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 ± 2.3 mBq/g and 18.5 ± 2.0 mBq/g, with a total average of 17.8 ± 7.4 mBq/g (15.5 mBq/cigarette). Similarly, the average concentrations of 210Pb in these samples are 18.5 ± 2.6 mBq/g and 20.3 ± 2.2 mBq/g, with a total average of 19.6 ± 8.1 mBq/g (17.0 mBq/cigarette). In Jordan, the average concentrations of 210Po in cigarette samples and narghile tobacco are 20.1 ± 2.4 mBq/g and 18.3 ± 4.1 mBq/g, with a total average value of 19.6 ± 9.9 mBq/g (18.0 mBq/cigarette), while the average concentrations of 210Pb are 22.2 ± 2.6 mBq/g and 20.2 ± 4.5 mBq/g, with a total average value of 21.6 ± 10.8 mBq/g (19.9 mBq/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 34.7 μSv/y to 186.5 μSv/y with an average of 109.5 μSv/y, while in Jordan 54.5 μSv/y to 289.1 μSv/y with an average of 130.9 μSv/y.

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 ± 2.74 mBq 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 ± 1.04 mBq 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.

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.

210Pb-dating of recent sediments with the χ-mapping CF and CSAR models. On the attractors

Conventional 210Pb-dating models use assumptions on sedimentary conditions that allow for analytical formulations. The novel χ-mapping models use numerical methods to generate and test a large number (∼106) of potential solvers. Empirical data (excess 210Pb vs. mass depth profile) serve to attract the solver that minimizes the χ function (the attractor), and it has been assumed that it also defines the most likely chronology. This work aims to test this assumption in a deep way. In synthetic and varved sediments, the performance of each solver can be quantified through a parameter ξa accounting for the deviation of the model and the true ages. This work studies the complex relationships between χ and ξa using the constant flux (χ-CF) and the constant sediment accumulation rate (CSAR) models, which operate in a parametric 3D space. The full mapping of the 3D χ function serves to find the absolute minimum, for the graphical representation of the complex topology of the attractors, which is model-specific, and for plotting clouds of chronological lines from solvers with varying χ values. The minimum value of ξa (the best chronology) is achieved for a wide range of χ values, including the region of the absolute minimum. In complex cases, tiny changes in χ can result in quite different chronologies. Alternative attractors that include a reference date and an objective function are studied. The results provide guidelines for strengthening the 210Pb-based chronologies.

210Pb-based dating of recent sediments with the χ-mapping version of the Constant Sediment Accumulation Rate (CSAR) model

The 210Pb-based method aims at determining the absolute age of recent sediments on the centennial scale. A family of models assumes that at the sediment-water interface the flux of unsupported 210Pb (210Pbexc), F, relates to its initial activity concentration, Ao, and the mass sedimentation rate, w, as: F=Aow. Additional specific assumptions that allow for analytical formulations of the models are: i) constant Ao (CIC), constant F (CF), and constant F with constant w (CFCS). A model with constant w (CSAR) was suggested for completeness but never used because of the lack of a suitable analytical formulation. The TERESA model assumes random and independent variability for Ao and w, described by normal distributions. It systematically generates a large number (∼105) of potential solutions, whose performance for fitting the empirical 210Pbexc profile is quantified through the χ-function. This work aims to adapt the above methodology to formulate the χ-mapping version of the CSAR model. The performance of the model is evaluated with a set of synthetic and real cores for which an independent chronology is available. CSAR is able to capture the mean sedimentation rate from the 210Pbexc data and provides reliable chronologies and paleorecords of Ao, useful for tracking past changes in sedimentary conditions. CSAR provides an interesting different perspective for researchers working with 210Pb-based dating of recent sediments.

210Pb-dating of sediments with models assuming a constant flux: CFCS, CRS, PLUM, and the novel χ-mapping. Review, performance tests, and guidelines

The 210Pb-based method has been widely used for five decades to determine absolute ages in recent sediments on the centennial scale. Decoding a chronology from the empirical data set requires a series of assumptions that define a mathematical model of the sedimentary conditions. This work aims to provide a comprehensive review of the fundamentals of the existing family of models assuming a constant flux of excess 210Pb at the sediment surface, namely the CFCS, CRS, and PLUM models, and to present the novel χ-mapping versions of the CFCS and CF models. Their performance is assessed with a selected group of five cores from literature data, with varve chronologies or independent time marks. The PLUM model did not produce reliable chronologies in any of the cores studied. The CRS model is too sensitive to an accurate estimation of the total inventory. A weighted-fit and the χ-mapping versions of the CFCS model are prone to over-represent the younger regions of the core. The CFCS model with least squares fitting and the χ-CF models performed best under the most common sedimentary conditions, which involve temporal variability in the fluxes randomly distributed in the time line. A practical strategy is suggested to identify the occurrence of such sedimentary conditions through the combined use of a set of models, providing this way further strength to the 210Pb-dating.

Atmospheric depositional fluxes of 210Pb in bulk precipitation at the Adriatic coast, Croatia

The atmospheric bulk depositional fluxes of 210Pb were measured at a station on the Adriatic coast, Croatia over 4 years period from March 2017 to December 2020. The monthly depositional fluxes followed oceanic deposition patterns with a lower flux between 0.0735 and 16.9 Bq m-2 month-1. The volume-weighted activities were 0.000514 and 1.35 Bq L-1 and decreased with increasing precipitation. A clear seasonal trend was observed with higher depositional flux in autumn and minimum value in the winter season. The average annual bulk depositional flux and volume-weighted activities of 210Pb were 73.8 Bq m-2 y-1 and 0.119 Bq L-1 respectively. The precipitation normalized enrichment factor (α) indicates higher depositional fluxes of 210Pb during summer and spring than desired value according to the amount of precipitation. We found that the 210Pb depositional fluxes in the coastal stations are lower due to 210Pb-depleted oceanic air masses and increase with the amount of precipitation.

Developments in Pb-210 methodologies to provide chronologies for environmental change

Chronologies generated from core profiles to apply dates to environmental changes commonly use the measurement of the activity of radionuclides deposited and stratified with physical environmental material. The most commonly reported nuclide to define chronologies covering the last 150 years is Pb-210, for which accepted data processing methodologies in the literature have focussed on the constant rate of supply (CRS) model and the more recently published Bayesian Plum model. This short communication describes a validation approach using defined sediment layers referred to as 'varve' counting, which provide known points of reference to account for uncertainty between generated dates from each model using published Pb-210 measurements. A significant improvement in the chronologies was observed when applying reference date corrections to the models. This was shown to be essential in providing confidence in reported datasets and accuracy of predicted chronologies, which will better inform the interpretation of environmental change, e.g. sedimentation rates, climate change, pollution pathways and land degradation. Generated chronologies from both the CRS and Plum methods showed good agreement with the established varve dates (typically < 4-year difference).

On 210Po and 210Pb in algae diet supplements - The assessed radiation hazard of aquatic superfoods

Algae are believed to give health benefits. However, the studies showed they contain toxic elements, including radionuclides, and may affect human health. The study presents the values of activity concentrations of ²¹⁰Po and ²¹⁰Pb in the algae supplements available worldwide for adults. The activity concentrations (Bq/kg dw) ranged from 0.07 to 14.5 (²¹⁰Po) and from 0.06 to 8.48 (²¹⁰Pb). Also, the effective radiation doses and the cancer risk from ²¹⁰Po and ²¹⁰Pb decay ingested with analyzed algal supplements have been assessed. The highest values of annual effective doses have been estimated for ²¹⁰Po in the recommended portion of Spirulina (Arthrospira platensis) from China (59.7 μSv/year) and Diatomaceous earth from the USA (50.4 μSv/year). The cancer morbidity and mortality risk ranged from 10^-4 to 10^-8. The study indicated the activity concentrations of ²¹⁰Po and ²¹⁰Pb were low, and algae supplements for human consumption could be considered safe food.

