210Po Activity Research Articles

Radioactivity measurements and dosimetric evaluation in meat of wild birds

ABSTRACTThe aim of this study was to determine the background activity concentration of natural radionuclides and 137Cesium (Cs) in meat of 14 migratory birds originating from central and northern Europe. This meat is largely consumed by the Italian population. 40K, 210Pb, and 137Cs were determined by gamma spectrometry and 210Po by alpha spectrometry. The mean 40K activity concentration detected was 490 ± 117 Bq/kgdw. In all the samples, 210Pb was below the limit of detection (LOD), and therefore it was not possible to calculate the ratio 210Po/210Pb. The 210Po activity concentration ranged between 0.11 ± 0.02 Bq/kgdw and 6.2 ± 0.93 Bq/kgdw with a mean value of 1.03 ± 1.75 Bq/kgdw. The 137Cs activity concentration was not detectable or near LOD except in two samples with 45 ± 0.7 Bq/kgdw (wood pigeon, from Italy) and 139.1 ± 1.9 Bq/kgdw (woodcock, from Sweden). The effective dose of 210Po ingested by consumption of wild birds meat accounts for only 0.01–0.6% of natural radiation exposure in Italy. These data indicate that the meat analyzed was safe.

Mobility indices and doses from 210Po and 210Pb activity concentrations data in Brazilian spas groundwaters

210Po and 210Pb activity concentrations in spas groundwaters occurring at São Paulo (SP) and Minas Gerais (MG) states, Brazil, have been reported in this paper with a dual purpose: to compare different indices for evaluating the radionuclides mobility into waters and to evaluate the drinking water quality from dose calculations. The waters (75 sampling points) are extensively used for drinking in public places, bottling and bathing purposes, among other. The samples were taken from springs and wells drilled at different aquifer systems inserted in Paraná and Southeastern Shield hydrogeological provinces. The WHO guideline reference value for 210Pb and 210Po of 0.1 Bq/L in drinking water was not reached for 210Pb but the 210Po levels were equal or above it in four spas groundwaters from MG State. The maximum WHO guidance dose level of 0.1 mSv/yr was also reached or surpassed in them. The 210Pb “mobility index” taking into account the ratio of the weight of the dissolved 210Pb per unit volume of solution to its weight per unit weight of the rock matrix yielded values in the range of 0.01–5.2 kg/m3. Another “mobility index” (Preference Ratio) expressing the ratio of 210Pb and 238U in the waters divided by the ratio of 210Pb and 238U in the rock matrices provided values between 0.004 and 7994. The 210Pb/238U activity ratios of some spas groundwaters suggested preferential 238U transport relative to 210Pb into the liquid phase, whereas the ratio of the 210Pb to 238U mobility indices indicated the opposite. Such finding showed a better usefulness of the mobility indices for evaluating processes affecting the radionuclides release into the liquid phase during the water/rock interactions.

Study about the radionuclides implanted on glass surfaces for the estimation of retrospective indoor radon concentrations

Indoor radon retrospective dosimetry can be performed by measuring the 210Po activity concentration deposited on surfaces. An experimental study about the implantation of 210Po on mirrors exposed to radon has been performed. Two cases were studied: exposure to high and low 222Rn concentrations. Results were compared with those calculated by using the activity evolution equations. Experimental results can be only explained assuming additional deposition of the long-lived 222Rn descendants.

The polonium-210 poisoning of Mr Alexander Litvinenko

Mr Litvinenko died on 23 November 2006 after having been poisoned with polonium-210 on 1 November. Measurements of the polonium-210 content of post-mortem tissue samples and samples of urine and blood showed the presence of large amounts of 210Po. Autoradiography of hair samples showed two regions of 210Po activity, providing evidence of an earlier poisoning attempt during October 2006, resulting in absorption to blood of about one-hundredth of that estimated for 1 November. Intake by ingestion on 1 November was estimated to be around 4 GBq, assuming 10% absorption to blood, and the resulting organ doses reached estimated values that were generally in a range from about 20 Gy to over 100 Gy. Comparison with estimates of protracted alpha particle doses required to cause irreversible organ damage supported the conclusion that death was the inevitable consequence of multiple organ failure, with destruction of the haemopoietic bone marrow, as well as damage to kidneys and liver, being important contributors. If the earlier poisoning during October 2006 had not been followed by a second major intake on 1 November, it is possible that the earlier intake of around 40 MBq, with absorption of 4 MBq to blood, might have caused irreversible kidney damage over a prolonged period of months or years, with doses of approaching 3 Gy.

