Assessment of natural radioactivity concentrations and gamma dose rate levels in Kayseri, Turkey

This study assesses the level of background radiation for Kayseri province of Turkey. Natural radionuclide activity concentrations in soil samples were determined using high-resolution gamma spectroscopy. Outdoor gamma dose measurements in air at 1 m above ground level were determined using a portable gamma scintillation detector. The obtained results of uranium and thorium series as well as potassium ((40)K) are discussed. The present data were compared with the data obtained from different areas in Turkey. From the measured gamma-ray spectra, the average activity concentrations were determined for (238)U (range from 3.91 to 794.25 Bq kg(-1)), (232)Th (range from 0.68 to 245.55 Bq kg(-1)) and (40)K (range from 23.68 to 2718.71 Bq kg(-1)). The average activity concentrations of (238)U, (232)Th and (40)K were found to be 35.51, 37.27 and 429.66 Bq kg(-1), respectively, and 11.53 Bq kg(-1) for the fission product (137)Cs. The highest values of (238)U, (232)Th and (40)K concentrations (794.25 Bq kg(-1), 245.55 Bq kg(-1), 2718.71 Bq kg(-1), respectively) were observed in abnormal samples at Hayriye village. The average outdoor gamma dose rate in air at 1 m above the ground was determined as 114.43 nGy h(-1). Using the data obtained in this study, the average annual effective dose for a person living in Kayseri was found to be about 140.34 μSv.     

Radioactivity concentration in soil samples in the southern part of the West Bank, Palestine

The activity concentrations of naturally occurring radioactive materials such as (238)U, (232)Th and (40)K were measured for 38 soil samples collected from diverse zones in the southern area of West Bank, Palestine using gamma-ray spectroscopy. The measured activities of (238)U, (232)Th and (40)K were found to range from 32.9 to 104.7, 14.5 to 76.6 and 297 to 962 Bq kg(-1) with averages value of 68.7, 48.0 and 630 Bq kg(-1), respectively. The obtained values of activity concentrations are higher than the world average of 35, 30 and 500 Bq kg(-1) for (238)U, (232)Th and (40)K, respectively. The measured (137)Cs activity concentration was found to range from 1.8 to 36.1 Bq kg(-1) with an average value of 8.5 Bq kg(-1). The detected activities were attributed to the fallout of (137)Cs, which is the only man-made radionuclide. The calculated average of the total gamma-radiation dose rate of natural radionuclides, (137)Cs and cosmic radiation is 121.4 nGy h(-1). The radium equivalent activity (R(aeq)), dose rate (D(r)), external hazard index (H(ex)) and radioactivity level index (I(gamma)) in all samples are presented. Some values were found to be in the range of worldwide values, whereas others were above the worldwide values.     

Assessment of radiological significance of naturally occurring radionuclides in soil and rock matrices around Kakrapar environment

The activity and gamma-absorbed dose rate due to the naturally occurring radionuclides in the terrestrial environment such as (238)U, (232)Th and (40)K were determined in soil and rock samples collected around Kakrapar Atomic Power Plant site, using gamma-ray spectrometry. The mean concentration levels measured in Kakrapar soil from naturally occurring radioisotopes such as (238)U, (232)Th and (40)K are lower than the corresponding global average values obtained in worldwide soil. The external hazard index (H(ex)) and absorbed gamma dose rate in air outdoors is observed to be 0.04-0.18 and 3.1-14.1 nGy h(-1), respectively.     

Natural activity concentrations in bottled drinking water and consequent doses

The radioactivity concentrations of nuclides (238)U, (232)Th and (40)K in bottled drinking water from six different manufacturers from Turkey were measured using high-resolution gamma-ray spectrometry. The measurement was done using a coaxial high-purity germanium detector system coupled to Ortec-Dspect jr digital MCA system. The average measured activity concentrations of the nuclides (238)U, (232)Th and (40)K are found to be 0.781, 1.05 and 2.19 Bq l(-1), respectively. The measured activity concentrations have been compared with similar studies from different locations. The annual effective doses for ingestion of radionuclides in the water are found to be 0.0246 mSv for (238)U and 0.169 mSv for (232)Th.     

