Distribution of naturally occurring radionuclides activity concentration in East Malaysian marine sediment

Studies of naturally occurring radioactive materials (NORM) distribution of ²²⁶Ra, ²²⁸Ra and ⁴⁰K in East Malaysia were carried out as part of a marine coastal environment project. The results of measurements will serve as baseline data and background reference level for Malaysia coastlines. Sediments from 21 coastal locations and 10 near shore locations were collected for analyses. The samples were dried, finely ground, sealed in a container and stored for a minimum of 30 days to establish secular equilibrium between ²²⁶Ra and ²²⁸Ra and their respective radioactive progenies. They were counted using a high-purity germanium (HPGe) spectrometer covering the respective progeny energy peak. For ⁴⁰K, the presence of this was measured directly via its 1460 keV energy peak. The concentration of ²²⁶Ra, ²²⁸Ra and ⁴⁰K in samples obtained from coastal Sarawak ranged between 23 and 41 (mean 30±2) Bq/kg, 27 and 45 (mean 39±4) Bq/kg and 142 and 680 (mean 462±59) Bq/kg, respectively. Meanwhile, the concentration of ²²⁶Ra, ²²⁸Ra and ⁴⁰K for samples obtained from coastal Sabah ranged between 16 and 30 (mean 23±2) Bq/kg, 23 and 45 (mean 35±4) Bq/kg and 402 and 842 (mean 577±75) Bq/kg, respectively. For the Sarawak near shore stations, the concentration of ²²⁶Ra, ²²⁸Ra and ⁴⁰K ranged between 11 and 36 (mean 22±2) Bq/kg, 21 and 65 (mean 39±5) Bq/kg and 149 and 517 (mean 309±41) Bq/kg, respectively. Meanwhile, the concentration of ²²⁶Ra, ²²⁸Ra and ⁴⁰K for samples obtained from Sabah ranged between 9 and 31 (mean 14±2) Bq/kg, 10 and 48 (mean 21±3) Bq/kg and 140 and 580 (mean 269±36) Bq/kg, respectively. The calculated external hazard values of between 0.17 and 0.33 (less than unity) showed that there is little risk of external hazard to the workers handling the sediments.     

Radioactivity levels of recent sediments in the Butrint Lagoon and the adjacent coast of Albania.

Sediment samples have been collected in the Butrint area, located in the south-west Albania to determine the radioactivity levels of (40)K, (137)Cs, (212)Bi, (212)Pb, (214)Bi, (214)Pb, (226)Ra and (228)Ac on the bed of the lagoon and adjacent sea, using direct counting gamma spectroscopy. The concentration of (137)Cs and (40)K varied from 2.8 to 37.5 Bq/kg and from 266 to 675 Bq/kg dry weight (dw), respectively (central values). The average concentrations of (238)U and (232)Th daughter products varied from 8 to 27 Bq/kg and from 13 to 40 Bq/kg dw, respectively. The measured (235)U activity ranged from 0.7 to 2.5 Bq/kg dw. Samples of different sedimentary properties, studied for the radioactivity concentration, revealed an inversely proportional relation between grain size and a linear combination of measured specific activities of (226)Ra, (232)Th ((228)Ac, (212)Bi and (212)Pb), (40)K and (137)Cs.     

Radiological impact assessment to the environment due to waste from disposal of porcelain

The present study aimed to assess the radiological parameters from gamma rays due to the uncontrolled disposal of porcelain waste to the environment. Qualitative and quantitative identification of radionuclides in the investigated samples was carried out by means of a high-purity germanium (HPGe) detector. The average activity concentrations of the local porcelain samples were measured as 208.28?Bq/kg for ²²⁶Ra, 125.73?Bq/kg for ²³⁸U, 84.94?Bq/kg for ²³²Th and 1033.61?Bq/kg for ⁴⁰K, respectively. The imported samples had an average activity of 240.57?Bq/kg for ²²⁶Ra, 135.56?Bq/kg for ²³⁸U, 115.74?Bq/kg for ²³²Th and 1312.49?Bq/kg for ⁴⁰K, respectively. Radiological parameters and the radium equivalent Ra_eq for the investigated samples were calculated. The external and internal hazard indices, representative level index (I_γ), alpha index (I_α), and the exemption level (I_x), were estimated to be higher than the recommended value (unity), while the average activity concentrations for the studied samples were higher than recommended levels. In conclusion, we are concerned that disposal of porcelain in the environment might be a significant hazard.     