Occurrence of 210Po in marine macroalgae inhabiting a coastal nuclear zone, southeast coast of India

The activity concentration of 210Po in 26 species of marine macroalgae found along coast near to a nuclear installation in southeast coast of India was studied. Phaeophytes were found to accumulate the maximum 210Po concentration and chlorophytes the minimum. The average 210Po activity concentration values in the three groups were 6.2 ± 2.5 Bq kg−1 (Chlorophyta), 14.4 ± 5.2 Bq kg−1 (Phaeophyta) and 11.3 ± 3.9 Bq kg−1 (Rhodophyta). A statistically significant variation in accumulation was found between groups (p < 0.05). The un-weighted dose rate to these algae due to 210Po was calculated to be well below the benchmark dose limit of 10 μGy h−1.

Activity concentration measurements of selected radionuclides in seals from Canadian Arctic

The activity concentrations of naturally occurring radionuclides (such as 226Ra, 210Pb and 210Po) and long lived 137Cs were measured in a total of 119 tissue samples (43 blubber, 43 liver, and 33 muscle samples) from 40 ringed seals and 4 bearded seals collected in the Arviat area of Canada during the fall of 2014. Activity concentration of 210Po was measured in all seal liver and muscle samples individually. The average 210Po activity concentrations were 25 ± 7.6 Bq/kg fresh weight (fw) in muscle and 211 ± 58 Bq/kg fw in liver for ringed seals, and 20 ± 6.1 Bq/kg fw in muscle and 231 ± 150 Bq/kg fw in liver for bearded seals. Due to insufficient sample material for most samples collected, gamma counting for radioactive caesium and radiochemical analysis for 226Ra and 210Pb were performed for pooled samples. Activity concentrations of 210Pb and 226Ra were generally below detection limits. While 134Cs activity concentration was not detectable, 137Cs activity concentration was detected in muscle and liver samples. On average, the 137Cs activity concentrations were 0.25 ± 0.05 and 0.12 ± 0.04 Bq/kg fw in muscle and liver samples of ringed seals, and 0.11 ± 0.02 and 0.10 ± 0.03 Bq/kg fw in muscle and liver samples of bearded seals, respectively. Neither 210Po nor 137Cs were detected in the blubber samples. This study confirmed that 210Po is the dominant contributor to radiation doses resulting from seal consumption. Man-made contaminant 137Cs only contributes less than 0.01% of the total ingestion dose obtained from Arviat seals.

Pb-210 and Po-210 atmospheric releases via fly ash from oil shale-fired power plants

During high temperature processes in the furnace volatile and semi-volatile elements and radionuclides are partially emitted to the environment, depending on their chemical form in the original fuel, the technological set-up of the combustion system, and the prevailing combustion conditions. Two of the world's largest oil shale-fired power plants (PPs) have been operational in Estonia from the 1960s, during which time creation of significant environmental emissions and waste containing naturally occurring radionuclides has occurred. Pb-210 and 210Po are considered natural radionuclides with the highest emission rates from PPs and possess elevated potential radiation exposure risks to humans and the environment. These radionuclides have the highest activity concentration values in fine ash fractions, especially in fractions remaining below 2.5 μm. To determine the activity concentrations of 210Pb and 210Po in the PPs' outlet, sampling was conducted from boilers operating on pulverized fuel (PF) technology with novel integrated desulphurization (NID) system and bag filters as well as with electrostatic precipitators (ESPs). The 210Pb and 210Po activity concentrations remained around 300 Bq kg−1 for the NID system compared to 60–80 Bq kg−1 in the ESP system. The dominant ash fraction in both systems was PM2.5, constituting over 50% of the fly ash mass collected from the outlet. The authors estimate that the total atmospherically emitted activity for the modernized PPs remains dominantly below 1% of the activity that is inserted via fuel. The implementation of higher efficiency purifications systems has significantly reduced the negative effect of these PPs. Based on annually emitted fly ash and boilers' working hours, the 210Pb and 210Po activity released relative to energy production were up to 68.3 kBq GWhel−1 for 210Pb and 64.6 kBq GWhel−1 for 210Po. These values are 1 to 2 orders of magnitude lower compared to the situation in the 1980s. These findings represent the first publicly available quantitative results estimating the 210Po emissions from large oil shale-fired PPs.

