological hazard has been also determined from the pertinent concentration levels of radium, thorium and potassium isotopes. Therefore, we obtained that the radioisotopes have heterogeneous distribution which must be caused by the nature and types of the soil in the area where this investigation was conducted for.

Radiological hazard assessments of radionuclides in building materials, soils and sands from the Gaza Strip and the north of Sinai Peninsula

Radiological hazards to the residents of the Gaza Strip, Palestine and the north of the Sinai Peninsula, Egypt, were determined using the naturally occurring radionuclides (²²⁶Ra, ²³²Th and ⁴⁰K) in 69 samples of building materials (demolition debris, plasters, concretes, from recycling plants and raw cements from suppliers), soils and sands collected in the field. The radiological hazard indices and dose rates calculated with the activity concentrations of radionuclides in those materials determined by gamma-ray spectrometry indicate that the values are all within the global limits recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation 2000 and European Commission 1999. The results of Spearman's correlation and hierarchical cluster analysis for ²¹⁰Pb in the building materials, soils and sands suggest that the samples include ²¹⁰Pb from the atmospheric fallout. The medium correlation between ²³²Th and ⁴⁰K in demolition debris implies that their activity concentrations are characteristic of the building materials and constituents of the demolition debris. Non-natural ratio of ²³⁸U/²³⁵U was found in the soil and sand samples collected in the Gaza Strip. Furthermore, ¹³⁷Cs and ²⁴¹Am were detected in some soil, sand and demolition debris samples analyzed in this study. The origins of those anthropogenic radionuclides were considered.

Assessing the natural and anthropogenic radionuclide activities of the Pechora River estuary: Bottom sediments and water (Arctic Ocean Basin)

This paper studies the activity of natural and technogenic radionuclides in bottom sediments and surface water of the Pechora River estuary, which is the largest Arctic river within the European part of Russia. The relevance of conducting radioecological studies of this region is associated with active oil and gas activities in the Pechora basin and the presence of potential sources of radiation hazard. The average activities of ¹³⁷Cs, ²²⁶Ra, ²³²Th, and ⁴⁰K in bottom sediments were 0.16, 18.72, 13.36, and 373.59 Bq·kg^-1, respectively. The average activity of ²²⁶Ra in the bottom sediments of the Pechora delta was two times higher than in other rivers of the Arctic basin of the European part of Russia, which is associated with oil and gas activities that are carried out in the Pechora basin. This is due to the fact that the decay products of uranium are the main by-products of oil and gas production. The specific activity of technogenic ¹³⁷Cs in bottom sediments of the Pechora River delta was low and did not exceed 2.2 Bq·kg-1. We did not detect any radioactive ⁹⁰Sr in bottom sediments. The low ¹³⁷Cs activity in the bottom sediments of the Pechora delta was associated with both the larger granulometric composition of the sediments in comparison with the estuaries of the Siberian rivers, and with low concentrations of ¹³⁷Cs in the terrigenous material (soil) entering the river from the catchment area. This was due to the low levels of ¹³⁷Cs contamination in the soil of the Pechora river basin. We did not find any negative radiation effects of the underground nuclear explosion "Pyrite" carried out in the northern part of the delta, since there were no other technogenic radionuclides. The values of the radionuclides ³H, ¹³⁷Cs, ²²⁶Ra, ²³²Th and ⁴⁰K, as well as the total alpha activity in the surface waters of the Pechora River delta, turned out to be below the detection limit. In surface waters, we were able to determine only the total beta activity, which varied over a range from 19.6 to 59.6 Bq·m^-3 with an average value of 33.9 Bq·m^-3, which was significantly lower than the radiation safety standards. The values of the radiation hazard parameters were below the world average levels and were not significantly hazardous to the health of people living in the area of the Pechora River delta. We concluded that at present, in the Pechora River delta, there are pastures for reindeer with low levels of natural and man-made radioactivity. These conducted studies are the source material in a series of comprehensive studies of the current radioecological state of the tundra territories of the European part of Russia.

