Gamma-emitting radionuclides in the shallow marine sediments off the Sindh coast, Arabian Sea

Determination of gamma emitting radionuclides in shallow marine sediments off the Sindh coast has been carried out using a gamma spectrometry technique. The activity concentration measured in various sediment samples off the Sindh coast has been found to vary from 15.93 +/- 5.22 to 30.53 +/- 4.70 Bq kg(-1) for 226Ra, from 11.72 +/- 1.22 to 33.94 +/- 1.86 Bq kg(-1) for 228Ra and from 295.22 +/- 32.83 to 748.47 +/- 28.75 Bq kg(-1) for 40K. The calculated mean values of radium equivalent activity, absorbed dose rate and effective dose are 98 Bq kg(-1), 49 nGy h(-1) and 0.06 mSv y(-1), respectively. No artificial radionuclide was detected in the samples measured from the study area. As no data on radioactivity of the coastal environment of Pakistan are available, the data presented here will serve as baseline information on radionuclide concentration in shallow sea sediments off the Sindh coast. The data will also be useful for tracking pollution inventories from unusual radiological events (if any) in the territorial waters of the study area. Further, the information presented will contribute to modelling of a regional radioactivity database from the perspectives of the International Atomic Energy Agency's Asia-Pacific Marine Radioactivity Database and Global Marine Radioactivity Database.     

Natural background dose and radium equivalent measurements at Ikogosi warm spring, Nigeria

The natural background dose and the radium equivalent due to the natural radioactivity levels in rocks and sediments collected around Ikogosi warm spring, Nigeria, has been determined in this study using a highly sensitive HpGe detector. The mean activity concentration of (40)K, (226)Ra and (228)Ac were measured to be 585.50 +/- 17.40 Bq kg(-1), 66.91 +/- 5.23 Bq kg(-1) and 48.91 +/- 2.10 Bq kg(-1), respectively, in rock samples while in sediment samples the activity concentrations were found to be 113.89 +/- 5.64 Bq kg(-1) for (40)K, 21.47 +/- 5.14 Bq kg(-1) for (226)Ra and 14.20 +/- 1.07 Bq kg(-1) for (228)Ac. This mean values give rise to average absorbed dose rate of 85.87 nGy h(-1) at a distance of 1.0 m above the ground level and a mean human effective dose equivalent of 0.53 man Sv y(-1) for rock samples. A radium equivalent of 50.55 Bq kg(-1) was measured for the sediment samples. The radium equivalent value is far less than the 370 Bq kg(-1) limit for materials that can be used as building materials while the human effective dose equivalent falls below the world average background dose of 2.4 man Sv y(-1).     

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.     

Investigations on the activity concentrations of 238U, 226RA, 228RA, 210PB and 40K in Jordan phosphogypsum and fertilizers

The activity concentrations of naturally occurring radionuclides ((238)U, (226)Ra, (228)Ra, (210)Pb and (40)K) in Jordanian phosphate ore, fertilizer material and phosphogypsum piles were investigated. The results show the partitioning of radionuclides in fertilizer products and phosphogypsum piles. The outcome of this study will enrich the Jordanian radiological map database, and will be useful for an estimation of the radiological impact of this industrial complex on the immediate environment. The activity concentration of (210)Pb was found to vary from 95 +/- 8 to 129 +/- 8 Bq kg(-1) with a mean value of 111 +/- 14 Bq kg(-1) in fertilizer samples, and from 364 +/- 8 to 428 +/- 10 Bq kg(-1) with a mean value of 391 +/- 30 Bq kg(-1) in phosphogypsum samples; while in phosphate wet rock samples, it was found to vary between 621 +/- 9 and 637 +/- 10 Bq kg(-1), with a mean value of 628 +/- 7 Bq kg(-1). The activity concentration of (226)Ra in fertilizer samples (between 31 +/- 4 and 42 +/- 5 Bq kg(-1) with a mean value of 37 +/- 6 Bq kg(-1)) was found to be much smaller than the activity concentration of (226)Ra in phosphogypsum samples (between 302 +/- 8 and 442 +/- 8 Bq kg(-1) with a mean value of 376 +/- 62 Bq kg(-1)). In contrast, the activity concentration of (238)U in fertilizer samples (between 1011 +/- 13 and 1061 +/- 14 Bq kg(-1) with a mean value of 1033 +/- 22 Bq kg(-1)) was found to be much higher than the activity concentration of (238)U in phosphogypsum samples (between 14 +/- 5 and 37 +/- 7 Bq kg(-1) with a mean value of 22 +/- 11 Bq kg(-1)). This indicates that (210)Pb and (226)Ra show similar behaviour, and are concentrated in phosphogypsum piles. In addition, both isotopes enhanced the activity concentration in phosphogypsum piles, while (238)U enhanced the activity concentration in the fertilizer. Due to the radioactivity released from the phosphate rock processing plants into the environment, the highest collective dose commitment for the lungs was found to be 1.02 person nGy t(-1). Lung tissue also shows the highest effect due the presence of (226)Ra in the radioactive cloud (0.087 person nGy t(-1)).     

