210Pb Concentrations Research Articles

A new procedure to validate and optimize 210Po measurements in atmospheric aerosols

The exposure to air fine aerosols can cause health effects due to inhalations of alpha emitters such as 222Rn daughters. Lead-210 and 210Po are mainly associated to aerosols with median aerodynamic diameter lower than 1 μm. The 210Po is characterized by having a high radiotoxicity. The precise measurement of 210Po in surface air aerosols is usually quite complex due to the significant contribution of the 210Pb on their concentrations. Additionally, there is no possible means to manufacture a certified material to validate the measurements of 210Pb and 210Po concentrations in surface air aerosols. For these reasons, this study aims to develop a novel and comprehensive methodology to validate 210Po measurements in surface air aerosols by preparing in our laboratory “standard samples” with known activities of both 210Pb and 210Po. A detailed sensitivity analysis on the precision of 210Po concentration measurements has been carried out as a function of the involved variables such as sampling time, time elapsed between the sampling start and 210Po self-deposition and the 210Po/210Pb activity ratio in surface air aerosols. This study is necessary to find the optimum conditions for a precise measurement of 210Po in surface air aerosols. In addition, this methodology has been applied for the determination of 210Po concentrations in 30 samplings campaigns of atmospheric aerosols carried out at the El Carmen campus (Huelva province) from March 25th to July 15th, 2022. The results obtained for 210Pb and 210Po concentrations and atmospheric aerosol residence times (via 210Po/210Pb activity ratio) were consistent with other previous works.

Characterization of natural radioactivity and relative dose due to consumption of edible bivalves inhabiting the Cochin Backwater Lagoon, Kerala, southwestern coast of India

The study on natural radionuclides in edible bivalves from the Cochin backwater lagoon, Kerala, employing alpha spectrometry, revealed higher concentrations of 210Po and 210Pb compared to 238U and 232Th. The annual committed effective dose (ACED) for the adult coastal population was calculated at a range of 1494.9 to 5783.4 μSv y−1, with 210Po being the predominant contributor, responsible for about 85 % of the dose. This highlighted significant health risks, underscored by a calculated cumulative mortality and morbidity risk range between 5.23 × 10−3 and 2.02 × 10−2. These findings emphasized the need for further research and the development of regulatory measures to mitigate exposure risks.

An Evaluation of the Radioactive Content of Ashes Obtained from the Use of Fuels from Recycled Materials by Co-Processing in the Cement Industry.

The co-processing of different wastes as fuels in the manufacture of cement clinker not only meets the objectives of a circular economy but also contributes to the reduction in CO2 emissions in the manufacture of Portland cement. However, waste used as alternative fuels, such as sludge or organic-rich residues, may contain naturally occurring radionuclides that can be concentrated during the combustion process. In this study, the presence of natural radionuclides (radioactive series of uranium, thorium, and 40K) and anthropogenic radionuclides (137Cs) in these wastes has been investigated by gamma spectrometry. Possible relationships between the radioactive content and the obtained chemical composition, determined by X-ray fluorescence, have also been studied by applying a principal component analysis (PCA). The results showed that the wastes with the highest radioactive content were sewage sludge with activity concentrations of 238U and 210Pb of 321 ± 38 Bq kg-1 and 110 ± 14 Bq kg-1, respectively. A correlation between radioactive content and Fe2O3 concentration was also observed. The annual effective dose rates to workers for the ashes estimated from the ash content ranged from 0.0033 mSv to 0.092 mSv and therefore do not pose a risk to workers as they are lower than the 1 mSv per year limit for the general public (DIRECTIVE 2013/59/EURATOM).

