Activity Concentration Values Research Articles

Selected aspects of caesium-137 contamination in wild boars (Sus scrofa)

Monitoring the activity of radionuclides in food is part of the monitoring system of foreign substances. A close correlation between gamma spectrometry determined by 137Cs activity concentration in the meat and stomach wall (r = 0.984) was found in monitored Slovak wild boars with a low activity of 137Cs . The transfer factors of the soil and the stomach content and the soil and the meat were approximately 0.07 at the median. The median transfer factor between the stomach content and the stomach wall is similar to that of the stomach wall and the meat (2.412 and 1.805). The mean value of 137Cs activity concentration in the muscles of wild boars from the Czech Republic was 46.7 Bq·kg-1. The mean value of 137Cs activity concentration in the stomach wall was 23.7 Bq·kg-1. The mutual correlation was r = 0.988. There was further correlation of 137Cs activity concentration between the heart and the diaphragm (r = 0.977), the heart and the tongue (r = 0.902), and the heart and the lungs (r = 0.906). Based on the results from Slovakia and the Czech Republic, there is hope that it will be possible to use a sample from the stomach wall to determine the activity concentration of 137Cs in meat, thereby replacing the commonly used and highly valued top side sample. In practice, monitoring soil contamination to predict the meat contamination of wild boars is more important than monitoring elements of the food chain. The potassium-caesium coefficient reached 5.57 in the muscles and 17.25 in the stomach wall.

The impact of MR-guided attenuation correction (compared to CT-based AC) on the diagnosis of anosmia based on 99m-Tc Ethyl-Cysteinate-Dimer SPECT images

99m-Tc Ethyl-Cysteinate-Dimer SPECT and MR imaging play a significant role in diagnosing anosmia. In this study, two-tissue class and three-tissue class attenuation maps (2C-MR and 3CMR) obtained from MR images were compared with CT-based attenuation correction (CTAC). Afterward, the presence of hypo-perfusion in brain lobes was evaluated in SPECT images. The 2C-MRAC map was generated through segmentation of T1-W MR images into air and soft-tissue, while in the 3C-MRAC map, the cortical bone was also considered. For investigating MRAC approaches, the difference between activity concentration (ACC) values was estimated in 144 volumes of interest. Ten normal and fourteen anosmic patients were compared by calculating the average normalized count and standard uptake value ratio parameters in the brain lobes. The comparison between attenuation correction strategies represented that MRAC images resulted in underestimation of the ACC values which was more substantial in the cortical area rather than in central regions (maximum 9% vs. 6% for 2C-MR and maximum 5.5% vs. 3.5% for 3C-MR). Nevertheless, there was a strong correlation between the MRAC and CTAC methods with a correlation coefficient of 0.7 for both 2C-MR and 3C-MR. The statistical analysis between normal and affected groups indicated the hypoperfusion in the cortex of Lh_frontal, Rh and Lh_temporal lobes with p-values < 0.05. Using MRAC resulted in underestimation of activity concentration which was partly eliminated by considering the cortical bone in the 3C-MR attenuation map. Hypo-perfusion was perceived in Frontal and Temporal lobes in SPECT-MRAC images of the anosmic group.

Environmental radioactivity measurement in soils of an abandoned potash deposit at Holle, Republic of Congo

The main objective of the present study was to assess natural radioactivity level from soils of an abandoned potash mine and its surroundings at Holle locality in Hinda district, the Republic of Congo. Samples were analyzed using an HPGe gamma spectrometer. Activity concentration values obtained varied from 21.01 ± 6.47 to 117.3 ± 2.69 Bq/kg with a mean value of 46.15 ± 4.69 Bq/kg of 40K; that of 238U varied from 17.36 ± 10.74 to 40.04 ± 8.58 Bq/kg with a mean value of 25.14 ± 10.06 Bq/k, while that of 232Th varied from 8.68 ± 3.7 to 27.33 ± 2.69 Bq/kg with a mean value of 18.16 ± 2.94 Bq/kg. Mean activity concentration values obtained for 238U, 232Th and 40K were relatively low compared to the world average values. Radiological hazard indices associated were also calculated and found to be under recommended limits. Results pointed out that radioactivity level in the region was relatively low. Consequently, soils of the surrounding abandoned potash mine can be used for buildings construction.

