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1.
The radionuclides 210Po and 210Pb widely present in the terrestrial environment are the final long-lived radionuclides in the decay of 238U in the earth’s crust. Their presence in the atmosphere is due to the decay of 222Rn diffusing from the ground. The range of activity concentrations in ground level air for 210Po is 0.03-0.3 Bq m−3 and for 210Pb 0.2-1.5 Bq m−3.In drinking water from private wells the activity concentration of 210Po is in the order of 7-48 mBq l−1 and for 210Pb around 11-40 mBq l−1. From water works, however, the activity concentration for both 210Po and 210Pb is only in the order of 3 mBq l−1.Mosses, lichens and peat have a high efficiency in capturing 210Po and 210Pb from atmospheric fallout and exhibit an inventory of both 210Po and 210Pb in the order of 0.5-5 kBq m−2 in mosses and in lichens around 0.6 kBq m−2. The activity concentrations in lichens lies around 250 Bq kg−1, dry mass.Reindeer and caribou graze lichen which results in an activity concentration of 210Po and 210Pb of about 1-15 Bq kg−1 in meat from these animals. The food chain lichen-reindeer or caribou, and Man constitutes a unique model for studying the uptake and retention of 210Po and 210Pb in humans. The effective annual dose due to 210Po and 210Pb in people with high consumption of reindeer/caribou meat is estimated to be around 260 and 132 μSv a−1 respectively.In soils, 210Po is adsorbed to clay and organic colloids and the activity concentration varies with soil type and also correlates with the amount of atmospheric precipitation. The average activity concentration levels of 210Po in various soils are in the range of 20-240 Bq kg−1.Plants become contaminated with radioactive nuclides both by absorption from the soil (supported Po) and by deposition of radioactive fallout on the plants directly (unsupported Po). In fresh leafy plants the level of 210Po is particularly high as the result of the direct deposition of 222Rn daughters from atmospheric deposition. Tobacco is a terrestrial product with high activity concentrations of 210Po and 210Pb. The overall average activity concentration of 210Po is 13 ± 2 Bq kg−1. It is rather constant over time and by geographical origin.The average median daily dietary intakes of 210Po and 210Pb for the adult world population was estimated to 160 mBq day−1 and 110 mBq day−1, corresponding to annual effective doses of 70 μSv a−1 and 28 μSv a−1, respectively. The dietary intakes of 210Po and 210Pb from vegetarian food was estimated to only 70 mBq day−1 and 40 mBq day−1 corresponding to annual effective doses of 30.6 μSv a−1 and 10 μSv a−1, respectively. Since the activity concentration of 210Po and 210Pb in seafood is significantly higher than in vegetarian food the effective dose to populations consuming a lot of seafood might be 5-15 fold higher.  相似文献   

2.
Polonium-210 (210Po) radioactive concentrations were determined in human semen fluid of vasectomized non-smoker volunteers. The 210Po levels ranged from 0.10 to 0.39 mBq g−1 (mean: 0.23 ± 0.08 mBq g−1). This value decreased to 0.10 ± 0.02 mBq g−1 (range from 0.07 to 0.13 mBq g−1) after two weeks of a controlled diet, excluding fish and seafood. Then, volunteers ate during a single meal 200 g of the cooked mussel Perna perna L., and 210Po levels were determined again, during ten days, in semen fluid samples collected every morning. Volunteers continued with the controlled diet and maintained sexual abstinence through the period of the experiment. A 300% increase of 210Po level was observed the day following mussel consumption, with a later reduction, such that the level returned to near baseline by day 4.  相似文献   