Radioactivity of coals and ashes from Catalağzi coal-fired power plant in Turkey

The ?atala?z? coal-fired power plant (CFPP) is the Turkish CFPP that uses the hard coals produced in Zonguldak, located in the West Black Sea region of the country. Gamma-ray spectrometry was used to determine (226)Ra, (232)Th and (40)K contents in pulverised coal, bottom ash and fly ash samples. The natural radionuclide concentrations in pulverised coal ranged from 29 to 61 Bq kg(-1) for (226)Ra, from 32 to 55 Bq kg(-1) for (232)Th and from 229 to 414 Bq kg(-1) for (40)K. The fly ash fraction gave concentrations ranging from 80 to 98 Bq kg(-1) for (226)Ra, from 64 to 85 Bq kg(-1) for Th and from 754 to 992 Bq kg(-1) for (40)K, respectively. The enrichment factors from coal to fly ashes are 1.7, 2.24 and 2.6 for (232)Th, (226)Ra and (40)K, respectively. Therefore, it is advisable to monitor the environmental impact of the power plant.     

Activity concentrations of 226Ra and 228Ra in drilled well water in Finland

The activity concentrations of (226)Ra and (228)Ra in drinking water were determined in water samples from 176 drilled wells. (226)Ra activity concentrations were in the range of <0.01-1.0 Bq l(-1) and (228)Ra activity concentrations in the range of <0.03-0.3 Bq l(-1). The mean activity concentration of (226)Ra and (228)Ra were 0.041 and 0.034 Bq l(-1), respectively. High radium activity concentrations in drinking water were rare. Only 2-4% of the drilled wells exceeded a (226)Ra concentration of 0.5 Bq l(-1) and 1-2% of the wells exceeded a (228)Ra concentration of 0.2 Bq l(-1). These are the activity concentrations that cause a 0.1 mSv annual effective dose for users of drinking water. The maximum annual effective doses from (226)Ra and (228)Ra for users of drilled wells were 0.21 mSv, and 0.16 mSv respectively. The elevated activity concentrations of (226)Ra and (228)Ra did not occur simultaneously in the same groundwaters and the correlation between (226)Ra and (228)Ra was small.     

Gamma activity and radiation dose in concrete building blocks used for construction of dwellings in Jos, Nigeria

Radioactivity concentrations of concrete building block samples made and used in Jos, Nigeria, were determined using a gamma ray spectrometry method. The mean values of the radioactivity concentrations were calculated as 66, 126 and 589 Bq kg(-1) for (226)Ra, (232)Th and (40)K, respectively. The radium equivalent activities ranged between 131 and 712 Bq kg(-1), with six of the samples exceeding the UNSCEAR reported maximum permissible level of 370 Bq kg(-1). The mean radium equivalent activity (292 Bq kg(-1)) is higher than the values available in the literature for some countries by factors ranging between 2 and 5, a situation that can be traced to the practice of sourcing sand aggregates from mining sites. The indoor annual effective dose for a dwelling of dimension 3.6 x 3.6 x 3.0 m(3) was calculated as 0.81 mSv.     

Natural radioactivity in granite stones used as building materials in Iran

Due to increasing concern about environmental radiological protection, specific radioactivity concentrations of (226)Ra, (232)Th and (40)K in different types of commonly used granite stone samples collected from the Tehran city of Iran have been determined by means of a high-resolution HPGe gamma-spectroscopy system. The activity concentrations of (232)Th, (226)Ra and (40)K in the selected granite samples ranged from 18 to 178, 6 to 160 and 556 to 1539 Bq kg(-1), respectively. The radium equivalent activities (Ra(eq)) are lower than the limit of 370 Bq kg(-1) set by NEA-OECD [Nuclear Energy Agency. Exposure to radiation from natural radioactivity in building materials. Report by NEA Group of Experts. OECD (1979)], except in two samples. The internal hazard indexes have been found well below the acceptable limit in most of the samples. Five samples of investigated commercial granite stones do not satisfy the safety criterion illustrated by UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation. Exposure from natural sources of radiation. Report to the General Assembly (1993). Applying dose criteria recently recommended by the EC [European Commission Report on Radiological Protection Principles Concerning the Natural Radioactivity of Building Materials. Radiation Protection 112 (1999)] for superficial materials, all investigated samples meet the exemption dose limit of 0.3 mSv y(-1).     

