Measurement of natural radioactivity in soil from Peshawar basin of Pakistan

Natural radioactivity in the environment may change with time due to human activities, chemical and biological changes. From the view of radiation risk to population, the knowledge of natural radioactivity levels and the measurement of collective radiation dose received by the population is very vital. Radiological constraints on soil of thickly populated Peshawar basin in northern Pakistan were assessed through radiometric assay. Soil samples collected from different locations of four districts of this basin were analysed using an HPGe gamma spectrometer. Activity concentrations of ⁴⁰K, ²²⁶Ra and ²³²Th in these samples was 648 ± 121 (421–996), 45 ± 7 (32–60) and 59 ± 7 (46–72) Bq kg^?1, respectively that followed lognormal distribution. The average concentrations of primordial radionuclides were found to be higher than that reported for the worldwide soil. Radium equivalent activity and gamma index derived from these activity concentrations were lesser than their respective limits. The average absorbed dose rate and the annual effective dose for both indoor and outdoor cases were found to be higher than the values given in the UNSCEAR 2000 report. The results of the present study were compared with those for other locations of Pakistan along with that for the world. The radiological impact of the measured data was evaluated using hazard assessment models. A thoughtful discussion of the above mentioned evaluation is also given.     

Investigation of radon and thoron concentrations in a landmark skyscraper in Tokyo

The temporal variation of the radon concentration, and the radon and thoron concentrations every 3 months for a year were measured using two types of devices in a landmark skyscraper, the Tokyo Metropolitan Government Daiichi Building. In the measurement of temporal variation of the radon concentration using a pulse type ionization chamber, the average radon concentration was 21 ± 13 Bq m^?3 (2–68 Bq m^?3). The measured indoor radon concentration had a strong relationship with the operation of the mechanical ventilation system and the activities of the office workers. The radon concentration also increased together with temperature. Other environmental parameters, such as air pressure and relative humidity, were not related to the radon concentration. In the long-term measurements using a passive radon and thoron discriminative monitor, no seasonal variation was observed. The annual average concentrations of radon and thoron were 16 ± 8 and 16 ± 7 Bq m^?3, respectively. There was also no relationship between the two concentrations. The annual average effective dose for office workers in this skyscraper was estimated to be 0.08 mSv y^?1 for 2000 working hours per year. When considering the indoor radon exposure received from their residential dwellings using the annual mean radon concentration indoors in Japan (15.5 Bq m^?3), the annual average effective dose was estimated to be 0.37 mSv y^?1. This value was 31 % of the worldwide average annual effective dose.     

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.     

Terrestrial gamma dose rate in Pahang state Malaysia

Environmental terrestrial gamma radiations (TGR) were measured in Pahang state Malaysia between January and April 2013. The TGR dose rates ranged from 26 to 750 nGy h^?1. The measurements were done based on geology and soil types of the area. The mean TGR dose rate was found to be 176 ± 5 nGy h^?1. Few areas of relatively enhanced activity were located in Raub, Temerloh, Bentong and Rompin districts. These areas have external gamma dose rates of between 500 and 750 nGy h^?1. An Isodose map of the state was produced using ArcGIS9 software version 9.3. To evaluate the radiological hazard due to terrestrial gamma dose, the annual effective dose equivalent and the mean population weighted dose rate were calculated and found to be 0.22 mSv year^?1 and 168 nGy h^?1 respectively.     

Natural indoor gamma background in Coonoor environment of South India

Indoor natural radiation dose existing in dwellings of Coonoor have been estimated using thermoluminescent dosimeters. TLDs are displayed in indoors and are replaced after three-month period. The seasonal averages of the dose rate and the annual effective dose equivalent are calculated from the measured results. Geographical and seasonal variations as well as the differences between indoor to outdoor dose rates have also been studied. Very good correlation exists between the indoor dose rates measured by TLD and environmental radiation dosimeter with correlation coefficient of 0.91. The annual effective dose equivalent to the Coonoor population due to indoor gamma radiation was estimated to be 970 mSv/y for the period of 1997–1998.     