Assessment of radioactivity and radiological risk indices in the sediments of the Tam Giang-Cau Hai, Thi Nai, and Nai lagoons in the Center of Vietnam

Abstract Using gamma and alpha spectrometers, the radioactive isotopes 226Ra, 210Pb, 232Th, and 40K were determined in three sediment cores from the Tam Giang-Cau Hai (TG), Thi Nai (TN), and Nai (DN) lagoons, and radiation risk indices were computed. The radioactivity concentrations of 210Pb, 40K, 232Th, and 226Ra were 55.46 Bq/kg, 675.78 Bq/kg, 67.22 Bq/kg, and 34.15 Bq/kg, respectively. The Raeq, ADR, AEDE, Iγr, AUI, Hex, and AGDE indices were 182.31 Bq/kg, 84.46 nGy/h, 0.10 mSV/y, 1.35, 1, 18, 0.49, and 598.71 µSV/y, respectively; the values of 40K, 232Th, AEDE, ADR, Iγr, and AGDE were greater than the global average and UNSCEAR values. The radioactivity and radiation risk indices decreased in the order DN > TN > TG.

Assessment of cancer risk and radiological effects from 210Po and 210Pb with consumption of wild medicinal herbal plants

BackgroundPlants' raw materials can accumulate chemical elements, including radioisotopes, to some extent and reflect the region they grow in. Due to their high environmental content and toxicity, natural radionuclides – polonium 210Po and lead 210Pb are the most dangerous radioisotopes for human health. Methods70 raw medicinal herbal materials from 54 popular wild-growing medicinal plant species, most of them included in the European Pharmacopoeia, were collected across three regions. In 210 samples, the activity concentrations of 210Po and 210Pb were determined, and their radiotoxicity and cancer risk were calculated. ResultsThe results of 210Po and 210Pb activities measured in herbal raw material were from 0.12 mBq g−1 dry weight in the fruits of the common chestnut (Aesculus hippocastanum) to 19.7 mBq g−1 dw in herb of ground elder (Aegopodium podagraria) for 210Po, while for 210Pb ranged from 0.16 mBq g−1 dw to 34.3 mBq g−1 dw in the same plants. There were statistically significant differences between 210Po and 210Pb content in leaves, herbs, flowers, and fruit. The studies indicated that the estimated annual effective radiation dose from Polish medicinal herbs consumption was low, ranging 0.03–105 µSv from 210Po and 0.02–98.2 µSv from 210Pb, while the risk of cancer morbidity and mortality ranged from 10−5 to 10−9. ConclusionsConsumption of the tested medicinal herbs is safe from the radiological point of view and, based on the predictions related to the calculated risk of cancer, should not increase the probability of its occurrence.

Estimation of 210Po and 210Pb and its doses to human beings due to consumption of freshwater species of Ponnusamuthiram Lake, South India

Abstract A systemic study on the natural radionuclides such as 210Po and 210Pb in the environmental matrices and biota of Ponnusamuthiram Lake (Kumarapalayam) has been undertaken to establish a baseline data on the radiation profile of Ponnusamuthiram Lake ecosystem. The environmental samples, such as water, sediment, and biota (Catla catla, Channa punctata, Clarias batrachus, and Oreochromis mossambicus), crustaceans (Macrobrachium rosenbergii and Macrobrachium malcolmsonii), and bivalves (Lamellidens marginalis), have been subjected to analyses. It has been observed that the concentration of 210Po and 210Pb in the water samples of Ponnusamuthiram Lake was 1.95 and 3.70 mBq L−1, respectively. The activity concentration of 210Po and 210Pb in the sediment sample was 65.31 and 21.12 Bq kg−1, respectively. The bivalve mollusc Lamellidens marginalis have been identified to accumulate higher concentrations of 210Po and 210Pb suggesting that they could serve as bioindicators of radionuclides in the Ponnusamuthiram Lake ecosystem. The concentration factor of 210Po for the biotic components ranged from 1.0 × 103 to 3.0 × 105, while for 210Pb, it ranged from 1.0 × 103 to 4.7 × 104. The committed effective dose for human beings was found at 21.74–248.20 and 16.84–118.67 μSv y−1 for 210Po and 210Pb, respectively.

The presence of radiotoxic 210Po and 210Pb in Ukrainian wild medicinal plants and the assessment of related dose and cancer risk.

