Terrestrial absorbed dose rate measurement in the Jhangar valley of Pakistan

Specific activity of natural radionuclides; ²²⁶Ra, ²³²Th and ⁴⁰K were measured in the agricultural soil of eastern salt range of Pakistan using gamma ray spectrometry. The soil samples were collected within the ploughing region (up to 12 cm depth) and processed before analysis. The average specific activities of different radionuclides in the dry mass of soil samples were: ⁴⁰K, (666 Bq/kg), ²²⁶Ra (51 Bq/kg), and ²³²Th (59 Bq/kg). The average outdoor terrestrial absorbed dose rate in air from gamma radiation one meter above ground surface was found to be 93 nGy/h.     

Natural radioactivity in surface marine sediments near the shore of Vizag, South East India and associated radiological risk

Naturally occurring radioactive materials were determined in surface sediments from the marine environment near the shore of Vizag in the South eastern part of India using gamma spectrometry technique. The mean activity concentration was found to be 36 ± 11, 34 ± 15, 75 ± 38 and 782 ± 223 Bq/kg and ranged from 19 to 48 Bq/kg, 11 to 57 Bq/kg, 31 to 145 Bq/kg and 363 to 1,024 Bq/kg for ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K, respectively. The mean radium equivalent activity, external hazard index, air absorbed gamma dose rate and annual effective dose equivalent are 203 ± 62 Bq/kg, 0.6 ± 0.2, 94 ± 27 nGy/h and 0.12 ± 0.03 mSv/year respectively. This data will serve as the baseline level for naturally occurring radionuclides in the study area and will be useful for tracking and assessing any pollution inventory in the environment of this region.     

Statistical assessment of radiological data of tiles collected from Jordan

ABSTRACT

In this present study, activity concentration of natural radionuclides such as ²²⁶Ra, ²³²Th and ⁴⁰K were determined using gamma ray spectrometer based on High Purity Germanium (HPGe) detector in ceramic tiles collected from Jordan. The average activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K were found to be 63.75 ± 24.12, 93.65 ± 13.89 and 180.9 ± 45.69 Bq.kg^?1. respectively. Using activity concentration of ²²⁶R, ²³²Th and ⁴⁰K, the radiological parameters such as radium equivalent activity (Ra_eq), Criteria formula (CF), absorbed dose rate (D_R), annual effective dose rate (H_R), activity utilisation index (AUI), external hazard index (H_ex), international hazard index (H_in), alpha index and gamma index (I_γ) has been calculated to assess the radiation hazards in the Tiles. The calculated average value of all radiological parameters is less than the recommended limit. The calculated values of annual effective dose rate (H_R), show that about 30% of the samples exceeded the recommended limit of 1 mSv.y^?1. Moreover, multivariate statistical techniques such as Pearson correlation, factor and cluster analysis were performed between the radioactive variables to know the existing relation between them.     

Preliminary studies on 226Ra, 228Ra, 228Th and 40K concentrations in foodstuffs consumed by inhabitants of Accra metropolitan area, Ghana

Knowledge of radioactivity levels in human diet is of particular concern for the estimation of possible radiological hazards to human health. However, very few surveys of radioactivity in food have been conducted in Ghana. The natural radionuclides ²²⁶Ra, ²²⁸Ra, ²²⁸Th and ⁴⁰K were measured in the foodstuffs using gamma ray spectrometry. All samples were found to contain high ⁴⁰K content in the range 87.77?C368.50?Bq?kg^?1. The maximum concentration of ²²⁸Th and ⁴⁰K were found in cassava to be 14.93?±?3.86 and 368.50?±?19.20?Bq?kg^?1, respectively. The total annual committed effective dose was estimated to be 4.64?mSv. The daily intake of radionuclides from food consumption reveals that cassava and plantain are the highest contributors, while millet is the lowest. The daily radionuclide intake from the foodstuffs consumed by the general public was 411.32?Bq and the daily internal dose resulting from ingestion of the radionuclides in the foodstuffs was 0.01?mSv. The radionuclide concentrations were comparable with those reported from other countries.     