In-situ assessment of natural terrestrial-radioactivity from Uranium-238 (238U), Thorium-232 (232Th) and Potassium-40 (40K) in coastal urban-environment and its possible health implications

The risk of natural terrestrial radioactivity on human health is often underestimated, and environmental safety awareness is necessary. Hence, this study aims to assess natural sources of gamma radiation emitter in coastal urban-environment using the radiometric technique. The dosage of gamma radiation from a parent radionuclide such as Uranium-238 (²³⁸U), Thorium-232 (²³²Th) and Potassium-40 (⁴⁰K) and were measured using portable gamma spectroscopy. The result showed that the measured value of ²³⁸U activity was between 10.81 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document}± 0.69 and 46.31 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document}± 1.43 Bqkg⁻¹. The mean value was estimated to be 35.44 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document}± 0.97 Bqkg⁻¹ which is slightly higher than the world average. Meanwhile, ²³²Th activity ranges from 28.42 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document}± 1.12 to 69.43 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document}± 1.76 Bqkg⁻¹ with the calculated mean value of 92.57 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document}± 1.17 Bqkg⁻¹ while ⁴⁰K activity ranged between 31.30 ± 1.32 and 328.65 ± 2.32 Bqkg⁻¹ with the estimated mean 137.59 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pm$$\end{document}± 2.42 Bqkg⁻¹. Radiological parameters such as radium equivalent (R_eq), internal hazard (H_int) and external hazard (H_ext) assessment were in the range of 66.00 Bqkg⁻¹ to 141.76 Bqkg⁻¹, 0.232 to 0.452 and 0.178 to 0.383, respectively. The measured values of gamma dose-rates ranged between 54.283 ± 0.78 and 117.531 ± 1.14 nGyh⁻¹ with the calculated mean value of 84.770 ± 0.97 nGyh⁻¹.

Spatial distribution, risk assessment and influence factors of terrestrial gamma radiation dose in China

The current spatial distribution of the risk of terrestrial gamma radiation in China were investigated by using spatial interpolation. And the driving factors influence on the terrestrial gamma radiation dose (TGRD) distribution were identified using the geographic detector, a new statistical method based on the nonlinear hypothesis. The results showed that the values of TGRD were range from 60 to 195 nGy h^-1 with the average of 86.5 nGy h^-1, and the higher values were recorded in Qingahi-Tibet Plateau, which were all within the range of background value in China. In addition, the radiological indices, ELCR (Excess Lifetime Cancer Risk), TGRD and AEDE (Annual Effective Dose Equivalent) were also within the acceptable range of values by risk assessment. The results by use of the geographic detector showed that sunshine duration, atmosphere pressure, altitude, and rainfall condition have closely related to the TGRD distribution. In addition, these meteorological factors and altitude had more impact on TGRD than the air pollution-related factors. Our study can provide useful information on studying the influence mechanism of the TGRD distribution, the variability of the natural terrestrial gamma radiation in China, and exposure data for risk assessment from low dose chronic exposures.

Assessment of naturally occurring radiation in lithofacies of oil field in Niger Delta region and its possible health implications

The accumulation and increase in radionuclide activities of NORMs beyond permissible levels, will lead to health hazards and environmental damages if proper measures are not taken to control their occurrence as well as protect the lives of drillers and the environment. Therefore, evaluations and risk assessments of subsurface lithofacies is inevitable in order to protect people and the environment. Lack of existing Federal environmental regulations to address the presence of NORMs in oil and gas exploration activities in Nigeria, gives credence to this study. However, before these regulations can be developed, adequate research knowledge is needed to better understand the occurrence and distribution of Norms in subsurface lithofacies, as well as quantify the hazards posed by these NORMs to the people in the environment. This study then investigates the occurrence of natural radiation in lithofacies of an oil field region in Niger-Delta area using Hyper Germanium (HPGe) detector. Six (6) samples of different subsurface layers of lithofacies were collected during drilling, and analyzed. The results showed that the measured activity concentration of ²³⁸U decreased as the depth increased; the activity concentration of ²³²Th ranged between 11.8 ± 9.29 Bq/kg and 23.1 ± 8.43 Bq/kg, while the activity concentration of ⁴ K ranged from 161.8 Bq/kg to 245.4 Bq/kg. The estimated radiological risks such as absorbed dose rates, annual effective dose rates, radium equivalent index, external hazard index and internal hazard index were determined. The mean values for the estimated radiological parameters were 12.32 nGyh^-1, 15.1049 Svy^-1, 44.7720 Bqkg^-1, 0.1209 and 0.1318 respectively. The gamma index estimated for the samples used were within the standard values recommended by Unscear, 2000. Significantly, this study reveals a distinctive decrease in 232Th activity with depth within the area under consideration. Based on the compared results, the measured radioactive concentrations and estimated radiological risks were below international reference values.