3.
A sequential extraction protocol has been used to determine the solid-phase partition of 210Po and 210Pb in anoxic marine sediment from the roads of Cherbourg (France) in the central English Channel. Measurements were also obtained in pore waters, in which 210Po activities range between 1 and 20 mBq L−1 and 210Pb activities between 2.4 and 3.8 mBq L−1, with highest activities in the topmost layer. These activities are higher than in seawater, suggesting that sediment act as a source of both 210Po and 210Pb for overlying water. The 210Po profile in the pore waters is apparently correlated with those obtained for Fe, Mn and SO42, suggesting an influence of early diagenetic processes on the 210Po solid-liquid distribution. In the sediment, 210Po is predominantly bound to organic matter or chromium reducible sulphides, and residuals (clay minerals and refractory oxides). Our results indicate that 210Po is not significantly bound to AVS, i.e. acid volatile sulphides: bioturbation could play a role by the early redistribution of 210Po bound to acid volatile sulphides in the sediment. 210Po, 210Pb and Pb exhibit differences in terms of distribution, probably due to a different mode of penetration in the sediment. This work provides information on solid and liquid distribution of 210Po and 210Pb in marine sediment. These data are very scarce in the litterature.  相似文献   

4.
Total 210Pb and 7Be fallout rates were measured on the coastal region of Niteroi, Brazil. The monthly depositional flux of 210Pb and 7Be varied by a factor of 26, from 1.7 to 43.3 mBq cm−2 year−1 and ∼27, from 7.5 to 203.5 mBq cm−2 year−1, respectively. The relatively large oscillations in the depositional flux of 210Pb at this study site were likely due to variations in air mass sources, while the 7Be fluctuations may be driven by a combination of weather conditions. Local geology could support the periodic high fluxes of 210Pb from continental air masses, as shifting oceanic wind sources were affirmed by the uncorrelated 210Pb and 7Be fallout activities and 7Be/210Pb ratios. The 210Pb atmospheric deposition was found to be in agreement with local sediment inventories, an important consideration in geochemical studies that estimate sedimentation processes.  相似文献   

5.
The determination of 210Po and 210Pb was performed in marine organisms from the seashore to abyssal depths, encompassing a plethora of species from the microscopic plankton to the sperm whale. Concentrations of those radionuclides ranged from low values of about 5 × 10−1 Bq kg−1 (wet wt.) in jellyfish, to very high values of about of 3 × 104 Bq kg−1 (wet wt.) in the gut walls of sardines, with a common pattern of 210Po > 210Pb.These radionuclides are primarily absorbed from water and concentrated by phyto- and microzooplankton, and then are transferred to the next trophic level along marine food chains. Investigation in epipelagic, mesopelagic, bathypelagic and abyssobenthic organisms revealed that 210Po is transferred in the marine food webs with transfer factors ranging from 0.1 to 0.7, and numerically similar to those of the energy transfer in the marine food chains. As 210Po preferentially binds to amino acids and proteins, its transfer in food chains likely traces protein transfer and, thus, 210Po transfer factors are similar to ecotrophic coefficients. 210Pb is transferred less efficiently in marine food chains and this contributes to increased 210Po:210Pb activity ratios in some trophic levels.  相似文献   

6.
Transfer factors of Polonium from soil to parsley and mint   总被引:1,自引:0,他引:1  
Transfer factors of 210Po from soil to parsley and mint have been determined. Artificial polonium isotope (208Po) was used as a tracer to determine transfer factor of Po from soil to plant in pot experiments. Two plant growing systems were used for this study namely, an outdoor system and a sheltered system by a polyethylene tent. 208Po and 210Po were determined in soil and different parts of the studied plants (stem and leaf), using alpha spectroscopy. The results have shown that there was a clear uptake of 208Po by roots to leaves and stems of both plants. Higher values of transfer factors using the 210Po activity concentrations than the 208Po activity concentration were observed. Transfer factors of 210Po from soil to parsley varied between 20 × 10−2 and 50 × 10−2 and 22 × 10−3 and 67 × 10−3 in mint, while 208Po transfer factors varied between 4 × 10−2 and 12 × 10−2 for parsley and 10 × 10−2 and 22 × 10−2 in mint. Transfer factors of Po were higher in those plants grown in the sheltered system than in the open system; about 75% of Po was transferred from atmosphere to parsley parts using the two systems. Ratios of transferred Po from soil to mint stem and leaf in the sheltered system were higher by 2 times from those in the open system.  相似文献   