The use of carbon dioxide as the reaction cell gas for the separation of uranium and plutonium in quadrupole inductively coupled plasma mass spectrometry (ICP-MS) for nuclear forensic samples

²²⁶Ra, ²³⁸U, ²³²Th, and ⁴⁰K radionuclides have been determined using gamma-ray spectrometry in soil samples collected from urban areas in the southern governorates of Jordan and showed average concentrations of (39 ± 18), (45 ± 20), (23 ± 13), and (233 ± 128) Bq kg^?1, respectively. The corresponding radio-elemental concentrations in the existing geological features were obtained and examined for the relative depletion/enrichment processes and state of equilibrium in soils. Radium equivalent activity, hazard indices, and annual gonadal dose equivalent do not exceed the permissible limits. Absorbed dose rates in air outdoor and external effective dose showed average values of 44.0 nGy h^?1 and 54.4 μSv y^?1, respectively.     

Natural radioactivity and its gamma dose rate in Mission (Texas) soils

The activity concentration of radionuclides in ²³⁸U, ²³²Th, and ⁴⁰K were determined in Mission (Texas) surface soils through gamma-ray spectrometry measurements using hyper pure germanium detector. Activity concentrations of ²³⁸U, ²³²Th, and ⁴⁰K were 13–32 Bq kg^?1 (mean value: 23 Bq kg^?1), 17–47 Bq kg^?1 (mean value: 31 Bq kg^?1), and 100–460 Bq kg^?1 (mean value: 300 Bq kg^?1) respectively. The absorbed gamma dose rate in air from these soils were found in the range of 23 to 56 nGy h^?1 with an average value of 42 nGy h^?1. The contribution to the absorbed gamma dose rate in air was observed as 26 % from ²³⁸U, 45 % from ²³²Th, and 29 % from ⁴⁰K. The outdoor annual effective dose equivalent varied between 28 and 69 μSv y^?1 with the mean value of 52 μSv y^?1.The evaluated data were compared with the data from different countries and also with the world mean value.     

A study of indoor radon in greenhouses in Mexico City, Mexico

Enclosed spaces in contact with soil, the main source of radon, like greenhouses have potentially high radon (²²²Rn) concentrations. Greenhouses are frequented by visitors and also are workplaces. The study of radon concentrations in greenhouses is, thus, a relevant concern for public health and environmental radiation authorities. For this study, the radon concentrations in 12 greenhouses in different locations within Mexico City were measured using nuclear track methodology. The detectors used for the study consisted of the well-known closed-end cup device, with CR-39 Lantrack^® as detector material. The measurements were carried out over a period of one year, divided into four three-month sub-periods. The lowest and highest annual mean radon concentrations found in individual greenhouses were 17.0 and 45.1 Bq/m³, respectively. The annual mean averaged over all 12 greenhouses was 27.3 Bq/m³. No significant seasonal variation was observed. Using the highest annual mean radon concentration found in an individual greenhouse, and an equilibrium factor of 0.4, the effective dose from ²²²Rn and its progenies was calculated to be 339.9 nSv/h. This corresponds to an annual dose rate of 679.8 μSv/y (0.057 WLM/y) for a worker spending 4 h a day, 5 days a week, 50 weeks a year, inside the greenhouse. For a visitor spending 12 h a year inside the greenhouse the annual dose is 2.469 μSv/y. The study of indoor radon concentrations in closed buildings such as greenhouses, which are both workplaces and open to visitors, is an important public health consideration.     

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.     

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.     

Measurement of cosmic radiation dose to air crew connecting for a typical polar route flight

In order to compare cosmic radiation dose for air crew including pilot and flight attendant between polar route flight and non-polar route flight, a typical polar flight route that is from Beijing to New York was selected and compared with non-polar route. Optically stimulated luminescence dosimeter and track etch detector CR-39 were worn as personal dosimeters to measure the cosmic radiation dose to air crew. The mean annual effective dose for air crew from polar route and non-polar route was (5.79 ± 0.92) mSv/year and (2.14 ± 0.64) mSv/year, respectively. The effective dose per 1,000 flight hours for air crew was (3.10 ± 0.27) mSv/1,000 h and (2.21 ± 0.46) mSv/1,000 h, respectively. The result is analyzed by using SPSS 15.0 statistical software. There was significant difference between the two groups for both mean annual effective dose (t = 30.25, P < 0.05) and the effective dose per 1,000 flight hours (t = 7.60, P < 0.05). The dose to pilot was higher than that of flight attendant for both polar route and non-polar route, and there was significant difference between them, for polar route (t = 7.96, P < 0.05), for non-polar route (t = 4.70, P < 0.05). The effective dose from cosmic radiation to air crew of polar route was higher than that of non-polar route, however, it did not exceed 20 mSv/year, which is the limit on cosmic radiation exposure set by many countries in the world.     