Natural radioactivity in Algerian building materials.

Samples of natural and manufactured building materials collected from Algiers have been analysed for 226Ra, 232Th and 40K using a high-resolution HPGe gamma-spectrometry system. The specific concentrations for 226Ra, 232Th and 40K, from the selected building materials, ranged from (12-65 Bq kg(-1)), (7-51 B qkg(-1)) and (36-675 Bq kg(-1)), respectively. The measured activity concentrations for these natural radionuclides were compared with the reported data of other countries and with the world average activity of soil. Radium-equivalent activities were calculated for the measured samples to assess the radiation hazards arising from using those materials in the construction of dwellings. All building materials showed Ra(eq) activities lower than the limit set in the OECD report (370 Bq kg(-1)), equivalent to external gamma-dose of 1.5 mSv yr(-1).     

云南省部分地区大米和玉米放射性核素水平调查

目的 调查云南省部分地区大米和玉米放射性核素水平,充实云南地区食品放射性水平基线数据,评估其对居民产生的健康风险。方法 依据国家标准《生物样品中放射性核素的γ能谱分析方法》《高纯锗γ能谱分析通用方法》《食品中放射性物质检验总则》《土壤中放射性核素的γ能谱分析方法》,对云南省20个县（区）大米和玉米样品进行放射性核素检测,对检测结果进行处理与分析。结果 大米样品中²³⁸U、²³²Th、²²⁶Ra、⁴⁰K和¹³⁷Cs活度浓度均值分别为（0.416±0.403）、（0.045±0.034）、（0.030±0.013）、（28.4±18.8）和（0.014±0.019）Bq/kg,玉米样品中²³⁸U、²³²Th、²²⁶Ra、⁴⁰K活度浓度均值分别为（0.308±0.230）、（0.035±0.031）、（0.053±0.072）、（56.8±38.6）Bq/kg,¹³⁷Cs的活度浓度低于探测下限。结论 云南省20个县（区）大米和玉米中²³⁸U、²³²Th、²²⁶Ra、⁴⁰K和¹³⁷Cs的放射性水平均在国家标准正常范围内,食入后不会对居民的健康造成影响。     

Natural gamma-emiting radionuclides in Pakistani Portland cement.

Studies of the natural gamma-emitting radionuclides in Portland cement manufactured in the North West Frontier Province (NWFP) of Pakistan and the various raw materials which compose the product have been carried out using gamma-spectrometric techniques. For data acquisition a high-purity germanium detector (HPGe) was used. The range of the total specific activity (minimum and maximum values) due to all the three radionuclides (40K, 226Ra and 232Th) were found to be 187.8+/-63.5-573.2+/-73.1 Bq kg(-1) (Portland cement); 54.5+/-16.1-183.9+/-31.4 Bq kg(-1) (limestone); 87.1+/-30.7-297.1+/-64.4 Bq kg(-1) (gypsum); 696.4+/-79.1-1043.9+/-85.0 Bq kg(-1) (slate); and 490.9+/-54.5-570.2+/-59.8 Bq kg(-1) (latrite). The average specific activities due to 40K in Portland cement and all the raw materials were found to be higher when compared with 226Ra and 232Th. Such materials do not pose any excess radiological health problem.     