241Am and 137Сs in the Khoiniki district of Belarus: updated radiological assessment of the local existing exposure situation

The results covered in this paper relate to the “Khoiniki” research sub-unit of a larger-scale sequence of studies focused on the local assessments of the present-day 241Am and 137Cs concentrations in the soils and locally produced foods, with the estimation of the public internal radiation doses in the residential areas of the Gomel region of the Republic of Belarus most closely adjacent to the ChNPP resettlement zone. The objective was to make a conservative estimate of a committed annual dose of internal exposure from 241Am and 137Сs received by the villagers of 96 farmsteads in 30 settlements of the private sector of Khoiniki countryside through both, inhalation and consumption of local foodstuffs. The results obtained in this study include an update of the existing contamination levels of 241Am and 137Сs present in the local soils and foods grown or produced in private backyards and households. 241Am in food samples was determined by alpha-spectroscopy radiochemical analysis with the use of selective extraction-chromatographic resins. Gamma-spectrometry techniques were used to measure 241Am in soil samples and 137Сs in soil and food samples. Based on our findings, the present-day deposition density of 241Am in the soils does not exceed 4 kBq/m2 , while the values of 137Cs contamination are by one to two orders of magnitude higher than that of 241Am and vary between 30 and 500 kBq/m2 . Generally, the values of activity concentration of 241Am detected in local soils are well within 10 Bq/kg in the majority of inspected villages, with the exception of three sites where higher levels of 241Am contamination is soils were detected ranging from 14 to 16 Bq/kg. The ambient dose rates in the countryside range from 0.05 to 0.38 μSv/hour, with the average of 0.15 μSv/hour. No cases of 137Сs contamination above the established reference levels of 80, 100 and 90 Bq/ kg have been found in the local food samples of, respectively, potatoes, vegetables (incl. roots and tubers) and grains. The content of 241Am in the staple foods produced in the area varies from single digits to tenths of mBq/ kg, which is less by three orders of magnitude than 137Сs activities concentrationd found in the same staples. Of the two pathways contributing to the local committed internal exposure from 241Am, the dominant one is through inhalation (0.006–0.038 mSv/year) prevailing over the consumption pathway of this same radioisotope by at least one order of magnitude. At the time of gardening and other household field works, the existing levels of 241Am contamination in soils are estimated to produce from 85 to 98% of the internal radiation dose received by individuals from inhaling the total of 241Am and 137Сs. The maximum committed annual doses of internal exposure from 137Сs are estimated to be above 1 mSv/year in 6 out of 30 villages engaged in our study. At the same time, the estimated internal radiation dose due to 241Am does not surpass 0.04 mSv/year. The 137Сs major contribution to the internal exposure of villages in the Khoiniki countryside is through food consumption.

Assessment of Radionuclides in Some Fruits from Niger Delta, Nigeria and Its Health Risks