Gis predictive mapping of terrestrial gamma radiation in the Northern state, Sudan

This study presents the evaluation of absorbed dose in air due to gamma-emitting nuclides from (238)U and (232)Th series, (40)K and (137)Cs and the corresponding geographical information system (GIS) predictive mapping for the Northern State. Activity concentration of (238)U, (232)Th , (40)K and (137)Cs in soil samples collected from different locations have been measured using high-resolution gamma spectrometry. On average, activity concentrations were 19±4 ((238)U), 47±11 ((232)Th), 317±65 ((40)K) and 2.26 Bq kg(-1) for (137)Cs. Absorbed dose rate in air at a height of 1 m above ground surface was calculated using seven sets of dose rate conversion factors (DRCFs) and the corresponding annual effective dose was estimated. On average, the values obtained fall within a narrow range of 44 and 53 nGy h(-1), indicating that the variation in absorbed dose rate is insignificant for different DRCFs. The corresponding annual effective dose ranged from 53 to 65 μSv y(-1). Using GIS, prediction maps for concentrations of (238)U, (232)Th, (40)K and (137)Cs were produced. Also, a map for absorbed dose rate in air at a height of 1 m above the ground level was produced, which showed a trend of increasing from the west towards south-east of the State.     

Preliminary survey of outdoor gamma dose rates in Lesvos Island (Greece)

This study reports the first attempt to record the radioactive background due to gamma radiation in Lesvos Island (Greece). The study reports the results from 335 outdoor total gamma effective dose rate measurements conducted using GPS navigation and a Geiger-Muller detector (Bicron, Micro Sievert) on the whole surface of the island together with a digital map produced by appropriate mapping GIS programme. The study also reports the measurements of outdoor gamma dose rates due to the 238U, 232Th and 40K radionuclides as estimated via in situ gamma-ray spectrometry measurements performed at 26 sites using a 3 x 3 inch NaI (thallium activated) portable detector. The results from the outdoor total gamma effective dose rates range between 0.0023 and 0.28 microSv h(-1). The highest outdoor total gamma effective dose rates (0.013-0.28 microSv h(-1)) were detected in the northeastern part of the island and the intermediate rates (0.066-0.13 microSv h(-1)) in the central region. The outdoor gamma dose rates due to 238U, 232Th and 40K radionuclides range between 1.7 +/- 0.8 and 154 +/- 7 nGy h(-1) with an average of 86 +/- 6 nGy h(-1). The average contribution of each of the examined radionuclides (238U, 232Th and 40K) to the total gamma dose rate was found to be equal to 12 +/- 4% for 238U, 58 +/- 6% for 232Th and 29 +/- 7% for 40K, respectively.     

Radioactivity concentrations and dose assessment in surface soil samples from east and south of Marmara region, Turkey

The activity concentrations of 137Cs, 40K, 232Th, 238U and 226Ra were measured in surface soil samples from East and South of Marmara region, Turkey. The physico-chemical parameters (organic matter, CaCO3 contents and pH-value) of the soil samples were determined in the samples collected from 100 sampling stations. The average activity concentrations of 137Cs, 40K, 232Th, 238U and 226Ra were found to be 27.46+/-21.84, 442.51+/-189.85, 26.63+/-15.90, 21.77+/-12.08 and 22.45+/-13.31 Bq kg(-1), respectively. The mean value of total annual external gamma radiation dose equivalent for the natural radionuclides was calculated to be 54.86 microSv. The current data were compared with those found in the other locations of Turkey and different countries.     

A study of environmental radioactivity measurements for Cankiri, Turkey

This study is the first to assess the level of background radiation for the Cankiri province of Turkey. Indoor air radon concentrations were determined using Columbia Resin-39 nuclear track detectors and the average (222)Rn activity was found to be 44 Bq m(-3) (equivalent to an annual effective dose of 1.1 mSv). Measurements of gamma doses in outdoor air were performed using a portable plastic scintillation detector and the average gamma absorbed dose rate was found to be 8 μR h(-1) (corresponding to an annual effective dose of 87.7 μSv). Radionuclide activity concentrations in soil samples were measured through gamma-ray spectrometry and the average activities were determined as 17.7, 22.3, 357 and 4.1 Bq kg(-1) for the radionuclides (238)U, (232)Th, (40)K and (137)Cs, respectively. The average annual effective dose from the natural radioactivity sources ((238)U series, (232)Th series and (40)K) was calculated to be 44.4 μSv. Radioactivity levels of drinking water samples were carried out using a low-background proportional counter and the average gross alpha and beta activities were obtained as 0.25 and 0.26 Bq l(-1), respectively (equivalent to an annual effective dose of 184 μSv). The average radon concentrations in indoor air and the average radionuclide activities in soil were found to be lower than most Turkish cities while higher levels of outdoor gamma dose rate and water radioactivity were observed. The results of this study showed that the region's background radioactivity level differs considerably from the reported data for Turkish cities.     