拉萨市天然石材放射性水平调查

目的 对拉萨市天然石材进行放射性水平调查研究,了解其放射性核素比活度范围及使用限制。方法 对拉萨市各天然石材矿区进行辐射监测和调查取样,对采集的样品进行放射性核素含量分析,根据分析结果计算内、外照射指数,并根据建筑材料放射性核素限量标准进行分类。结果 拉萨市天然石材样品中⁴⁰K、²²⁶Ra、²³²Th和²³⁸U比活度均值分别为912、59.0、77.1和64.4 Bq/kg,样品内、外照射指数均<1。结论 本次调查的拉萨市产天然石材放射性核素含量水平总体低于全国平均水平,可作为建筑主体材料及A类装饰装修材料。     

Determination of the natural radioactivity levels in north west of Dukhan, Qatar using high-resolution gamma-ray spectrometry

This study is aimed at the determination of the activity concentrations of naturally occuring and technologically enhanced levels of radiation in 34 representative soil samples that have been collected from an inshore oil field area which was found to have, in a previous study, the highest observed value of 226Ra concentration among 129 soil samples. The activity concentrations of 238U and 226Ra have been inferred from gamma-ray transitions associated with their decay progenies and measured using a hyper-pure germanium detector. Details of the sample preparation and the gamma-ray spectroscopic analysis techniques are presented, together with the values of the activity concentrations associated with the naturally occuring radionuclide chains for all the samples collected from NW Dukhan. Discrete-line, gamma-ray energy transitions from spectral lines ranging in energy from ～100 keV up to 2.6 MeV have been associated with characteristic decays of the various decay products within the 235.8U and 232Th radioactive decay chains. These data have been analyzed, under the assumption of secular equilibrium for the U and Th decay chains. Details of the sample preparation and the gamma-ray spectroscopic analysis techniques are presented. The weighted mean value of the activity concentrations of 226Ra in one of the samples was found to be around a factor of 2 higher than the values obtained in the previous study and approximately a factor of 10 higher than the accepted worldwide average value of 35 Bq/kg. The weighted mean values of the activity concentrations of 232Th and 40K were also deduced and found to be within the worldwide average values of 30 and 400 Bq/kg, respectively. Our previous study reported a value of 201.9±1.5Stat.±13Syst.Bq/kg for 226Ra in one sample and further investigation in the current work determined a measured value for 226Ra of 342.00±1.9Stat.±25Syst.Bq/kg in a sample taken from the same locality. This is significantly higher than all the other investigated soil samples in the current and previous works. Notably, the Th levels in the same sample are within the worldwide average expectations, implying that the increased 226Ra concentration arises from TENORM processes.     

Behavior and environmental impacts of radionuclides during the hydrometallurgy of calcareous and argillaceous rocks, southwestern Sinai, Egypt

The hydrometallurgy of radionuclides means getting the radioelements from the rocks into solution by leaching, getting the radionuclides from the solution by extraction process, and then precipitation of the desired elements to obtain concentrate. The follow-up of the radionuclides during these processes is the main target of this work to identify the identity of the original samples, pregnant solutions (leachates), residuals and the concentrate. Six samples were chosen to achieve this work. The leaching process was carried out under the conditions; 20-30% acid (H(2)SO(4)) concentration, 1:3 solid/liquid ratios, 60 min stirring time at room temperature. The activity concentrations of (238)U, (235)U, (234)U, (226)Ra, (214)Pb, (214)Bi, (232)Th and (40)K were measured in the original samples, residuals and U-concentrate (Bq/kg), and leachates (Bq/?). The results indicate that, the radionuclides before (226)Ra in the (238)U decay series are more leachable (released) than those from (226)Ra to (214)Bi in the order; (234)U>(238)U=(235)U > (226)Ra>(214)Pb>(214)Bi. (232)Th and (40)K are immobile under the present conditions. The radiological hazards of natural radioactivity in the original samples, leachates, residuals and U-concentrate were calculated and compared with the internationally recommended values and were found to be much higher than the world average values.     

Spatial and monthly variations of radium isotopes in produced water during oil production.