Determination of radionuclides’ activity concentration in fruits is essential for the protection of human health. Fruits can be radioactive due to the present of naturally occurring radioactive materials (NORMs) and technically enhanced radioactive materials (TENORMs) in the environment. The Assessment of Radionuclide activity concentration in Some Fruits from Niger Delta, Nigeria and its Health Risks were carried out using gamma ray spectroscopy. The study measured the activity concentration of radionuclides in fruits and the results showed that the total activity concentration of 40K, 232Th and 226Ra in fruits were 578.24 Bqkg-1, 263.84 Bqkg-1 and 128.35 Bqkg-1 respectively. The study found out that 40K has the highest value of activity concentration while apricot has the highest value of radionuclide concentration compared to other fruits. The statistical analysis of data was also done using statistical packages. The average estimated AED for Infants, Children and Adults due to the radioactivity in Avocado, Apricot, Guava and Pear were; 829.02 µSvy-1, 565.865 µSvy-1, and 838.725 µSvy-1, 2737.665 µSvy-1, 4361.4875 µSvy-1 and 2497.9025 µSvy-1, 651.20833 µSvy-1, 1202.6767 µSvy-1 and 813.22167 µSvy-1, and 1164.7883 µSvy-1, 1724.2933 µSvy-1 and 1088.8933 µSvy-1 respectively. The estimated AED due to the consumption of various fruits are above the world value. However, the estimated excess lifetime cancer risks for the various fruits are far below the world (WHO) limit. The study concluded that there is no cancer risk associated with the consumption of fruits in the study area and that the fruits that have tap root systems recorded highest value of radionuclides’ activity concentration.

TENORM employed as inert material for house building: a model for evaluating the radon activity enhancement.

Radon exhalation from soil and ores is among the most dangerous risks for the public health care. The impact becomes even more powerful when technological enhanced naturally occurring radioactive materials (TENORM) are used for public and private building. Here, webuilt a down-scaled model (a 1.0 m × 1.0 m × 0.5 m parallelepiped) of a dwelling, whose construction materials contain TENORM harvested in a site in Crotone (Italy). We observed an increase of the radon activity in the model when TENORM residues are employed, reaching a value around 120 Bq/m3, i.e. up to three times higher than the typical values of Crotone indoor environment, which ranges around 40 Bq/m3. These results have then been compared to a real use case. The correspondence found between the values of radon activity concentration in the model and in the use case suggests that estimating the radon concentration is a useful method to target TENORM presence inside buildings.

Natural and artificial radionuclide activity concentrations and dose assessments of some medicinal plants in Balikesir, Turkey

ABSTRACT In this study, natural and artificial radionuclide concentrations were determined and radiological dose values of nine different medicinal plants {Sweet marjoram (Origanum majorana), Rosemary (Rosmarinus officinalis) Lavender (Lavandula x intermedia), Thyme (Thymus vulgaris), Sage (Salvia officinalis), Peppermint (Mentha piperita), Holy basil (Ocimum Sanctum), Bush basil (Ocimum minimum) and Lemon balm (Melissa officinalis)} used in Balikesir province from Turkey were evaluated. Gamma-ray spectrometry was used to determine the natural and artificial radionuclide concentrations of these medicinal plants. To evaluate radiological dose values, absorbed gamma dose rate (D), radium equivalent activity (Raeq) annual gonadal dose equivalent (AGDE), exposure dose (ER), annual effective dose (AED), excess lifetime cancer risk (ELCR), internal hazard index (Hin), external hazard index (Hex) and gamma representative level (GRL) were determined. Mean values of 226Ra and 232Th activity concentrations are lower than the world average values, whereas mean values of 40K activity concentrations are higher than the world average values for present medicinal plants. Lavandula x intermedia has the highest 137Cs concentration, whilst Thymus vulgaris L. has the lowest 137Cs activity concentration. D, Raeq, AGDE, ER, AED and ECLR values are the highest for Lavandula x intermedia, whilst they are the smallest for Rosmarinus officinalis L. among the studied medicinal plants. Average values of Hin and Hex are lower than the permissible value of 1, whilst the average value of GRL is higher than permissible limit value of 1.

