Radiological significance of beach sand used for climatotherapy from Safaga, Egypt

As a part of national survey to evaluate natural radioactivity in the environment, concentration levels of radioactivity were analysed for sand samples from Safaga, Egypt, which is an ideal area for climatotherapy of psoriasis. Gamma dose rates of three beaches in Safaga were measured. The values ranged from 195.1 to 210.7 nGy h(-1). The activity concentrations (Bq kg(-1)) of radionuclides 238U series, 232Th series and 40K in three different sand profiles (0-5, 5-10, 10-15, 15-25 and 25 - 40 cm) were measured using gamma-ray spectrometry. The annual effective doses were 259 microSv y(-1) for Minveila, 255 microSv y(-1) for Ganet Safaga and 239 microSv y(-1) for Masab El-Ghazel beaches. The dose rates, radium equivalent activities and external hazard indices were evaluated and compared with the international data. These results may contribute to the determination of absorbed dose rate reference levels in Red Sea Coast at Safaga city.     

Assessment of background radioactivity level for Gaziantep region of southeastern Turkey

This study presents the measurement results of environmental radioactivity levels for Gaziantep, an industrial and trade centre in the southeastern part of Turkey. The outdoor gamma absorbed dose was measured as 50.1 nGy h(-1), corresponding to a total gamma radiation level (of terrestrial and cosmic origin) of 61.5 microSv y(-1). The activity concentrations in the surface soil samples collected from the study area were determined as 25.2, 23.7 and 289.2 Bq kg(-1) for the natural radionuclides (238)U, (232)Th and (40)K, respectively, and 8.02 Bq kg(-1) for the fission product (137)Cs. These natural radioactivity sources result in a terrestrial gamma level of 46.9 microSv y(-1). The drinking water samples collected from the region carry an average of 0.0493 Bq l(-1) of gross alpha and 0.1284 Bq l(-1) of gross beta activities, which together cause an annual effective dose of 1.83 microSv. The measurement results obtained in this study indicate that the region has a background radiation level that is within the natural limits and shows no significant departure from the other parts of the country.     

Soil radioactivity and radiation absorbed dose rates at roadsides in high-traffic density areas in Ibadan metropolis, southwestern Nigeria

The effect of ionising radiation on biological systems depends among other factors on time and place of exposure and population involved. Socio-economic factors in human daily activities have subjected humans to certain environmental health risks. In most cases the risk appears to be higher outdoors than indoors. In order to quantify the radiation exposure levels to individuals in the outdoors in areas with high human and vehicular densities, roadside soil samples were collected from major bus stops and round-about in the metropolis of Ibadan and were analysed for their activity concentration levels using gamma-ray spectrometry. The 40K activity concentration ranged between 96.1 and 336.5 Bq kg(-1) with a mean of 219.8 +/- 71.4 Bq kg(-1); 238U was in the range of 10.2-40.7 Bq kg(-1) with a mean of 20.3 +/- 6.9 Bq kg(-1) while that of 232Th ranged between 13.3 and 29.7 Bq kg(-1) with a mean of 21.2 +/- 5.3 Bq kg(-1). The total gamma absorbed dose rates in air ranged between 17.2 and 41.8 nGy h(-1) with an average of 32.0 +/- 5.8 nGy h(-1). The gamma absorbed dose rates at the roadsides in traffic density areas were found to be lower when compared with previously reported values in natural and undisturbed locations in non-traffic density areas in the city.     

Annual effective dose due to natural radionuclides in building blocks in eight cities of Southwestern Nigeria

The specific absorbed dose rates due to (226)Ra, (232)Th and (40)K in building blocks have been determined for a model dwelling dimension of 3.6 x 3.6 x 3.0 m(3), wall thickness 10 cm and density of 1.73 x 10(3) kg m(-3) in eight cities across Southwestern Nigeria. The Mustonen method of calculating gamma-ray annual exposure rate from the radioactivity concentrations (Bq kg(-1)) of (226)Ra, (232)Th and (40)K in the blocks have been adopted with modifications to suit the Nigerian situation. The specific absorbed dose rates obtained were as follows: 11.36, 14.94 and 0.92 microGy y(-1) per Bq kg(-1) for (226)Ra, (232)Th and (40)K, respectively. These dose rates were used to calculate the annual effective dose in the model dwelling. The annual effective dose obtained varied between 209.20 (Osogbo) and 400.36 microSv y(-1) (Abeokuta). The values are in the range of values obtained for the German Democratic Republic (309 microSv y(-1)) and Jordan (470 microSv y(-1)).     

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.     

Dose rate assessment of terrestrial gamma radiation in the Delta region of Nigeria

In situ gamma spectroscopy has been employed to characterise natural radiation in the soil at 32 locations in the Delta region of Nigeria. The outdoor gamma dose rates in the air due to 40K, 238U and 232Th in the soil were 1.5 +/- 0.9 nGy h(-1), 6.9 +/- 1.6 nGy h(-1) and 16.3 +/- 3.1 nGy h(-1) respectively. The estimated total annual outdoor effective dose to the people in the region was 31.6 microSv y(-1).     