Spatial and monthly variations of radium isotope concentrations in produced water have been evaluated during oil production. Samples of produced water were collected and analyzed on a monthly basis over a period of 5 months, the samples being derived from 11 main oil production wells at three Syrian oilfields. The highest average 226Ra, 228Ra and 224Ra concentrations in these samples of water were found to be 41, 37.5 and 1.1 Bql(-1), respectively. The data obtained for 226Ra, 228Ra and the 228Ra/226Ra activity ratio were evaluated statistically and displayed using the Box Plot method; clear variations can be observed from one field to another, indicating differences in the geological formation of the reservoir. The 228Ra/226Ra activity ratio variations reflect the variability of the Th/U mass ratio of the geological formation, suggesting two different source rock types. The calculated mean Th/U mass ratio for these two possible types of source rock were 2.4 and 5.78. In addition, the 228Ra/226Ra mean activity ratio was also used to estimate the age of some deposited scales in tubulars; the results were compared with the 224Ra/228Ra activity ratio dating method. Monthly variations of 226Ra and 228Ra activity concentrations and the 228Ra/226Ra activity ratio in produced water were also observed, the major causes for these variations being related to the type of injection water and interwell reactions. Possible relationships between 226Ra and 228Ra activity concentrations, the 228Ra/226Ra activity ratio and physical and chemical properties of produced water were statistically evaluated; no linear correlations were found.     

The natural radioactivity in Guarani aquifer groundwater, Brazil.

The measurements of gross alpha and gross beta radioactivity in groundwater samples from Guarani aquifer in Brazil are reported in this paper together with the activity concentration of the natural dissolved radionuclides (40)K, (238)U, (234)U, (226)Ra, (222)Rn, (210)Po, (210)Pb, (232)Th, (228Th), and (228)Ra. Most of the gross alpha radioactivity values were below the critical level of detection corresponding to 1mBq/L, however, the whole data set for the gross beta radioactivity and radionuclides (40)K, (238)U, (234)U, (226)Ra, (222)Rn, (210)Po, (210)Pb, and (228)Ra was submitted to a statistical treatment, considering class intervals arranged in geometric progression, because of the great variability of the activity. The analysis indicated lognormal distribution of the data, as usually observed in samples taken from the natural context. An inverse relationship between the gross alpha and gross beta activity has been identified and is related to an increase in the K content in the water. The mobility coefficient has been estimated for (238)U, (226)Ra, (232)Th and (228)Ra in Guarani aquifer and the results indicated that the radioelement solubility in the studied system varies according to the following order: radium>uranium>thorium. The implications of the data obtained in terms of standards established for defining the drinking water quality have also been discussed.     

Distribution of 226Ra, 232Th and 40K in soils and sugar cane crops at Corumbataí river basin,São Paulo State,Brazil

The common use of phosphate fertilizers NPK and amendments in sugar cane crops in Brazilian agriculture may increase the ²²⁶Ra, ²³²Th and ⁴⁰K activity concentrations in soils and their availability for plants and human food chain. Thus, the main aim of this study was to evaluate the distribution of ²²⁶Ra, ²³²Th and ⁴⁰K in soils and sugar cane crops in the Corumbataí river basin, São Paulo State, Brazil. The gamma spectrometry was utilized to measure the ²²⁶Ra, ²³²Th and ⁴⁰K activity concentration in all samples. The soil-to-sugar cane transfer factors (TF) were quantified using the ratio between the radionuclide activity concentration in sugar cane and its activity concentration in soil. The results show that, although radionuclides incorporated in phosphate fertilizers and amendments are annually added in the sugar cane crops, if utilized in accordance with the recommended rates, their use does not lead to hazards levels in soils. The soil-to-sugar cane transfer of radionuclides occurred in the following order ⁴⁰K>²²⁶Ra>²³²Th. Therefore, under these conditions, radionuclides intake through consumption of sugar is not hazardous to human health.     

Determination of radioactivity levels and hazards of soil and sediment samples in Firtina Valley (Rize, Turkey).

