Environmental radioactivity measurements in Greece following the Fukushima Daichi nuclear accident

Since the double disaster of the 9.0 magnitude earthquake and tsunami that affected hundreds of thousands of people and seriously damaged the Fukushima Daichi power plant in Japan on 11 March 2011, traces of radioactive emissions from Fukushima have spread across the entire northern hemisphere. The radioactive isotope of iodine (131)I that was generated by the nuclear accident in Fukushima arrived in Greece on 24 March 2011. Radioactive iodine is present in the air either as gas or bound to particles (aerosols). The maximum (131)I concentrations were measured between 3 and 5 April 2011. In aerosols the maximum (131)I values measured in Southern Greece (Athens) and Northern Greece (Thessaloniki) were 585±70 and 408±61 μΒq m(-3), respectively. (131)I concentrations in gas were about 3.5 times higher than in aerosols. Since 29 April 2011, the (131)I concentration has been below detection limits. Traces of (137)Cs and (134)Cs were also measured in the air filters with an activity ratio of (137)Cs/(134)Cs equal to 1 and (131)I/(137)Cs activity ratio of about 3. Since 16 May 2011, the (137)Cs concentration in air has been determined to be about the same as before the Fukushima accident. Traces of (131)I were also measured in grass and milk. The maximum measured activity of (131)I in sheep milk was about 2 Bq l(-1) which is 5000 times less than that measured in Greece immediately after the Chernobyl accident. The measured activity concentrations of artificial radionuclides in Greece due to the Fukushima release, have been very low, with no impact on human health.     

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)).     

Vertical distributions of 137Cs, 40K, 232Th and 226Ra in soil samples from Istanbul and its environs, Turkey

Determining the distribution of natural and artificial radionuclides in soil profiles as well as the surface layer of the soil is necessary due to the fact that radionuclides can enter the food chain from deeper soil layers and also contaminate ground water. In the current study, the activity-depth profiles of (137)Cs were determined in soil samples from 20 sites in and around the city of Istanbul. Naturally occurring radionuclides were determined at 12 of the locations. Uncultivated soil samples were taken in six horizontal layers at each location. Activity concentrations were measured with a gamma spectrometer. The impacts of texture, organic matter and pH of the soil on the vertical distribution of the radionuclides were also studied. The average and standard deviations of (137)Cs and (40)K activity concentrations in soil at a depth of 5 cm were found to be 16.46±14.71 and 450.2±239.1 Bq kg(-1), respectively. The activity concentrations of (40)K, (232)Th and (226)Ra were distributed uniformly with regard to soil depth. The depth distribution of (137)Cs generally fitted a linear function. The study revealed that >20 y after the Chernobyl disaster of 1986, 55 % of (137)Cs still remains in the upper 10 cm of soil in the Istanbul environment.     

Measurement of radioactivity in the soil of Bahawalpur division, Pakistan

Bahawalpur is the largest division of the Punjab province in Pakistan. It is larger than many countries of the world. Gamma activity from the naturally occurring radionuclides namely 226Ra, 232Th, the primordial radionuclide 40K and the artificial radionuclide 137Cs was measured in the soil of the Bahawalpur division using gamma spectrometry technique. The mean activity of 226Ra, 232Th, 40K and 137Cs were found to be 32.9 +/- 0.9, 53.6 +/- 1.4, 647.4 +/- 14.1 and 1.5 +/- 0.2 Bq kg(-1), respectively. The mean radium equivalent activity Raeq, external hazard index, internal hazard index and terrestrial absorbed dose rate for the area under study are 158.5 +/- 4.1 Bq kg(-1), 0.4, 0.5 and 77.32 nGy h(-1), respectively. The annual effective dose equivalent to the public was found to be 0.5 mSv.     

Activity Concentration of 137Cs in soil samples from Punjab province (Pakistan) and estimation of gamma-ray dose rate for external exposure

Punjab is one of the most populated provinces of Pakistan having 34 districts. There is always a need to have baseline background level information about 137Cs and the corresponding gamma-ray doses to the population. In this respect, soil samples were collected to a depth of 30-50 cm from all 34 district headquarters of the Punjab province of Pakistan and 137Cs activity concentrations were measured. 137Cs activity concentration was found to be in the range from 1.1 +/- 1.0 to 5.3 +/- 2.5 Bq kg(-1). The average value of estimated external gamma-ray dose rate from all 34 districts of Punjab province was computed to be 0.18 +/- 0.07 nSv h(-1) from 137Cs in soil samples. The measured 137Cs activity concentration range was compared with the reported ranges in the literature from some of the other locations in the world. Results obtained in this study show that 137Cs concentration is of a lower level in the investigated area. The average value of estimated external effective dose rate is found far below the dose rate limit of 1.0 mSv y(-1) for members of the general public recommended by the International Commission on Radiological Protection (ICRP) as well as the external gamma radiation dose of 0.48 mSv y(-1) received per head from the natural sources of radiation assessed by UNSCEAR (2000). It is concluded that 137Cs soil contamination does not pose radiation hazards to the population in the investigated areas.     