Herbal plants are considered natural pharmaceuticals but also accumulate chemical elements and compounds at high levels. 210Po and 210Pb are highly radiotoxic and may cause carcinogenesis due to ionizing radiation. Thirteen of the most popular wild-growing herbaceous plant species, mostly included in the European Pharmacopoeia, were collected across Ukraine. 210Po and 210Pb were determined in the medicinal plants, and their radiotoxicity and cancer risk were calculated. The results of 210Po activities measured in herbal raw material ranged from 2.28Bq kg-1 dw (where dw is dry weight) in herb of common horsetail (Equisetum arvense L.) collected near Lviv to 37.7Bq kg-1 dw in leaves of common birch (Betula pendula Roth.) from Rava Ruska. The activity concentrations of 210Pb varied from 0.44Bq kg-1 dw in leaves of common birch from Starokostyantyniv to 28.4Bq kg-1 dw in leaves of common birch from Mizhhirya. There were statistically significant differences between 210Po and 210Pb content in flowers, leaves, and aerial portions. The studies indicated that the estimated annual effective radiation dose from Ukrainian herbs consumption was low, ranging 5.00-82.6 µSv from 210Po and 0.56-35.8 µSv from 210Pb, while the cancer morbidity and mortality risk ranged from 10-4 to 10-6. The presented data indicated no radiological risk related to using herbal plant materials.

210Po and 210Pb radioactivity levels in local and imported tobacco used in Palestine and Jordan.

This study aimed to assess the concentrations of 210Po and 210Pb in various tobacco samples from Palestine and Jordan. Cigarette smoking is recognized as a significant contributor to the radiation dose received by individuals, primarily due to the elevated levels of 210Pb and 210Po found in tobacco. The analysis revealed that the average concentrations of 210Po in locally sourced tobacco and cigarette samples in Palestine are 16.8 ± 2.3mBq/g and 18.5 ± 2.0mBq/g, with a total average of 17.8 ± 7.4mBq/g (15.5mBq/cigarette). Similarly, the average concentrations of 210Pb in these samples are 18.5 ± 2.6mBq/g and 20.3 ± 2.2mBq/g, with a total average of 19.6 ± 8.1mBq/g (17.0mBq/cigarette). In Jordan, the average concentrations of 210Po in cigarette samples and narghile tobacco are 20.1 ± 2.4mBq/g and 18.3 ± 4.1mBq/g, with a total average value of 19.6 ± 9.9mBq/g (18.0mBq/cigarette), while the average concentrations of 210Pb are 22.2 ± 2.6mBq/g and 20.2 ± 4.5mBq/g, with a total average value of 21.6 ± 10.8mBq/g (19.9mBq/cigarette). The annual effective doses resulting from inhalation were calculated for smokers of these samples. The findings revealed that the levels of 210Po and 210Pb radioactivity in certain investigated samples exceeded the results of studies in many countries of the world. The associated effective doses per year from smoking for all brands products in Palestine range from 34.7μSv/y to 186.5μSv/y with an average of 109.5μSv/y, while in Jordan 54.5μSv/y to 289.1μSv/y with an average of 130.9μSv/y.

Assessment of Be-7, Pb-210 and Po-210 Activities in Airborne Particulate Matter Over Istanbul, Türkiye.

Airborne particulate matter is one of the air pollutants which can have detrimental health effects in the human body. Radionuclides adsorb onto air particles and make their way to humans primarily through inhalation. Naturally-occurring radionuclides, 210Pb and 210Po, are of notable health concern due to their relatively elevated ingestion and inhalation doses. In the current study, activity concentrations of 7Be, 210Pb and 210Po were determined in air particulate matter (PM). PM2.5 was collected on the European side, while PM10 was collected on the Anatolian side of Istanbul. Be-7, 210Pb and 210Po activities were found to be 5.17 ± 2.35, 0.96 ± 0.42; 0.25 ± 0.14 mBq m- 3 in Anatolian side, respectively. Be-7, 210Pb and 210Po activities were found to be 3.81 ± 2.27, 0.62 ± 0.29, 0.29 ± 0.26, mBq m- 3 in European side, respectively. The ratio of 210Po/210Pb was found to be higher (0.47 ± 0.31 for PM2.5 and 0.34 ± 0.27 for PM10) than the global average of 0.1. This result can be explained by the fact that Po is more volatile than Pb and enhanced in the air by the combustion process. Inhalation dose rates of 210Pb and 210Po due to PM10 exposure were calculated to be 7.70 ± 3.30 and 4.05 ± 2.31 µSv year- 1, respectively. Pb-210 bioaccessibility was assessed by the extraction of the particles in simulated lung fluids. Approximately 24.8% of inhaled 210Pb was estimated to be bioaccessible. This study suggests that 210Po and 210Pb activities are partially enhanced in the air particles in Istanbul and should be regularly monitored.