Assessment of the radiological hazards due to naturally occurring radionuclides in soil samples collected from the north western areas of Pakistan

(226)Ra, (232)Th and (40)K were measured in soil samples, these were collected from different localities of the North West Frontier Province and Federally Administered Tribal Areas, Pakistan. In order to measure the specific activities in these samples P-type coaxial high purity germanium based gamma-ray spectrometer was used. Average values of the measured activities of (226)Ra, (232)Th and (40)K were 26 +/- 11, 39 +/- 17 and 485 +/- 177 Bq kg(-1), respectively. Average radium equivalent activity was found to be 122 +/- 42 Bq kg(-1). External and internal hazard indices were also calculated and found to be 0.33 +/- 0.12 and 0.40 +/- 0.14, respectively. Average effective dose received due to gamma rays was 0.34 +/- 0.12 mSv y(-1). Measured natural radioactivity, hazard indices and effective doses received by the population were found within the recommended limits. The aim of this work was to make a baseline data of natural radioactive elements for the soil of the area and to assess it radiological significance if used as a building material for the construction of houses.     

Gamma-ray spectroscopic analysis of selected samples from Nile river sediments in upper Egypt

Selected sedimentary samples from different locations on the east and west banks of the Nile River in Upper Egypt were analysed by natural radioactivity measurements to detect the presence of radioactive elements. From the analysis of radiations from 226Ra, 232Th and (40)K isotopes, the samples were found to contain Ra, Th and K in concentrations up to 52 +/- 7.3, 76.2 +/- 6.2 and 351.9 +/- 17.6 Bq kg(-1), respectively. The absorbed dose rate in air was found to be in the range of 9.6-84.8 nGyh(-1). The representative external hazard index values for the corresponding samples were also estimated.     

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.     

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.     

Measurement of natural radioactivity in beach sands from Rizhao bathing beach, China

The natural radioactivity of (226)Ra, (232)Th and (40)K was determined for beach sand samples collected from Rizhao bathing beach, China, using gamma ray spectrometry. The measured activity in beach sand ranges from 7.6 to 17.2, 7.8 to 25.1 and 883.4 to 1313.6 Bq kg(-1) for (226)Ra, (232)Th and (40)K with mean values of 12.0, 15.2 and 1079.2 Bq kg(-1), respectively. The activity concentrations of (226)Ra and (232)Th in beach sands are lower, while (40)K is higher than the world average. The radium equivalent activity in all beach sand samples is lower than the safe limit set in the OECD report (370 Bq kg(-1)). The values of the external hazard index are less than unity. The mean outdoor air absorbed dose rate is 59.8 nGy h(-1) and the corresponding outdoor effective dose rate is 0.073 mSv y(-1).     

Population dose due to building materials in Ibadan, Nigeria

The natural radionuclide contents of some concrete building blocks randomly sampled in the city of Ibadan have been determined using NaI(Tl) gamma ray spectrometry. The radionuclides 226Ra, 232Th and 40K were determined with city mean specific activities 47 +/- 21 Bq.kg-1, 52 +/- 21 Bq.kg-1, and 352 +/- 222 Bq.kg-1, respectively. These activities amount to a radium equivalent of about 150 Bq.kg-1, which is lower than the recommended maximum value of 370 Bq.kg-1. The mean value of the external hazard index was found to be 0.41 which implies that the building blocks used in the city of Ibadan are within the acceptable level of radioactivity. The mean indoor gamma dose equivalent to individuals due to the walls was calculated to be 412 microSv.y-1 and the collective dose equivalent 563 man.Sy.y-1.     