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.     

Environmental gamma radiation measurement in district Swat, Pakistan

External exposure to environmental gamma ray sources is an important component of exposure to the public. A survey was carried out to determine activity concentration levels and associated doses from (226)Ra, (232)Th, (40)K and (137)Cs by means of high-resolution gamma ray spectrometry in the Swat district, famous for tourism. The mean concentrations for (226)Ra, (232)Th and (40)K were found to be 50.4 +/- 0.7, 34.8 +/- 0.7 and 434.5 +/- 7.4 Bq kg(-1), respectively, in soil samples, which are slightly more than the world average values. However, (137)Cs was only found in the soil sample of Barikot with an activity concentration of 34 +/- 1.2 Bq kg(-1). Only (40)K was determined in vegetation samples with an average activity of 172.2 +/- 1.7 Bq kg(-1), whereas in water samples, all radionuclides were found below lower limits of detection. The radium equivalent activity in all soil samples is lower than the limit set in the Organisation for Economic Cooperation and Development report (370 Bq kg(-1)). The value of the external exposure dose has been determined from the content of these radionuclides in soil. The average terrestrial gamma air absorbed dose rate was observed to be 62.4 nGy h(-1), which yields an annual effective dose of 0.08 mSv. The average value of the annual effective dose lies close to the global range of outdoor radiation exposure given in United Nations Scientific Committee on the Effects of Atomic Radiation. However, the main component of the radiation dose to the population residing in the study area arises from cosmic ray due to high altitude.     

Contribution of different foodstuffs to the internal exposure of rural inhabitants in Russia after the Chernobyl accident

In a large village, Veprin of the Bryansk region of Russia contaminated with radionuclides as a result of the Chernobyl accident, 137Cs concentration in food products of agricultural produce and natural origin was regularly measured, local inhabitants were polled on the composition of their diet, and the 137Cs content in their bodies was measured at the same time. These results were used as the basis for calculation of annual effective doses of internal exposure to inhabitants and for reconstruction of the dose during the entire period after the accident (1986-1996). The efficiency of countermeasures performed for reduction of the internal dose was assessed. The internal dose in inhabitants during the 10 years after the accident was shown to be reduced by countermeasures by a factor of 2, namely down to 35 mSv instead of the expected 70 mSv. The dose of external gamma radiation during the same time period is close to the obtained dose of internal exposure. The presence of peat and water-meadow soils in the vicinity of this village that are characterised by high transfer factors for radionuclides from soil to vegetation causes a high contribution of internal exposure to the total dose of population exposure. The contribution of natural products to the internal dose increased from 6% in 1987 increased to 25% in 1996. The individual content of 137Cs in the body of inhabitants reliably correlates with consumption of milk in the initial period after the accident and with consumption of forest mushrooms in the subsequent period.     

Natural radioactivity and external gamma radiation exposure at the coastal Red Sea in Egypt

Radionuclides which present in different beach sands are sources of external exposure that contribute to the total radiation exposure of human. In this work, superficial samples of beach sand were collected from the Red Sea coastline (Ras Gharib, Hurghada, Safaga, Qusier and Marsa Alam areas) and at 20 km on Qena-Safaga road. The distribution of natural radionuclides in sand beach samples was studied by gamma spectrometry. The activity concentrations of primordial and artificial radionuclides in samples that are collected from the coastal environment of the Red Sea were 19.2 +/- 3 Bq kg(-1) for (210)Pb, 21.1 +/- 1 Bq kg(-1) for (226)Ra, 22.7 +/- 2 Bq kg(-1) for (238)U, 1.0 +/- 0.1 Bq kg(-1) for (235)U, 11.6 +/- 1 Bq kg(-1) for (228)Ra, 13.0 +/- 1 Bq kg(-1) for (228)Th, 12.4 +/- 1 Bq kg(-1) for (232)Th, 930 +/- 32 Bq kg(-1) for (40)K and 1.2 +/- 0.3 Bq kg(-1) for (137)Cs. The mean external gamma-dose rate was 62.5 +/- 3.2 nSv h(-1), 54.4 +/- 2.8 nGy h(-1) Ra equivalent activity (Ra(eq)) was 107 +/- 5.8 Bq kg(-1), 0.86 +/- 0.04 Bq kg(-1) for representative level index (I(gamma)) and effective dose rate was 0.067 +/- 0.003 mSv y(-1) in beach sand red sea, in air due to naturally occurring radionuclides.     