Natural radioactivity and evaluation of effective dose equivalent of granites in Turkey

Annual effective dose equivalent due to natural gamma radiation from (238)U, (232)Th and (40)K have been evaluated from granites in Turkey. Forty samples were taken for spectrometric analysis. Specific concentrations of (238)U, (232)Th and (40)K in granite samples were determined. Spectroscopy system was used with 1.8 keV (FWHM) coaxial high purity germanium (HPGe) detector. Average values of concentrations of (238)U, (232)Th and (40)K were detected at 15.85, 33.76 and 359 Bq kg(-1), respectively. The average value of radon varies from 0.073 to 0.185 Bq m(-2) h(-1) exhalation depends on the specific concentration of uranium. The dose rate due to this highest activity which have been evaluated by a Monte Carlo transport calculations does not exceed 0.4 mSv a(-1).     

Natural radioactivity measurements in beach-rock samples of south-east coast of Tamilnadu, India

The concentration of primordial radionuclides in beach-rock samples of the south-east coast of Tamilnadu, India has been measured using gamma ray spectrum of rock. The mean activities of 232Th, 238U and 40K are 144.18, 29.25 and 267.48 Bq kg(-1) respectively. In situ measurements were also carried out using environmental radiation dosemeter. The linear correlation coefficient was obtained. The average activity of concentration of 232Th in the present study is 2.5 times higher than the world median value while the activity of 238U and 40K were found to be lower. This may be due to the heavy minerals present in the study area. In the present study, the calculated activity ratio (Th/U) is higher than the crustal rocks. This may be due to changes in the crustal composition through time (mafic to felsic) that are reflected by a change in the Th and U abundances in sedimentary rocks, and also increase in carbon content with time resulted in the decrease in U content and increase in Th/U ratio.     

Natural radioactivity contents in tobacco and radiation dose induced from smoking

One of the causative factors for cancer-inducing mechanisms in humans is radioactive elements present in tobacco leaves used in the manufacture of cigarettes. Smoking of tobacco and its products increases the internal intake and radiation dose due to naturally occurring radionuclides that are considered to be one of the most significant causes of lung cancer. In this work, different commercial types of cigarettes, cigar and moassel were collected from market. Naturally occurring radionuclides (226)Ra and (214)Bi ((238)U series), (228)Ac and (228)Ra ((232)Th series), (40)K and man-made (137)Cs were measured in tobacco using gamma-ray spectrometer. Results show that the average concentrations of (238)U, (232)Th and (40)K were 4.564, 3.940 and 1289.53 Bq kg(-1), respectively. This reflects their origin from the soil by root uptake and fertilisers used in the cultivation of tobacco plants. Concentration of (137)Cs was 0.348 Bq kg(-1) due to root uptake or deposition onto the leaf foliage. For smokers, the annual effective dose due to inhalation of (238)U varied from 49.35 to 139.40 μSv(-1) (average 104.27 μSv y(-1)), while of (232)Th from 23.86 to 111.06 μSv y(-1) (average 65.52 μSv y(-1)). The annual effective dose resulting from (137)Cs was varied from 10.96 to 24.01 nSv y(-1) (average 19.41 nSv y(-1)).     

Radioactivity risk associated with the handling of compact fluorescent lamps

The objective of this work is focused in measuring the level of naturally occurring radionuclides in compact fluorescent lamps commonly used in Egypt. The activity concentration of radionuclides in the (238)U and (232)Th decay chains and from (40)K were determined through gamma-ray spectrometry measurements using high-purity germanium in a low-background configuration. It was found that the activity concentrations ranged from 45 to 198 Bq kg(-1) for (238)U, from 30 to 191 Bqkg(-1) for (232)Th and from 419 to 935 Bq kg(-1) for (40)K.     