7.
To provide baseline data on background radiation levels for the future assessment of the impact of nuclear and thermal power stations, a systematic study was carried out in the Mallipattinam ecosystem of Tamil Nadu, India. Mallipattinam is located between the Kudankulam and Kalpakkam nuclear power plants and near to Tuticorin thermal power plant. Water, sediments, seaweeds, crustaceans, molluscs, and fish were collected to measure the concentrations of 210Po and 210Pb. The concentrations of 210Po and 210Pb in most samples are comparable to values reported worldwide. In fish, the concentrations of 210Po and 210Pb are in the range 16-190 Bq kg−1 and 8-153 Bq kg−1, respectively. The concentration factors of 210Po and 210Pb for the biotic components ranges from 103 to 106.  相似文献   

8.
Radionuclide analyses were performed in tissue samples including muscle, gonad, liver, mammary gland, and bone of marine mammals stranded on the Portuguese west coast during January-July 2006. Tissues were collected from seven dolphins (Delphinus delphis and Stenella coeruleoalba) and one pilot whale (Globicephala sp.). Samples were analyzed for 210Po and 210Pb by alpha spectrometry and for 137Cs and 40K by gamma spectrometry. Po-210 concentrations in common dolphin’s muscle (D. delphis) averaged 56 ± 32 Bq kg−1 wet weight (w.w.), while 210Pb averaged 0.17 ± 0.07 Bq kg−1 w.w., 137Cs averaged 0.29 ± 0.28 Bq kg−1 w.w., and 40K 129 ± 48 Bq kg−1 w.w. Absorbed radiation doses due to these radionuclides for the internal organs of common dolphins were computed and attained a 1.50 μGy h−1 on a whole body basis. 210Po was the main contributor to the weighted absorbed dose, accounting for 97% of the dose from internally accumulated radionuclides. These computed radiation doses in dolphins are compared to radiation doses from 210Po and other radionuclides reported for human tissues. Due to the high 210Po activity concentration in dolphins, the internal radiation dose in these marine mammals is about three orders of magnitude higher than in man.  相似文献   

9.
A survey was carried out on the activity concentrations of 210Pb and 210Po in cereal grains produced in Finland. The cereal species were wheat (Triticum aestivum), rye (Secale cereale), oats (Avena sativa) and barley (Hordeum vulgare), which account for 90% of the Finnish consumption of cereal products. The survey consisted of 18 flour and 13 unprocessed cereal samples and one hulled grain sample from 22 flour mills. According to the results, the mean 210Pb/210Po concentrations in wheat grains, wheat flour, rye flour, oat grains and barley grains were 0.29, 0.12, 0.29, 0.36 and 0.36 Bq kg−1, respectively. Combined with the consumption rates of the products, we assess that the mean effective doses from 210Pb and 210Po in cereal products for the adult male and female population are 22 and 17 μSv per year, respectively.  相似文献   