Natural and artificial radionuclide measurements and radioactivity assessment of soil samples in eastern Sichuan province (China)

The activity concentrations of natural and artificial radionuclides were measured in the eastern region of Sichuan province (China). One hundred and ninety-three soil samples from this region were collected and analysed by high-purity germanium gamma spectrometry. The measured results show that the average radioactivity concentrations of (226)Ra, (232)Th, (40)K and (137)Cs in the soil samples are 26, 49, 440 and 6 Bq kg(-1), respectively. The calculated average radium equivalent activity is 130 Bq kg(-1), which is less than the recommended limit of 370 Bq kg(-1). The absorbed dose rate and annual effective dose are 60 nGy h(-1) and 74 μSv, respectively. This is the first time the absorbed dose rate in the east region of Sichuan has been mapped. Overall, the environmental radiation background is greater in the southern part of the area studied than in the northern.     

Independent regulatory examination of radiation situation in the areas of spent nuclear fuel and radioactive wastes storage in the Russian far east

This paper describes the findings of the radiation situation analysis on-site near Sysoeva and Razbojnik Bays. The results of radiation monitoring performed by radiological laboratory of DalRAO and studies performed by the experts from the Burnasyan Federal Medical Biophysical Centre have been used in the course of analysis. On the industrial sites, gamma dose rate reaches 60 μSv h(-1), and the specific activities of man-made radionuclides in soil reach 2.5 × 10(4) Bq kg(-1) for (137)Cs, 7.6 × 10(3) Bq kg(-1) for (90)Sr and 2.0 × 10(3) Bq kg(-1) for (60)Co. Beyond the industrial sites, there are three local parts of the area on the coast and in the off-shore water area, contaminated with man-made radionuclides. Gamma dose rate reaches 8 μSv h(-1). The radionuclide contents in soil at this area reach 3.6 × 10(3), 2.8 × 10(3) and 19 Bq kg(-1) for (137)Сs, (90)Sr and (60)Со, respectively. At the remaining part of the area nearby Sysoeva Bay, the radiation situation complies with natural background.     

Measurement of natural radioactivity and dose rate assessment of terrestrial gamma radiation in the soil of southern Punjab, Pakistan

Activity concentrations of (226)Ra, (232)Th, (40)K and (137)Cs in soil samples collected from the most populous area of southern Punjab of Pakistan have been measured by gamma-ray spectrometry. The measured activity concentrations for these radionuclides are compared with the reported data from different other countries and it is found that measured activity concentrations are comparable with the worldwide measured average values reported by the UNSCEAR. Subsequently assessed radiological effects show that the mean radium equivalent activity (Ra(eq)) is 96.7 +/- 15.2 Bq kg(-1) and air absorbed dose rate (D) is 46.1 +/- 7.3 nGy h(-1). The values of internal and external radiation hazard indices are found to be less than unity. The annual effective radiation dose is calculated to be 0.28 +/- 0.05 mSv, which is well below the limit of 1.0 mSv y(-1) recommended by the International Commission on Radiological Protection, for the general public.     

Modelling the 137Cs ingestion dose from consumption of marine fish in Hong Kong

This paper presents a compartmental model for estimating the ingestion dose, due to 137Cs, arising from the consumption of marine fish in Hong Kong. 137Cs is one of the more important radionuclides released in routine liquid effluents discharged from the Guangdong Nuclear Power Station at Daya Bay, which began commercial operation in 1994. In the model, three sea/ocean compartments are considered. Assuming the discharge of this radionuclide is maintained at a constant rate, the model shows that the concentration of 137Cs in the water and in the marine fish in the three sea compartments would become steady after 5 years. The predicted annual dose to an average local individual in Hong Kong, for a release rate of 10 GBq.y(-1), is 3.2 x 10(-5) microSv, which is dominated by the contribution from fish cultured in Hong Kong waters. The cumulative collective dose to the local population of 6 million, at 50 years of discharge, amounts to 9.0 x 10(-3) man.Sv. The annual dose to members of the critical group of local fish farmers does not exceed 3.0 x 10(-3) microSv. All these doses are small compared to the dose of around 1.2 microSv.y(-1) arising from ingestion of naturally occurring radionuclides found in marine fish. Sensitivity of model parameters and uncertainties of prediction are also studied. Difficulties encountered in model validation are discussed. Despite such difficulties. limited field data that are available show that the predicted results are generally within one order of magnitude with measurements.     