Radionuclide concentrations in soils of Northern Namibia, Southern Africa

Activity concentrations of the naturally occurring radionuclides like (238)U, (232)Th and (40)K in 400 soil samples collected from four major towns across the northern region of Namibia have been determined using gamma-ray spectrometry with the objective of providing baseline data on the radiation level in the region. The average concentrations of radionuclides in the towns vary from 7.5 +/- 2.3 to 14.2 +/- 3.3 Bq kg(-1) for (238)U, 5.8 +/- 2.6 to 24.9 +/- 6.1 Bq kg(-1) for (232)Th and 52.1 +/- 28.7 to 380.1 +/- 112.9 Bq kg(-1) for (40)K. These concentrations were used to calculate the mean absorbed dose rate and the mean annual effective dose in the region. The low value of 21 +/- 16 microSv obtained for the mean annual effective dose indicates that the region has normal background radiation.     

Assessment of the natural radioactivity in the soils of Windhoek city, Namibia, Southern Africa

The radioactivity concentrations of (238)U, (232)Th and (40)K in 160 soil samples collected from 16 geographical areas across Windhoek city, Namibia, have been determined using an HPGe detector and found to vary from 15.0 +/- 1.3 to 37.8 +/- 2.1 Bq kg(-1) for (238)U, 17.5 +/- 2.7 to 62.1 +/- 3.3 Bq kg(-1) for (232)Th and 168.9 +/- 15.0 to 784.9 +/- 30.1 Bq kg(-1) for (40)K. These concentrations were used to calculate the mean absorbed dose rate and the mean annual effective dose for the city. The value of 0.07 +/- 0.01 mSv y(-1) obtained for the mean effective dose is less than the maximum permissible dose of 1 mSv y(-1) recommended for the public by the International Commission on Radiological Protection.     

Natural radionuclides content and associated dose rates in fine-grained sediments from Patras-Rion sub-basins, Greece

The activity concentrations of the natural radionuclides (238)U, (226)Ra, (232)Th and (40)K were measured in soil samples collected from the Patras-Rion sub-basins (Southern Greece) and were found to be 28, 27, 30 and 483 Bq kg(-1), respectively. These values compare well with the average Greek and worldwide values for crustal soil and sedimentary rocks. The mean (226)Ra/(238)U activity ratio was close to 1, implying secular radioactive equilibrium in the uranium series. All soil samples have Ra(eq) values lower than the limit of 370 Bq kg(-1), indicating their safe use in brick production. The average annual terrestrial absorbed dose rate in air was 51±14 nGy h(-1), and the average annual effective dose 0.06±0.02 mSv y(-1), which is consistent with the average worldwide exposure to external terrestrial radiation outdoors (0.07 mSv y(-1)). Non-significant differences between soils with different age and depositional environments were found, which could be attributed to a common source of sediments.     

Determination of uranium, thorium and potassium activity concentrations in soil cores in Araba valley, Jordan

Soil samples were collected from six different locations in Araba valley, situated between Aqaba port and Dead sea. The samples have been analysed by using gamma-ray spectrometry. From the measured gamma-ray spectra, activity concentrations are determined for (238)U, (232)Th and (40)K. The mean activity concentration for (238)U, (232)Th and (40)K was found to be in the range 19 +/- 1.4 to 38.7 +/- 3, 14.3 +/- 0.8 to 35 +/- 3.2 and 94 +/- 18.9 to 762 +/- 47.4 Bq kg(-1), respectively. These results indicate that the mean concentrations of (238)U, (232)Th and (40)K in the populated Araba valley are lower than those in other populated areas. On the other hand, the concentrations of the major oxides (Al(2)O(3), SiO(2), K(2)O, CaO and Fe(2)O(3)) in the samples were determined using wavelength dispersive X-ray fluorescence. High potassium and iron content in some samples might be attributed to the active faults, which refer to the Dead sea transform fault.     