The natural radioactivity levels in soil and sediment samples of Firtina Valley have been determined. To our knowledge, there seems to be no information about radioactivity level in the Firtina Valley soils and sediments so far. For this reason, soil and sediment samples were collected along the Firtina Valley and analysis on the collected samples were carried out to determine 238U, 232Th, 40K and 137Cs radioisotopes using high purity germanium detector. The activity concentrations obtained for 226Ra, 214Pb, 214Bi, 228Ac, 208Tl, 40K and 137Cs are given in the unit of Bq/kg. The results have been compared with other radioactivity measurements in different country's soils and sediments. The radium equivalent activity (Raeq), the absorbed dose rate (D), the external hazard index (Hex), the annual gonadal dose equivalent (AGDE) and the annual effective dose equivalent (AEDE) were also calculated and compared with the international recommended values.     

Radioactive content of charcoal

Coal and charcoal present similar physical and chemical characteristics. There is no standardized procedure to distinguish them. However, their differences in age and origin result in several differences in their natural radionuclide content. Moreover, charcoal can be contaminated with fallout.In this work, activity concentrations of ²²⁸Th, ²²⁶Ra, ⁴⁰K, and ¹³⁷Cs were determined in charcoal and coal samples in order to obtain evidence to distinguish the two kinds of sample.     

Natural radioactivity and gamma dose from Sri Lankan clay bricks used in building construction.

The specific radioactivity concentrations of 226Ra, 232Th and 40K have been determined by gamma ray spectrometry with an HPGe detector in clay brick samples from kiln sites located in 17 towns. The average values of the measured activities are 35, 72, and 585 Bq kg(-1), respectively, for the above radionuclides. The average estimated radium equivalent concentration is 183 Bq kg(-1) and is comparable with reported values for many countries in the world. This value and the value obtained from the criteria formula suggest that the use of local clay bricks do not pose a radiological hazard. The calculated average absorbed dose rate in air within buildings was found to be 102 nGy h(-1) while the population weighted indoor annual effective dose was 0.20 mSv.     

238U 226Ra 210Pb, 232Th and 40K activities in soil profiles of the Flysch sector (Central Spanish Pyrenees).

Distributions of natural gamma-emitting radionuclides were determined in three soil profiles developed on Tertiary sedimentary materials in mountain landscapes of the Central Spanish Pyrenees. Radioisotope activities (Bq kg(-1)) lie in the range of 0-53 for 238U; 19-33 for 226Ra; 7-75 for 210Pb; 24-48 for 232Th and 335-562 for 40K. 238U and 210Pb activities show an important variability down the soil profiles. 238U was markedly depleted in all upper soil layers and highly enriched in lower layers of two soil profiles. 210Pb exhibits very dissimilar distribution patterns in all three soils. 226Ra and 232Th had quite uniform depth distributions. 40K showed depletion in both upper and lower layers in one soil profile but remained fairly constant in the other two profiles. 238U/226Ra activity ratios (ARs) have been used to assess equilibrium in the 238U decay chain and as indicators of edaphogenesis in the studied soil profiles. Maintenance of initial proportionality in the ratio of 232Th/238U activities has been assessed through ARs of their progenies. Additionally, a variety of soil properties were measured down the soil profiles. Among soils, variation in radionuclide activies may be due to differences in carbonate content, organic matter and/or grain size. In this environment, soil properties differently affect mobilization of natural radionuclides. The association of some radiologic properties with soil layers suggest a relationship between soil processes and radionuclide distribution.     