Measurement of natural radioactivity and radiation hazard assessment in the soil samples of Visakhapatnam,Andhra Pradesh,India

The present work aims to measure and estimate radioactivity and hazardous radiation indices of the soil. Soil samples were collected from various locations in the Visakhapatnam district in Andhra Pradesh, India. The measurement of specific activity of ²²⁶Ra, ²³²Th, and ⁴⁰K radionuclides is carried out with the help of HP-Ge based gamma spectrometer system. Activity concentration of radionuclides in the samples ²²⁶Ra, ²³²Th and ⁴⁰K ranged from 20 ± 2 to 91 ± 2 Bq.kg^-1, 45 ± 3 to 365 ± 3 Bq.kg^-1, and 400 ± 9 to 607 ± 8 Bq.kg^-1, and the respective mean values are 53.36 Bq.kg^-1, 203.74 Bq.kg^-1 and 479.19 Bq.kg^-1. The measured mean value of the absorbed dose rate is 171.41 nGy.h^-1, which was beyond the worldwide mean outdoor value of 60 nGy.h^-1. Thus, the annual effective dose estimated from the above value is 1.04 mSv.y^-1. The correlation was done among the measured ²²⁶Ra, ²³²Th, and ⁴⁰K activity concentrations. The estimated radium equivalent dose is 381.60Bq.kg^-1. The estimated health hazard index and annual effective dose rates of dwellers of Visakhapatnam were studied and compared to Indian average values. The study will help to generate the baseline data for assessing hazard indices to the public and geological mapping of natural radiation in India.     

Measurement of activity concentration of primordial radionuclides in soil samples from Thirthahalli taluk and the assessment of resulting radiation dose

The activity concentration of primordial radionuclides ²²⁶Ra, ²³²Th, and ⁴⁰K in soil samples of Thirthahalli taluk were measured systematically by using a low background HPGe detector coupled to 16 K MCA. The measured activity concentration of ²²⁶Ra lies between 5.1?±?0.2 and 79.5?±?1.7 Bq kg^?1with an average activity of 25.99 Bq kg^?1, ²³²Th ranges from 5.1?±?0.3 to 95.3?±?2.2 Bq kg^?1with an average activity of 33.60 Bq kg^?1and that of ⁴⁰K varies from 18.3?±?1.5 to 833.4?±?17.5 Bq kg^?1with an average activity of 175.52 Bq kg^?1. Higher concentration of these radionuclides were found in the soil samples where the regional geology is granites. The consequential gamma dose and the corresponding radiation hazard was also estimated and is found to be within the permissible limits. The possible radiological impact on the public was also determined and these results are presented in this paper.     

Radioanalytical assessment of environmental contamination around non-remediated uranium mining legacy site and radium mobility

During the past century extensive uranium mining took place in Portugal for radium and uranium production. One such uranium mine was the Boco Mine, in operation during the 1960s and 70s. Mining waste and open pits were left uncovered since mine closure. During the nineties a quarry for sand extraction was operated in the same site and water from a local stream was extensively used in sand sieving. Downstream the mine area, agriculture soil is used for cattle grazing. Water from the stream, water wells, soil, pasture and sheep meat were now analyzed for radionuclides of uranium natural series. The U-series radionuclide ²²⁶Ra was generally the highest in concentrations especially in soil, pasture, and in internal organs of sheep. ²²⁶Ra concentrations were 1,093 ± 96 Bq/kg (dry weight, dw) in soil, 43 ± 3 Bq/kg (dw) in pasture, and 193 ± 84 mBq/kg (wet weight, ww) in muscle tissue of sheep. Other sheep internal organs displayed much higher ²²⁶Ra concentrations, such as the brain and kidneys with 1,850 ± 613 mBq/kg (ww) and 6,043 ± 6,023 mBq/kg (ww), respectively. Results of analyses of tissue samples from sheep grown in a comparison area were 2 to 16 times lower, depending on the organ. Absorbed radiation doses for internal organs were computed and may exceed 5.2 mGy/y in the case of kidneys, near three times higher than in animals from the reference area, but below the threshold for biological effects. Radionuclide transfer in the terrestrial food chain and radiation exposure of the human population is discussed.     