Vertical distribution and radiological risk assessment of 137Cs and natural radionuclides in soil samples

The aims of this study were to investigate the vertical distributions of natural radionuclides 232Th, 226Ra and 40K as well as anthropogenic radionuclide 137Cs in soil samples and to analyze the correlation among the radioactivity of these radionuclides and the physiochemical characteristics of soil samples namely pH, grain size, carbonate content and organic matter. Risk assessment of the radiological hazard has also been estimated. Forty-four soil samples were collected from eleven locations in Qatar at four depth levels from 0 to 16 cm. The average concentrations of 232Th, 226Ra, 40K and 137Cs in the soil depth of 16 cm were 10, 17, 201 and 4 Bq/kg, respectively, which were within the reported world mean. The external absorbed gamma dose rate, the annual effective dose, the mean radium equivalent activity, the external hazard index and the lifetime cancer risk were 22 nGy/h, 0.027 mSv/y, 47 Bq/kg, 0.125 and 0.096 × 10-3, respectively. These values were far below the minimum recommended international values. The level of radioactivity concentrations in the soil was affected by the physiochemical characteristics of the soil. The positive correlation with highest R2 value was found among the radioactivity concentrations of 232Th and 40K and the soil clay content. Total organic carbon was also positively correlated for 226Ra and 137Cs activity concentrations, whereas, carbonate content was negatively correlated with the radioactivity concentrations of 232Th and 40K. As far as soil moisture content is concerned, the positive correlation with highest R2 value was obtained for 226Ra activity concentrations.

Natural radioactivity in urban soils of mining centers in Armenia: Dose rate and risk assessment

Soil radioactivity levels, dose rate and radiological health risk were assessed in metal mining centers of Armenia, at the towns of Kapan and Kajaran. Archive soil samples of the multipurpose soil surveys implemented in Kapan and Kajaran were used for estimation of total alpha and total beta activity levels using gas-less iMatic™ alpha/beta cօunting system (Canberra). Ten representative soil samples per town were randomly selected from different urban zones for naturally occurring radionuclide measurements (238U, 232Th, 40 K) using high purity germanium detector. Four radiological indices: radium equivalent activity, outdoor absorbed dose rate, annual effective dose equivalent and excess lifetime cancer risk were estimated based on naturally occurring radionuclide activity concentrations in soils. Results suggest that in Kapan the soil radioactivity, although enhanced by copper and gold-polymetallic mining, are not a significant risk factor to human health. In Kajaran, the soil radioactivity levels were above the background and world average values provided by UNSCEAR, but radionuclides originated in a natural geogenic source and not from mining activities. Generally, in this region no significant radiological risks were identified in relationship with molybdenum, copper, and gold-polymetallic ore mining.