Partitioning behavior of natural radionuclides during combustion of coal in thermal power plants

ABSTRACTCoal-fired power generation produces huge amounts of fly ash and bottom ash of different properties. Coal contains many naturally occurring radionuclides, which on burning are enriched in the ashes; their discharge to the environment may cause significant exposure of the public to this technologically enhanced naturally occurring radioactive material. Most of these nuclides tend to become particle bound and hence are adsorbed on the ash particles. It is thus important to assess the behavior of radionuclides under combustion in the particle phase. To study the behavior of radionuclides in the particle phase, i.e., in combusted coal ashes, radioactivity measurement of coal and ash samples from different power plants was carried out using alpha and γ-ray spectrometry. The activity of 210Po in fly ash ranged from 12.6 to 91.3 Bq kg−1, while the range of activity concentrations of 238U, 226Ra, 232Th, 40K in fly ash were 56.1–133, 44.3–119, 9.3–144, and 34.5–221 Bq kg−1, respectively. Partitioning behavior of the radionuclides, their relative enrichment factors, and effect of particle size on enrichment of the nuclides in fly ash were also studied. Radionuclides were also grouped using their relative enrichment factors, a consequence of their volatile nature. A good correlation between the partitioning behavior, volatility, and relative enrichment factors of the radionuclides was observed in this study. This outcome of the study could be very useful for determining the fate of the radionuclides, from the bulk low-concentration mineral state in coal mines to the high-concentration particle phase of ashes after burning in power plants. This is important since it is the higher concentration of radionuclides in the particle phase that is a potential source of exposure to the public.

210Po Activity Concentrations in Cooked Marine Food

In this work the 210Po activity concentrations determined in the most common marine species consumed by the population of Southern Spain are shown and discussed. The determinations have been done on aliquots of the raw edible materials and in aliquots previously cooked in the usual way they are ingested. The obtained activity concentrations in the edible parts of the cooked products ranged up to three orders of magnitude with concentration factors for some species as high as 104-105 L/kg fresh weight, and due to the cooking processes in some cases a considerable variation in the 210Po activity concentrations have been observed in relation with the determined ones in the aliquots not processed. The importance of this study is based in the fact that 210Po is one of the main contributors to the radiation dose received by the population by ingestion, being the 210Po doses by ingestion particularly high when a population has a diet with a high proportion of marine products.

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.

210Po in the marine biota of Korean coastal waters and the effective dose from seafood consumption

The activity concentrations of 210Po were determined in plankton and selected species of macroalgae, crustaceans, molluscs, and fish from Korean coastal waters to understand 210Po distribution in these trophic levels and to assess the effective dose of 210Po from seafood ingested by the average Korean. The activity concentration of 210Po in macroalgae, mixed plankton, anchovy (whole body), abalone muscle, and abalone viscera was 0.97–1.43, 32–137, 59–392, 2.93 ± 0.86, and 1495 ± 484 Bq kg−1 (w.w.), respectively. Polonium-210 concentration in the whole flesh of mussel and oyster were 47.8 ± 5.9 and 45.3 ± 7.1 Bq kg−1 (w.w.), respectively. Polonium-210 concentration in the muscle of the five tested species of fish other than anchovy ranged from 0.51 to 5.56 Bq kg−1 (w.w.), with the lowest amount in a demersal species. In fish, 210Po activity concentration was as much as three orders of magnitude higher in viscera than in muscle. The average annual effective 210Po dose per average Korean adult, who consumes 42.8 kg of seafood a year (excluding anchovy), was estimated to be 94 μSv y−1, with 42–71% of this attributed to shellfish. Further studies are required to assess the dose of 210Po from anchovy owing to its high activity concentration and the manner in which anchovy is consumed.

210Po secretion from sweat glands

The results of the research indicated that the 210Po activity concentration in sweat samples was between 0.22 ± 0.03 to 2.10 ± 0.15 mBq·g−1 d.w. The obtained results of the studies showed that smoking and eating fish led to higher activity concentrations of 210Po in sweat in comparison to the control group. Statistical analysis of 210Po activity concentrations in sweat samples showed significant differences between control, smoking, fish eating and age groups, while no significant differences was found for 210Po between volunteers as far as gender is concerned.

Lichens and mosses as polonium and uranium biomonitors on Sobieszewo Island

In the study the activities of polonium 210Po and uranium 234U, 238U radionuclides in moss and lichen samples were determined using the alpha spectrometry. Different lichens and mosses were collected around the Sobieszewo Island (northern Poland) and investigated for potential use as biomonitors for 210Po and 238U deposition. Mosses and lichens have a high efficiency in capturing 210Po and 238U from atmospheric fallout. The obtained results showed that 210Po, 238U concentrations are changing in analyzed thallophytes samples depending on the type of thallus.