Assessment of natural and fallout radioactivity in soil samples of Visakhapatnam

Environmental gamma radiation levels around the new Bhabha Atomic Research Centre site at Visakhapatnam have been assessed. Natural and anthropogenic radionuclide activity concentrations in soil samples collected were determined using high-resolution gamma spectroscopy. Average activity concentrations of ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K were found to be 38, 38, 230 and 520 Bq kg^?1, respectively. No anthropogenic radionuclide except fallout ¹³⁷Cs having mean concentration range ≤ 0.2–2.2 Bq kg^?1 was detected in the soil samples. The observed values are compared with the values reported for different areas in India and other parts of the world. The annual total external gamma radiation dose to the members of public estimated using the above observations ranged from 0.13 to 0.38 mSv y^?1 with an average of 0.25 mSv y^?1.     

Evaluation of radon induced lung cancer risk in occupants of the old and new dwellings of the Dera Ismail Khan City,Pakistan

In order to carry out indoor radon measurement in new and old buildings of the Dera Ismail Khan city, CR-39 based radon detectors were installed in bed rooms and sitting rooms/TV lounges in 25 (each) old and new houses and were exposed to indoor radon for 90 days. After processing, mean weighted average indoor radon concentrations in old and new houses were found to be 275 ± 33 and 86 ± 18 Bq m^?3 whereas mean annual effective doses expected to be received by the occupants were 6.86 ± 0.79 and 2.1 ± 0.43 mSv year^?1, respectively. From the measured weighted average indoor radon concentration, excess relative risk factor was calculated using the risk model of BEIR VI for the age group of 35 and 55 years. Average excess lung cancer risk was found to be 1.63 ± 0.19 and 1.35 ± 0.16 and 0.5 ± 0.10 and 0.4 ± 0.08 for old and new houses, respectively.     

Evaluation of radon concentration and heavy metals in drinking water and their health implications to the population of Quetta,Balochistan, Pakistan

ABSTRACT

The purpose of this study is to estimate the concentrations of radon and heavy metals in drinking water and assess their health implications to the population of Quetta, Pakistan. The concentration of radon and heavy metals was measured in drinking water collected from tube wells of different depths of the Quetta, Balochistan, Pakistan, using RAD7 detector and Atomic Absorption Spectrometer, respectively. The results show that the concentration of radon ranged from 3.56 ± 0.98 to 8.56 ± 1.32Bq/L with an average of 5.67 ± 1.34Bq/L. The average value of contribution of radon in water to indoor air was found 2.02 ± 0.47mBq/L. In addition to concentration of radon in drinking water, physiochemical parameters like pH and electrical conductivity (EC), and annual effective doses for different age groups were also estimated. Positive correlation of (R² = 0.8471) was observed between depth of well and concentration of radon, however no such relations were found among pH and EC with concentration of radon. Average values of annual effective doses due to intake of radon for age groups 0–1 years (infants), 2–16 years (Children) and ≥17 years (adults) were found (3.00 ± 0.71)×10^?2, (1.1 ± 0.26)×10^?2 and (1.45 ± 0.34)×10^?2 mSv/y, respectively. Average values of heavy metals concentrations were found 1.85 ± 0.64, 3.21 ± 0.75, 5.06 ± 1.19, and 2.47 ± 0.77 and 5.58 ± 1.23 µg/L for As, Cr, Ni, Cd and Pb, respectively. The values of radon concentration and heavy metals in drinking water were found below the USEPA permissible limits, Thus we conclude that, the investigated waters are safe.     

Long term and equilibrium factor indoor radon measurements

This paper presents the annual radon gas concentrations obtained during the 1994–1995 monitoring campaign using passive electret system (type E-PERM). Radon levels were measured in 154 single family dwellings, in normal occupancy conditions (open house condition) in the metropolitan zone of Mexico City. At the same time radon monitoring was performed outdoors. The results show the general log-normal distribution of integrated indoor radon concentration with an annual indoor mean of 3.8 pCi·l⁻¹. The seasonal variations show the minimum mean values in the summer season which are 39% lower than that in autumn. Equilibrium factors (F) were measured in 12 typical houses both in autumn and winter using a continuous working level monitor for short-lived radon decay products and H-chamber loaded with a short term electret (HST, E-PERM) for radon gas. The obtained total mean equilibrium factors are:F=0.41±0.17 andF=0.29±0.04 for indoor and outdoor, respectively. A quality program was also improved.     