10.
When used with an atmospheric transport model, the 222Rn flux distribution estimated in our previous study using soil transport theory caused underestimation of atmospheric 222Rn concentrations as compared with measurements in East Asia. In this study, we applied a Bayesian synthesis inverse method to produce revised estimates of the annual 222Rn flux density in Asia by using atmospheric 222Rn concentrations measured at seven sites in East Asia. The Bayesian synthesis inverse method requires a prior estimate of the flux distribution and its uncertainties. The atmospheric transport model MM5/HIRAT and our previous estimate of the 222Rn flux distribution as the prior value were used to generate new flux estimates for the eastern half of the Eurasian continent dividing into 10 regions.The 222Rn flux densities estimated using the Bayesian inversion technique were generally higher than the prior flux densities. The area-weighted average 222Rn flux density for Asia was estimated to be 33.0 mBq m−2 s−1, which is substantially higher than the prior value (16.7 mBq m−2 s−1). The estimated 222Rn flux densities decrease with increasing latitude as follows: Southeast Asia (36.7 mBq m−2 s−1); East Asia (28.6 mBq m−2 s−1) including China, Korean Peninsula and Japan; and Siberia (14.1 mBq m−2 s−1). Increase of the newly estimated fluxes in Southeast Asia, China, Japan, and the southern part of Eastern Siberia from the prior ones contributed most significantly to improved agreement of the model-calculated concentrations with the atmospheric measurements. The sensitivity analysis of prior flux errors and effects of locally exhaled 222Rn showed that the estimated fluxes in Northern and Central China, Korea, Japan, and the southern part of Eastern Siberia were robust, but that in Central Asia had a large uncertainty.  相似文献   

11.
Mosses and lichens are useful biological indicators of environmental contamination for a variety of metals and radionuclides of both natural and artificial origin. These plants lack a well-developed root system and rely largely on atmospheric deposition for nourishment. Therefore in the study, different lichens (Cladonia convoluta, Cladonia foliacea) and mosses (Homalothecium sericeum, Hypnum lacunosum, Hypnum cupressiforme, Tortella tortuosa, Didymodon acutus, Syntrichia ruralis, Syntrichia intermedia, Pterogonium graciale, Isothecium alopecuroides, Pleurochatae squarrosa) were collected around the Yata?an (Mu?la), Soma (Manisa), Seyitömer - Tunçbilek (Kütahya) coal-fired power plants and investigated for potential use as biomonitors for 210Po and 210Pb deposition. While the activity concentrations of 210Po and 210Pb in lichens are in the ranges of 151 ± 7-593 ± 21 and 97 ± 5-364 ± 13 Bq kg−1, for mosses the ranges for 210Po and 210Pb are 124 ± 5-1125 ± 38 and 113 ± 4-490 ± 17 Bq kg−1, respectively. In the study, the moss samples were observed to accumulate more 210Po and 210Pb compared to lichens. While the most suitable biomonitor was a moss species (H. lacunosum) for Yata?an (Mu?la), it was another moss species (S. intermedia) for Soma (Manisa) and Seyitömer - Tunçbilek (Kütahya) sites. 210Po concentrations were found higher than 210Pb concentrations at the all sampling stations.  相似文献   

12.
Recent developments regarding environmental impact assessment methodologies for radioactivity have precipitated the need for information on levels of naturally occurring radionuclides within and transfer to wild flora and fauna. The objectives of this study were therefore to determine activity concentrations of the main dose forming radionuclides 210Po and 210Pb in biota from terrestrial ecosystems thus providing insight into the behaviour of these radioisotopes. Samples of soil, plants and animals were collected at Dovrefjell, Central Norway and Olkiluoto, Finland. Soil profiles from Dovrefjell exhibited an approximately exponential fall in 210Pb activity concentrations from elevated levels in humus/surface soils to “supported” levels at depth. Activity concentrations of 210Po in fauna (invertebrates, mammals, birds) ranged between 2 and 123 Bq kg−1 d.w. and in plants and lichens between 20 and 138 Bq kg−1 d.w. The results showed that soil humus is an important reservoir for 210Po and 210Pb and that fauna in close contact with this media may also exhibit elevated levels of 210Po. Concentration ratios appear to have limited applicability with regards to prediction of activity concentrations of 210Po in invertebrates and vertebrates. Biokinetic models may provide a tool to explore in a more mechanistic way the behaviour of 210Po in this system.  相似文献   