Studies on radionuclides around Hemavathi river basin of Karnataka,India

The activity concentration and total annual effective dose of the terrestrial naturally occurring radionuclides (²³²Th, ²²⁶Ra and ⁴⁰K) were measured in soil and rock samples collected from various locations of Hemavathi river basin in Karnataka, using HPGe detector. The results revealed that activity concentration of radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K in the soil had geometrical mean values of 16.7 ± 0.6, 33.9 ± 1.2 and 359.9 ± 9.2 Bq kg^?1, respectively. In rock samples activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K had geometrical mean values of 20.2 ± 0.7, 18.0 ± 0.9 and 276 ± 9.6 Bq kg^?1, respectively. The external Hazard index and indoor hazard index were found to be within safety limits prescribed by European commission 1999 report.     

Natural radioactivity studies of Bidar soil samples using gamma spectrometry

The activity of the terrestrial primordial radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K are measured for Bidar soil samples. The collected soil samples are analyzed using HPGe detector based on high resolution gamma spectrometric system. The activity of the three radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K were found to be in the range of BDL–47.68, 7.65–59.08 and BDL–260.65 Bq kg^?1 respectively. The mean gamma absorbed dose rate in air above 1 m from ground is estimated to be 34.47 nGy h^?1. Annual effective dose equivalent and the radium equivalent activity were within the limits in the present study and it is found that the activity of the radionuclides are comparable with the worldwide literature values. Also the external hazard indices for the soil samples of Bidar district were within the limit of unity.     

Geochemistry and health burden of radionuclides and trace metals in shale samples from the North-Western Niger Delta

Organic sedimentary rock samples were collected from three Oil Wells in the North-Western Niger Delta, Nigeria in order to determine their natural radioactivity and elemental geochemistry, with the aim of determining the concentrations of major radionuclides and their radiological and environmental health implication. The PIXE method of IBA technique and an accurately calibrated Si(Li) detector system was used to measure the elemental concentration of the sediment samples. The radionuclides identified belong to the decay series of naturally occurring radionuclides headed by ²³⁸U and ²³²Th along with the non-decay series radionuclide, ⁴⁰K. The activity concentrations of the radionuclides and their derived dose were then calculated. The average activity concentrations of ⁴⁰K were 248 Bq/kg for Well A, 261 Bq/kg for Well B and 273 Bq/kg for Well C. For ²³²Th the activity concentrations were 1,043 Bq/kg for Well A, 1,400 Bq/kg for Well B, 1,434 Bq/kg for Well C. ²³⁸U activity concentrations were 2,210, 3,508 and 250 Bq/kg for the Oil Wells A, B, C, respectively. The equivalent dose ranges from 8.5 ± 1.1 to 24.3 ± 2.1 mSv/year with a mean of 14.5 ± 2.2 mSv/year for Oil Well A, 2.4 ± 0.1–75.0 ± 1.2 mSv/year with a mean of 21.5 ± 1.1 mSv/year for Oil Well B and 3.7 ± 0.2–10.7 ± 0.6 mSv/year with a mean of 9.4 ± 2.5 for Oil Well C. The detected trace metals were majorly V, Ni, Pb, Fe, Cr, Cu, Zn, Co and their concentrations together with those of the radionuclides are compared with the relevant world standard limits. The results obtained were high, and hence, the radioactivity level and trace element content of the sediment samples from the North-Western Niger Delta Oil province could constitute health hazard to occupationally exposed workers, and to the public if not properly disposed. However, despite the careful disposal practice claims by the Oil industries, and given the high concentrations, the sediments could still pose an intrinsic health hazard considering their cumulative effects in the environment.     

A simple correction method for isobaric interferences induced by lead during uranium isotope analysis using secondary ion mass spectrometry

The present study is to determine the activity concentration of radioactive nuclide in plant fertilizers used in agriculture in Iraqi Kurdistan region using high- purity germanium detector (HPGe) gamma spectrometer. The results showed that the range of activity concentrations for ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs in chemicals and organic fertilizers are (0.1–134), (0.1–74), (1–12,000) and (0–1) Bq/kg respectively, based on the measured activities that were used to assess the radiological hazards. Radium equivalent activity in some samples exceeds the value (370 Bq/kg) which recommended by the OECD.     

Distribution of 238U, 226Ra, 232Th and 40K in soil samples around Tarapur,India

The radioactivity concentrations of ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K in soil samples around Tarapur vary from 11.5 ± 2.6 to 50.3 ± 6.6, 14.9 ± 0.6 to 40.5 ± 1.2, 18.1 ± 0.4 to 75.0 ± 1.5 and 130.1 ± 1.6 to 295.1 ± 2.6 Bq/Kg respectively. The measured activity concentrations for ²³⁸U and ²²⁶Ra were compared and found in good agreement with the Indian as well as world average. The average ²³²Th and ⁴⁰K concentrations in Tarapur were lower than the Indian average value.     

