Appraisal of radioactivity and associated radiation hazards in sand samples of four rivers of Punjab province,Pakistan

Natural and anthropogenic radioactivity of sand and water samples collected from the four big rivers of Punjab province, Pakistan, was measured using a high-purity germanium detector coupled with a high resolution multichannel analyser. The average concentration of the naturally occurring radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K in all the sand samples from the rivers Jhelum, Chenab, Ravi and Indus was found to be 22±0.6, 36±1 and 287±10 Bq?kg ^?1, respectively, while the concentration of the anthropogenic radionuclide ¹³⁷Cs was found to be below the minimum detectable activity, i.e. ～ 1.2 Bq?kg ^?1. All the sand samples have Ra_eq concentrations lower than the limit of 370 Bq?kg ^?1. Indoor (H _in) and outdoor (H _out) radiation hazard indices were calculated for the samples to assess the radiation hazards arising due to the use of this sand in construction, and were found to be less than unity in the study area. Calculated values of the absorbed dose rate were less than the typical world average value of 59 nGy?h ^?1, and the annual effective dose rate was also less than the typical world value of 70 μSv, except in the Indus river, in which it is slightly higher then the world average. Results show that the measured values are comparable with other global radioactivity measurements. None of the studied riverbeds was considered a radiological hazard, and their sand can be safely used in construction.     

Measurement of radionuclides and absorbed dose rates in soil samples of Peshawar, Pakistan, using gamma ray spectrometry

The analysis of gamma-emitting radionuclides in nature, i.e. (226)Ra, (232)Th, (40)K and (137)Cs, has been carried out in soil samples collected from Peshawar University Campus and surrounding areas using a high purity germanium detector coupled with a computer-based high-resolution multichannel analyser. The activity concentrations in soil ranged from 30.20±0.65 to 61.90±0.95, 50.10±0.54 to 102.80±1.04, 373.60±4.56 to 1082±11.38 and 9.50±0.11 to 46.60±0.42?Bq?kg(-1) for (226)Ra, (232)Th, (40)K and (137)Cs, with a mean value of 45±7.70, 67±12.50, 878±180 and 19±9.20?Bq?kg(-1), respectively. The radium equivalent activity, internal and external hazard indices have mean values of 203.40±29.40?Bq?kg(-1), 0.56 and 0.68, respectively. The mean values of outdoor and indoor absorbed dose rates in air and the annual effective dose equivalents were found to be 106.50 and 128?nGy?h(-1) and 0.19 and 0.54?mSv?y(-1), respectively. In the present study, (40)K was the major radionuclide present in soil samples. The presence of (137)Cs indicates that this area also received some fallout from the nuclear accident of the Chernobyl power plant in 1986. The activity concentrations of radionuclides found in soil samples during the current investigation were nominal. Therefore, they are not associated with any potential source of health hazard to the public.     

Radioactivity of sand,groundwater and wild plants in northeast Sinai,Egypt

The radioactivity levels are poorly studied in non-coastal arid regions. For this reason, 38 locations covering an area of about 350 km² in northeast Sinai, Egypt, were investigated by γ-ray spectroscopy. Moderately significant correlations among ²³⁸U, ²³⁴Th, and ²²⁶Ra isotopes and low significant correlations between the concentrations of ²³⁸U-series and ²³²Th in sand were obtained. No evidence of correlation was found between the concentrations of radioisotopes and pH, grain size, total organic matter content, bicarbonate or calcium carbonate concentrations of the sand samples. The mean values of soil-to-plant transfer factor were 0.15, 0.18, 1.52 and 0.74 for ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs, respectively. The range of concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K in water samples collected from five wells were<0.4–0.16,<0.4–0.13, and<0.15–1.62 Bq l^?1, respectively. The mean absorbed dose rate in outdoor air at a height of 1 m above the ground surface for the sand samples was 19.4 nGy h^?1. The Ra_eq activities of the sands are lower than the recommended maximum value of 370 Bq kg^?1 criterion limit for building materials.     

Assessment of health hazard due to natural radioactivity in Kluang District,Johor, Malaysia

The radiation survey of the ambient environment was conducted using two gamma detectors, and the measurement results were used in the computation of the mean external radiation dose rate, mean-weighted dose rate and annual effective dose, which are 144 nGy h^?1, 0.891 mSv y^?1 and 178 μSv, respectively. A high-purity germanium detector was used to determine the activity concentrations of ²³²Th, ²²⁶Ra and ⁴⁰K in soil samples. The results of the gamma spectrometry of the soil samples show radioactivity concentration ranges from 19±1 to 405±13 Bq kg^?1 with a mean value of 137±5 Bq kg^?1 for ²³²Th, from 21±2 to 268±9 Bq kg^?1with a mean value of 78±3 Bq kg^?1 for ²²⁶Ra and from 23±9 to 1268±58 Bq kg^?1 with a mean value of 207±13 Bq kg^?1 for ⁴⁰K. Radium equivalent activity (Ra_eq) and external hazard index (H_ex) were 290 Bq kg^?1 and 0.784, respectively, which were safe for the population. The mean lifetime dose and lifetime cancer risk for each person living in the area with average lifetime (70 y) were 12.46 mSv and 7.25×10^?4 Sv year, respectively. The results were compared with values given in United Nations Scientific Committee on the Effects of Atomic Radiation 2000.     