Accumulation of lead radionuclides in 18 leaf vegetable types in Viet Nam

Studying the concentration of radioactive lead in soil and plants, and using plants for phytoremediation are important for the environment and human health protection. In this study, we used gamma spectrometry to determine activity concentration in soil - plants, transfer factor. The average activity concentration of lead radionuclides in soil and plants were in the following order of 210Pb > 214Pb > 212Pb. The average activity ratio of 214Pb and 212Pb to 210Pb in soil were 0.70 and 0.59 and in plants were 0.69 and 0.14, respectively. The results showed that there was not much difference between the ratio of radioactive 214Pb and 210Pb concentrations in vegetable and plant samples. Ming aralia (Polyscias fruticose) and lettuce (Lactuca sativa) contained the highest concentrations of 210Pb, and Malabar spinach (Basella alba) contained the lowest concentration. Ming aralia could be used for the radioactive decontamination of 210Pb. There vegetable samples from Ho Chi Minh City were considered safe for human consumption in the aspect of lead radionuclides.

ANALYSIS OF 210PB DEPOSITION DISTRIBUTION CHARACTERISTICS IN WINTER AT ROKKASHO IN AOMORI BASED ON HIGH RESOLUTION ATMOSPHERIC TRANSPORT/DEPOSITION MODEL CALCULATION

To evaluate 210Pb deposited on the surface of sea around Japan in detail, the performance of atmospheric transport/deposition model for 222Rn and its progenies was examined. To test the model's reproducibility of 210Pb deposition in winter, it was applied at Rokkasho in Aomori, where the model had been reported to significantly underestimate when the horizontal grid interval of 9 km was used. It was shown that the precipitation on the Pacific Ocean side and Mutsu Bay and hence the 210Pb deposition at Rokkasho were significantly improved with the grid interval of 3 km although the deposition was still underestimated by the observation. This underestimation was considered to be caused by model's neglect of horizontal drift of snow and rain. It was also pointed out that the deposited 210Pb was mainly contributed by the lower atmosphere up to 2-3 km.

LONG-RANGE ATMOSPHERIC TRANSPORT OF RADON IN EAST ASIA AND DEPOSITION OF ITS PROGENIES IN JAPAN

A three-dimensional long-range atmospheric transport model for 222Rn and its progenies was applied to simulate 210Pb deposition in Japan and its adjacent waters. Monthly precipitation and 210Pb deposition simulated by the model for winter months were favorably compared with observational data although they were exceptionally underestimated in Aomori. The large monthly deposition along the Japan Sea coast lines during winter was successfully simulated by the model to be nearly 200 Bq m-2, which was contrasted by about 10-fold smaller deposition in other regions. It was also pointed out that the heavy deposition areas formed a narrow band structure along the coastline with width of several tens of kilometers and 210Pb deposition amount positively correlated with the height of mountains located leeward of the heavy deposition areas.

VERTICAL MIXING NEAR THE SEA SURFACE OBSERVED BY SHORT-LIVED NATURAL RADIONUCLIDES ( 214PB AND 214BI)

I performed continuous gamma-ray measurements in seawater to observe the temporal variation of radon progenies ( 214Pb and 214Bi) derived from atmospheric precipitation. Underwater gamma-ray measurements using two NaI(Tl) detectors at different installation depths (1 and 4 m) were recorded from July to November 2011 at the marine observation buoy. An increase in the concentration of 214Pb + 214Bi in seawater was observed due to precipitation when the wind velocity was <2 m s-1. However, this increase was only detected at 1 m depth and a downward spread of 214Pb + 214Bi was not observed. In contrast, at a wind velocity of >8 m s-1, the 214Pb + 214Bi concentration ratio at 4 m/1 m was almost constant (0.6-0.7) for most of the measurement irrespective of precipitation intensity. Assuming one-dimensional diffusion in the water column, the apparent vertical diffusion coefficient estimated from the temporal variation of 214Pb + 214Bi concentrations at 4 m/1 m varied from <10 to 500 cm2 s-1 depending on the wind velocity.

DISTRIBUTIONS OF 210PB, 137CS AND PHYSICAL PROPERTIES IN BOTTOM SEDIMENTS OF WEST NANAO BAY, JAPAN

This study revealed sedimentation processes based on 137Cs and 210Pb distribution, grain size and magnetic susceptibility of bottom sediments in West Nanao Bay, Japan. Surface sediment concentrations and inventories of these radionuclides were relatively low in the middle and eastern areas of the bay and high in the western area, which has several major river mouths, suggesting that the contribution of riverine input affected only the western area. In the middle and eastern areas, the level of 137Cs inventory was much lower than that of the soils, and the excess 210Pb inventory was at the same level or lower. These results indicate that removal effects are stronger than accumulation effects (riverine input) in these areas. The patterns of radionuclides were consistent with the results, that grain size was relatively large in the middle and eastern areas, implying strong current conditions, and that fine sediment accumulated less in these areas.

Be-7 and Pb-210 in fallout and aerosols in 2000-2016 in central Europe - Deposition velocity and dependence on meteorological parameters

The main aim of this research was to determine the transport and deposition velocities of ⁷Be and ²¹⁰Pb based on a vast database containing the results of measurements of ⁷Be and ²¹⁰Pb in fallout and aerosol samples carried out at several stations located throughout Poland in the period from 2000 to 2016. The monthly deposition flux of ⁷Be and ²¹⁰Pb showed an unequivocal downward trend but was also subject to seasonal changes, with maximum values in the summer period. The same patterns were found in the case of the deposition rate, the average values of which were 0.7 cm s^-1 for ⁷Be and 0.5 cm s^-1 for ²¹⁰Pb. A strong, statistically significant dependence of the deposition rate on the amount of dust was demonstrated, whereby a 10 μg m^-3 decrease in dust increases the ⁷Be deposition rate by 0.1 cm s^-1. Reduction of the concentration of carrier particles reduces the share of dry deposition in favour of precipitation convection, which is much more significant for the transport of both isotopes to the surface. Study of the effect of meteorological parameters showed that the concentrations of ⁷Be in fallout and aerosol samples and ²¹⁰Pb in fallout increase with increasing temperature, indicating a significant share of convection processes in isotope transport. The concentrations of ²¹⁰Pb in aerosols did not show any significant statistical changes over time. Their maximum values were observed in the winter period, indicating an additional source of this isotope related to combustion processes in the heating season. The studies confirmed the dominant role of convective precipitation and large-scale precipitation processes in the elution of ⁷Be from the atmosphere by showing the monthly deposition of this isotope to be strongly dependent on the total precipitation (r = 0.618).

Determination of 210Po and 210Pb in cannabis (Cannabis sativa L.) plants and products

The concentrations of polonium ²¹⁰Po and radio-lead ²¹⁰Pb in cannabis (Cannabis sativa L.) plants and products now legally available in Poland were determined. Limiting the delivery of radionuclides to the body is an important aspect of civil protection in many countries. Reduction in use and awareness of the risks associated with tobacco and cannabis smoking have a great impact. The ²¹⁰Po and ²¹⁰Pb concentrations in 44 hemps, 20 hashish and 8 hemp tea samples, as well as in 3 types of cannabis plants (highest parts of mature hemp plant Fenola, Fedora and Futura) were determined. Each of the sample names means a different type and cross of C. sativa L. Being numerous, the are recognized on the market precisely by these names. Effective doses were calculated and compared to the doses of the other combustion products, such as tobacco. In the case of hemp, the highest concentration of ²¹⁰Po was found in samples of dried Sweet Carmel (34.7 ± 0.23 mBq·g^-1), while the lowest in the Hemp Berry (0.57 ± 0.23 mBq·g^-1). In the case of ²¹⁰Pb, the highest concentration was in Strawberry Kush (2.32 ± 0.05 mBq·g^-1), while the lowest in Strawberry Haze (0.19 ± 0.03 mBq·g^-1). In hashish, the highest and lowest concentrations of ²¹⁰Po were in Strawberry Diesel 164 ± 3 mBq·g^-1 and in Mango Kush 2.5 ± 0.2 mBq·g^-1. The highest and lowest concentrations in the case of ²¹⁰Pb in hashish were in Pollen Hashish 45.1 ± 0.2 mBq·g^-1 and in Mango Kush Hashish 0.45 ± 0.05 mBq·g^-1, respectively. These radionuclides did not constitute a radioactive equilibrium (²¹⁰Po/²¹⁰Pb).

