Distribution Of 210Po Research Articles

Distribution of 210Po in the trophic levels of a brackish lagoon in Uruguay.

An extensive study on 210Po was conducted at Castillos Lagoon, a shallow brackish lagoon on the east coast of Uruguay, aiming to determine the activity concentrations of 210Po in various compartments and to derive the activity fluxes among them. The activity concentration of 210Po was determined in water, sediments, six different species of fishes, crabs, shrimps, phytoplankton, and zooplankton. 210Po was determined using alpha spectrometry, performing radiochemical separation and self-deposition on silver disc. The activity concentrations of 210Po obtained in the water samples ranged from 0.5 ± 0.1 to 30.5 ± 0.7mBq/L, while in the sediment samples varied between 24 ± 1 and 129 ± 5Bq/kg. In the case of biota, the ranges obtained were 15 ± 1 to 33 ± 2Bq/kg in phytoplankton, 33 ± 2 to 200 ± 6Bq/kg in mixed zooplankton, 125 ± 4 to 183 ± 6Bq/kg in the soft tissue of razor clam (Tagelus aff. plebeius), 94 ± 2Bq/kg in the soft tissue of blue crab (Callinectes sapidus), 10 ± 1 to 28 ± 2Bq/kg in shrimp muscle, and 232 ± 6 to 422 ± 10Bq/kg in shrimp hepatopancreas (Penaeus paulensis). In the case of fish, the ranges were 1.8 ± 0.2 to 497 ± 10Bq/kg in muscle tissue and 47 ± 2 to 1750 ± 32Bq/kg in stomach and intestine tissue. The transfer coefficient (CR) values vary between 101 and 105 depending on the aquatic organism and the tissue considered. The results obtained in this work are consistent with the theory that 210Po is primarily absorbed from water and concentrated by phytoplankton and zooplankton, then transferred to the next trophic levels along food chains. This theory has also been observed by F.P. Carvalho (2018a) and IAEA (2017). These data contribute to increase the limited CR 210Po datasets in fresh and brackish waters and in the Southern Hemisphere.

Radiotoxic 210Po concentration in the Mediterranean Sea sediment and radiation risk assessment of biota

This research presents the levels and distribution of 210Po in different sediments of the northeastern coast of the Mediterranean Sea. The 210Po activity concentrations were measured using an alpha spectroscopy system. The activity concentrations of 210Po in the sediment samples were in the range between 20.5 ± 0.7 and 92.8 ± 1.6 Bq kg−1 dw with an average of 48.2 ± 1.4 Bq kg−1 dw. The microorganism-enriched sampling sites (bedrock sites) indicated low 210Po concentration than sandy coastal sites. As a result of these measurements, the RESidual RADioactivity (RESRAD) biota code was applied to calculate the tissue concentration rate (CR), internal dose rate, external dose rate, and total dose rate of the exposed tissues. The total dose rates of aquatic animals were found higher than that of riparian animals. The 210Po sediment resource doses to aquatic and riparian animals were found less than the dose level recommended by International Commission on Radiological Protection (ICRP).

Distribution of 210Po in body organs of bigeye scad and greater lizardfish species at Binh Thuan, Vietnam

Distribution of 210Po in body organs of bigeye scad and greater lizardfish species at Binh Thuan, Vietnam

Distribution of 210Po in spice plants cultivated by conventional farming

Purpose To study the distribution of 210Po concentrations in various parts of spice plants cultivated by conventional farming in Nilgiris, South India and estimate effective radiation dose received. Materials and methods Parts of plant such as leaf, fruit, seed, flower bud and rhizome of selected spice plants cultivated at various locations in the study area have been collected for estimation of 210Po concentration. Organic materials in known mass of processed samples have been removed by chemical method. 210Po concentration in the digested sample has been electrostatically deposited on pre-polished silver disks at constant temperature. ZnS(Ag) detector-based alpha counting system with minimal detectable value 3.2 mBq has been used for estimation of 210Po activity concentration. Results Leaves of Curcuma longa have registered a high concentration of 45.6 ± 4.5 Bq kg−1 of 210Po and rhizome of Allium sativum has registered a low value of 4.7 ± 0.8 Bq kg−1. Leaves of spice plants have registered higher concentration of 210Po than their fruits, seeds, flower buds or rhizomes. Soil to plant transfer factor of 210Po has been found to vary from 0.13 for rhizome of A. sativum to 2.23 corresponding to leaf of C. longa. Concentration of 210Po estimated in leaves and mean leaf areas of spice plants has been found to have a correlation coefficient of 0.83, which indicates that absorption of 210Po deposited on surface area of leaves is the main source of this isotope in plant parts. Conclusions Consumption of various parts of spice plant does not pose significant radiological risk as effective dose received by the general public as 210Po has been found to vary from 6.34 to 46.05 µSv y−1, less than the value recommended by ICRP.