Natural Radionuclide Analysis on Crude Petroleum from Some Oil Fields in Ghana

The petroleum industries benefit immensely from developing scientific processes and procedures that determine characteristics of crude oils and distinct them. This is because crude oils are acquired from various geological sources and each sedimentary rock has its own distinct chemical properties that affect extraction, refinery and environmental safety. Extraction of crude oils may result in exposure of some radionuclide elements from sedimentary rocks into the environments. This nuclear exposure may affect lives and can cause ecological imbalance. Applications of gamma emission spectroscopy has grown rapidly around the world because of its accurate measurement and precision. Such technique has not been applied for the study of naturally occurring radionuclide materials (NORMs) in crude oils from the active oil fields in Ghana. The study employed the use of gamma spectroscopic technique for characterization of crude oil samples from Jubilee Oil Field, Tweneboa Enyenra Ntomme (TEN) Oil Field and Saltpond Oil Field. The technique was applied on four crude oil samples. The results of this paper actually report on radionuclide concentrations of naturally occurring radioactive materials in four crude samples using a Gamma-Ray spectrometer. Three radionuclides, radium-226 (226 Ra), thorium-232 (232 Th) and potassium-40 (40 K), were identified from each crude sample (JF, TF SF-1 and SF-2). It was observed that samples from Saltpond Oil Field estimated the highest activity concentration and the least was crude oil from Jubilee Oil Field. The activity concentration values were far less than the approved values by International Atomic Energy Agency for basic safety standard. Therefore, the radionuclides activity concentration values of crude oil samples from Jubilee, TEN, and Saltpond oil fields were within the basic safety standards exemption levels of the International Atomic Energy Agency (IAEA). The crude oils from the oil fields can therefore be considered safe to handle. Also, the results of the activity concentrations from the sample used for this study indicate that crude petroleum from the oil fields may relatively have little nuclear activity impact to ecology and human health. The result of this study may be adopted by the Environmental Protection Agency and the Petroleum Stakeholders of Ghana for development of petroleum geo-radionuclides radiation safety measures.

Radiological Hazard Assessment of Radionuclides in Sediment Samples of Tigris River in Mosul city, Iraq

The natural radionuclides present in sediments such as 226Ra, 232Th and 40K contribute to the amount of radiation in a large way, as most of the population is exposed to that radiation in those areas, and calculating the value of that radiation is of great importance in knowing the radiation that humans are exposed to by measuring that values with the world recommended values. This study was conducted in order to measure the levels of natural radiation in sediments of the Tigris River in the city of Mosul, in northern Iraq, by using gamma spectroscopy technique to calculate the activity concentrations of natural radionuclides in the sediments, The results showed that the activity concentrations of 226Ra, 232Th, and 40K. ranged between (6.30±0.319-13.73±0.411) Bq.kg-1 and an average(9.86±0.385) Bq.kg-1 for 226Ra, and between (13.39±0.626-29.84±0.923) Bq.kg-1 and an average of (23.05±0.838) Bq.kg-1 for 232Th, while potassium-40 ranged between (166.83±6.456-275.96±7.601) Bq.kg-1 and with an average (232.91±6.456) Bq.kg-1 .And all the results of the activity concentration values were less than the internationally recommended values. The radiation hazard indicators were calculated on according to the activity concentrations of those natural radionuclides in the studied areas. And it was found that the value of the effectiveness of the radium equivalent was between (38.52-71.96) Bq.kg-1 and an average of (60.76) Bq.kg-1, which is less than the internationally recommended value, which should not exceed (370) Bq.kg-1,As for the value of the absorbed dose percentage Dɣ, it ranged between (17.81-33.07) nGy.h-1 and an average of (28.16) nGy.h-1

226Ra, 228Ra and 40K as tracers of erosion and accumulation processes: A 3-year study on a beach with different sediment dynamics

The aim of this study is to analyse the role of natural radionuclides 226Ra, 228Ra, 40K and unsupported 210Pb (210Pbex), as erosion and accumulation process tracers. For this purpose, a complex system, including both the characteristic dynamics of a closed beach and those associated with a beach open to wave action, was studied. A 3-year study of monthly variation of 226Ra, 228Ra, 40K and 210Pbex was carried out at Las Canteras beach, on the Island of Gran Canaria (Spain), covering several erosion and accumulation periods. A correlation analysis, ANOVA test and Tukey’s Honestly Significant Difference (HSD) Test proved that the marine erosion and accumulation agents influenced the activity concentration values found for the different radionuclides. Moreover, the geochemical analysis of samples from maximum and minimum activity concentration values showed that the natural radionuclides studied could be suitable tracers for studying beach sediment dynamics in erosion and accumulation periods.