2013—2020年辽宁红沿河核电站周围地区的食品放射性水平及公众内照射剂量研究

目的 评价辽宁红沿河核电站运行后对周边地区食品放射性水平的影响。方法 通过对2013年至2020年核电站运行期间周边30 km范围内食品放射性水平的分析,对比核电站运行前后及对照点的放射性水平,评估核电站的运行对当地食品放射性水平的影响。结果 当地食品中未发现¹³¹I、¹³⁴Cs、⁶⁰Co、⁵⁸Co、¹¹⁰Ag^m等人工放射性核素,天然放射性核素²³⁸U、²²⁶Ra、²³²Th、⁴⁰K均在正常本底水平,平均值分别为（0.088±0.053）、（0.155±0.178）、（0.314±0.388）和（81.3±18.1） Bq/kg （鲜重）。食品样品中人工放射性¹³⁷Cs活度浓度平均值为（0.013±0.010） Bq/kg （鲜重）。与对照点及运行前水平比较,放射性核素水平未见增加。结论 红沿河核电站的运行未对周边食品放射性水平带来影响。     

Disequilibrium in naturally occurring radioactive series in some phosphate ores

Eight phosphate ore samples from Egypt and Saudi Arabia were studied by atomic absorption spectrometry for the Bi, Pb, Th and Al concentrations in ppm or ppb or per cent. Also X-ray diffraction spectrometry was applied for determining the mineral and chemical composition of the phosphate ore samples. A gamma spectrometry system, based on HPGe crystal, was applied for determining the concentrations of the radioactive elements in (238)U, (226)Ra and (232)Th series as well as (40)K, in Bq/kg dry weight. Concentrations in ppm were found to be from <10.0 to 20.48, from <7.50 to 27.30 and from <1.0 to 50.0 for Bi, Pb and Th, respectively. Al ranged from <0.05 to 3.13%. Major, minor and trace chemical and mineral compositions were assigned for each sample by XRD spectrometry. Concentrations of the different elements in both radioactive series, (238)U, (226)Ra and (232)Th were compared. Disequilibrium was found in both series.     

Assessment of natural radioactivity levels and radiation hazards due to cement industry

The cement industry is considered as one of the basic industries that plays an important role in the national economy of developing countries. Activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in Assiut cement and other local cement types from different Egyptian factories has been measured by using γ-ray spectrometry. From the measured γ-ray spectra, specific activities were determined. The measured activity concentrations for these natural radionuclides were compared with the reported data for other countries. The average values obtained for ²²⁶Ra, ²³²Th and ⁴⁰K activity concentration in different types of cement are lower than the corresponding global values reported in UNSCEAR publications. The obtained results show that the averages of radiation hazard parameters for Assiut cement factory are lower than the acceptable level of 370 Bq kg^?1 for radium equivalent Ra_eq, 1 for level index Iγr, the external hazard index Hex ≤1 and 59 (nGy h^?1) for absorbed dose rate. The manufacturing operation reduces the radiation hazard parameters. Cement does not pose a significant radiological hazard when used for construction of buildings.     

The effect of uranium migration on radionuclide distributions for soil samples at the El-Gor area,Sinai, Egypt

The concentrations and distributions of the activity of natural radionuclides in soil samples were investigated in fifteen soil samples at El-Gor area representing two profiles (A and B) using a HP–Ge detector and alpha counting by SSNTD (CR-39), respectively. The average concentrations of the radionuclides ²³⁸U, ²²⁶Ra, ²³⁵U, ²³²Th and ⁴⁰K are 203.4, 177.23, 9.77, 43.33 and 386.22 Bq kg⁻¹ (dry weight), respectively, and profile A and ²³⁸U, ²²⁶Ra, ²³⁵U, ²³²Th and ⁴⁰K have average concentrations of 232.58, 246, 11.7, 31.7, and 277.07 Bq kg⁻¹ for profile B, respectively. The eTh and eU were estimated to detect the migration process of uranium into or out of an area or uranium to or from the studied profiles. The results indicate a migration of uranium by 29% for profile A and 65.37% for profile B. The activity ratio (²³⁸U/²²⁶Ra) was found to be 0.9 in profile A and 1.15 in profile B. These ratios coincide with the uranium migration processes. The responsible mass corresponding to the measured ²²⁶Ra activity was also calculated. The radon activity concentrations for the two profiles are nearly 300 Bq m⁻³. The emanation coefficient (η) was calculated from the ratio of the expected radon activity to the measured radon for the studied soil samples. The value of η was found to depend only on the radium activity regardless to soil formation.