Health and ecological hazards due to natural radioactivity in soil from mining areas of Nasarawa State,Nigeria

Nasarawa State is located in north central Nigeria and it is known as Nigeria's home of solid minerals. It is endowed with barite, copper, zinc, tantalite and granite. Continuous releases of mining waste and tailings into the biosphere may result in a build-up of radionuclides in air, water and soil. This work therefore aims to measure the activity concentration levels of primordial radionuclides in the soil/sediment samples collected from selected mines of the mining areas of Nasarawa State. The paper also assesses the radiological and radio ecological impacts of mining activities on the residents of mining areas and their environment. The activity concentrations of primordial radionuclides (²²⁶Ra, ²³²Th and ⁴⁰K) in the surface soils/sediment samples were determined using sodium iodide-thallium gamma spectroscopy. Seven major mines were considered with 21 samples taken from each of the mines for radiochemistry analysis. The human health hazard assessment was conducted using regulatory methodologies set by the United Nations Scientific Committee on the Effects of Atomic Radiation, while the radio ecological impact assessment was conducted using the ERICA tool v. 1.2. The result shows that the activity concentrations of ⁴⁰K in the water ways of the Akiri copper and the Azara barite mines are 60 and 67?% higher than the world average value for ⁴⁰K, respectively. In all mines, the annual effective dose rates (mSv y^?1) were less than unity, and a maximum annual gonadal dose of 0.58 mSv y^?1 is received at the Akiri copper mine, which is almost twice the world average value for gonadal dose. The external hazard indices for all the mines were less than unity. Our results also show that mollusc-gastropod, insect larvae, mollusc-bivalve and zooplankton are the freshwater biotas with the highest dose rates ranging from 5 to 7 µGy h^?1. These higher dose rates could be associated with zinc and copper mining at Abuni and Akiri, respectively. The most exposed terrestrial reference organisms are lichen and bryophytes. In all cases, the radio ecological risks are not likely to be discernible. This paper presents a pioneer data for ecological risk from ionizing contaminants due to mining activity in Nasarawa State, Nigeria. Its methodology could be adopted for future work on radioecology of mining.     

Evaluation of some pollutant levels in environmental samples collected from the area of the new campus of Taif University

The levels of radioactivity and heavy metals in soil, plant and groundwater samples collected from the area of the new campus of Taif University, Saudi Arabia, and its neighbouring areas have been determined. High-resolution gamma-ray spectroscopy was used for radioactivity measurements, and inductively coupled plasma atomic emission spectroscopy was used to determine the concentration of heavy metals. The means of ²²⁶Ra, ²²⁸Ra and ⁴⁰K concentrations in water samples collected from four wells were found to be 0.13±0.03, 0.05±0.03 and 1.3±0.5 Bq l^?1, respectively. The means of ²³⁸U, ²²⁶Ra, ²²⁸Ra (²³²Th for soil samples) and ⁴⁰K concentrations in wild plant and soil samples were found to be 3.7±4.1, 8.8±11.6, 3.8±2.9 and 1025±685, and 8.6±3.4, 12.8±3.4, 16.6±7.1 and 618±82 Bq kg^?1 dry weight (DW), respectively. The ¹³⁷Cs of artificial origin was also detected in soil samples with a mean concentration of 3.8±2.2 Bq kg^?1 DW. Evaluating the results, it can be concluded that the concentrations of ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K in soil samples fall within the world average. Furthermore, 19 trace and major elements in groundwater samples and 22 elements in soil and plant samples were determined. The sampling locations of soil can be classified into three groups (relatively high, medium and low polluted) according to their calculated metal pollution index using the contents of trace and major elements. A cluster analysis of the contents of radioactivity and trace element contents in soil samples shows the presence of two main distinct clusters of sampling locations.     