Radiation dose in the high background radiation area in Kerala, India

A systematic radiological survey has been carried out in the region of high-background radiation area in Kollam district of Kerala to define the natural gamma-radiation levels. One hundred and forty seven soil samples from high-background radiation areas and five samples from normal background region were collected as per standard sampling procedures and were analysed for (238)U, (232)Th and (40)K by gamma-ray spectroscopy. External gamma dose rates at all sampling locations were also measured using a survey meter. The activities of (238)U, (232)Th and (40)K was found to vary from 17 to 3081 Bq kg(-1), 54 to 11976 Bq kg(-1) and BDL (67.4 Bq kg(-1)) to 216 Bq kg(-1), respectively, in the study area. Such heterogeneous distribution of radionuclides in the region may be attributed to the deposition phenomenon of beach sand soil in the region. Radium equivalent activities were found high in several locations. External gamma dose rates estimated from the levels of radionuclides in soil had a range from 49 to 9244 nGy h(-1). The result of gamma dose rate measured at the sampling sites using survey meter showed an excellent correlation with dose rates computed from the natural radionuclides estimated from the soil samples.     

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.     

Study of radionuclide distribution around Kudankulam nuclear power plant site (Agastheeswaram taluk of Kanyakumari district, India)

The activity concentration of primordial radionuclides 238U, 232Th and 40K have been measured in the sand samples of Agastheeswaram taluk of Kanyakumari district using gamma-ray spectrometer. The average activity of 232Th, 238U and 40K are found to be 5787.1, 1082.9 Bq kg(-1) and BDL, respectively. The total average absorbed dose rate owing to the presence of 232Th, 238U and 40K is found to be 3900.4 nGy h(-1). The annual effective dose is 4.7 mSv y(-1) and the results are discussed in this paper.     

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.     

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.     

Assessment of absorbed dose rate in air over plowed arable lands in Sinnar State, central Sudan

The absorbed gamma-dose rate in air at a height of 1 m above ground level was calculated from activity concentrations of gamma-emitting radionuclides in arable soil samples collected from eight locations within Sinnar State using the published Dose Rate Conversion Factors. Measurements were carried out using high-resolution gamma-spectrometry. On average, the activity concentrations obtained were 38 +/- 8 ((232)Th), 17 +/- 2 ((226)Ra), 174 +/- 19 ((40)K) and 0.9 +/- 0.2 Bq kg(-1) for the fallout radionuclide (137)Cs. The average value obtained here for (232)Th is slightly higher than the corresponding world-average. The calculated absorbed dose rate in air at a height of 1 m for all sampled locations ranges from 31 to 47 nGy h(-1) with an average value of 39 +/- 7 nGy h(-1) which is characteristic of normal background radiation areas. The corresponding annual effective dose was 47.8 +/- 6 microSv y(-1). The major contribution to the total absorbed dose rate comes from (232)Th, which amounts to 61%. Recalculation of the absorbed dose rate-based gamma-energies of individual nuclides from uranium and thorium decay series and (40)K showed that the greater part of the absorbed dose from the uranium series is due to (214)Bi, whereas for the (232)Th series it is equally attributed to (228)Ac and (208)Tl.     

Natural radioactivity and external dose assessment of surface soils in Vietnam

In this study, natural radioactivity in surface soils of Vietnam and external dose assessment to human population, deduced from activities of (226)Ra, (232)Th and (40)K nuclides, were determined. From 528 soil samples collected in 63 provinces of Vietnam, including five centrally governed cities, the average activities were obtained and equal to 42.77 ± 18.15 Bq kg(-1) for (226)Ra, 59.84 ± 19.81 Bq kg(-1) for (232)Th and 411.93 ± 230.69 Bq kg(-1) for (40)K. The outdoor absorbed dose rates (OADRs) in air at 1 m above the ground level for 63 provinces were calculated, and their average value was 71.72 ± 24.72 nGy h(-1), with a range from 17.45 to 149.40 nGy h(-1). The population-weighted OADR of Vietnam was 66.70 nGy h(-1), which lies in the range of 18-93 nGy h(-1) found in the World. From the OADRs obtained, it was estimated that the outdoor annual effective dose and indoor annual effective dose to the population were 0.082 and 0.458 mSv, which are higher than the corresponding values 0.07 and 0.41 mSv, respectively, of the World. The radium equivalent activity Ra(eq) and the external hazard index H(ex) of surface soils of Vietnam are lower than the corresponding permissible limits of 370 Bq kg(-1) and 1, respectively. Therefore, soil from Vietnam is safe for the human population when it is used as a building material.     

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.     

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 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.     