On the use of 210Pb-based records of sedimentation rates and activity concentrations for tracking past environmental changes

Lead-210 from natural atmospheric fallout is widely used in multidisciplinary studies to date recent sediments. Some of the ²¹⁰Pb-based dating models can produce historical records of sediment accumulation rates (SAR) and initial activity concentrations (A₀). The former have been profusely used to track past changes in the sedimentary conditions. Both physical magnitudes are differently affected by model errors (those arising for the partial or null accomplishment of some model assumptions). This work is aimed at assessing the effects on SAR and A₀ of model errors in the CRS, CS, PLUM and TERESA dating models, due to random variability in ²¹⁰Pb fluxes, which is a usual sedimentary condition. Synthetic cores are used as virtual laboratories for this goal. Independently of the model choice, SARs are largely affected by model errors, resulting in some large and spurious deviations from the true values. This questions their general use for tracking past environmental changes. A₀ are less sensitive to model errors and their trends of change with time may reflect real changes in sedimentary conditions, as it is shown with some real cores from varved sediments.

On the occurrence, origin, and intake of the nuclides, 210Po and 210Pb, in sclerotia of Wolfiporia cocos collected in China

The dried sclerotium of the fungus Wolfiporia cocos is edible and has medicinal value. This study aimed to understand the accumulation of radioactivity arising from the alpha ²¹⁰Po, and beta-emitting ²¹⁰Pb, in the sclerotium's shell and core and assess a potential effective dose for consumers. Sclerotia were collected in the wild and from cultivars in China's Anhui and Yunnan provinces. The mean values of ²¹⁰Po activity concentration levels were 0.36 Bq kg^-1 dry weight in the core and 12.0 Bq kg^-1 dw in the shell; ²¹⁰Pb activities were 0.43 and 9.84 Bq kg^-1 dw, respectively. The potential effective radiation doses from core layers (as a major raw material of the sclerotium) ranged from 0.13 to 3.43 µSv kg^-1 dw from ²¹⁰Po decay and from 0.11 to 1.52 µSv kg^-1 dw from ²¹⁰Pb decay. Corresponding values for shell ranged from 0.80 to 42.4 for ²¹⁰Po and from 0.53 to 13.6 µSv kg^-1 dw for ²¹⁰Pb. In general, the intake of W. cocos sclerotia varies between consumers, but this would not significantly change the effective radiation doses from ²¹⁰Po and ²¹⁰Pb isotopes. The consumption thus appears to be safe from a radiological protection point of view.

Sedimentation rates and sediment age of the high-altitude cold desert Ramsar Wetland, the Chandratal, inferred from radionuclide (210Pb and 137Cs) technique

In the current scenario, the pristine Himalayan Wetlands are under endangerment due to higher sedimentation rate, including siltation, reduction of ecological value, pollution, and significant anthropogenic encroachment along with advanced civilization. The more increased sedimentation reduces the depth and existing expansion of the Wetland. This study articulates the record of sedimentation in the Chandratal present in Western Himalaya, Himachal Pradesh, India, at the altitude of 4300 m. The sedimentation rate of the Chandratal was calculated based on a 1-m core sample considering isotopes of ¹³⁷Cs and ²¹⁰Pb dating techniques. The present study based on the Constant Rate of Supply (CRS) model of ²¹⁰Pb reveals that the Wetland experienced an average sedimentation rate of 1.75 ± 0.04 cm/year during the last 63 years observed from 1953 to 2016. The ¹³⁷Cs peak method-based calculated sedimentation rate of the Chandratal is 1.6 ± 0.02 cm/year representing the years for about 62 years from 1954 to 2016. The Wetland's functional survival prevalence was estimated to be 420 and 459 years based on ²¹⁰Pb and ¹³⁷Cs dating techniques, respectively. The study communicates that the magnified human interference in the catchment area of the Chandratal is accountable for the faster sedimentation in recent years.

Enhanced Polonium Concentrations in Aerosols from the Gulf Oil Producing Region and the Role of Microorganisms

This study provides the first data set of 210Po and 210Pb activity concentrations in the organic and inorganic components of several particle size classes of aerosols collected at two sampling stations in Kuwait. The 210Po concentrations in the aerosols (Bq/g) were similar in all of the particle size classes, but as most (91%) of the aerosol load was made of fine fraction particles of PM0.39-2.5 µm, most of the 210Po activity was carried by this aerosol fraction. At the two sampling stations, the 210Po/210Pb activity concentration ratios in the aerosols were similar, stable around the year, and averaged 1.5 (range 1.2-1.9), much higher than the typical activity concentration ratios of these radionuclides in unmodified (background) aerosols, with Po/Pb < 0.1. The aerosol enrichment in 210Po was likely originated from the oil industry, specifically by gas flaring and oil refining in the Gulf region. Radionuclide analysis in the organic and inorganic components of aerosols showed that the 210Po concentration in the organic component was one order of magnitude higher than the 210Po concentration in the inorganic component, in contrast with 210Pb, which displayed similar concentrations in both organic and inorganic aerosol components. The 210Po carrying organic component of aerosols was investigated and it was found to be largely composed of microorganisms with high microbial and fungi diversity, with the phyla Proteobacteria, Ascomycota, and Basidiomycota being dominant among the bacteria and with Zygomycota being dominant among the fungi. Therefore, we are facing an active concentration process of the atmospheric 210Po carried out by microorganisms, which underlies the 210Po enrichment process in the organic component of aerosols. This bioconcentration of polonium in bioaerosols was unknown.

Assessment of intake of 210Po and 210Pb isotopes from cow's milk in Poland

Milk has been known for its nutritional properties for centuries and is often the staple of the diet in many countries. Therefore, monitoring of milk composition seems to be a relevant task as it was the purpose of this study to compare levels of ²¹⁰Po and ²¹⁰Pb in several Polish voivodeships. The methodology was based on mineralization, loss on an inorganic matrix and concentration measurement on an alpha spectrometer. The concentrations of ²¹⁰Po and ²¹⁰Pb in collected milk samples were measured using alpha spectrometry and calculations, respectively. The results showed that the lowest concentration of ²¹⁰Po is 2.8 ± 0.2 mBq l^-1 and the highest is 56.3 ± 0.7 mBq l^-1 while the ²¹⁰Pb concentrations are in the range from 2.8 ± 0.2 to 44.0 ± 1.7 mBq l^-1. The associated annual effective doses for adults jmrange from 3.5 ± 0.1 to 11.0 ± 0.2 µSv a^-1 for ²¹⁰Po and from 2.0 ± 0.1 to 5.0 ± 0.1 µSv a^-1 for ²¹⁰Pb. The lowest doses were noticed in Kuyavian-Pomeranian Voivodeship and the highest values were found in Lesser Poland Voivodeship. The results show that the annual effective dose in individual provinces is not dangerous to health. However, there are significant differences between highly and lowly industrialized voivodeships.

210Pb and 210Po concentration levels in tobacco products and resulting radiation dose for Egyptian smokers

The activity concentrations of ²¹⁰Pb and ²¹⁰Po in the most popular cigarettes and moassel tobacco brands consumed in Egypt were determined by the spontaneous deposition method using alpha spectrometry. It turned out that the activity concentration of ²¹⁰Po was higher than that of ²¹⁰Pb in all tobacco brands. Higher activity concentrations for both ²¹⁰Pb and ²¹⁰Po were found in cigarette than in moassel tobacco. The average activity concentrations of ²¹⁰Pb and ²¹⁰Po in cigarette tobacco were 11.79 ± 1.67 and 15.00 ± 1.83 mBq cig^-1, respectively, whereas in moassel tobacco the values were 7.08 ± 1.91 and 9.12 ± 1.12 mBq g^-1, respectively. The daily activities inhaled in the lung of a smoker and the inhalation effective doses due to cigarette and shisha smoking were calculated. The results revealed that the total ²¹⁰Pb and ²¹⁰Po daily activities inhaled and the total annual inhalation effective doses due to shisha smoking were two times greater than the corresponding values due to cigarette smoking. Also, the results indicated that the annual effective doses from inhalation of ²¹⁰Pb and ²¹⁰Po due to smoking 20 cigarettes per day are 14 and 16 times greater than the annual ingestion doses from the diet, respectively. In contrast, the annual effective doses from inhalation of ²¹⁰Pb and ²¹⁰Po due to shisha smoking (27 g moassel tobacco per day) are 26 and 33 times greater than the annual ingestion doses from the diet, respectively.