Distribution of 210Pb and 210Po in ground water around uranium mineralized area of Jaduguda, Jharkhand, India

In present study, distribution of 210Po and 210Pb in ground water in uranium mineralized zone of Jaduguda in East Singhbhum region of Jharkhand state, India is evaluated. Activity concentration of 210Po ranges from < 0.08 to 7.41 ± 0.90 mBq L−1 and activity concentration of 210Pb was ranging from 0.76 ± 1.27 to 34.43 ± 3.89 mBq L−1. Comparable results were observed for the samples from upstream and downstream direction with respect to uranium mining and ore processing facilities at Jaduguda reflecting restriction of migration of radionuclides from facilities. Activity concentrations of 210Pb and 210Po observed were below the guidance value of WHO. Average ingestion doses from 210Pb and 210Po in groundwater were calculated to 1.91 ± 1.60 µSv year−1 and 5.75 ± 4.45 µSv year−1respectevely. 210Po was observed to be decreasing with SO42− in ground water indicating possible fixation of 210Po with process involving formation of sulfates.

210Po levels and distribution in different environmental compartments from a coastal lagoon. The case of Briozzo lagoon, Uruguay

This paper presents the levels and distribution of 210Po in different compartments of a coastal lagoon on the east coast of Uruguay (South America). Activity concentrations of 210Po have been obtained in different matrices, such as water, superficial sediments, clams (Diplodon sp.), freshwaters snails (Pomacea sp.), zooplankton, and fishes (Jenynsia sp.), collected at different points of the lagoon and during several sampling campaigns. In addition, the organic matter content of the sediment was determined to study the variation of 210Po along the lagoon.The activity concentrations of 210Po in the water samples are in the range between 1.1 ± 0.2–3.5 ± 0.4 mBq/L while in the sediment samples vary between 17.1 ± 1.4 and 540 ± 12 Bq/kg, DW. In the case of biota, the ranges obtained were 182 ± 5–265 ± 6 Bq/kg, DW in clams and 134 ± 4–1245 ± 16 Bq/kg, DW in snail samples.A good correlation of 210Po with the organic fractions of the sediment was observed (r = 0.8798, p-value < 0.001), being obtained high values for the distribution coefficient Kd (104 -105). In the biota samples, a clear difference was observed in the 210Po concentration values in both species, mainly due to the different feeding habits of both aquatic organisms, as it is reflected in the associated concentration ratios (CR).In this paper, a good set of results of 210Po, Kd, and CR have been obtained in different matrices, enhancing the limited archives available for modelers concerning these parameters for 210Po and freshwater systems.

Determination and distribution of 210Po in different morphological parts of tobacco plants and radiation dose assessment from cigarettes in Turkey.

Both sides of tobacco leaves accumulate 210Po through their sticky hairs (trichomes) by means of diffusive deposition. It is known that tobacco leaves may contain high amounts of 210Po concentrations. However, there is less information about radionuclides in tobacco plants. In the study, the 210Po concentrations were determined monthly in different morphological parts of tobacco plants (leaf, stem, root) and soil samples and soil-to-plant transfer factor for 210Po was determined and the activity concentrations of 210Po radionuclide in 16 different popular brands of cigarettes were investigated in order to estimate the annual effective doses of 210Po to smokers. Besides the study investigated (focused on) the correlation between the amount of rainfall and 210Po concentration of tobacco leaf. The results of the present study indicated that the activity concentration of 210Po in cigarettes distributed in Turkey ranged from 16.1±1.0 to 37.6±2.6mBq per cigarette and the mean value of their activity concentrations was 22.4±1.5mBq per cigarette. The mean value of annual effective doses of 210Po to smokers (20 cigarettes smoked by an individual per day) obtained from these activity concentrations was estimated to be 188.5±12.4μSv y-1.

Distribution of 210Po and 210Pb radionuclides and their dependence on physico-chemical parameters of soil in Madikeri taluk, Coorg district, Karnataka, India

The paper deals with distribution of 210Po and 210Pb radionuclides in a vertical profile of illuviated soil, in Madikeri taluk of Coorg district, Karnataka, India. The activity concentration of 210Po and 210Pb radionuclides was determined using radioanalytical method and the dependence of these radionuclides on physico-chemical parameters of soil was also investigated through a statistical study. In all the layers of the soil in a vertical profile, the 210Po nuclides were found to be in disequilibrium with 210Pb. The frequency distribution of 210Po and 210Pb radionuclides was analysed using Kolgomorov–Smirnov test.