Radioactivity measurement of primordial radionuclides in and dose evaluation from marble and glazed tiles used as covering building materials in Turkey

Measurements of the natural radioactivity arising from primordial radionuclides ((226)Ra, (232)Th and (40)K) in marble and glazed tile samples used covering building materials in Turkey were carried out by gamma-ray spectrometer with a high purity germanium detector. The mean activity concentrations of the (226)Ra, (232)Th and (40)K in marble and glazed tile samples were found as 8.2, 5.5 and 58.1 Bq kg(-1) and 81.2, 65.4 and 450.1 Bq kg(-1), respectively. The radiation doses received by occupants of buildings in which the sample marble and glazed tiles might be used are estimated using measured activity concentrations of constituent primordial radionuclides and dose conversion factors evaluated by the European Commission from models of tile use. Results obtained are presented for each radionuclide, analysed and compared with relevant national and international legislation, guidance and report, and with the results obtained from other studies. Results show that the use of such decorative building materials in the construction of domestic homes or workplaces in Turkey is unlikely to lead to any significant radiation exposure to the occupants.     

Measurements of activity concentrations of naturally occurring radionuclides in soil samples from Punjab province of Pakistan and assessment of radiological hazards

The natural level of radioactivity in soil is one of the major causes of external gamma rays exposure. It was considered imperative to measure gamma-ray activity concentrations due to naturally occurring, potentially hazardous radionuclides from 232Th, 226Ra and 40K in soil samples from Punjab, the most populated province of Pakistan. The activity concentrations were measured in soil samples collected from all 34 district headquarters of Punjab province using a P-type coaxial high purity germanium (HPGe)-based gamma-ray spectrometer having a relative efficiency of 60%. The mean activity concentrations for 232Th, 226Ra and 40K were found to be 41 +/- 8, 35 +/- 7 and 615 +/- 143 Bq kg(-1), respectively in soil samples from all 34 district headquarters of Punjab. The mean values of radium equivalent index (Ra(eq)) and total annual external gamma radiation dose were found to be 141 +/- 27 Bq kg(-1)and 0.38 mSv, respectively. Since these estimated radiological impact assessment factors are lower than the recommended values there seems to be no potential radiological health hazard associated with the soils from the district headquarters in the Punjab province of Pakistan. Geological studies show that most of the soils in Punjab have developed on the extensive fluviatile deposits of five rivers and a stable ratio of natural activity concentrations is observed in soil samples of the areas under study.     

Measurement of natural radioactivity in sand samples collected along the bank of rivers Indus and Kabul in northern Pakistan

Radioactivity is a part of the natural environment. The presence of natural radioactivity in sand and other building materials results in internal and external exposure to the general public. Therefore, it is desirable to determine the concentration of naturally occurring radionuclides, namely (232)Th, (226)Ra and (40)K in sand, bricks and cement which are commonly used as building materials in Pakistan. In this context, sand samples were collected from 18 different locations covering an area of ～1000 km(2) along the banks of river Indus (Ghazi to Jabba) and river Kabul (Nowshera to Kund) in the northern part of Pakistan, whereas bricks and cement samples were collected from local suppliers of the studied area. In order to measure the specific activities in these samples, a P-type coaxial high-purity germanium-based gamma-ray spectrometer was used. In sand samples, the average specific activities of (226)Ra, (232)Th, and (40)K were found to be 30.5±11.4, 53.2±19.5 and 531±49 Bq kg(-1), whereas in brick samples, specific activities of 30±14, 41±21 and 525±183 Bq kg(-1) were observed, respectively. In cement samples, measured specific activity values were 21±5, 14±3 and 231±30 Bq kg(-1), respectively. Radium equivalent activities were calculated and found to be 143.8±38.6, 124±49.8 and 56.69±7 Bq kg(-1) for sand, brick and cement samples, respectively. The annual mean effective dose for the studied sand samples was found to be 0.40 mSv. External and internal hazard indices were less than unity for all the studied samples. The present results have been compared with those reported in the literature.     

Natural radioactivity levels of granites used in Turkey

Thirty granite samples commonly used in Turkey were surveyed for natural radioactivity. Concentrations of natural radionuclides in all samples were determined by gamma-ray spectroscopy with hyper-pure germanium detector. The activity concentrations measured for (226)Ra and (232)Th ranged from 0.7±0.1 to 186±1 Bq kg(-1), and from 0.5±0.1 to 249±2 Bq kg(-1), respectively. The activity concentrations obtained for (40)K varied from minimum detectable activity (0.4 Bq kg(-1)) to 1935±11 Bq kg(-1). The radium equivalent activity (Ra(eq)), the absorbed dose rate (D), the external hazard index (H(ex)) and the annual effective dose equivalent were also calculated and compared with the international recommended values. Granite samples were also analysed mineralogically. It was observed that the presence of large amount orthoclase and radiogenic accessory minerals are the sources of high activity concentration levels.     

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.     

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.