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.     

Estimation of beta-ray skin dose from exposure to fission fallout from the Hiroshima atomic bomb

Beta-ray skin dose due to the fission fallout from the Hiroshima atomic bomb is potentially related to the epilation in the black rain area. The absorbed dose to the skin from beta-rays emitted by fission fallout has been estimated for an initial 13?Cs deposition of 1 kBq m?2 on the ground at 0.5 h after the explosion. The estimated skin dose takes into account both external exposure from fission fallout radionuclides uniformly distributed in 1 mm of soil on the surface of the ground and from a 26 μm thickness of contaminated soil on the skin, using the Monte Carlo radiation transport code MCNP-4C. The cumulative skin dose for 1 month after the explosion is taken as the representative value. The estimated skin dose for an initial 13?Cs deposition of 1 kBq m?2 was determined to be about 500 mSv.     

Estimation of annual effective dose due to natural and man-made radionuclides in the metropolitan area of the Bay of Cadiz (SW of Spain)

In order to investigate the radiological hazard of naturally occurring radioactive material (NORM) and man-made (137)Cs radionuclide in the Bay of Cádiz, 149 samples of sediments have been analysed. Activity concentration in all the samples was determined using a HPGe detection system. Activity concentrations values of (226)Ra, (232)Th, (40)K and (137)Cs in the samples were 12.6±2.6 (2.5-40.6), 18.5±4.0 (2.8-73.4), 451±45 (105-1342) and 3.2±1.3 (0.2-16.0) Bq kg(-1), respectively. Outdoor external dose rate due to natural and man-made radionuclides was calculated to be 35.79±1.69 (4.71-119.16) nGy h(-1) and annual effective dose was estimated to be 43.89±2.27 (5.78-146.14) μSv y(-1). Results showed low levels of radioactivity due to NORM and man-made (137)Cs radionuclide in marine sediments recovered from the Bay of Cádiz (Spain), discarding any significant radiological risks related to human activities of the area. Furthermore, the obtained data set could be used as background levels for future research.     

Vertical distributions and gamma dose rates of 40K, 232Th, 238U and 137Cs in the selected forest soils in Izmir, Turkey

This paper presents the results obtained from a radioecological study carried out in the selected forest sites of Izmir, Turkey. The levels of gamma-emitting radionuclides, 40K, 232Th, 238U and 137Cs, in soils were determined using gamma spectroscopy. The activity profile for 40K, 232Th and 238U exhibits a uniform distribution with respect to depth. The depth distribution of 137Cs activity was established by fitting the experimental points to an exponential or a Gaussian function. About 42-97% of the 137Cs deposition was found in the first 10 cm of soil even after 18 y from Chernobyl accident. The dose-rate and annual-effective dose received from external irradiation were quantified. It is indicated that 137Cs from the fallout plays a less role in external radiation exposures in forest sites of Izmir than in potential exposures from naturally occurring radionuclides accounted for by soil.     

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.     

Natural and artificial radioactivity distribution in soil of Fars Province, Iran

Fars province is a large populated large province located in the southwest of Iran. This work presents a study of natural and radioactivity levels in soil samples of this province. For this purpose, 126 samples were gathered from different regions of the province and analysed by gamma spectroscopy to quantify radioactivity concentrations of radionuclides using a high-purity germanium detector and spectroscopy system. The results of this investigation show the average concentrations of 271 ± 28 Bq kg(-1), 6.37 ± 0.5 Bq kg(-1), 14.9 ± 0.9 Bq kg(-1) and 26.3 ± 1.9 Bq kg(-1) for (40)K, (137)Cs, (232)Th and (238)U in soil, respectively. Finally, baseline maps were established for the concentrations of each of the radionuclides in different regions. The absorbed dose rate and the annual effective dose (AED) were also calculated for the radionuclides according to the guidelines of UNSCEAR 2000. The average AED from the radioactivity content of soil in this province was found to be 39.9 ± 1.8 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.