Levels and Distributions of 210Pb and 210Po in Selected Seafood Samples in China and Assessment of Related Dose to Population

In this study, the activity concentrations levels of 210Pb and 210Po in the edible portions of eight seafood samples collected from the Fujian coast of China were determined. The activity concentrations ranged from 0.74 ± 0.08 to 12.6 ± 1.0 Bq/kg for 210Po and from the minimum detectable limit (MDL, 0.80 Bq/kg) to 11. 7 ± 1.1 Bq/kg for 210Pb. The 210Po activity concentration in all the fish organs ranged from 0.68 to 204 Bq/kg (w.w.), and the 210Po activity was mainly concentrated in the stomach, spleen, heart, liver, gonad, and intestine samples. The 210Pb activity concentration in all the fish organs ranged from the MDL to 15.2 Bq/kg (w.w.), and the 210Pb activity was concentrated in the head, fish scale, and gill samples. The annual effective ingestion doses ranged from 82.8 to 255 μSv/a for all age groups, and the lifetime risk of cancers were estimated. Both the effective ingestion doses and cancer risk to humans were within the acceptable ranges.

Correlations between 7Be, 210Pb, dust and PM10 concentrations in relation to meteorological conditions in northern Poland in 1998-2018

Analysis of a twenty-year (1998-2018) data series on ⁷Be concentrations in weekly collected aerosol samples in northern Poland showed a clear pattern of seasonal changes in ⁷Be with a maximum in the summer period associated with the most intensive thermal convection and vertical mixing. Activity concentrations of ⁷Be ranged from 480 μBq m^-3 to 9370 μBq m^-3. A strong relationship has been shown between ⁷Be concentrations observed in years and the activity of the Sun related to the sunspot number. Activity concentrations of ²¹⁰Pb in aerosol ranged from 17 μBq m^-3 to 1490 μBq m-3 with maximum occurring in the winter. The difference in the seasonal pattern in ⁷Be and ²¹⁰Pb concentrations were directly related to the different sources of both isotopes, as an additional source of ²¹⁰Pb was the products of combustion during the heating season. Similar pattern with maximum concentrations in winter was observed for PM10, as the main source is the same as in the case ²¹⁰Pb. A content of PM10 was in the range from 6.5 to 81.7 μg m^-3. A statistically significant correlation between both isotopes occurs. At the same time, ⁷Be, ²¹⁰Pb and PM10 are visibly related to the dust concentrations ranged from 7.3 μg m^-3 in winter to 134.8 μg m^-3 in spring. Statistical analysis carried out with simple regression model, stepwise multiple regression, and Random Forest models showed that the sunspots number, air temperature and sunshine duration have the most substantial impact on transport, and hence the concentration of ⁷Be in the surface layer of the atmosphere. The increase in relative humidity and precipitation and higher wind speed have a statistically significant effect on the reduction of ⁷Be concentrations in surface air.

Distribution of Pu isotopes and 210Pb in the Bohai Sea and Yellow Sea: Implications for provenance and transportation

Particle-reactive radionuclides are useful for tracing sediment dynamics in marginal seas. We collected a suite of surface sediment samples in May 2014 from the Bohai Sea (BS) and Northern Yellow Sea (NYS) to observe the spatial distribution of Plutonium (Pu) isotopes and ²¹⁰Pb activities. ^239+240Pu activities ranged from 0.001 to 0.288 and 0.040-0.269 Bq kg^-1 in BS and NYS surface sediments, respectively. ²¹⁰Pb_ex shows a significant correlation with ^239+240Pu (r = 0.84, p < 0.01) that suggested these two nuclides were scavenged to the same grade. ²⁴⁰Pu/²³⁹Pu atom ratios in BS (0.173-0.256) and NYS (0.196-0.275) were slightly higher than the global fallout value of 0.18 and lower than the Pacific Proving Ground (PPG) value of 0.36, indicating that some fraction of Pu originating from the PPG was capable of being transported to the BS and NYS. Mass balance results showed that 41% of ^239+240Pu (8.9 × 10⁹ Bq yr^-1) and 18% of ²¹⁰Pb (2.4 × 10¹² Bq yr^-1) in the NYS originated in the oceanic input. In the BS, 63% of ²¹⁰Pb originated from atmospheric deposition and 84% of ^239+240Pu originated from riverine input. Using Pu and ²¹⁰Pb as tracers, we estimate that (1.8-2.6) × 10⁸ t yr^-1 and (3.6-3.8) × 10⁸ t yr^-1 of sedimentary particles could be transported from the BS to the NYS and from the NYS to the Southern Yellow Sea, respectively. Furthermore, the ²²⁶Ra/²³⁸U activity ratio distribution suggested that sedimentary particles derived from the Yellow River could be transported to the middle of the BS and coastal areas of the NYS.

What can gross alpha/beta activities tell about 210Po and 210Pb in the atmosphere?

²¹⁰Po and ²¹⁰Pb represent the most abundant part of atmospheric aerosol long-lived natural radioactivity. Moreover, ²¹⁰Pb-²¹⁰Po monitoring in the atmosphere can be of interest for tracking extreme natural events that can enhance the level of alpha/beta radioactivity in air. In this paper, we question the possibility to use routine gross alpha/beta measurements in order to monitor ²¹⁰Po, ²¹⁰Pb and ²¹⁰Po/²¹⁰Pb ratio in the atmosphere. Based on joint gross alpha/beta measurement and ²¹⁰Pb-²¹⁰Po specific determination on 16 atmosphere samples, we show that (i) gross beta activity systematically overestimates ²¹⁰Pb activity due to the presence of interfering beta emitters and (ii) gross alpha activity mostly reflects ²¹⁰Po activity even if an underestimation is always observed due to alpha particle attenuation in the sample. In order to determine ²¹⁰Po/²¹⁰Pb ratio, we discuss the advantages of using gross alpha activity time variation compared to specific ²¹⁰Po measurements. Finally, the gross alpha/beta ratio appear to be a good proxy of the ²¹⁰Po/²¹⁰Pb ratio when large-scale variations are to be monitored. We report a first reference level for the activity level of airborne ²¹⁰Po in France of 13 ± 6 μBq/m³.

serac: an R package for ShortlivEd RAdionuclide chronology of recent sediment cores

Short-lived radionuclides are measured in surface sediment to provide a geochronology for the past century. Age-depth models are produced from ²¹⁰Pb_ex activity-derived sedimentation rates and corroborated by known events, such as ¹³⁷Cs and ²⁴¹Am activities that are result of fallout from nuclear weapon tests and the Chernobyl accident. Different methods of age depth modelling using such data require expertise in lake sedimentation processes. Here, we present a package, serac, that allows the user to compute an age-depth model and generate a graph, the age-depth correspondence in a text file, and metadata, using the free open-source statistical software R. serac ensures the reproducibility of age-depth or age-mass depth models and allows testing of several ²¹⁰Pbex models (CFCS, CIC, CRS, CRS piecewise) and sedimentation hypotheses (changes in sedimentation rates, presence of instantaneous deposits, varved sedimentation, etc.). Using several case studies, including lakes and lagoon in different environments, we demonstrate the use of the program in diverse situations that may be encountered. The rising number of sediment cores in recent palaeo studies and the need to correlate them require reproducible methods. serac is a user-friendly code that enables age model computation for the past century and encourages the standardisation of outputs.

210Pb-derived sediment accumulation rates across the Wider Caribbean Region

The Wider Caribbean Region is an important tourist destination where agricultural, industrial and shipping activities are also carried on. Coastal zones are heavily populated and receive a high human pressure; however, few monitoring programmes allow assessing long-term anthropogenic impact trends in these areas, which are especially useful for integrated management programs. Through the support of the International Atomic Energy Agency (project RLA/7/012), sediment core activities of ²¹⁰Pb and ¹³⁷Cs were used to evaluate changes in sedimentation rates in 11 relevant coastal areas of the region, where environmental information is scarce, but needed to support national environmental policies. Most ²¹⁰Pb activity profiles were atypical, attributed to non-steady sedimentation conditions; whereas ¹³⁷Cs activity profiles, showing very low values, were of little help for ²¹⁰Pb-dating corroboration. Results evidenced conspicuous changes in mass accumulation rates (MAR), specially through the Anthropocene (i.e. since ~1950s) in most cases, attributed to deforestation and land erosion (one of the clearest indicators of global change), and the input of urban and industrial untreated wastes. The recent MAR decrease in Havana Bay (Cuba) was attributed to the implementation of environmental policies, which showed that ²¹⁰Pb-derived reconstruction of environmental changes is also useful to verify the effectiveness of management programs to control land-derived erosion and siltation issues. Since siltation can be detrimental to valuable coastal resources around the world, retrospective evaluations of sedimentation rates, based on ²¹⁰Pb-dated cores, are highly recommended to assist integrated coastal zone management programs in the region and elsewhere.