Uncertainty and detection limits of 241Pu determination by liquid scintillation counting (LSC)

Determination of 241Pu is an essential issue for radiation protection, as it is the precursor of some nuclides with high radiotoxicity. 241Pu is a low energy beta emitter, which makes its measurement more challenging than that of Pu alpha emitters. The most widely used method for the measurement of 241Pu is liquid scintillation counting (LSC). In this method, the assessment of Pu radiochemical yield is done by measuring the sample by alpha spectrometry before being lixiviated and measured by LSC. This double measurement affects uncertainty analysis, as well as decision threshold and detection limit, considering that both components of the total yield (radiochemical and lixiviation) should be contemplated.In this paper, and for quality assurance (QA) purposes, in-depth uncertainty and detection limit formulae for the proposed method, controlling correlations and considering all the parameters involved including chemical and lixiviation yields, have been developed. A sensitivity analysis of the uncertainty budget together with an assessment of 242Pu tracer quantity to be used, ensuring a total yield of at least 50% and a relative uncertainty of the leaching yield of at most 5%, have been carried out. In addition, an analysis of the impact of the real lixiviation yield value and its uncertainty on the results has been done.As a general conclusion, and considering the values of the parameters chosen for this work (samples of 1 g measured for 24 h by LSC), the 241Pu uncertainties range from 5% to 30% depending on the activity concentration values and the detection limits range from 14 to 30 Bq kg-1, depending on yield values. The main components of the uncertainty budget are the net 241Pu and background counts obtained in the LSC measurement for low contaminated samples while this is the case for the alpha gross count rate in LSC measurement of the alpha calibration source for highly contaminated samples.In addition, an analysis of possible interference by Pu alpha emitters in the 241Pu signal and a comparison of quench standard curves of 3H and 241Pu are also performed.

Assessment of internal radiation exposure to Antarctic biota due to selected natural radionuclides in terrestrial and marine environment

The present article introduces data on natural radioactivity (40K, 230,232Th, 234,238U) in the Antarctic marine and terrestrial environment. Various biota samples were analysed due to internal exposure to 40K, 230,232Th, 234,238U. Activity concentration of 40K was the highest in both marine and terrestrial samples. Mean values of 40K activity concentration are 1340 Bq/kg and 370 Bq/kg for the marine and terrestrial samples respectively. 234U/238U ratios analysis revealed that sea waters and sea spray are the main source of the uranium in the terrestrial samples. Average 230,232Th, 234,238U activity concentrations in the Antarctic biota do not exceed 6 Bq/kg. Weighted internal dose rates are relatively low; they range from approximately 0.1 to 0.6 μGy/h. Statistically significant differences in radionuclide accumulation were discovered between the mosses and lichens. It may point to various mechanisms of the nutrient absorption from the environment by these organisms.

Online monitoring of lead-214 (214Pb) on atmospheric aerosols by low-resolution gamma-ray spectrometry.

This paper provides a new approach that simplifies the monitoring of 214Pb activity concentration on aerosols in the atmospheric surface layer. The approach allows obtaining data on 214Pb activity concentration with the discreteness of 2h. The experimental setup described in the paper made it possible to achieve a minimum detectable activity level of 0.4Bqm-3. Using this approach, the data on the diurnal variability of 214Pb activity concentration in the atmosphere of Sevastopol city for a period of 18months were obtained. The 214Pb activity concentration varied from < 0.4 (less than 1% of the data series) to 8.9Bqm-3, mean value 2.0 ± 1.0Bqm-3. The analysis of the temporal variability of 214Pb activity concentration on different time scales (diurnal, seasonal) was carried out. Annually averaged diurnal variation curve of 214Pb activity concentration showed a peak at 6:00 local time and a minimum at 18:00. The maximum variability in the seasonal averaged diurnal cycle of 214Pb activity concentration is observed in summer (± 30% of the daily average value) and the minimum in winter (± 13%). The maximum seasonal average value of 214Pb activity concentration is observed in winter (2.5Bqm-3) and the minimum in summer (1.4Bqm-3). A quantitative estimate of the annual effective dose due to exposure to outdoor radon was obtained by using 214Pb data, and it was 0.03mSva-1.