210Po and 210Pb in fish from northern Aegean Sea and radiation dose to fish consumers

This paper presents the activity concentrations of 210Po and 210Pb in 15 different commercial fish species collected around Gokceada Island (northern Aegean Sea) in 2016. The distribution of 210Po and 210Pb was investigated in fish tissues and significant differences (P < 0.05) in radionuclide concentrations were noted between muscle, gills, and liver in each species. 210Po activity concentrations in tissues were systematically higher than those of 210Pb and the average values of 210Po/210Pb concentration ratios were calculated at 6.6 ± 1.5, 8.4 ± 3.2, and 10.2 ± 1.6 in muscle, gills, and liver, respectively. The annual effective dose to consumers through 210Po ingestion with fish filet averaged 62 µSv year−1 (range 5.5–160 µSv year−1). This effective dose is in the range of natural radiation doses reported worldwide for humans through ingestion of sea food.

Distribution of 210Ро in lichen thalli

Distribution of 210Po in thalli of soil and wood (epiphytic) lichens was studied. Four fractions containing the corresponding 210Ро forms were obtained by sequential extraction: (1) intercellular, (2) extracellular, (3) intracellular, and (4) insoluble thallus residue. The 210Ро uptake by lichens is mainly passive, as the total content of the radionuclide in fractions 1, 2, and 4 reaches 88–97%. From 3 to 12% of 210Ро is taken up actively (fraction 3), and for soil lichens this parameter is approximately 2.75 times higher than for epiphytic lichens. Presumably, 210Ро is supplied into soil and epiphytic lichens in the form of different chemical compounds and is therefore characterized by different bioavailability.

210Po distribution after high temperature processes in coal-fired power plants

In this paper, the distribution of 210Po after high temperature processes in six units of coal-fired power plants (CFPs) were evaluated. The coal, bottom ashes, fly ashes from electrostatic precipitators (ESP), and flue gases from stacks were sampled from four CFPs and analyzed for 210Po contents. The results showed that 210Po was mainly captured by the ESP, with little left in the bottom ash, and a small fraction of 210Po was directly discharged into the environment through the stacks, accounting for 0.06%–0.6%, which was consistent with the reported data. It was also found that part of the 210Po could not be accounted for in the mass balance analysis for the whole combustion process in CFPs, which was also in line with the reported data. The results obtained in this study provided essential basic data for environmental radiological risk analysis for CFPs.

Distribution of 210Po in soils of Virajpet taluk, Coorg District, Karnataka

The present investigation involves the distribution of 210Po in the soils of Virajpet taluk, in Coorg District. The soil samples were collected along a vertical profile at various locations. The samples were analyzed for determination of 210Po activity using standard radiochemical analytical method. The distribution of 210Po along vertical profile was found. The dependence of 210Po activity on organic matter and clay in a vertical profile were analysed. The texture of soil shows that soil is sandy loam or loamy sand, in which illuviation takes place easily. The 210Po activity varies from 1.59 Bqkg−1 to 13.95 Bqkg−1 in first layer, 0.49 Bqkg−1 to 9.79 Bqkg−1 in second layer and 0.58 Bqkg−1 to 6.14 Bqkg−1 in third layer. A negative correlation between organic matter percentage and 210Po activity was found in all the three layers with correlation coefficient −0.872, −0.643 and −0.505. A negative correlation was observed between clay percentage and 210Po activity, in all the three layers with correlation coefficient −0.749, −0.512 and −0.402. The organic matter leaches vertically downwards, due to flow of rainwater.

Modelling the relationship between zooplankton biomass and environmental variations in the distribution of 210Po during a one year cycle in northwestern Mediterranean coastal waters

To clarify the relationship between zooplankton biomass and the environmental kinetics of the natural radionuclide 210Po during a one-year period (October 1995 to November 1996) in northwestern Mediterranean coastal waters, a modelling analysis was applied. Using 210Po concentrations in seawater and zooplankton, the 210Po uptake rate constant from food for zooplankton was evaluated using a biokinetics calculation involving the uptake and the excretion rate constants between seawater and zooplankton. Using the transfer constants obtained, the 210Po concentrations in zooplankton were reconstructed and validated by observed concentrations. The simulation results were in good agreement with the measured 210Po concentrations in zooplankton. Assuming that 210Po fecal excretion represents the majority of the excretion of 210Po from zooplankton, the fecal matter associated 210Po vertical flux was calculated, and compared with the observed vertical fluxes of 210Po measured in sediment traps. The modelling evaluation showed that fecal pellet vertical transport could not fully explain the observed sinking fluxes of particulate organic matter at 150 m depth, suggesting that other sinking biodetrital aggregates are also important components of the plankton-derived vertical flux of 210Po.The relationship between 210Po concentration in seawater and that in rain and dry fallout and their potential effect on 210Po concentrations in zooplankton at this location were also examined. A similar, but diphased trend between 210Po in zooplankton and 210Po in rain and dry fallout deposition rate was demonstrated. 210Po concentrations in the dissolved phase of seawater tended to diminish as mean daily rainfall increased suggesting that rain inputs serve as a 210Po dilution mechanism in seawater at this location.