13.
Natural radionuclides, such as 210Po and 210Pb were measured in the water samples collected from six stations at Kuala Selangor, Malaysia. Results for 210Po and 210Pb in dissolved and particulate phases have showed the difference in distribution and chemical behavior. The fluctuation activities of 210Po and 210Pb depend on wave action, geology and degree of fresh water input occurring at study areas and probably due to different sampling dates. The distribution coefficient, Kd, values of 210Po and 210Pb ranged from 2.0 × 103 l g−1 to 265.15 × 105 l g−1, and from 3.0 × 103 l g−1 to 558.16 × 105 l g−1, respectively. High Kd values of 210Po and 210Pb indicated that a strong adsorption of 210Po and 210Pb onto suspended particles, and the sinking of both nuclides on the seabed at study locations were controlled by the characteristics of suspended particles.  相似文献   

14.
The activity of 210Po and 210Pb was determined in mussels of the same size (3.5-4.0 cm shell length) sampled monthly over a 17-month period at the Atlantic coast of Portugal. Average radionuclide concentration values in mussels were 759 ± 277 Bq kg−1 for 210Po (range 460-1470 Bq kg−1 dry weight), and 45 ± 19 Bq kg−1 for 210Pb (range 23-96 Bq kg−1 dry weight). Environmental parameters and mussel biometric parameters were monitored during the same period. Although there was no seasonal variation of radionuclide concentrations in sea water during the study period, the concentration of radionuclide activity in mussels varied seasonally displaying peaks of high concentrations in winter and low concentrations in summer. Analysis of radionuclide data in relation to the physiological Condition Index of mussels revealed that 210Po and 210Pb activities in the mussel (average activity per individual) remained nearly constant during the investigation period, while mussel body weight fluctuated due to fat storage/expenditure in the soft tissues. Similar variation of radionuclide concentrations was observed in mussels transplanted from the sea coast into the Tejo Estuary. However, under estuarine environmental conditions and with higher food availability throughout the year, transplanted mussel Condition Index was higher than in coastal mussels and average radionuclide concentrations were 210 ± 75 Bq kg−1 (dry weight) for 210Po and 10 ± 4 Bq kg−1 (dry weight) for 210Pb, therefore lower than in coastal mussels with similar shell length. It is concluded that the apparent seasonal fluctuation and inter-site difference of radionuclide concentrations were mostly caused by mussel body weight fluctuation and not by radionuclide body burden fluctuation. This interpretation can be extended to the apparent seasonal fluctuation in concentrations of lipophilic and lipophobic contaminants in mussels, and provides an explanation for occasional high concentrations of 210Po and man-made contaminants measured in mussels far from pollution sources.  相似文献   

15.
Several medicinal plants used in Italy were analysed to determine natural and artificial radioactivity in those parts (leaves, fruits, seeds, roots, peduncles, flowers, barks, berries, thallus) used generally as remedies. The radionuclides were determined by alpha (238U, 210Po) and gamma (214Pb-Bi, 210Pb, 40K and 137Cs) spectrometry. 238U ranged between <0.1 and 7.32 Bq kgdry−1; 210Po between <0.1 and 30.3 Bq kgdry−1; 214Pb-214Bi between <0.3 and 16.6 Bq kgdry−1; 210Pb between <3 and 58.3 Bq kgdry−1; 40K between 66.2 and 3582.0 Bq kgdry−1; 137Cs between <0.3 and 10.7 Bq kgdry−1. The percentage of 210Po extraction in infusion and decoction was also determined; the arithmetical mean value of percentage of 210Po extraction resulted 20.7 ± 7.5.  相似文献   

16.
External gamma radiation levels were measured in the catchment areas of the Sharavathi River and the dose rates in air were found to be in the range 26.0-61.0 nGy h−1. Soil and sediment samples of the riverine environment were analysed for natural radionuclides such as 226Ra, 232Th and 40K using a NaI(Tl) gamma spectrometer. The activity concentration of 210Pb and 210Po in soil and sediment samples was determined by radiochemical separation techniques. Evaluation of the activity concentration of radionuclides with grain size revealed an increase in the activity of 226Ra, 232Th and 40K towards fine grain size. The activity concentrations for all isotopes in all samples were not significantly correlated with pH. However, the activity of 210Po and 210Pb in sediment showed a moderate positive correlation with organic matter content and a good correlation with clay content of sediment.  相似文献   