Investigating radiation profiles and conducting risk assessment for ecological and environmental components on Vaan and Koswari islands in the Tuticorin group of islands, India.

Natural radioactive concentration assessment was conducted on sediment, water, and biota obtained on Vaan and Koswari islands in the Tuticorin group of islands, Tamil Nadu, India. For biotic and abiotic components, radiation profiles such as gross alpha, beta, primordial radionuclide, polonium, and lead analyses were performed. The gross α and β range from BDL to 15.18 ± 1.7Bq/kg and 40.43 ± 4.9Bq/kg to 105.12 ± 11.7Bq/kg, respectively. Primordial radionuclides were analyzed using Nal(TI)-based scintillator with PC-MCA, and the concentrations ranged from 13.43 ± 3.3Bq/kg to 30.97 ± 9.6Bq/kg with a mean of 21.31 ± 2.7Bq/kg for 238U; for 232Th, the values ranged from 11.09 ± 2.6Bq/kg to 33.55 ± 9.5Bq/kg with an average value of 23.89 ± 3.7Bq/kg; and for 40K, the values are 93.33 ± 27.3Bq/kg to 219.91 ± 39.6Bq/kg with an average value of 148.27 ± 21.7Bq/kg. The present study values are lesser than the world average values. 210Po and 210Pb concentrations with an average value were determined to be 33.13Bq/L and 16.56Bq/L, 47.55Bq/L and 22.37Bq/L in the water sample, and 50.437Bq kg1 and 62.012Bq kg1, 46.99Bq/kg and 58.625Bq/kg in sediments of Vaan island and Koswari island. The concentrations of 210Po and 210Pb of Pogonias cromis were 19.27 ± 1.5Bq/kg and 8.27 ± 1.01Bq/kg, Belonidae 28.54 ± 2.4Bq/kg and 18.32 ± 2.3Bq/kg, Lepisosteidae 18.68 ± 1.4Bq/kg and 11.17 ± 1.8Bq/kg. The committed effective dosage was determined to be 35.74-54.61 µSv/y for 210Po and 25.39-56.25 µSv/y for 210Pb, in which the 210Pb value is lower; however, the 210Po value is higher than the global average value. The annual committed effective dosage as well as the radiological hazard indices were assessed and found to be much below the global average and the recommended limit, respectively. This research provides an extensive analysis of natural background radiation and establishes a baseline report on the radiological profile of biotic and abiotic factors in the Tuticorin group of islands, namely Vaan and Koswari, in Tamil Nadu, India.

Characterizing 226Ra and its daughters in coastal zone groundwater of a typical human-activity affected bay: occurrence, safety, and source evaluation.