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.     

Radiological dose assessment of naturally occurring radioactive materials in concrete building materials

Previous studies have shown that the natural radioactivity contained in building materials have significantly influenced the dose rates in dwelling. Exposure to natural radiation in building has been of concerned since almost 80 % of our daily live are spend indoor. Thus, the aim of the study is to assess the radiological risk associated by natural radioactivity in soil based building materials to dwellers. A total of 13 Portland cement, 46 sand and 43 gravel samples obtained from manufacturers or bought directly from local hardware stores in Peninsular of Malaysia were analysed for their radioactivity concentrations. The activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in the studied building materials samples were found to be in the range of 3.7–359.3, 2.0–370.8 and 10.3–1,949.5 Bq kg^?1 respectively. The annual radiation dose rates (μSv year^?1) received by dwellers were evaluated for 1 to 50 years of exposure using Resrad-Build Computer Code based on the activity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K found in the studied building material samples. The rooms modelling were based on the changing parameters of concrete wall thickness and the room dimensions. The annual radiation dose rates to dwellers were found to increase annually over a period of 50 years. The concrete thicknesses were found to have significantly influenced the dose rates in building. The self-absorption occurred when the concrete thickness was thicker than 0.4 m. Results of this study shows that the dose rates received by the dwellers of the building are proportional to the size of the room. In general the study concludes that concrete building materials; Portland cements, sands, and gravels in Peninsular of Malaysia does not pose radiological hazard to the building dwellers.     

Measurement of soil radioactivity levels and radiation hazard assessment in mid Rechna interfluvial region,Pakistan

Radioactivity levels in soil samples, collected from mid Rechna interfluvial region, Pakistan have been estimated by using gamma ray spectrometric technique. ²²⁶Ra, ²³²Th, the primordial radionuclide ⁴⁰K and the artificial radionuclide ¹³⁷Cs have been measured in the soil of the study area. The mean radioactivity levels of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs were found to be 49.0 ± 1.6, 62.4 ± 3.2, 670.6 ± 33.9 and 3.5 ± 0.4 Bq kg⁻¹ respectively. The mean radium equivalent activity (Ra_eq), outdoor radiation hazard index (H _out), indoor radiation hazard index (H _in) and terrestrial absorbed dose rate for the area under study were determined as 189.9 ± 8.8 Bq kg⁻¹, 0.51, 0.65 and 70.1 nGy h⁻¹ respectively. The annual effective dose to the public was estimated to be 0.43 mSv. The measured values are comparable with other global radioactivity measurements and are found to be safe for public and environment.     

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.     

Geological and radiological studies of the Mount Arafat, Mekkah, Saudi Arabia

Mount Arafat is a sacred place for Muslims. It has been classified as a granodiorite rock which mainly consists of feldspar and quartz, muscovite, etc. During the Hajj and Umra, Muslims visit this holly place and stay there for some time. In order to study the geology and thermal history as well as to assess the radiological hazards due to the presence of primordial radionuclides, systematic studies using petrographic, fission track dating and γ-spectrometric (HPGe) techniques were carried out. Our study yielded fission track age of 9.13 ± 1.05 Ma of the Mount Arafat granodiorite. Rifting, magmatism, volcanism and sea floor spreading that resulted in the formation of Red Sea seems may have altered the original age of the Arafat granodiorite under study to 9.13 ± 1.05 Ma. Measured radioactivity concentrations due to ²²⁶Ra, ²³²Th and ⁴⁰K were found to be 10.75 ± 3.92, 29.21 ± 4.34 and 664.49 ± 7.45 Bq kg^?1, respectively. From the measured radioactivity, gamma index (Iγ) and radium equivalent (Ra_eq) were calculated as 0.402 and 103.23 Bq kg^?1 whereas outdoor external dose (D_out) and annual effective dose (E_out) were estimated to be 40.30 nGyh^?1 and 0.045 mSvy^?1 respectively. All the above mentioned values are well below the recommended limits. The Mount Arafat thus does not pose any radiological health hazard to the general public.