From radiometry to chronology of a marine sediment core: A 210Pb dating interlaboratory comparison exercise organised by the IAEA

Laboratories from 14 countries (with different levels of expertise in radionuclide measurements and ²¹⁰Pb dating) participated in an interlaboratory comparison exercise (ILC) related to the application of ²¹⁰Pb sediment dating technique within the framework of the IAEA Coordinated Research Project. The laboratories were provided with samples from a composite sediment core and were required to provide massic activities of several radionuclides and an age versus depth model from the obtained results, using the most suitable ²¹⁰Pb dating model. Massic concentrations of Zn and Cu were also determined to be used for chronology validation. The ILC results indicated good analytical performances while the dating results didn't demonstrate the same degree of competence in part due to the different experience in dating of the participant laboratories. The ILC exercise enabled evaluation of the difficulties faced by laboratories implementing ²¹⁰Pb dating methods and identified some limitations in providing reliable chronologies.

Distribution of radiocarbon in sediments of the cooling pond of RBMK type Ignalina Nuclear Power Plant in Lithuania

The vertical distribution of radiocarbon (14C) was examined in the bottom sediment core, taken from Lake Drūkšiai, which has served as a cooling pond since 1983 for the 26 years of the Ignalina Nuclear Power Plant (INPP) operation using two RBMK-1500 reactors (Russian acronym for"Channelized Large Power Reactor"). 14C specific activity was measured in alkali-soluble and -insoluble fractions of the sediment layers. Complementary measurements of the 210Pb and 137Cs activity of the samples provided the possibility to evaluate the date of every layer formation, covering the 1947-2013 period. In addition, 14C distribution was examined in the scales of pelagic fish caught between 1980 and 2012. Our measurements reveal that, during the period 1947-1999, the radiocarbon specific activity in both fractions exhibits a parallel course with a difference of 5 ± 1 pMC (percent of modern carbon) being higher in alkali-soluble fraction, although 14C specific activity in both fractions increased by 11.4-13.6 pMC during the first 15 years of plant operation. However, during the 2000-2009 period, other than previously seen, a dissolved inorganic carbon (DIC) → aquatic primary producers → sediments 14C incorporation pattern occurred, as the radiocarbon specific activity difference between alkali-soluble and -insoluble fractions reached 94, 25, and 20 pMC in 2000, 2006, and 2008, respectively. Measurements in different sediment fractions allowed us to identify the unexpected organic nature of 14C contained in liquid effluences from the INPP in 2000-2009. The discrepancy between 14C specific activity in fish scales samples and DIC after 2000 also confirmed the possibility of organic 14C contamination. Possible reasons for this phenomenon might be industrial processes introduced at the INPP, such as the start of operation of the cementation facility for spent ion exchange resins, decontamination procedures, and various maintenance activities of reactor aging systems and equipment.

The activities of 210Po and 210Pb in cigarette smoked in Tunisia

In this study, the activity concentration of polonium 210 in cigarette for Tunisian consumers was investigated by alpha spectrometry. After chemical digestion of tobacco, ²¹⁰Po was extracted, auto-deposited on disc and measured. The activity of ²¹⁰Pb was assessed after radioactive equilibrium was achieved. The activity levels of ²¹⁰Po ranged between 7.8 ± 0.3 and 17 ± 0.5 mBq per cigarette with an average of 12.9 ± 0.4 mBq per cigarette. Effective doses per year due to cigarette smoking were calculated assuming that 22% of the ²¹⁰Pb and ²¹⁰Po in tobacco were retained in the lungs of the smokers. It is concluded that for a smoker in Tunisia, the average effective dose is about 90.6 ± 3.3 μSv per year for a cigarette consumption of one pack of cigarettes per day. This value is somewhat lower than 106.4 ± 5.3 μSv per year estimated as the mean global effective dose from smoking.

Activity concentrations of 210Po and 210Pb in fish and mussels in İzmir, Turkey, and the related health risk assessment (dose assessment and pesticide levels) to the consumers

The activity concentrations of natural radionuclides (²¹⁰Po and ²¹⁰Pb) and residual pesticide levels were determined from the fish (red mullet, common sole, anchovy, horse mackerel, gray mullet, and sardine) and mussel samples collected in İzmir Bay seasonally from October 2012 and July 2013. The ²¹⁰Po and ²¹⁰Pb concentrations varied between 5.7 ± 4.0 Bq kg^-1 dry weight (dw) to 353.7 ± 45.0 Bq kg^-1(dw) and 0.7 ± 0.2 Bq kg^-1 (dw) to 4.3 ± 0.8 Bq kg^-1 (dw), respectively. From a public health point of view, the fish and mussel collected from the İzmir Bay are not harmful to consumers.

210Pb dating of recent sediments from the continental shelf of western India: factors influencing sedimentation rates

Several cores from the continental shelf of the Arabian Sea along the Indian Coast were investigated for change in sedimentation rates duly constrained for chronology based on ²¹⁰Pb and ¹³⁷Cs dating techniques. The emphasis was to look for spatial and temporal variation in the sedimentation rate along the continental shelf of eastern Arabian Sea between Goa to Kochi for water depth ≤ 150 m. This study showed varying sedimentation rates in coastal and distant sediment cores. Both ²¹⁰Pb and ¹³⁷Cs dating techniques showed comparable sedimentation rate in most sediment cores. The sedimentation in the continental shelf region of the coastal Arabian Sea is primarily controlled by discharge of sediments from rivers during Indian summer monsoon. Increased sedimentation rate from the north (off Goa) to the south (off Kochi) was triggered by high riverine flux and longshore sediment transport.

Occurrence and Geochemistry of Lead-210 and Polonium-210 Radionuclides in Public-Drinking-Water Supplies from Principal Aquifers of the United States

On the basis of lifetime cancer risks, lead-210 (²¹⁰Pb) and polonium-210 (²¹⁰Po) ≥ 1.0 and 0.7 pCi/L (picocuries per liter), respectively, in drinking-water supplies may pose human-health concerns. ²¹⁰Pb and ²¹⁰Po were detected at concentrations greater than these thresholds at 3.7 and 1.5%, respectively, of filtered untreated groundwater samples from 1263 public-supply wells in 19 principal aquifers across the United States. Nationally, 72% of samples with radon-222 (²²²Rn) concentrations > 4000 pCi/L had ²¹⁰Pb ≥ 1.0 pCi/L. ²¹⁰Pb is mobilized by alpha recoil associated with the decay of ²²²Rn and short-lived progeny. ²¹⁰Pb concentrations ≥ 1.0 pCi/L occurred most frequently where acidic groundwaters inhibited ²¹⁰Pb readsorption (felsic-crystalline rocks) and where reducing alkaline conditions favored dissolution of iron-manganese- (Fe-Mn-) oxyhydroxides (which adsorb ²¹⁰Pb) and formation of lead-carbonate complexes (enhancing lead (Pb) mobility). ²¹⁰Po concentrations ≥ 0.7 pCi/L occurred almost exclusively in confined Coastal Plain aquifers where old (low percent-modern carbon-14) groundwaters were reducing, with high pH (>7.5) and high sodium/chloride (Na/Cl) ratios resulting from cation exchange. In high-pH environments, aqueous polonium (Po) is poorly sorbed, occurring as dihydrogen polonate (H₂PoO₃(aq)) or, under strongly reducing conditions, as a hydrogen-polonide anion (HPo^-). Fe-Mn- and sulfate-reduction and cation-exchange processes may mobilize polonium from mineral surfaces. Po²⁺ occurrence in low-to-neutral-pH waters is attenuated by adsorption.