Due to their extremely toxic properties, 226Ra and it daughters (222Rn, 210Pb, and 210Po) in drinking groundwater require monitoring. Recent studies have reported exceptionally high levels of natural 210Po (up to 10,000Bq/m3), 226Ra, and 222Rn isotopes in groundwater. This study aims to provide background data on 226Ra and its daughter radionuclides in the typical agricultural-industrial Dongshan Bay (DSB) before the construction of Zhangzhou Nuclear Power Plant (Zhangzhou NPP). The measurement results indicate that no abnormally high activities of 210Po and 210Pb were detected in the investigated wells. Strong positive correlations between 210Pb and 210Po, as well as between 222Rn and 210Pb activities, suggest that the origins of 210Pb and 210Po in groundwater are strongly influenced by the decay of the parent radionuclides 222Rn and 210Pb, respectively. In the DSB coastal zone groundwater, significant deficiencies of 210Po relative to 210Pb and 210Pb relative to 222Rn were observed, providing further evidence that 210Po and 210Pb are also effectively scavenged due to their geochemical properties (specifically particle affinity) within the groundwater-aquifer system. A systematic comparison among all relevant water bodies in the DSB revealed that the activity concentrations of 210Pb and 210Po in groundwater were the highest, except for rainwater. Based on the evaluation of 210Pb sources, the results imply that submarine groundwater discharge (SGD) is an important pathway for transferring radionuclides (such as 210Pb) from land to the nearshore marine environment, even though the study area has a lower 210Pb background groundwater. By considering all the 210Pb's sources in the DSB, we found low 210Pb background groundwater discharge still needs to be taken into account for small-scale bays. This is because SGD was calculated to be one of the most important 210Pb sources in the bay during observation season. Regardless of whether the system is in a normal state or a nuclear accident emergency state, greater attention should be paid to the groundwater discharge of radionuclides into the ocean.

The activity of 210Pb in cigarette smoked in Kazakhstan.

The radon decay product 210Pb is a known component of tobacco. In this study, the activity concentration of 210Pb in the most popular cigarette brands (six samples) for Kazakhstan consumers was determined by beta spectrometry. The activity levels of 210Pb ranged between 2.69 ± 0.27 and 27.42 ± 2.74mBq per cigarette. Higher activity concentrations for 210Pb were found in Sample No.4 and showed an excess of the world average by 1.8 times. The average activity concentrations of 210Pb in cigarette tobacco were 10.42 ± 1.04mBq cig-1. The daily activities inhaled in the lungs of a smoker, and the resulting effective doses due to cigarette smoking were calculated. Effective doses per year due to cigarette smoking were calculated assuming that 42.13% of the 210Pb in tobacco were retained in the lungs of the smokers. It is concluded that for a smoker in Kazakhstan, the average effective dose ranges from 9.1 ± 0.9 μSv/year to 92.8 ± 9.3 μSv/year for a cigarette consumption of one pack of cigarettes per day. The results indicate that the annual effective doses from inhalation of 210Pb due to smoking one pack of cigarettes per day are from 7 to 58 times (for different types of cigarettes) greater than the annual effective doses from ingestion of radionuclides via the diet.

Unveiling threats to glacier biota: Bioaccumulation, mobility, and interactions of radioisotopes with key biological components

Contemporary melting glaciers are considered a secondary source of pollutants including radionuclides. Cryoconite - biogenic sediment on the glacier surface - exhibits high concentrations of natural and anthrophogenic radioisotopes. Understanding the interactions between radioisotopes and organisms is essential for evaluating their potential impact on glacier-related ecosystems. Using a multidimensional approach and intensive sampling (17 glaciers), we investigated the relationships between activity concentrations of 137Cs and 210Pb and various biotic components of cryoconite such as the amount of organic matter, chlorophyll concentration, the ratio of cyanobacteria to all bacteria, and size of cryoconite granules. Additionally, to better understand the bioavailability and fate of radioisotopes in this ecosystem, we measured the uptake ratio of 137Cs, 210Pb, 238Pu, and 239+240Pu in the top consumers, and examined the mobility of radioisotopes by measuring 137Cs and 210Pb activity concentrations after a parallel extraction using media with different specific ion exchange capacities. The activity concentrations of both 137Cs and 210Pb showed a large variability reaching 5.8 kBq kg−1 and 7.2 kBq kg−1, respectively. Their activity concentrations were positively related to the amount of organic matter, however, the 210Pb also increased with the chlorophyll concentration. This might be due to the difference in the deposition of both elements: lead, being deposited constantly, binds also to currently developing communities, while caesium deposition peaked in the 1960s. The mobility analysis revealed that the loosely bound fraction of 210Pb was more strongly related to organic-metallic complexes than 137Cs. Firmly bound radioisotope fractions (anhydrous interlayer sites of minerals) were three times higher for 137Cs than for 210Pb. The median uptake ratios of radioisotopes were determined as 0.07–0.111 for 137Cs, 0.177 for 210Pb, 0.07 for 239+240Pu. Our findings emphasize the importance of organisms in the accumulation of radioisotopes on glaciers and suggest an impact of radionuclides on glacier organisms.