Assessment of radiation hazard indices due to natural radioactivity in soil samples from Orlu, Imo State, Nigeria

The use of a Radiation Alert Inspector device and a gamma-spectrometry system fitted with a Sodium Iodide (NaI) detector was used to determine the radioactivity concentration level of natural radionuclides 238U, 232Th, and 40K in soil in several locations in Orlu, Imo State, Nigeria. 19 soil samples were collected for analysis from several locations of factories, agricultural farming-lands, gullies and water eroded areas, and soil deposits very close to flowing waters from rocks, due to environmental concerns arising from human activities in this region. The activity concentration values for 238U, 232Th, and 40K were found to range from 0.14 to 9.34 Bq.kg−1, 0.03–3.75 Bq.kg−1, and 16.83–783.06 Bq.kg−1, respectively, with average mean values of 4.15, 1.64, and 134.13 Bq.kg−1. Radium equivalent activity, absorbed dose rate, and gamma index mean values for the samples were 16.822 Bq.kg−1, 8.528 nGyh-1, and 0.133 mSv respectively, the obtained values were below the safe limit values set by the United Nations Scientific Committee on the Effects of Atomic Radiation of 370.0 Bq.kg−1, 59.0nGyh−1, and 1.0 mSv. According to the findings, the regions under study are reasonably safe for human outdoor activities such as agriculture, construction, and factory operations.

Headspace/GC-MS Analysis and Investigation of Antibacterial, Antioxidant and Cytotoxic Activity of Essential Oils and Hydrolates from Rosmarinus officinalis L. and Lavandula angustifolia Miller.

In this work, essential oils (EOs) and hydrolates (Hys) of Rosmarinus officinalis L. and Lavandula angustifolia Mill., grown in Tuscany (Italy), were studied to describe their chemical composition and biological activities. The aromatic profile of the EOs liquid phase was carried out by gas chromatography–mass spectrometry (GC–MS), while the volatile composition of vapor phase EOs and Hys was performed by headspace (HS)/GC–MS. The obtained results show that monoterpene hydrocarbons (71.5% and 89.5%) were the main compounds, followed by oxygenated monoterpenes (26.0% and 10.5%) in the liquid and vapor phase of R. officinalis EO, respectively. The oxygenated monoterpenes were the main components of L. angustifolia EO, reaching 86.9% in the liquid phase and 53.7% in the vapor phase. Regarding Hys, they consisted only of oxygenated monoterpenes, and 1,8-cineole (56.2%) and linalool (42.9%), were the main components of R. officinalis and L. officinalis Hys, respectively. Their cytotoxicity was investigated on an SHSY5Y neuroblastoma cell line by thiazolyl blue tetrazolium bromide (MTT) test, showing a notable effect of the EOs with a time-independent manner of activity and half maximal effective concentration (EC50) values quite similar for the two plant species (from 0.05% to 0.06% v/v for the three time points evaluated). A measurable activity of Hys was also obtained although with higher EC50 values. The antibacterial activity against Escherichia coli ATCC® 25922, Pseudomonas fluorescens ATCC® 13525, Acinetobacter bohemicus DSM 102855 as Gram-negative bacteria and Kocuria marina DSM 16420, Bacillus cereus ATCC® 10876 as Gram-positive bacteria, was evaluated by the agar disk-diffusion method and the VPT (vapor phase test) to determinate the MIC (minimal inhibitory concentration) and the MBC (minimal bactericidal concentration) values. Both EOs possessed a high activity against all the bacterial strains with MIC values ranging from 0.19% to 3.13% v/v. Unlike EOs, Hys did not show an inhibition of the bacterial growth at the tested concentrations. Furthermore, antioxidant power was measured by 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt-based (ABTS•+) and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays, showing a remarkable ability to reduce radicals by both EOs; Hys were slightly less active. The findings highlighted that R. officinalis and L. angustifolia EOs and Hys have a chemical composition rich in bioactive molecules, which can exert different biological activities.