Depleted uranium assessment and natural radioactivity monitoring in North West of Iraq over a decade since the last Gulf War

For the sake of completeness of the surveillance process concerning the spread of depleted uranium (DU) in the Arabian Gulf region, we have applied a simple gamma spectroscopy technique to evaluate its content in Al Jolan, Nazzal and Askari districts in Al Fallujah area, Iraq for the first time and after more than one decade. The measurements were carried out along the lines of the wars that have been witnessed in Iraq last period and expected to be the region of impact of residuals of a large quantity of DU. The observed radionuclides are ⁴ K and other naturally occurring radioactive members of uranium and thorium series. The obtained results show that, the average specific activity concentrations of ²²⁶Ra, ²³²Th, ⁴ K, ²¹⁰Pb ²³⁸U and ²³⁵U in different soil samples collected from Al Fallujah area, Iraq in range of 20.09 ± 4.0 to 21.94 ± 2.4, 11.51 ± 2.3 to 11.75 ± 3.2, 96.53 ± 8.0 to 112.13 ± 49.8, 19.98 ± 4.6 to 20.76 ± 4.8, 25.4 ± 3.9 to 26.1 ± 6.0 and 1.28 ± 0.18 to 1.34 ± 0.21 respectively. The obtained values of Ra_eq for all the investigated samples are less than the recommended limit of 370 Bq kg^-1 and those for H_ex are less than one. These results have been compared with the previous works and the world mean values specified by the UNSCEAR reports. The mean ratio of ²³⁸U/²³⁵U activity in all cases is about the natural value (21.73) which is less than its value in case of DU (76.92). The present obtained results of DU levels show that although a large amount of DU was released in Iraq during the Gulf wars, the tested samples are DU free. This may be attributed to the reduction of DU from the soil surface by wind or sandstorms and the downward leaching process.

A national survey of natural radionuclides in soils and terrestrial radiation exposure in Iran

In the past, some efforts have been made for measuring natural radioactivity and evaluating public exposure to natural radiation in certain areas of Iran especially in well-known High Level Natural Radiation Areas (HLNRA) in Ramsar and Mahallat. However, the information on radionuclide concentrations, and, consequently, terrestrial radiation exposure for many other areas are not available. There was therefore a need for a systematic and nation-wide survey. For this purpose, 979 soil samples from 31 provinces were collected. The activity concentrations of ⁴⁰K, ²²⁶Ra and ²³²Th were measured by HPGe detector. The average activity concentrations for Iran were found to be 457.7 Bq/kg for ⁴⁰K, 24.3 Bq/kg for ²²⁶Ra and 25.8 Bq/kg for ²³²Th. Results were compared with previous regional or provincial surveys. The population-weighted average outdoor and indoor annual effective dose due to external exposure to terrestrial sources of radiation are 0.06 mSv and 0.33 mSv, respectively. It was shown that there is a significant correlation between the activity concentrations of ²³²Th and ⁴⁰K in soil. In addition, the results of chi square tests show normal and lognormal distributions cannot be considered for the frequency distributions of activity concentration of ²³²Th and ²²⁶ Ra while ⁴⁰K has a normal distribution.

Study of the radioactivity in environmental soil samples from Eastern Anatolia Region of Turkey

In this study, a detailed γ-ray spectrometer survey was performed to obtain the baseline data on natural and fallout radioactivity in soil samples (10–30 cm depth) collected from Iğdır which is a province in Eastern Anatolia Region of Turkey and located along the border with Armenia. Metsamor Nuclear Power Plant in Eastern Armenia is only about 20 km away from Iğdır province. The average activity concentrations of 226Ra, 232Th, 40K and 137Cs in the soil samples were found as 19.1±0.6 (range: 12.8–31.2 Bq kg−1), 21.9±0.6 (range: 11.6–36.8 Bq kg−1), 437.7±10.3 (range: 285.0–613.7 Bq kg−1) and 11.8±1.1 Bq kg−1, (range: 2.5–51.1 Bq kg−1), respectively. The radiological hazards caused by ionizing radiation emitted from these radionuclides on the population living in the region were assessed by estimating radiological parameters such as absorbed γ dose rate in outdoor and the corresponding annual effective dose rate from external exposure, annual effective dose rate from inhalation of radon and excess lifetime cancer risk. The results revealed that there is no significant radiological hazard for human population because the average values of radiological parameters are within the recommended limits.