Leaching behaviour and mechanism of U, 226Ra and 210Pb from uranium tailings at different pH conditions

A large number of radionuclides remain in uranium tailings, and U, 226Ra and 210Pb leach out with water chemistry, causing potential radioactive contamination to the surrounding environment. In this paper, uranium tailings from a uranium tailings pond in southern China were collected at different depths by means of borehole sampling, mixed and homogenised, and analysed for mineral and chemical composition, microscopic morphology, U, 226Ra and 210Pb fugacity, static leaching and dynamic leaching of U, 226Ra and 210Pb in uranium tailings at different pH conditions. The variation of U, 226Ra and 210Pb concentrations in the leachate under different pH conditions with time was obtained, and the leaching mechanism was analysed. The results showed that the uranium tailings were dominated by quartz, plagioclase and other minerals, of which SiO2 and Al2O3 accounted for 65.45% and 13.32% respectively, and U, 226Ra and 210Pb were mainly present in the residue form. The results of the static leaching experiments show that pH mainly influences the leaching of U, 226Ra and 210Pb by changing their chemical forms and the particle properties of the tailings, and that the lower the pH the more favourable the leaching. The results of dynamic leaching experiments during the experimental cycle showed that the leaching concentration and cumulative release of U, 226Ra and 210Pb in the leach solution were greater at lower pH conditions than at higher pH conditions, and the leaching of U, 226Ra and 210Pb at different pH conditions was mainly from the water-soluble and exchangeable states. The present research results are of great significance for the environmental risk management and control of radioactive contamination in existing uranium tailings ponds, and are conducive to ensuring the long-term safety, stability and sustainability of uranium mining sites.

Root uptake and foliar deposition of 226Ra, 210Pb, and 210Po in medicinal plants of Western Ghats of Karnataka

The concentrations of radionuclides 226Ra, 210Pb, and 210Po in naturally grown medicinal plants and the soil of their rooting area from Western Ghats section of Karnataka were estimated by using HPGe gamma spectrometer and alpha counting system. The soil to plant transfer factors (TF) of each radionuclide was found. The TFs varied in the range 0.04–1.92, 0.22–5.41, and 0.6–3.81 for 226Ra, 210Pb, and 210Po respectively. The TF was found to be more than unity in some of the medicinal plants. The study may help to form the database of radionuclide concentration and TF for these medicinal plants.

Investigation on the radioactivity levels of seawater, sediments, and biota in Daya Bay, China

ObjectiveTo investigate the radioactivity levels of seawater, sediments, and biota in the Daya Bay sea area, China, in order to establish the radioactivity baseline values, and provide basic data for the assessment of potential radiological risks that might result from the application of nuclear technology or human activities. MethodsSamples of seawater, sediments, and biota were collected from the Daya Bay sea area and analyzed. Their radioactivity baseline data were then compared with information from other regions in China and around the world reported in related literature. ResultsFor the seawater samples, the activity concentrations of natural radionuclide 40K were 9.9–10.4 Bq/L, while 238U, 226Ra, 210Pb, 137Cs, and 110Agm were below the minimum detectable activity (MDA). Regarding the sediment samples, the activity concentrations of 238U, 228Ra, 226Ra, 210Pb, 40K, and 137Cs were 38.1–40.4, 49.1−53.7, 32.6−38.6, 59−95, 590−650, and 0.48–0.88 Bq/(kg dry weight), respectively, while 110Agm was below the MDA. For the marine shrimps in the biota samples, the activity concentrations of 228Ra, 226Ra, 40K, and 137Cs were 1.14–2.75, 0.17−0.43, 63–76, and 0.038–0.045 Bq/(kg wet weight), respectively, while 238U, 210Pb, and 110Agm were all below the MDA. Furthermore, for the marine fishes in the biota samples, the activity concentrations of 228Ra, 226Ra, 210Pb, 40K, and 137Cs were 2.1–19.7, 0.32–3.78, <2.2–2.8, 59–70, and <0.007–0.026 Bq/(kg wet weight), respectively, while 238U and 110Agm were all below the MDA. 228Ra was found to be concentrated in Osteomugil ophuyseni with 19.7 Bq/(kg wet weight). ConclusionsThe radioactivity levels of seawater and marine sediments in the Daya Bay sea area are within the range of the normal background values. Osteomugil ophuyseni exhibited higher concentrations of 228Ra than other species in this study, while the other species in the biota show no significant difference in the radioactivity levels from data in relevant literature.