Study of natural radionuclides and its radiation hazard index in Malaysian building materials

The main component of most building materials in Malaysia is rock. All rocks are known to contain natural radionuclides such as ²³⁸U and ²³²Th series as well as ⁴⁰K. In order to estimate the radiological impact to the dweller, the level of radionuclides present in various building materials available in Malaysia were analyzed using γ-spectrometry. The radiation hazard indexes were calculated based on the above results. The results showed that the activity concentration of natural radionculides ²³⁸U, ²³²Th, ⁴⁰K was between 19.0–42.2 Bq/kg, 16.5–28.8 Bq/kg and 243.3–614.2 Bq/kg, respectively. On the whole, the radionuclides concentration was still below the global average of 50 Bq/kg, 50 Bq/kg and 500 Bq/kg for ²³⁸U, ²³²Th, and ⁴⁰K, respectively The radiation hazard indexes of the building materials were also lower than the maximum value suggested.     

Preliminary analyses of natural radionuclides in selected Turkish power plant lignites

This preliminary study presents the experimental results concerning the concentrations of selected radionuclides (²³⁸U, ²³²K, ²²⁶Ra, ²³²Th) in Af?in-Elbistan, Çan, Çay?rhan, Erzurum, Göynük, Kangal, Orhaneli, Saray, Seyitömer, Soma, Tunçbilek, Yata?an and Yeniköy lignites, which are primarily utilized as fuel for thermal power plants in Turkey. Gamma-spectrometry of 39 representative lignite samples gave results with the following concentration ranges: 8 to 296 Bq/kg for ²³⁸U, 3 to 79 Bq/kg for ²³²Th, 17 to 360 Bq/kg for 40K, and 5 to 130 Bq/kg for ²²⁶Ra. The ²³⁸U results reported here are higher than other literature values for various world coals, earth's crust and world average.     

Measurements of natural radioactivity in infant formula and radiological risk assessment

A set of measurements have been conducted to determine the levels activity of gamma-emitters present in infant formula. The study of different samples shows the presence of the following radionuclides: ²²⁶Ra, ²³²Th and ⁴⁰K with respectively average activity of 0.52 ± ?0.087, 0.51 ± 0.062, 371.98? ± 3.68 Bq/kg. The mean annual doses lead to 0.62 and 0.24 mSv/year whereas the total risk is about 7.91 × 10^?6 and 5.32 × 10^?6 respectively ≤ 1 year and 1–2 years old infants. The obtained results show that no significant radiation dose and no risk to the infants due to consumption of these milks.     

Assessment of ingestion dose due to radioactivity in selected food matrices and water near Vizag,India

Activity concentrations of ²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K and ¹³⁷Cs were measured in milk, egg, fruit and fish samples collected around a proposed site for setting up nuclear facilities, near Vishakhapatanam. The activity concentrations of the radionuclides ranged from 0.002 to 10.6, 0.002 to 2.8, 0.1 to 7.2, 3 to 110.8, 0.03 to 3 mBq g^?1 for ²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K and ¹³⁷Cs considering analysed food matrices. Natural uranium was measured in drinking water samples and the values were below 15 ppb. The average ingestion dose was 2.07 ± 2.01, 2.81 ± 4.38, 7.66 ± 8.24, 1.28 ± 0.84 and 0.04 ± 0.05 μSv year^?1 for ²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K and ¹³⁷Cs in milk, egg, fruit, fish and water. The ingestion dose received was the highest for milk, due to its high ingestion rate. It was observed that ²²⁶Ra is the largest contributor of measured radionuclides in this study for the different food matrices analysed due to its high dose conversion factor. The study was carried out as a part of baseline data generation for this region with which future changes in the radiological scenario can be compared.     