137Cs and 40K activity concentration measurements and elemental analysis in lichen samples collected from the Giresun province of northeastern Turkey

About 21 years after the Chernobyl accident, ¹³⁷Cs and ⁴⁰K activity concentration measurements using gamma-ray spectroscopy and elemental analysis using energy dispersive X-ray spectroscopy were performed in five different lichen species collected from the Giresun province of northeastern Turkey. Being a symbiosis of algae and fungi, lichens are mostly used for environmental measurements since the fungal partner is responsible for the uptake of necessary nutrients or harmful substances, such as heavy metals of radionuclides. The gamma activity results showed that ¹³⁷Cs, an artificial radionuclide released from the Chernobyl power plant accident, is still eminent in the environment of the province. The mean activity concentrations of ¹³⁷Cs and ⁴⁰K ranged from 24 to 254 with the mean value of 102 Bq kg^?1 and from 345 to 2103 with the mean value of 1143 Bq kg^?1 in dry weight. The results of the elemental analyses showed potassium, calcium, titanium, iron, tin, and barium in different concentrations.     

Effect of salinity on the concentrations of radioisotopes in the aquatic environment of a hypersaline coastal lagoon

Research of the effect of salinity on the fate of radionuclides has been focused on seas or estuarine systems while there is almost no information on marine environments with a salinity higher than that of sea water. The hypersaline Bardawil lagoon is a concentration basin, with evaporation exceeding precipitation. This study presents the characteristics of some environmental factors including salinity and their influence on the distribution of natural and artificial radionuclides in different compartments of the lagoon. The concentrations of ²³⁸U, ²³⁴Th, ²²⁸Ra and ¹³⁷Cs in sediments show some degree of dependency on the water's salinity. Migration of these radionuclides in the lagoon's sediments must take place from high salinity to low-salinity regions. Cluster analysis revealed the data structure for sediment by separating ¹³⁷Cs and ⁴⁰K from ²³²Th, ²²⁶Ra, and ²³⁴Th and for sand by separating ⁴⁰K from the other radioisotopes.     

Transfer of radioactivity from soil to vegetation in Rechna Doab,Pakistan

In Rechna Doab, samples of the most common vegetation, perennial grass Desmostachya bipinnata (dab), were collected along with soil samples from 29 sites. Natural radioactivity of ²²⁶Ra, ²³²Th/²²⁸Ac and ⁴⁰K was measured by using high purity germanium-based gamma ray spectrometer. Activity concentration levels of ²²⁶Ra, ²³²Th/²²⁸Ac and ⁴⁰K in soil were found to be 46.8±6.2 (36.0–57.6), 61.4±5.9 (48.2–73.2) and 644.8±73.9 (537.7–868.4) Bq kg^?1 (dry mass), respectively, and those in vegetation were 2.74±1.70 (1.00–6.39), 2.24±0.59 (1.56–2.61) and 172.72±113.37 (53.14–469.24) Bq kg^?1 (dry mass), respectively. The measured values of the activity concentration in vegetation are comparable with some other international data. Calculated soil to vegetation transfer factors of ²²⁶Ra, ²²⁸Ac and ⁴⁰K were 0.06±0.03 (0.02–0.14), 0.04±0.01 (0.03–0.04) and 0.26±0.16 (0.09–0.69). The mean outdoor absorbed dose rate in air for the area under study was determined as 8.22 nGy h^?1 and the mean indoor absorbed dose rate in air was 11.52 nGy h^?1. The total annual effective dose to the general public from the vegetation was found to be (0.02–0.16) mSv, which is below the recommended limit value of 1 mSv y^?1 for the general public. The dab vegetation under study was found to be radiologically safe for the population and environment.     

Assessment of natural radioactivity in rice and their associated population dose estimation

ABSTRACT

The concentration of natural radioactivity in rice is an important parameter for the determination of population exposure by the ingestion of natural radionuclides during habitual consumption of food. All types of food including rice contain a detectable amount of natural radioactivity which successively relocate into the human body via the ingestion pathway. Rice is the main cultivated crop in Bangladesh and most of the Bangladeshi people consume rice as their staple food. Hence, studies on the evaluation of natural radioactivity in rice have been performed by gamma-ray spectrometry using High Purity Germanium (HPGe) detector in order to estimate various radiation hazards due to rice consumption. The average activity levels of natural radionuclides ²²⁶Ra, ²²⁸Ra and ⁴⁰K in the rice samples were 1.09?±?0.31, 0.17?±?0.21 and 4.70?±?1.59?Bq?kg^?1, respectively. The estimated effective doses for the respective radionuclides caused by the rice consumption were 43.69, 16.39 and 4.15?µSv?y^?1, respectively which was below the UNSCEAR compiled value. The calculated excess lifetime cancer risk (ELCR) values via rice consumption were found below the acceptable limit of 0.29?×?10^?3 for radiological risk.     