Natural and anthropogenic radionuclides in the granitic region of Kapidag peninsula, Western Anatolia, Turkey

Naturally occurring radionuclides of terrestrial origin (also called primordial radionuclides) are present in various degrees in all media in the environment. This study represents the reports on the natural and anthropogenic radionuclides in the Kapidag granitic region. For this purpose, activities of radionuclides in soil, beach sands and rocks of the region have been investigated to assess the radiological hazard of the natural radioactivity. The radium equivalent activities, the absorbed dose rates and the external hazard indexes have been calculated, and also in situ gamma dose rates have been measured in the region. The mean activities of (238)U, (232)Th and (40)K with the ranges were determined as 31.1±15.7 (12.1-71.9), 42.5±15.9 (19.7-94.9), 590.3±192.2 (184.7-892.5), in the soil, as 16.5±9.5 (4.9-40.8), 67.1±106.9 (18.5-433.0), 569.2±212.6 (162.0-821.1) in the sand and as 25.4±12.8 (4.8-50.7), 37.8±21.5 (4.5-96.7), and 592.4±285.5 (62.4-1121.6) Bq kg(-1) in the rocks, respectively. It was also observed that the average activities of (137)Cs were ranged 0-27.8 Bq kg(-1) in the soil and 0.6-3.8 Bq kg(-1) in the beach sands. The mean Ra(eq) activities of the rocks, sands and soil were found to be 125.1±59.5, 156.3±157.2 and 137.3±48.8 Bq kg(-1), respectively, lower than the recommended maximum value of 370 Bq kg(-1) with some exceptions. The maximum contributors to the total absorbed gamma dose rates in air were determined as (238)U (45%) for the beach sands, (238)U (40%) for the soil and (40)K (41%) for rocks. The average outdoor gamma dose rates for the soil due to terrestrial and cosmic radiations were found to be 64.6±22.7 and 47.1±9.6 nGy h(-1), respectively, with the total of 111.7±29.5 nGy h(-1) outdoor gamma exposure rate and the annual average effective outdoor gamma dose was calculated as 137±36.2 μSv for the region. The results of the study were discussed with similar studies in close regions and the worldwide averages.     

Radioactivity concentrations and dose assessment for soil samples from Kestanbol granite area, Turkey

The concentrations and distribution of natural and anthropogenic radionuclides in soils from around the Kestanbol (Canakkale), Turkey were investigated with an aim of evaluating the environmental radioactivity and radiological health hazard. Concentrations of radionuclides in the samples were determined by gamma ray spectrometer using HPGe detector. In the soils in general, the concentration of (232)Th was found to be higher than that of the (238)U and the activities of (232)Th and (238)U in this area are higher than the world average. (137)Cs was observed in all the samples, ranging from 0.37 +/- 0.22 to 36.03 +/- 0.54 Bq kg(-1). The mean radium equivalent activity, external hazard index and terrestrial absorbed dose rate for the area under study are 498 Bq kg(-1), 1.4 and 219 nGy h(-1), respectively. The annual effective dose to the public was found to be 269 muSv. The present data were compared with data obtained from different countries.     

Assessment of gamma dose rates from terrestrial exposure in Serbia and Montenegro

The gamma dose rates due to naturally occuring terrestrial radionuclides ((226)Ra, (232)Th and (40)K) were calculated based on their activities in soil samples, determined by gamma-ray spectrometry. A total of 140 soil samples from 21 different regions of Serbia and Montenegro were collected. The gamma dose rates ranged from 7.40 to 29.7 nGy h(-1) for (226)Ra, from 12.9 to 46.5 nGy h(-1) for (232)Th and from 12.5 to 37.1 nGy h(-1) for (40)K. The total absorbed gamma dose rate due to these radionuclides varied from 34.5 to 97.6 nGy h(-1) with mean of 66.8 nGy h(-1). Assuming a 20% occupancy factor, the corresponding annual effective dose varied from 4.23 x 10(-5) to 11.9 x 10(-5) Sv with mean of 8.19 x 10(-5) Sv, i.e. the dose was lower than world wide average value. According to the values of external hazard index (mean: 0.39) obtained in this study, the radiation hazard was found to be insignificant for population living in the investigated area.     

Study on external exposure doses from terrestrial radioactivity in Southern Vietnam

This paper presents the radioactivity concentrations of 226Ra, 232Th and 40K for 106 samples of surface soil collected in Southern Vietnam. The mean values of mass activity of radionuclides 226Ra, 232Th and 40K for Southern Vietnam are 28.6, 50.7 and 292.6 Bq kg(-1), respectively, which lead to the population-weighted absorbed dose rate of 54.5 nGy h(-1). The average annual effective doses outdoors, indoors and in total of Southern Vietnam are estimated to be 0.067, 0.374 and 0.441 mSv, respectively. The radium equivalent activity and the external hazard index of soil in Southern Vietnam are in the range 23.2-254.1 Bq kg(-1) and 0.06-0.69, respectively.