Estimation of annual effective dose due to ingestion of natural radionuclides in foodstuffs and water at a proposed uranium mining site in India

Purpose: To study the distribution of 210Po, 226Ra, 230Th and U(nat) (naturally occurring radioisotopes of uranium [234U, 235U and 238U]) in food and water around the Bagjata uranium mining area in India.Materials and methods: Radionuclides were analyzed in food samples of plant and animal origin after acid digestion. Intake and ingestion dose of the radionuclides were estimated.Results: 210Po, 226Ra, 230Th and U(nat) in all the dietary components ranged widely from < 0.2–36, < 0.02–1.58, < 0.01–2.8 and < 0.017–0.39 Bqkg-1, respectively. The range of 226Ra and U(nat) in water was < 3.5–206 and < 12.6–693 mBql−1, respectively. The intake of radionuclides considering food and water was calculated to be 760 BqY−1 while the ingestion dose was 601 μSvY−1. The estimated doses reflect the natural background dose via route of ingestion, which is below the 1 mSvY−1 limit set by the International Commission on Radiological Protection (ICRP). However, the doses are more than the dose constraint of 300 μSvY−1 as suggested by the ICRP for members of the public for planned disposal of long-lived radioactive waste.Conclusion: The study confirms that current levels of radionuclides do not pose significant radiological risk to the local inhabitants, but they need close investigation in the near future.

Po-210 and Pb-210 in water and fish from Taboshar uranium mining Pit Lake, Tajikistan

Polonium-210 in water and 210Pb and 210Po in different fish organs from 3 different fish species in Taboshar Pit Lake (n = 13), located in the uranium mining area in Tajikistan, and in Kairakkum Reservoir (reference lake, n = 3), have been determined as part of a Joint project between Norway, Kazakhstan, Kyrgyzstan and Tajikistan.The average activity concentration of 210Pb and 210Po in liver, muscle and bone of Carassius auratus was higher than the concentration in similar tissues of C. carpio and Sander lucioperca from the reference site. The accumulation of 210Po was higher than for 210Pb, and the accumulation of 210Po was highest in the liver of C. auratus (3673 ± 434 Bq kg−1 ww). Although the average activity concentration of 210Pb in liver and bones of C. auratus from Pit Lake were fairly similar, a huge variation in the liver activity concentrations (25–327 Bq kg−1 ww) was found. The results confirm direct uptake of unsupported 210Po into the liver, and that the distributions of 210Po and 210Pb in fish organs were different. The BCF (L/kg) for 210Po in bone, liver and muscle clearly demonstrates high accumulation of 210Po in C. auratus, especially in the liver. The average BCFs of liver, bone and muscle were >1.4 × 105, >2.5 × 104 and >1.4 × 104, respectively. All fish in the Pit Lake were found to be in the same trophic level, however, a linear correlation between log 210Po in liver and δ15N could indicate biomagnification of 210Po in liver of C. auratus.In regards to the recommended Annual Limit of Intake (ALI) for 210Po, the concentration of 210Po in muscle tissues of C. auratus is alarming, as there is a high probability for the local population at risk to exceed the recommended ALI through consumption of fish from Taboshar Pit Lake.

Dependence of 210Po activity on organic matter in the reverine environs of coastal Kerala

This paper deals with the distribution of 210Po in the river bank soil samples of three major rivers namely Bharathapuzha, Periyar and Kallada river of Kerala. The dependence of 210Po activity on organic matter content in the samples was also studied. The soil samples were collected and analyzed for 210Po radionuclide using standard radiochemical analytical method. Activity of 210Po increases with increase in organic matter content in samples. Along the Bharathapuzha river bank the 210Po activity ranges from 2.96 to 12.48 Bq kg−1 with mean 5.62 Bq kg−1. The organic matter percentage in the samples ranges from 0.4 to 2.8 and a good correlation with correlation coefficient 0.9 was found between activity and organic matter percentage. In the Periyar river environs 210Po activity ranges from 3.47 to 13.39 Bq kg−1 with mean value 9.27 Bq kg−1. Organic matter percentage in these samples ranges from 1.20 to 4.10 and the correlation coefficient between 210Po activity and organic matter percentage was found to be 0.8 In the Kallada river bank soil samples 210Po activity ranges from 4.46 to 6.45 Bq kg−1. The organic matter percentage ranges from 1.4 to 3. The correlation coefficient between 210Po activity and organic matter percentage in the samples was found to be 0.9.