Growth rate estimation by 210Pb chronology in precious corals collected off the southern coast of Japan

The Lead 210 (210Pb) concentrations were determined to estimate the skeletal growth rates in the four species of precious corals including Japanese red coral (Corallium japonicum), pink coral (Pleurocorallium elatius), white coral (P. konojoi), and a deep-sea coral (Coralliidae sp.), and in a bamboo coral (Keratoisis sp.). Colonies were collected from the southern coast of Japan, western North Pacific margin. The 210Pb concentrations typically showed the exponential decrease with distance from the edge to the center of the skeleton axis in a cross section of main stem of colonies. The mean radial growth rates for colonies were estimated from the slopes of the best fit curves for exponential decrease in 210Pb concentration along the multiple transects. The obtained mean and standard deviation of radial growth rates in the diameter (the number of transects, n) for three colonies of C. japonicum were 0.31 mm/y (n = 1), 0.21 ± 0.05 mm/y (n = 2), and 0.36 ± 0.13 mm/y (n = 2), respectively, which were broadly comparable to the previously reported growth rates obtained by growth ring counting. Those obtained for three white coral colonies were 0.52 mm/y (n = 1), 0.60 mm/y (n = 1), and 0.36 ± 0.25 mm/y (n = 2). The radial growth rate for the bamboo coral colony was 0.13 mm/y in radius. The linear growth of the main steam of some colonies was analyzed from several cross sections. The linear growth rates of colonies could be estimated from the slope of the best fit curve (1) for increasing mean 210Pb concentration along the cross transects of the axis and (2) for increasing center 210Pb concentration of the skeleton axis. The linear growth rates calculated from the mean and center concentrations for two C. japonicum colonies were 8.5 and 6.1 mm/y, and 1.8 and 1.4 mm/y, respectively. Those for a P. elatius colony were 4.7 and 3.4 mm/y. The difference between the two estimates may reflect the morphological structure of the skeleton. The growth rates measured for the radial increase and linear extension of the main stem of the colonies could provide basic information for the demographic study of these coral species thereby fostering a rational exploitation of their populations.

Physicochemical and radiological characterization of flue gas desulfuration waste samples from Brazilian coal-fired power plants

Flue gas desulfurization (FGD) waste is an industrial by-product generated during the flue gas desulfurization process in coal-fired power plants. This by-product contain trace quantities of naturally occurring radionuclides and elements such as As, Ba, Co, Cr, Zn. The characteristics of FGD waste are important for its reuse and are mainly depend on the desulfurization process. In this work, two types of FGD materials collected from three coal-fired power plants using semi-dry and wet processes were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), X-ray fluorescence (XFR) and particle size analysis. The radioactive content of 238U, 232Th, 228Th, 226Ra, 228Ra, 210Pb and 40K and trace elements were also determined using Neutron activation analysis and Gamma-ray spectrometry. The major constituents for all samples were Ca, Si, S, Al and Fe. Wet FGD by-product presented also high magnesium content. The wastes contain mainly semi-hydrate calcium sulfite and calcium sulfate. The particle size of FGD from semi-dry process was lower than that from the wet process. The average activity concentration of 238U, 232Th, 226Ra, 210Pb, 228Ra, 228Th and 40K varied between were 50-71, 33-42, 28-52, 113-150, 26-33, 33-39, 161-390 Bq kg-1, respectively. According to the results of leaching and solubilization tests, FGD samples were classified as non-hazardous and non-inert. The obtained data are useful for evaluation of possible applications of FGD by-products.