Annual Effective Dose of &lt;sup&gt;210&lt;/sup&gt;Po from Sea Food Origin (Oysters and Mussels) in Korea

Background: Ingestion of 210Po laden seafood accounts for a substantial amount of the effective dose of 210Po. Among seafood items, mollusks, especially domestically produced oysters and mussels, are highly enriched in 210Po and are consumed in large quantities in Korea. Materials and Methods: Oysters and mussels around the Korean coasts were collected from major farm areas in November 2013. Samples were spiked with an aliquot of 209Po as a yield tracer, and they were digested with 6 mol·L-1 HNO3 and H2O2. The 210Po and 209Po were spontaneously deposited onto a silver disc in an acidic solution of 0.5 mol·L-1 HCl and measured using an alpha spectrometer. The activity concentrations of 210Pb and 210Po were decay corrected to the sampling date, accounting for the possible in-growth and decay of 210Po. Results and Discussion: 210Po activity concentrations in oysters were in a range from 41.3 to 206 Bq·(kg-ww)-1 and mussels in a range from 42.9 to 46.7 Bq·(kg-ww)-1. The 210Po activity concentration of oysters in the turbid Western coast was higher than the Southern coast. The 210Po activity concentration of the oysters was positively correlated (R2 = 0.89) with those of the suspended particulate matter in the surface water. The calculated annual effective dose of 210Po from oysters and mussels consumed by the Korean population was 21-104 and 5.01-5.46 μSv·y-1. The combined effective dose due to the consumption of oysters and mussels appears to account for about 35 ± 19% of that arising from seafood consumption in the Korean population. Conclusion: The annual effective dose of 210Po for oysters in the Korean population was found to be higher than other countries. The total annual effective dose of 210Po due to consumption of oysters and mussels consumed in Korea was found to be 76 ± 42 μSv ·y-1 , accounting for 28 ± 16% of the total effective dose of 210Po from food in Korea.

Association between radionuclides (210Po and 210Pb) and antioxidant enzymes in oak (Quercus coccifera) and mastic tree (Pistacia lentiscus)

The activity levels of naturally occurring radionuclides Polonium-210 and lead-210 in different subjects including plant species have direct or indirect impact on human beings. High levels of ionising radiation cause oxidative stress and the interaction between antioxidative defense and radionuclides is not well established in plant systems. In this study, we aimed to understand the impact of oxidative stress caused by 210Po and 210Pb in two Mediterranean plants; Quercus coccifera and Pistacia lentiscus. We analysed the constitutive and seasonal levels of 210Po, 210Pb, lipid peroxidation levels, superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities in the field-collected samples. The highest activity concentrations of 210Po and 210Pb were detected in both plants in summer and Q. coccifera had higher levels than that of P. lentiscus. SOD and APX activity trends were different between oak and mastic; as compared to P. lentiscus, Q. coccifera efficiently used the two major components of antioxidative defense. Lipid peroxidation levels were low in both plants in all seasons except that of spring which were in good agreement with high antioxidant enzyme activities. In conclusion, we found that high 210Po and 210Pb activity concentrations in oak and mastic did not interfere with their growth and life cycles. The ability of both plants for survival and adaptation to Mediterranean environmental constraints provided an additional advantage for coping radionuclide induced oxidative stress as well.

Determination of 210Po and 210Pb in red-capped scaber (Leccinum aurantiacum): bioconcentration and possible related dose assessment.

The paper presents the studies on 210Po and 210Pb activity determination in red-capped scaber (Leccinum aurantiacum (Bulliard) Gray) collected in northern Poland. The aims of the studies were to determine 210Po and 210Pb content in analyzed mushrooms, evaluate the bioconcentration levels, and estimate possible related annual effective radiation dose to mushrooms consumers. The activities of 210Po and 210Pb in red-capped scaber were un-uniform and depended on sampling sites. But 210Po and 210Pb activity concentrations did not reflect their concentrations in topsoil. The results showed that the consumption of analyzed mushrooms should not increase significantly the total effective radiation dose from 210Po and 210Pb decay.

A modified method for the sequential determination of 210Po and 210Pb in Ca-rich material using liquid scintillation counting

This research describes methods for the sequential determination of 210Pb and 210Po activity concentrations in Ca-rich ash samples collected from oil shale-fired power plants in Estonia. The procedure involves digestion of Ca-rich ash samples in a microwave digestion system, radiochemical separation of 210Pb and 210Po and their measurements. All samples, blanks and standards were measured by liquid scintillation counting (Quantulus 1220). The method was tested using IAEA (International Atomic Energy Agency) RGU-1 and IAEA-444 reference materials. Spectral calibration/peak identification which included the optimization of α/β discrimination system (pulse shape analyser), and recovery have been made by 209Po and 210Pb standard solutions.