Distributions of 210Po and 210Pb radioactivity in the intermediate layer of the northwestern North Pacific

The distributions of 210Po and 210Pb in the intermediate layer (400–2000 m) of the northwestern North Pacific were determined to elucidate the export flux of particulate matter. 210Po generally showed depletion relative to 210Pb in the intermediate layer, suggesting that 210Po was scavenged by particles. Because the removal rate constants of 210Po in the western region were higher than those in the eastern region and this trend coincided with that of the particle fluxes in the surface layer, the export production in the surface layer was assumed to influence the particle flux in the intermediate layer of the northwestern North Pacific.

Distribution of 210Po and export of organic carbon from the euphotic zone in the southwestern East Sea (Sea of Japan)

The distribution of the natural radionuclide 210Po in the water column along a horizontal transect of the continental shelf, slope and deep basin regions of the East Sea (Sea of Japan), a marginal sea of the Northwest Pacific Ocean, was investigated, and its behavior is described here. The settling fluxes of particulate 210Po in the deep basin along with 210Pb, 234Th and biogenic matter were also determined. 210Po inventories in the water column were observed to decrease from winter to summer in all stations, probably due to increased influx of 210Po-poor Kuroshio Water of the Northwest Pacific Ocean during summer. Vertical profiles of dissolved and particulate 210Po along with the settling fluxes of particulate 210Po in the deep basin station have enabled us to evaluate temporal variations and residence times of 210Po. In the slope and basin, activities of dissolved 210Po generally decreased from the surface to the bottom water, with maximum activity just below the subsurface chlorophyll a maximum at 50–75 m depth in spring and summer. These subsurface peaks of dissolved 210Po activity were attributed to the release of 210Po from the decomposition of 210Po-laden biogenic particulate organic matter. In the deep basin, despite the decrease in total mass flux, the sinking flux of particulate 210Po was higher in the deeper trap (2000 m) than in the shallower one (1000 m), probably due to scavenging of dissolved 210Po from the water column during particle descent and/or break-down of 210Po-depleted particulate matter between 1,000 m and 2,000 m depths. In general, the ratios of the particulate phase to the dissolved phase of 210Po (Kd) increased with depth in the slope and basin stations. 210Po removal from the water column appears to depend on the primary productivity in the upper waters. There is an inverse relationship between Kd and suspended particulate matter (SPM) concentration in the water column. From the 210Po activity/chlorophyll a concentration ratios, it appears that sinking particles arriving at 1000 m depth were similar to those in the surface waters.

Distribution of 210Po and 210Pb in riverine environs of coastal Karnataka

The concentrations of 210Po and 210Pb have been measured in soil, sediment and rock samples collected from major rivers of coastal Karnataka, viz. Kali, Sharavathi and Netravathi. The activity of 210Po and 210Pb in the samples were separated by radiochemical methods and the activity was counted using ZnS(Ag) alpha-counter. The activity ratio of 210Po and 210Pb and the dependence of organic matter content on the activity of these radionuclides were studied.

Studies on the distribution of 210Po and 210Pb in the ecosystem of Point Calimere Coast (Palk Strait), India

A systematic study on the natural radionuclides such as 210Po and 210Pb in the environmental matrices of Point Calimere ecosystem has been undertaken to establish a baseline data on the radiation profile of Point Calimere environment. The environmental samples such as water, sediment and biota (seaweeds, crustaceans, molluscs and fish) have been subjected to analyses. It has been observed that the concentration of 210Po and 210Pb in the water samples of Point Calimere to be 0.5 mBq/l and 1.3 mBq/l, respectively. The soft tissues of the organisms accumulated higher 210Po content while shells and bones contained more 210Pb. The bivalve molluscs Meretrix casta have been identified to accumulate higher concentration of 210Po suggesting that they could serve as bio-indicator of radionuclides like 210Po in the Point Calimere ecosystem. The concentration factor of 210Po for the biotic components ranged from ∼10 3 to 10 6 while for 210Pb it ranged from ∼10 3 to 10 5.