Atmospheric fallout impact on 210Po and 210Pb content in wild growing mushrooms

The atmospheric fallout impact on ²¹⁰Po and ²¹⁰Pb content in fruitbodies of wild growing mushrooms collected from different environments were investigated. The samples of morphologically different mushroom species, namely bay bolete (Imleria badia (Fr.) Vizzini), slippery jack (Suillus luteus (L.) Roussel), fairy ring mushroom (Marasmius oreades (Bolton) Fr.) and common earthball (Scleroderma citrinum Pers.) with their mycelium and soil substrate were collected. Their fruitbodies were separated into cap skin, cap flesh and stem. Also mycelium and soil substrate were collected. The results showed the highest ²¹⁰Po and ²¹⁰Pb activity concentrations were found in Marasmius oreades cap skin: 3.20 ± 0.12 and 21.1 ± 0.5 Bq kg^-1 ww, respectively, which constituted 31.2 and 78.7% of their content in the total fruitbody mass. In the case of open space wild growing mushrooms, their whole caps contain a significantly higher amount of ²¹⁰Po and ²¹⁰Pb when compared to the stem, and their content in the whole cap was determined mainly by concentrations in the cap skin.

The southern Gulf of Mexico: A baseline radiocarbon isoscape of surface sediments and isotopic excursions at depth

The southern Gulf of Mexico (sGoM) is home to an extensive oil recovery and development infrastructure. In addition, the basin harbors sites of submarine hydrocarbon seepage and receives terrestrial inputs from bordering rivers. We used stable carbon, nitrogen, and radiocarbon analyses of bulk sediment organic matter to define the current baseline isoscapes of surface sediments in the sGoM and determined which factors might influence them. These baseline surface isoscapes will be useful for accessing future environmental impacts. We also examined the region for influence of hydrocarbon deposition in the sedimentary record that might be associated with hydrocarbon recovery, spillage and seepage, as was found in the northern Gulf of Mexico (nGoM) following the Deepwater Horizon (DWH) oil spill in 2010. In 1979, the sGoM experienced a major oil spill, Ixtoc 1. Surface sediment δ13C values ranged from -22.4‰ to -19.9‰, while Δ14C values ranged from -337.1‰ to -69.2‰. Sediment δ15N values ranged from 2.8‰ to 7.2‰, while the %C on a carbonate-free basis ranged in value of 0.65% to 3.89% and %N ranged in value of 0.09% to 0.49%. Spatial trends for δ13C and Δ14C were driven by water depth and distance from the coastline, while spatial trends for δ15N were driven by location (latitude and longitude). Location and distance from the coastline were significantly correlated with %C and %N. At depth in two of twenty (10%) core profiles, we found negative δ13C and Δ14C excursions from baseline values in bulk sedimentary organic material, consistent with either oil-residue deposition or terrestrial inputs, but likely the latter. We then used 210Pb dating on those two profiles to determine the time in which the excursion-containing horizons were deposited. Despite the large spill in 1979, no evidence of hydrocarbon residue remained in the sediments from this specific time period.

A Study of 219Rn Outgassing and 211Pb Contamination from 223Ra In dry, Liquid, and Murine Tissue Samples

INTRODUCTION

A study of Pb contamination caused by the outgassing of Rn from Ra in dry, liquid, and murine tissues samples has been made to help design proper handling procedures for Ra in preclinical biodistribution work.

MATERIALS AND METHODS

Pb activity levels were measured from Ra in dry, liquid, and tissue samples using aspiration and autoradiography techniques.

RESULTS

Using aspiration techniques on dry samples of Ra, an average Rn outgassing rate of 51% ± 21% was measured with one measurement reaching as high as 81%. 31% ± 4% Pb contamination was measured within a 4.3 cm radius of a dry Ra source placed inside a 10-cm-diameter petri dish where the lip of the petri dish contained the Rn dissemination. Without the containment of the petri dish, Rn can reach as far as 7.8 cm from the source with trace levels spreading further. Using aspiration techniques on liquid samples of Ra, outgassing rates of Rn were 0.9% ± 0.3%. The outgassing levels in harvested organs from a biodistribution were as high as 10.1% ± 0.4% for an intraperitoneally injected mouse and 0.204% ± 0.006% for an intravenously injected mouse. The outgassing of the intravenously injected mouse carcass was less than 0.1%.

CONCLUSION

In dry form, the high levels of Rn outgassing from a Ra source necessitate the use of ventilated biohoods when handling or preparing dry Ra from source vials. The very low levels of Rn outgassing from Ra liquid sources reduces exposure to Rn by a factor of 50. Rn exposure from murine organ tissue reaches levels of 10% when handling organs from an intraperitoneal injection and less than 0.2% for an intravenous injection.

Activity concentrations of 137Cs, 40K, and 210Pb radionuclides in selected medicinal herbs from Central Serbia and their effective dose due to ingestion

Specific activity of ¹³⁷Cs, ⁴⁰K, and ²¹⁰Pb radionuclides in fifteen selected medicinal herbs from three locations in Central Serbia (two mountains, Kopaonik and Zlatar, and a valley, Sokobanja) was measured using two semiconductor HPGe spectrometer systems. The obtained values are in intervals (<0.3 ÷ 9.7) Bq/kg, (<0.2 ÷ 24.7) Bq/kg, and (<0.2 ÷ 5.7) Bq/kg for ¹³⁷Cs; in intervals (125 ÷ 1100) Bq/kg, (104 ÷ 872) Bq/kg, and (103 ÷ 954) Bq/kg for ⁴⁰K, and in intervals (3.6 ÷ 49.0) Bq/kg, (3.9 ÷ 57.9) Bq/kg, and (2.8 ÷ 103) Bq/kg for ²¹⁰Pb, for herbs from Kopaonik, Sokobanja and Zlatar, respectively. The highest activity measured in individual herbs was: 24.7 Bq/kg for ¹³⁷Cs (Sokobanja valley), 1100 Bq/kg for ⁴⁰K (Mt. Kopaonik) and 103 Bq/kg for ²¹⁰Pb (Mt. Zlatar). The corresponding individual annual effective doses due to ingestion calculated from the measured activity concentrations, of the radionuclides are: in intervals (<1.7 ÷ 82.9) nSv, (<1.4 ÷ 211) nSv, and (<1.1 ÷ 48.7) nSv for ¹³⁷Cs; in intervals (0.76 ÷ 4.5) μSv, (0.64 ÷ 4.4) μSv, and (0.63 ÷ 4.9) μSv for ⁴⁰K, and in intervals (1.1 ÷ 18.2) μSv, (1.3 ÷ 21.6) μSv, (0.9 ÷ 38.3) μSv for ²¹⁰Pb, respectively. The specific activity concentration values of ¹³⁷Cs and ⁴⁰K obtained for the investigated herbs are similar to the literature data, while no information was found in literature about specific activity concentration of ²¹⁰Pb. The all values obtained for individual annual effective dose due to ingestion are less than 100 μSv, which means that the daily use of 200 mL of herbal infusion during a year made from the investigated herbs does not represent a radiological risk for health. However, a high individual annual effective dose of ingestion of ²¹⁰Pb obtained for some herbs indicate that their consumption in larger amounts 2-3 cups of infusion daily over a year could make the dose to exceed the recommended level, and points to necessity for extensive investigation of ²¹⁰Pb activity concentration worldwide.

210Pb dating to investigate the historical variations and identification of different sources of heavy metal pollution in sediments of the Pearl River Estuary, Southern China

In this study, we investigated the historical variation, source identification, and distribution of heavy metal pollution in sediments of the Pearl River Estuary (PRE) using ²¹⁰Pb dating. Our results suggest that the heavy metal concentrations were higher in the western part of the estuary. For all heavy metals, Cd was significantly enriched in the sediments. The Pearl River Delta (PRD) has experienced rapid economic development in the past 40 years, a decreasing trend in heavy metal fluxes after 2004 was identified, which suggests a reduction in heavy metal concentrations due to the removal of heavy polluting industries and the effective control of sewage discharge. A binary mixing model reveals that the contributions of anthropogenic Pb ranged from 45.4 to 64%. Based on lead isotopic ratios (^206/207Pb and ^208/206Pb), it was found that geologic materials and industrial pollution were the main sources of heavy metals in the PRE sediments.