Radiometric analysis of rock and soil samples of Leepa Valley; Azad Kashmir, Pakistan

In this article, we present results obtained from a radiometric survey that was conducted in the Leepa Valley of Azad Jammu & Kashmir, Pakistan. The purpose of current study is to appraise the radioactivity levels and the associated health hazards due to the terrestrial radionuclide in soil and rock samples. In this regard, 16 soil and 17 rock samples were collected from different locations of the Leepa Valley. After processing the samples, activity concentrations of primordial (²³²Th, ²²⁶Ra and ⁴⁰K) and anthropogenic (¹³⁷Cs) radionuclides were determined using a P-type coaxial high purity germanium detector. From the results obtained the mean activity concentrations of radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K in the soil samples were found to be 31.25 ± 0.46, 44.1 ± 1.07 and 575 ± 8.89 Bq kg^?1 respectively. Whilst, in rock samples ²²⁶Ra, ²³²Th and ⁴⁰K mean activities were found as 28.46 ± 0.45, 48.63 ± 1.12 and 666.7 ± 9.39 Bq kg^?1, respectively. The ¹³⁷Cs concentration level in soil and rock samples is found to be 15.04 ± 0.29 and 5.7 ± 0.16 Bq kg^?1, respectively. The average radium equivalent activity (R _aeq) was found as 143.16 and 142.93 Bq kg^?1 in soil and rock samples, respectively. These findings are less than the recommended safe value of 370 Bq kg^?1 as given in OECD report (1979). The values of external (H _ex) and internal hazard index (H _in) are also less than unity. Mean value of absorbed dose rate was found as 69.78 nGy h^?1 for the soil samples, which is in good agreement with the world wide average value (70 nGy h^?1). Mean value of absorbed dose rate from rock samples was found as 70.01 nGy h^?1. Mean values of the annual effective dose is also lower than the values reported for different other countries of the world.     

Natural and Artificial Radionuclides in Selected Lignites from Istanbul

The radioactivity levels of Istanbul environs lignites were determined. The gamma-spectrometric technique has been used for the determination of activity levels of naturally occurring radionuclides ^235+238U, ^228+232Th, ⁴⁰K, ²²⁶Ra and fallout radionuclides ¹³⁷Cs in lignites taken from 7 different parts of Istanbul. Concentration of ²³⁸U, ^228+232Th, ⁴⁰K, ²²⁶Ra ¹³⁷Cs and ²³⁵U were found up to 1.6 ppm, 1.7 ppm, 4.9 ppm, 56.8 Bq/kg, 34 Bq/kg, 1.8 Bq/kg, 1.6 Bq/kg, respectively. In addition total alpha- and beta-activity levels in lignite samples were found to be 7.6 and 15 eps, respectively.     

Distribution and environmental impact of radionuclides in marine sediments along the Venezuelan coast

The activity concentrations of ¹³⁷Cs, ⁴⁰K, ²²⁶Ra and ²³²Th in Bq/kg from 42 marine sediment samples collected at nine sampling sites were determined in order to establish a radiological baseline along the Venezuelan coast. The radioactivity levels were determined by means of a gamma-ray spectroscopy system using a hyper-pure germanium detector in a low-background configuration. Particle size distribution and total organic matter content were also determined. Activity concentrations of ¹³⁷Cs were lower than the detection limit of the analytical technique (0.9 Bq/kg) in all studied sites. The results suggest that the variation of grain-size distribution is one of the most important factors influencing the spatial variations of ⁴⁰K, ²²⁶Ra and ²³²Th in sediments along the Venezuelan coasts. In all sampling sites, average concentrations of ⁴⁰K, ²²⁶Ra and ²³²Th were lower than the world average values. Activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in coastal marine sediments along the Venezuelan coast could be considered to be low when compared with global average values, indicating that they are not apparently above of the range that might be considered normal or background. These results suggest that the studied sites do not pose any significant radiological threat to the population. The results attained in this study should be of considerable value as baseline data and background reference levels for Venezuelan coastlines.     

Lognormal distribution of natural radionuclides in freshwater sediments and coal-ash repositories

The distribution of natural radionuclides,⁴⁰K,²²⁶Ra, and²³²Th, in freshwater sediments and in coal-fired power-plant ash repositories has been tested for lognormality. Thereafter, lognormality for natural radionuclide concentration frequency distribution was accepted with a high probability. The lognormal natural radionuclide distribution in sediments and coal-ash indicated single population groups. The anthropogenic modifications of the natural radionuclide concentrations in the environment are indicated. The adsorbed dose rates, in mGy y^–1, in air from gamma field of the natural radionuclides were calculated.