Assessment of radioactivity in particulate matter and soil from selected mining towns of Erongo region, Namibia

The presence of radionuclides in particulate matter (PM) associated with mining operations in communities located at the edge of the mine sites have been either greatly ignored or poorly understood, leading to the underestimations of the radionuclides concentrations in PM and health impact. In this study, measurements of radioactivity in PM and soil were made in the two mining towns of Karibib and Arandis to assess the human health radiological impact on the people around the mining sites. Dust fall samples were collected for a period of six months i.e. May 2017 to October 2017 using open bucket sampler procedure according to the American Society for Testing and Materials Standard Method (ASTM D1739) while some soil samples were collected using a soil auger. The samples were measured for the presence radionuclides using a well calibrated gamma-ray spectrometer coupled with a high purity germanium detector.In particulate matter samples, the mean activity concentrations of 226Ra, 238U, 232Th, 210Pb, and 40K were found to be 81.24±1.00, 57.99±2.61, 72.10±1.67, 55.89±6.21, 682±19.81 Bq.kg−1, respectively. Similarly, in soil samples, the mean activity concentrations were found to be 66.41±1.77 Bq.kg−1 for 226Ra, 52.79±3.40 Bq.kg−1 for 238U, 71.30±2.40 Bq.kg−1 for 232Th, Bq.kg−1 for 71.50±5.99 210Pb and 797.36±18.26 Bq.kg−1 for 40K. The activity concentrations revealed higher levels of radionuclides associated with the 238U series, which were distributed unevenly across the sites. The results were comparable to global values of 11 to 64 Bq.kg−1 for 238U, 17 to 60 Bq.kg−1 for 232Th, and 140 to 850 Bq.kg−1 for 40K.The activity concentrations were used to compute the absorbed dose (D), annual effective dose equivalent (AEDE), radium equivalent activity concentrations (Ra eq), external and internal hazard indices (H ex and H in), Gamma Index (Iγ), Alpha Index (Iα) and excess lifetime cancer risk (ELCR). The mean radiological parameters in most samples were found to be within acceptable limits, with Raeq 370 Bq.kg−1, which corresponds to an upper safe limit of AEDE of 1 mSv.yr−1, the prescribed safe limit by the International Commission on Radiological Protection (ICRP), and thus the potential radiological health effects may not be significant.

Natural radioactivity of groundwater in Vendian deposits in St. Petersburg Region

The study is focused on the hydrogeological conditions and the chemistry of groundwater of the Vendian aquifer in the western part of the Leningrad oblast (Karelian Isthmus and the area near Sosnovy Bor town) and St. Petersburg City, where groundwater features higher radioactivity, but nevertheless it is used for drinking water supply. Data on the radiological characteristics, which have been determined in the estimation of the quality of groundwater used for drinking are generalized and analyzed. These characteristics include the gross alpha and gross beta activity and the specific activity of natural radionuclides 222Rn, 226Ra, 228Ra, 210Pb, 210Po, 238U, and 234U. The data were subjected to statistical and correlation analysis to determine the hygienic criteria for the use of groundwater of this aquifer for drinking water supply and to study the sources and the processes of formation of the natural radiological background. Groundwater quality standards were shown to be exceeded in the majority of the analyzed wells. The brackish water in the southern, deeper, part of the aquifer system was shown to have higher radioactivity and relatively high concentrations of 226Ra, 228Ra, 210Pb, and 210Po, compared with fresh water in the northern part of the territory, of which higher, though nonuniform, 222Rn activity is typical. Relationships between the radiation characteristics of groundwater are considered along with the causes of formation of groundwater radionuclide composition as a result of the higher radioactivity of the host deposits and the chemistry of groundwater; changes in the radiological and hydrochemical background groundwater characteristics from the north to the south are characterized in accordance with the subsidence of the aquifer system and an increase in the stagnation of the hydrochemical regime. The analysis of the well-known relationship between the concentrations of radium isotopes in groundwater, uranium and thorium isotopes in the host rocks, and groundwater residence time in the aquifer, along with the comparison of the available field data with calculation results, suggested the conclusion that the concentration of uranium in the water-bearing rocks in the major portion of the area under consideration is higher than its regional mean values.