Accumulation of 210Po in coastal waters (Gulf of Trieste, northern Adriatic Sea)

The total activity of 210Po was determined by alpha-spectrometry in various samples (matrices) collected in the Gulf of Trieste (northern Adriatic Sea) where fresh water inflows, especially from the Isonzo River in the northern part, affect water quality. Observed 210Po levels were: 1) 0.56–3.75 mBq/L in the dissolved phase (<0.45 μm) in the seawater column and local rivers, 2) 0.35–3.11 mBq/L (400–2300 Bq/kg, dry weight, dw) in suspended particulate matter (SPM, 0.45–20 μm) in the seawater column and local rivers, 3) 40 (Isonzo River) −158 Bq/kg (in a surface sediment cores collected in a NS transect in the gulf and sectioned to the depth of 20 cm) and 4) 239 (autumn) – 415 to 1800 (spring) Bq/kg (dw) in meso(zoo)plankton (>200 μm). In seawater and tributaries, up to 80% (mean 49%) of total 210Po was found in particulate form. In sediments, slightly higher levels were encountered in the Isonzo prodelta and in the central (depocenter) part of the gulf. KD (L/kg) calculated between seawater and SPM, and seawater and sediment amounted to about 5 × 106 and 6 × 104, respectively. Lower autumn 210Po levels can be a consequence of biological dilution by higher mesozooplankton biomass in the autumn compared to spring. Plankton fractionation revealed in general the highest levels in the >200 μm mesoplankton fraction (239–1800 Bq/kg) followed by 50–200 μm (388–996 Bq/kg) and 20–50 μm (318–810 Bq/kg) microplankton fractions. Obtained data show higher 210Po levels in all matrices analyzed in the Gulf of Trieste compared to other Adriatic (central Adriatic) and western Mediterranean areas. The 210Po/210Pb ratios in water, plankton and sediments were mostly below or around 1, while this ratio was much higher at higher trophic levels (up to about 50), reflecting a preferential bioaccumulation of 210Po over 210Pb. 210Po accumulation between seawater and SPM and seawater and mesozooplankton amounted to 3.7 × 104 and 1.1 × 104, respectively, similar to other Adriatic areas. Comparison of the relative importance of pelagic and benthic bioaccumulation pathways, excluding the filter feeder bivalves, suggests greater accumulation in pelagic-feeding species.

Speciation and behavior of 210Po and 210Pb in the riverine ecosystem of Cauvery, a major river of south India

The paper discusses the speciation and behavior of 210Po and210Pb in the soil and sediment samples in the Cauvery River environment. The samples were collected and the concentration of 210Po and 210Pb was measured using the standard radiochemical analytical method. The physicochemical parameters of the soil and sediment were studied to understand the dynamics of 210Po and 210Pb activity in the riverine environment. The dependence of the physicochemical parameters like clay and organic matter content on the speciation of 210Po and 210Pb in the riverine ecosystems were also studied. The mean activity of 210Po and 210Pb in soil was found to be 6.80 and 6.58 Bq kg–1, respectively. The mean activity of 210Po and 210Pb in the sediment was found to be 3.30 and 6.34 Bq kg–1, respectively. The activities of 210Po and 210Pb in both the soil and sediment are not in equilibrium. The activity concentrations of 210Po and 210Pb were correlated with the organic matter content in both the soil and sediment samples. Multivariate statistical analysis was used to confirm the interrelation between the physicochemical parameters and the activity of 210Po and 210Pb.

Polonium in size fractionated mainstream cigarette smoke, predicted deposition and associated internal radiation dose

In this study, size fractionated mass and 210Po activity concentrations in mainstream cigarette smoke (MCS) were monitored for three popular cigarette brands. Size segregated collection of MCS was carried out using a cascade type impactor, while mass and 210Po activity concentration were analyzed gravimetrically and alpha spectrometry (following the radiochemical separation) respectively. Multiple-Path Particle Dosimetry (MPPD V2.11) model is used for prediction of deposition fraction calculations for the MCS deposition in different compartment of human respiratory tract. The activity concentration of 210Po is founds 10.56 ± 2.46 mBq per cigarette for the tested cigarette brands. 210Po size distribution indicates most of this associates with fine fraction (Dp < 2.23 μm) of cigarette smoke. The committed annual effective dose to smokers (smoking on an average 20 cigarette a day), considering the 210Po and 210Pb concentrations (assuming it is in secular equilibrium with 210Po) in MCS, was estimated between 0.22 and 0.40 mSv, with mean value of 0.30 mSv for tested cigarette brands. Considering the risk factor of fatal cancer due to radiation exposure of lung (exposure time of 30 years); the average collective estimated fatal cancer risk is estimated as 1.5 × 10−4 due to 210Po and 210Pb exposure to smokers.