A REVIEW ON 210Po AND 210Pb IN INDIAN SEAFOOD AND DOSE TO CONSUMERS

India is the second largest seafood producer in the world marketing more than 7000 edible species. In this regard, commendable studies have been conducted since the 1970s by different research groups and more data are reported. In this work, all the studies on 210Po and 210Pb measurements in abiotic and biotic components of India have been combined and reviewed. The concentrations of 210Po and 210Pb are estimated by radiochemical separation followed by alpha counting. Grain size, season, Tsunami waves and place of sampling have a decisive bearing on 210Po and 210Pb concentration in abiotic components. Plankton shows a higher Kd factor (104) compared to seaweeds and sea grass (103). Pond ecosystems recorded the highest Kd factor (4·3 × 104) compared to other freshwater and marine ecosystems. Bioaccumulation of 210Po and 210Pb varies with respect to variety of seafood. The committed effective dose (CED) calculated for shellfish species maintained a higher range of 2.5 × 10-2 mSv/y to 9.8 × 10-1 mSv/y and for fish species fluctuated from 3.8 × 10-4 mSv/y to 2.0 × 10-1 mSv/y. The studies conducted so far are scattered, and need to be gathered for future reference and planning (i.e. There is not much information available for Kerala, Karnataka, Maharashtra, Gujarat, Andhra, West Bengal and Odessa coast). Therefore, it is strongly recommended that further and more complete research is undertaken to study the bioaccumulation of 210Po and 210Pb from seafood. Overall, the present review concludes that Indian seafood is radiologically safe.

Organic carbon sequestration in sediments of subtropical Florida lakes

Recent studies have shown that sediments of temperate and tropical lakes are sinks for organic carbon (OC), but little is known about OC burial in subtropical lakes. There are questions regarding the ability of subtropical lakes to store OC, given their relatively warmwater temperatures, lack of ice cover, frequent water-column mixing, and labile carbon forms. We used 210Pb-dated sediment cores from 11 shallow Florida (USA) lakes to estimate OC burial, i.e. net OC storage, over the last ~100 years. Shallow Florida water bodies average ~30% OC content in their sediments and displayed rates of net OC accumulation (63-177 g C m-2 a-1) that are similar to natural temperate lakes, but lower than temperate agricultural impoundments. We considered the influence of lake morphometry on OC storage in our study lakes, but did not observe an inverse relationship between lake size and OC burial rate, as has been seen in some temperate lake districts. We did, however, find an inverse relation between mean water depth and OC sequestration. Despite recent cultural eutrophication and the associated shift from macrophyte to phytoplankton dominance in the Florida study lakes, overall OC burial rate increased relative to historic (pre-1950 AD) values. Lakes cover >9000 km2 of the Florida landscape, suggesting that OC burial in sediments amounts to as much as 1.6 Mt a-1. The high rate of OC burial in Florida lake sediments indicates that subtropical lakes are important for carbon sequestration and should be included in models of global carbon cycling.

Levels of radionuclide concentrations in benthic invertebrate species from the Balearic Islands, Western Mediterranean, during 2012-2018

Baseline levels of radionuclides in the marine environment of the Balearic Islands in Western Mediterranean have not been reported in literature. Because of their ecological role and acknowledged sensitivity to pollutants, herein, the activity concentrations of ²¹⁰Po, ⁴⁰K, ²¹⁰Pb, ⁹⁰Sr, and ²³⁴Th were measured in two types of benthic invertebrate species (mussels and sea urchins) sampled during 2012-2018. The activity concentrations of ²¹⁰Po, ⁴⁰K, ²¹⁰Pb, and ²³⁴Th ranged from 38 ± 1 to 325 ± 11 Bq kg^-1 dry weight (d.w.), 220 ± 10 to 996 ± 46 Bq kg^-1 d.w., ND (lower than the limit of detection) to 55 ± 8 Bq kg^-1 d.w., and ND to 70 ± 15 Bq kg^-1 d.w., respectively. In all cases, no artificial ⁹⁰Sr activity was detected in the collected samples. The committed effective dose to humans was calculated to be in the range of 48-640 μSv year^-1.

Bioaccessibility and radioisotopes of lead in soils around a fertilizer industry in Lebanon

The use of phosphate ore by fertilizer industries is considered a major source of soil contamination by trace metals and radionuclides. Despite its low mobility and bioavailability, lead (Pb) is among soil contaminants that pose a serious risk to human health. This study evaluates the potential impact of a fertilizer factory in North Lebanon on the total content of Pb and the activity concentration of its radioisotopes in residential, non-agricultural lands around the industry, as well as its mobility and bioaccessibility in soil samples collected at different depths. Chemical extractions by EDTA and in vitro physiologically based extraction test were used to estimate, respectively, the available and bioaccessible fractions of Pb in soils. Radioisotopes ²¹⁴Pb, ²¹²Pb and ²¹⁰Pb have been analyzed by gamma spectrometry. Different physicochemical soil parameters, such as pH, carbonate content, electrical conductivity, cation exchange capacity, clay, total nitrogen and redox potential, were studied. The pseudo-total Pb varied between 12.8 and 68.5 mg kg^-1, while the extractable fractions were more variable, between 12 and 72% of total Pb concentration for the EDTA extracted fraction and up to 28.5% for the bioaccessible fractions. The processing of the data shows the decreases with depth in most sites of the total and available Pb and of the activity concentration of ²¹⁰Pb and their positive correlations with total nitrogen. These variations and relationships with the location of studied sites show the influence of emissions from the factory or the transport of ore and by-products. The correlations between available and bioaccessible Pb on one hand, between available Pb and ²¹⁰Pb on another hand, raise the question of health risk assessments taking into account the bioaccessibility of Pb and its radioisotopes.

Assessment of temporal variations of natural radionuclides Beryllium-7 and Lead-212 in surface air in Tanay, Philippines

Detection of radionuclides in surface air allows researchers to gain further insight on the behavior of radionuclides that may affect human radiation exposure especially in the event of a nuclear emergency. In this study, activity concentrations of naturally-occurring radionuclides Beryllium-7 (⁷Be) and Lead-212 (²¹²Pb) in surface air and meteorological data collected in Tanay, Philippines from January 2012 to December 2017 were evaluated to determine the impact of atmospheric conditions and processes to airborne radioactivity. Surface air concentrations of ⁷Be and ²¹²Pb were found to range from 0.00779 ± 0.00188 to 11.2 ± 0.116 mBq/m³ and from 1.371 ± 0.036 to 106.6 ± 1.075 mBq/m³, respectively. ⁷Be and ²¹²Pb show distinct annual trends, suggesting that atmospheric conditions affect both radionuclides differently and independently. ⁷Be shows two peak concentrations annually, with the first peak occurring between January to April and the second lower peak occurring between October and November. ²¹²Pb, on the other hand, shows annual peak concentrations occurring between April and June. Ambient temperature showed strong positive correlation with ²¹²Pb concentration in surface air and a weak negative correlation with ⁷Be; relative humidity and precipitation showed varying degrees of negative correlation with radionuclide concentrations in surface air. Source locations for the unusually high ²¹²Pb activity concentrations detected on 11-13 May 2013 and 19-31 May 2015 determined using WEB-GRAPE and HYSPLIT atmospheric transport models are presented as a case study. The data and findings of this study shall serve as basis for further studies on local and regional atmospheric transport and radiological impact assessment for the implementation of an effective nuclear and radiological emergency preparedness and response system in the country.

Spatial and temporal variations of sediment metals in the Tuul River, Mongolia

Mongolia has been a pristine environment without much pollution. Our objective is to study a section of the Tuul River to evaluate the present condition of this pristine environment. Sediment metal (Al, Fe, Mn, Cu, Zn, Pb, Ni, Cd, Hg, and Cr) concentrations and Pb-210 were sampled and analyzed. Results showed that metal concentrations are much higher at areas near the capital city and municipal sewage outlet, with enrichment factor values up to 18 for Cu, and 26 for Cr. Higher copper concentrations were found at sites about ~ 50 km downstream from the source, an indication that pollutions are spreading further down the river. Vertical metal concentration profiles indicated that pollutions could be traced back to the 1960s. Inefficient sewage treatment plants and poorly managed power plant ash ponds were major sources of metals leaking into the Tuul River. Sewage wastewater is carrying metals through Tuul River to the lower river basin. Dusts from ash ponds are airborne and transport to greater area. These findings indicate that new and alternative measures have to be enforced to prevent further pollution entering the Tuul River drainage basin and airborne dust to other broader regions of the Asia and ocean.