An assessment of the radiological scenario around uranium mines in Singhbhum East district, Jharkhand, India

The present work deals with the prevalent radiological scenario around uranium-mining sites in the Singhbhum East district of Jharkhand state, India. The concentration of naturally occurring radioactive materials (NORMs) was estimated from 27 soil samples collected around three regions in the study area, namely Bagjata, Turamdih and Jaduguda. The mean activity concentrations of (238)U in Bagjata, Turamdih and Jaduguda regions were found to be 128.6, 95.7 and 49.2 Bq kg(-1), respectively. Similarly for (232)Th and (40)K the activity concentrations were found to be 57.3, 78.4, 68.9 and 530, 425 and 615 Bq kg(-1) in the Bagjata, Turamdih and Jaduguda regions, respectively, which are comparable with other reported values worldwide, except for some high values. The calculated gamma dose rate, obtained from the concentrations of (238)U, (232)Th and (40)K in the samples, was compared with the observed dose rate in air. A good correlation (0.96) was observed between the calculated and the observed gamma dose rate. The annual outdoor effective dose rate was estimated and the values falls between 0.04-0.3, 0.07-0.3 and 0.07-.14 mSv y(-1) with mean values of 0.14, 0.12 and 0.11 mSv y(-1) for the Bagjata, Turamdih and Jaduguda regions, respectively. The terrestrial dose rates in all the three regions are comparable with other reported values worldwide, except for a few high values in Greece, Rio Grande Do Norte (Brazil) and Kalpakkam (India).     

Evaluation of absorbed dose rate and annual effective dose equivalent due to terrestrial gamma radiation in rocks in a part of Southwestern Nigeria

The average outdoor absorbed dose rate in air and the average annual effective dose equivalent due to terrestrial gamma radiation from 40K, 238U and 232Th in rocks in Ondo and Ekiti States, Southwestern Nigeria have been evaluated from measurements of the concentrations of these radionuclides in this environmental material. The concentration measurements were obtained using a very sensitive gamma spectroscopic system consisting of a 7.6 cm x 7.6 cm NaI(Tl) scintillation detector coupled to a computerised ACCUSPEC installation. The average absorbed dose rate and average annual effective dose equivalent was found to be 8.33 +/- 2.76 nGy x h(-1) and 8.7 +/- 2.9 microSv x y(-1) respectively.     

Assessment of gamma dose rate over a suspected uranium mineralisation area of Jebel Mun,Western Sudan

This study was conducted at the request of authorities in western Darfour State, to address the public concern about the levels of radioactivity in the area of Jebel Mun situated at Sudan-Chad international boundaries. It has been identified as a high background radiation area through aerial geological surveys conducted in late 1970s. The ambient gamma dose in the area was measured with the aid of a hand-held dose rate meter (Mini-Rad, Series 1000) and the surface rock samples were collected and analysed for their radioactivity content using a high-resolution gamma spectrometry equipped with HPGe with relative efficiency of 18%. The activity concentrations of 238U, 232Th and 40K were found to range from 39-253 Bq.kg(-1), 41-527 Bq.kg(-1) and 77-3027 Bq.kg(-1), respectively. From the values of the standard deviation it was concluded that the activity concentration of the considered primordial radionuclides was highly scattered (localised) which in turn indicates non-uniformity in the geological features and/or formations. 238U activity concentration corresponds to equivalent mass concentration of 7.77+/-6.12 ppm (3.19-20.73 ppm), which is of no economic importance. Samples are enriched in thorium relative to uranium as reflected by the Th:U mass ratio which ranges from 3 to 17. The absorbed dose rate in air as estimated from the measured activity concentrations of the primordial radionuclides using the DRCFs (dose rate conversion factors) falls within the range of 70-522 nGy.h(-1) with an average of 221+/-130 nGy.h(-1). It corresponds to an annual effective dose equivalent averaged of 0.27 mSv. The regression analysis has shown that the correlation between calculated and the measured ambient dose rate is marginally significant (r2 = 0.59). The 232Th series is the major producer of the surface radioactivity followed by 40K as they contribute 48% and 32% of the total absorbed dose, respectively.     

Radioactivity concentrations in soil and dose assessment for Samsun City Centre, Turkey

In this study, natural gamma radioactivity levels were determined in the soil samples of the Samsun city centre by using the gamma ray spectrometry method. The analysis carried out with the high-purity germanium gamma spectrometry system has shown that average activity concentrations of (238)U, (232)Th, (40)K and (137)Cs were 19±2, 22±4, 521±23 and 15±1 Bq kg(-1), respectively. From the gamma analysis of soil samples, the average value of the absorbed gamma dose rates in air and the average value of the external annual effective dose rates were calculated as 45±4 nGy h(-1) and 55±5 μSv y(-1), respectively. The external hazard index has also been calculated and it has been found that the radiation hazard in Samsun is insignificant.