Radiological Dose Assessment to Members of the Public Using Consumer Products Containing Naturally Occurring Radioactive Materials in Korea.

Various products containing a small number of added radionuclides are commonly available for use worldwide. However, frequent use of such products puts the public at risk of radiation exposure. In this study, dose assessments to members of the public using consumer products containing naturally occurring radioactive materials (NORMs) were conducted for various usage scenarios to evaluate the external and internal exposure dose. Data for this study were obtained from previous literature and were statistically analyzed using Boxplot to determine the input data for assessment. A normalized value of activity concentration was used for dose evaluation. In addition to other external and internal dose calculation codes, analytical calculations were used to perform age-dependent. Based on analytical calculations, the highest total effective dose equivalent (TEDE) received from necklace products at the upper whiskers with an activity concentration of 4.21 Bq/g for 238U, 24.4 Bq/g for 232Th, and 0.55 Bq/g for 40K for various age groups is 2.03 mSv/y for 1 year old, 1.24 mSv/y for 10 years old and 1.11 mSv/y for adult, which are above the international commission for radiation protection (ICRP) recommended public dose limit of 1 mSv/y. Results of external and internal exposure dose obtained using Microshield code, IMBA code and Visual Monte Carlo (VMC) code are all below the recommended public dose limit of 1 mSv/y.

Determination of warning level at Lang Son environmental radiation monitoring station

In this study, a method to estimate the baseline of ambient dose equivalent rate (ADER) of the Lang Son radioactive monitoring station was presented. The warning level is calculated from the arithmetic mean and standard deviation of the terrestrial background value. The terrestrial background value estimated from the Radon peak removal algorithm is 39.85 nSv/h with a standard deviation of 7.58 nSv/h. For comparison, the soil samples around the monitoring equipment were collected and analyzed the activity concentration of nuclides 226Ra, 232Th, 40K. The terrestrial background value estimated from these values of activity concentration is of 41.10 ± 2.96 nSv/h. There is a good agreement between the results evaluating ADER from Radon peak removal algorithm and from the activity concentration of nuclides 226Ra, 232Th, 40K.

Assessment of solid mineral to soil radioactivity contamination index in selected mining sites and their radiological risk indices to the public

ABSTRACT This study examined the radioactivity levels of soil samples within selected solid mining sites in Nigeria using high-purity germanium (HpGe) detector. Sixty soil samples in all were collected from the 10 solid mineral mining sites investigated and six samples were collected as control samples from non-mining environment for analyses. The results of the activity concentration values obtained for 40K, 226Ra and 232Th are 100.22 Bq kg−1, 33.15 Bq kg−1 and 77.31 Bq kg−1, respectively. The 226Ra and 40K activities were found to be within the United Nation Scientific Committee on the Effects of Atomic Radiation acceptable permissible limit, but the 232Th mean value was above the permissible limit of 30 Bq kg−1 for the public. In comparison, 40K, 226Ra and 232Th soil samples mean activity concentrations were higher than the control soil samples values by 48.6%, 43.7% and 62.3%, respectively. The results of estimated radiation hazard indices indicate average values of 150.72 Bq kg−1, 68.40 nGyh−1 , 83.65 µSvy−1 and 454.70 µSvy−1 for the Radium Equivalent (Ra eq ), Absorbed Dose Rate (D), Dose Equivalent (AEDE) and Annual Gonadal Equivalent Dose (AGED), respectively. The mean values for External Hazard Indices (Hex, Hin), Representative Gamma index () and Excess Life Cancer Risk (ELCR) were 0.41, 0.50, 1.06 and 0.29 × 10−3, respectively. The statistical analysis shows positive skewness.