Comparison of active and passive radon survey in cave atmosphere,and estimation of the radon exposed dose equivalents and gamma absorbed dose rates

Radon (²²²Rn) measurements were conducted in the Pileki Cave with Radim 3A Active Radon Monitor equipment. Measurements were also done with the passive sampling method with CR-39 nuclear track detectors by exposing them for three months in the cave. Radon concentrations obtained from the active and passive sampling methods showed that, firstly, the concentrations inside the cave measured by the latter method differed greatly due to high humidity levels up to 88%. The total inside radon exposure dose equivalent people were subjected to was estimated to be 19?µSv a^?1 for visitors and 24,065?µSv a^?1 for guides. The gamma absorbed dose rates were determined for inside and outside the cave. The dose rates were calculated by means of using the ²²⁶Ra, ²³²Th and ⁴⁰K activity concentrations and by means of real-time measurements. The gamma absorbed dose rates were found to be much higher than the value of 55?nGy?h^?1 given by UNSCEAR. In addition, the mineralogical compositions and elemental analyses of samples taken from the cave were determined by XRD and WD-XRF methods.     

Monte Carlo modelling of human body for dose conversion coefficients of 137Cs in soil of the Eastern Black Sea region of Turkey

Absorbed dose conversion coefficients for a human body standing on the soil surface were calculated for ¹³⁷Cs in the soil of Eastern Black Sea region of Turkey using the Monte Carlo simulation method. The results were given in nGy h^?1 per Bq cm^?2 as a function of depth. Simple numerical integration of this function multiplied with the known specific activity as a function of depth gives the absorbed dose conversion coefficients for any distribution of ¹³⁷Cs in soil. Gaussian distribution of ¹³⁷Cs in the soil was considered for calculations.     

Statistical relationship between activity concentrations of radionuclides 226Ra, 232Th, 40K,and 137Cs and geological formations in surface soil of Jordan

An extensive study was conducted to determine the activity concentrations of natural and artificial radionuclides ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs in soil samples of each governate of Jordan. A total of 370 samples have been measured using a high-purity germanium detector. The activity concentration for ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs has mean values of 42?±?3, 23?±?3, 309?±?21, and 3.7?±?0.9 Bq kg^–1, respectively. The highest mean activity concentration for ²²⁶Ra was found to be 138?±?4 Bq kg^–1 in the Alkarak governate. In the Ajloun and Jarash governates, the highest mean activity concentration was 35?±?3 Bq kg^–1 for ²³²Th, and 14.2?±?1.9 Bq kg^–1 for ¹³⁷Cs, respectively. Geological influence on the activity concentrations was investigated using the one-way analysis of variance (ANOVA) and independent samples. The ANOVA results indicate that there are strong significant differences between the activity concentrations of ²³²Th, ⁴⁰K, and ¹³⁷Cs based on geological formations the radionuclides occur. The main contribution to gamma dose rate was due to ²²⁶Ra activity concentration. Radium equivalent and external hazard index are associated with a mean value of 98 Bq kg^–1, and 0.266, respectively.     

Analysis of 226Ra, 232Th and 40K in soil samples for the assessment of the average effective dose

The activity concentrations of the natural radionuclides namely ²³⁸Ra, ²³²Th and ⁴⁰K are measured for soil samples collected from different locations of Faridkot and Mansa districts of Punjab. HPGe detector, based on high-resolution gamma spectrometry system is used for the measurement of activity concentration. The range of activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in the soil from the studied areas varies from 21.42 Bq kg⁻¹ to 40.23 Bq kg⁻¹, 61.01 Bq kg⁻¹ to 142.34 Bq kg⁻¹ and 227.11 Bq kg⁻¹ to 357.13 Bq kg⁻¹ with overall mean values of 27.17 Bq kg⁻¹, 95.22 Bq kg⁻¹ and 312.76 Bq kg⁻¹, respectively. Radium equivalent activities are calculated for the analyzed samples to assess the radiation hazards arising due to the use of these soil samples in the construction of dwellings. The absorbed dose rate calculated from activity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K ranges between 9.87 and 18.55, 38.01 and 88.68 and 9.40 and 14.79 nGy h⁻¹, respectively. The total absorbed dose in the study area ranges from 61.10 nGy h⁻¹ to 112.86 nGy h⁻¹ with an average value of 84.80 nGy h⁻¹. The calculated values of external hazard index (H _ex) for the soil samples of the study area range from 0.36 to 0.68. Since these values are lower than unity, according to the Radiation Protection 112 (European Commission, 1999) report, soil from these regions is safe and can be used as construction material without posing any significant radiological threat to population. The corresponding average annual effective dose for indoor and outdoor measured in the study area are 0.42 mSv and 0.10 mSv respectively.