17.
Several natural and anthropogenic radionuclides (210Pb, 226Ra and 137Cs) in guano-phosphatic coral sediments and pure guano particles collected from Ganquan, Guangjin, Jinqing and Jinyin Islands of the Xisha archipelago, South China Sea, were analyzed. The Constant Initial Concentration (CIC) model and the Constant Rate of Supply (CRS) model were applied for age calculation. The average supply rate of 210Pb was 126 Bq m−2 a−1, very close to the flux of northern hemisphere average (125 Bq m−2 a−1). The activities of anthropogenic radionuclides in the sediments were very low, indicating that human nuclear tests did not notably impact this region. The main source of radionuclides in the sediments was from atmospheric precipitation, and the organic matter derived from plant and produced by nutrient-rich guano could further enhance them.  相似文献   

18.
The Sambhar Salt Lake hydrological system, including river waters, groundwaters, evaporating pans and sub-surface brines, has been analyzed for the salt content (TDS) and naturally occurring radionuclides (210Po, 210Pb and 226,228Ra). The abundance of these radionuclides and their activity ratios show a wide variation in different hydrological regimes, which helps to geochemically characterize the lake system. A significantly lower Ra to total dissolved solids (TDS) ratio in the brines (by two to three orders of magnitude), when compared to the groundwaters and river waters, suggests removal of dissolved Ra by co-precipitation with Ca–Mg minerals at an early stage of the brine evolution. The concentration of Ra in evaporating lake/pan waters saturates at a value of about 35 Bq L−1 over the salinity range of 100–370 g L−1; attributable to its equilibration with the clay minerals. The two distinct regimes, saline lake system (lake water, evaporating pans and sub-surface brines) and groundwaters have been identified based on their differences in the distribution of 226,228Ra isotopes. This observation points to the conclusion that the groundwaters and the lake brines are not intimately coupled in terms of their origin and evolution. The abundances of 210Po and 210Pb along with their activity ratios (210Po/210Pb) are markedly different among the surface lake waters/evaporating pans, sub-surface lake brines and groundwaters. These differences are explained in terms of different geochemical behaviour of these nuclides in presence of algae and organic matter present in these water regimes.  相似文献   

19.
This paper presents the results of an investigation of the 210Po contents of Baltic marine invertebrates. The 210Po concentrations fall within the range 11·3–78·9 Bq kg−1 (dry wt), the higher values relating to polychaeta, priapulida and malacostraca and the lower levels to bivalvia. It is demonstrated that 10Po is non-uniformly distributed within the isopod Mesidotea entomon and the bivalve Mya arenaria. The 210Po contents of the internal organs decreasing in the order-hepatopancreas > alimentary tract > gill > muscle. Moreover, the results indicate the dominant role of the digestive organs of these invertebrates in controlling absorption and elimination of 210Po.  相似文献   

20.
Concentration of radionuclides 210Pb and 7Be, having half lives of 22.3 years and 53.29 days, respectively, in the surface air samples of Islamabad (33.38° N, 73.10° E and Altitude ∼536 m asl.) are measured. The non-destructive technique of gamma-spectrometry, with a high purity germanium HPGe detector, was employed for the analysis of all samples. The annual average concentrations of 210Pb and 7Be in the surface air samples were determined as 0.284 ± 0.15 and 3.171 ± 1.14 mBq m−3, respectively. Our results have shown a seasonal variation of the concentration of 7Be in air samples with high values for the spring season. High concentrations for 210Pb are obtained when air masses originate from plain areas of Pothohar region, located in the South-West, West and North West of Islamabad. Our values of concentrations show a nice agreement with the relevant reported results.  相似文献   

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