An alternative methodology to determine 210Pb activity soil profiles

Unsupported ²¹⁰Pb (Pb_exc) is generated in air and is subsequently deposited on soil surface. The Pb_exc can be used for sediment dating, soil erosion/sedimentation and air mass studies. In many cases, ²¹⁰Pb activity determination (gamma ray 46.5 keV) cannot be performed due to the lack of efficiency calibration curve, especially when radioactive patron source is not available. This work presents an alternative methodology to obtain the ²¹⁰Pb activity values, based on the activity definition and the attenuation coefficient determinations and assuming that soil samples coming from depth higher than 25 cm only contain ²¹⁰Pb generated in the soil (Pb_exc free, i.e., for those soil layers the ²¹⁰Pb activity is equal to the ²²⁶Ra activity, at secular equilibrium). The proposed methodology was evaluated using soils from La Plata region, Argentina. The same soil samples were also analyzed in a second laboratory by the conventional methodology. The obtained results indicated that the proposed procedure can be used as a good alternative in cases where a calibration sample is not available.

On the role of 210Bi in the apparent disequilibrium of 210Pb-210Po at sea

The disequilibrium of the grandparent-daughter pair ²¹⁰Pb (t_1/2=_{22.3 years})-²¹⁰Po (t_{1/2=138 days}) has been used to estimate the export fluxes of particulate organic carbon in the ocean using particulate-matter-associated ²¹⁰Po. ²¹⁰Po is produced from ²¹⁰Bi, not from ²¹⁰Pb. The half-life of ²¹⁰Bi (t_{1/2=5.01 days}) is sufficiently long compared to the rates of biological particle formation and decomposition or dissolution occurring at sea. The role of ²¹⁰Bi has not yet been assessed quantitatively in the apparent disequilibrium between ²¹⁰Pb and ²¹⁰Po, partly due to the non-existence of ²¹⁰Bi depth profile measurements at sea up to now. However, greater affinity of ²¹⁰Bi over ²¹⁰Po and ²¹⁰Pb was found recently in coastal waters and phytoplankton ²⁰⁷Bi uptake experiments. Build upon these findings, we developed a primitive and simple analytical approach to elucidate the role of ²¹⁰Bi in the ²¹⁰Po-²¹⁰Pb pair in the ocean using a simplified two-box irreversible steady-state ocean model. We assumed that the activity concentrations in the dissolved and particulate phases of ²¹⁰Pb, ²¹⁰Bi, and ²¹⁰Po in a given water column are solely determined by the concentration of the particles, their input and output, the distribution coefficients between dissolved and particulate phases, and decay constants of these radionuclides in the steady-state ocean. The ²¹⁰Bi contribution to the ²¹⁰Pb-²¹⁰Po activity difference in seawater is found to be significant, therefore, it needs to be considered in estimating particle fluxes using ²¹⁰Pb-²¹⁰Po secular equilibrium at sea.

Deposition of naturally occurring 7Be and 210Pb in Northern Finland

This study presents observations of naturally occurring ⁷Be and ²¹⁰Pb in total deposition collected in three deposition sampling stations located in three towns in Northern Finland at Rovaniemi, Sodankylä and Ivalo. The deposition samples were measured in three-month intervals and the collected data covered the years from 1991 to 2017 in Rovaniemi and the years from 1999 to 2017 in Sodankylä and Ivalo. The ⁷Be deposition was observed to be dependent on the amount of precipitation where higher amount of precipitation meant higher ⁷Be deposition. The ⁷Be deposition showed a distinctive seasonal cycle where the highest ⁷Be deposition values were observed occur during July-September and the lowest values during January-March. From the annual total deposition 72-84% occurred during the months of April-September (2^nd and 3^rd quarters). The precipitation normalized enrichment factor (α) determined the excess or deficiency of ⁷Be relative to the amount of rain. The most excess of ⁷Be in the deposition was observed during April-June (2^nd quarter) while the most ⁷Be depleted precipitation occurred during January-March (1^st quarter). The large excess of ⁷Be in precipitation during April-June (2^nd quarter) was an indication of injections of ⁷Be rich stratospheric air into troposphere. By using simultaneously collected ⁷Be aerosol concentration data at Rovaniemi and Ivalo, the ⁷Be deposition velocities were determined. The deposition velocities (V_D) were also found to have a strong seasonal cycle where low velocities were observed during winter and higher ones during summer. The ⁷Be deposition time series were also compared with other time series that are known to affect ground level ⁷Be aerosol concentrations. These were precipitation, sunspot number (SSN), galactic cosmic ray flux (GCR), Arctic Oscillation (AO), North Atlantic Oscillation (NAO) and Scandinavian Pattern (SCAND) indices. The Pearson correlation and wavelet coherence (WTC) was used to analyze possible correlations between the time series. The analyses showed that the coherences were location dependent. Rovaniemi ⁷Be deposition data correlated strongly with rain and weakly with the SCAND index at the 6-8 year scale. The Sodankylä ⁷Be deposition data correlated strongly with the precipitation and SSN and GCR and weakly with AO and NAO indices. Ivalo ⁷Be deposition data correlated with strongly with ⁷Be aerosol concentration data, SSN, GCR and NAO index and weakly with the AO index. The WTC analysis revealed anti-phase coherences with the AO and NAO indices at 4-6 year scale. The ²¹⁰Pb deposition data was sparse and only available from 2011 onwards. ²¹⁰Pb deposition had a seasonal cycle where higher deposition values were observed during summer and lower ones deposition during winter. The annual ²¹⁰Pb deposition was determined at Rovaniemi and Sodankylä during 2014. The values of ⁷Be/²¹⁰Pb ratio was found to vary significantly seasonally, higher ⁷Be/²¹⁰Pb ratios were measured during summer and lower ones during winter.

The level of 210Pb extraction efficiency in Polish herbal teas and the possible effective dose to consumers

The article presents the results of a study on the level of ²¹⁰Pb efficiency extraction in Polish herbal teas as a possible additional source of this radioactive isotope in the human diet. The twelve most popular herbal teas available in Poland and their infusions in filtered and tap water were analyzed as well as ²¹⁰Pb activity concentrations and effective doses (radiation) were calculated. The highest activity concentration of ²¹⁰Pb in dried plants was determined in cistus - 35.5 Bq kg^-1dry wt, while the lowest was in milk thistle - 3.25 Bq kg^-1dry wt what gives respectively for cistus 46.1 ± 0.7 and 6.50 ± 0.29 mBq for milk thistle per one tea bag. The extraction efficiencies in the filtered water oscillated from 5.1 ± 0.5 for milk thistle to 27.3 ± 0.8% for cistus, while for the tap water they ranged from 7.3 ± 0.6% for lime to 33.3 ± 2.2% for white mulberry. Based on the study, it was found that the analyzed herbal tea consumption would give a small portion of the annual effective dose of ²¹⁰Pb received in Poland - the annual effective radiation dose of ²¹⁰Pb taken with herbal tea infusions (one glass daily) was calculated from 0.08 ± 0.01 to 3.17 ± 0.08 µSv.

NEW DEVELOPMENT OF RADON PROGENY MEASUREMENT METHOD BASED ON ALPHA-BETA SPECTROMETRY

Accurate measurement of radon progeny concentration is important for the dose assessment of radon exposure and the study of radon progeny behaviours. For measuring 218Po, 214Pb and 214Bi concentration as well as EEC with high sensitivity, an alpha-beta spectrometry method was developed and applied in a step-advanced filter radon progeny monitor. The derivation details of this method is given in this paper and the uncertainty is discussed. The comparison experiments are carried out in radon chamber and in field. Results show that the alpha-beta spectrometry method can give 218Po, 214Pb and 214Bi concentration as well as EEC with high sensitivity either for 60 min or for 30 min cycle, which leads to low uncertainty. This method can be used as a reference method for radon chamber and is suitable for portable radon progeny monitor.