Clay mineralogy insights and assessment of the natural (228Ra, 226Ra, 210Pb, 40K) and anthropogenic (137Cs) radionuclides dispersion in the estuarine and lagoon systems along the Atlantic coast of Portugal

The activity concentrations of natural (228Ra, 226Ra, 210Pb, 40K) and anthropogenic (137Cs) radionuclides were measured by gamma spectrometry on sediments collected from aquatic systems. The mineralogy of clay fractions identified by X-ray diffraction (XRD) is composed by an illitic material (detrital mica, illite/smectite, and illite/smectite/vermiculite mixed-layers) ± kaolinite and illite. The Mg2+-saturated clay fractions show three distinct illitic populations within the illitic material: detrital mica, illite/vermiculite mixed-layers, and illite/smectite. Transmission electron microscopy (TEM) images show illitic material aggregates with a flaky- and lath-shapes, pseudohexagonal platy kaolinite and lath-shape illite.The 228Ra activity concentration values range from 30.1 to 403 Bq Kg−1, the 226Ra from 24.6 to 290 Bq Kg−1 and from 44 to 368 Bq Kg−1 for 210Pb. The Ra fluxes suggest a unique source where the mixing process and radioactive decay equilibrated the losses of short- (228Ra) and long-lived (226Ra) isotopes. The 210Pb/226Ra ratio shows an average value of 2.165, indicating that the radioactive secular equilibrium (~1) was reached. A decrease of the natural radionuclide (228Ra, 226Ra, 210Pb) activity concentrations was observed in estuaries and near shore coastal sediments from north to south of Atlantic Portuguese coast. Higher 210Pb and 226Ra activity concentrations were obtained in samples composed by illitic material + kaolinite and organic matter. The illite/smectite mixed-layers and kaolinite are suitable sorbents for Ra and 210Pb isotopes. Higher 40K values (473–1001 Bq Kg−1) were measured on feldspar, mica and clay sediments provided from granite weathering (north region).The 137Cs activity values range from 1.25 to 10.1 ± 1.9 Bq Kg−1 for samples collected from the northern and central part of estuarine areas. A higher 137Cs activity (31.2 ± 3.5 Bq Kg−1) was measured in the southern part of the Atlantic coast, corresponding to a sediment with a higher amount of illite.

Baseline radioactivity and associated radiological hazards in soils around a proposed nuclear power plant facility, South-South Nigeria

Increased concerns about human population exposure to increased ionizing radiations emanating from anthropogenic sources of radiation, as well as the associated environmental risk, have necessitated radioactivity baseline studies in many regions. This work based on standard procedures designed suite nuclear power plant (NPP) radiological monitoring plan was conducted to assess the radiological baseline of Itu, Nigeria (5ο10′0 N, 7°59′0 E). A total of 44 soil samples were collected and analyzed using High Purity Germanium detector. The average activity concentration values for soil samples were 47.98 ± 8 Bqkg−1226 for Ra, 15.15 ± 1 Bqkg−1 for 238U, 38.65 ± 6 Bqkg−1 for 232Th, and 41.55 ± 6 Bqkg−1for 4 K. These mean values were lower than the UN Scientific Committee on the effects of atomic radiation's world mean values of 33, 45, and 420 Bqkg−1 for 238U/226Ra, 232Th, and 4 K, respectively. The hazard indices calculated using the measured activity concentrations indicated 32.04 nGy/h, 0.042 mSv/yr, and 0.17 mSv/yr for mean GDR, outdoor, and indoor AEDE, respectively. In addition, the average radium equivalent resulting from terrestrial gamma of activity concentration was 113.94 Bqkg−1, with a mean ELCR of 0.15 × 10−3. These baseline data show that there is no substantial radiological concern for human health.