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1.
Naturally Occurring Radioactive Materials (NORM) are present in the environment and can be concentrated by technical activities, particularly those involving natural resources. These NORM deposits are highly stable and very insoluble under environmental conditions at the earth's surface. However reducing or oxidant conditions or pH changes may enable a fraction of naturally occurring radionuclides to eventually be released to the environment. In this paper the analytical methods to determine the chemical and radiochemical composition of a solid waste generated in an acid phosphoric production plant was shown. The sample, analysed by gamma spectrometry and radiochemical methods, contained 210Pb and 210Po and a high activity concentration of uranium isotopes but it shows a very low quantity of 226Ra. Also a sequential extraction method consisting of five operationally-defined fractions was used to evaluate the leachability of uranium isotopes, 210Pb and 210Po. The average leaching potential observed in the sample is 97.6% for 238U, 93.2% for 210Pb and 82.4% for 210Po. Moreover the results show that 210Pb and 210Po are leachable under only extreme conditions, whereas uranium is very more soluble. 相似文献
2.
A determination procedure has been developed for 210Bi and 210Po in environmental samples and was applied for pine needles. Bismuth-210 and 210Po separated from the parent nuclide 210Pb as BiOCl precipitate were extracted simultaneously by TOPO/toluene containing PPO and POPOP. The separation of 210Bi and 210Po from 210Pb was almost satisfactory. The activity of 210Bi+ 210Po in the TOPO/toluene was measured periodically by liquid scintillation counting for about 20 days after separation. The time course of the decreasing pattern of the activity was determined by the initial activity ratio 210Po/ 210Bi. The decreasing pattern of the activity was compared with theoretical patterns, and best estimates for 210Po and 210Bi were obtained by non-linear least-squares fitting. The activities of 210Bi and 210Po were determined for one-year and two-year old pine needles fro the same pine tree, and weathering half-time and deposition rate of these nuclides was discussed. 相似文献
3.
Transfer of 210Pb and 210Po from an uranium mine and mill to the environment was studied by measuring their concentrations in different stages of uranium extraction technology, in waste products from the mill and in environmental waters. A slightly modified radiochemical method was used for 210Po and 210Pb determination. 相似文献
4.
A method for 210Po and 210Pb determination in water samples is described. The nuclides are concentrated, in presence of added 208Po and lead carrier, by evaporation. Then the polonium is plated electroless from the acidic solution on a copper planchet and measured by alpha spectrometry. 210Pb separation from the other isotopes is based on the solutility of PbSO 4 in citrate. 210Pb content is determined by measuring the activity of its daughter 210Bi. The critical steps in the isolation of lead have been examined and discussed. 相似文献
5.
A radiochemical procedure is presented for the sequential determination of uranium isotopes, thorium isotopes, and 210Pb in coal and coal ash. This procedure consists of dry ashing the sample, a nitric—hydrofluoric acid dissolution, removal
of iron with ether extractions, and separation of the elements of interest by anion exchange chromatography. Uranium and thorium
isotopes are measured by alpha spectrometry, while 210Pb is measured by beta counting its daugther activity, 210Bi. For 10 g coal samples and 1 g ash samples, the chemical yields for the radioactivities measured were 70–80%, and the relative
standard deviations for replicate analyses were generally less than 9%. The deviations of the means from the reference values
were within the combined errors of each and were usually less than ±5%. Minimum detectable activities were about 0.02 pCi
for uranium and thorium isotopes and 0.2 pCi for 210Pb. 相似文献
6.
Activity concentrations of radionuclides, 7Be, 210Pb and 210Po, in precipitation (rain, throughfall and stemflow), wood and soil were determined by using gamma-ray and alpha-ray spectrometry
to estimate the migration behavior of these radionuclides in the forest canopy. The activity ratios between output and input
precipitations for the forest canopy were 0.53 of 7Be, 0.79 of 210Pb and 1.5 of 210Po for Pasania edulis forest. A dynamic model of the transport and fate of radionuclides in the forest ecosystem was constructed.
Mean residence times of radionuclides were 56 days for 7Be, 765 days for 210Pb and 653 days for 210Po for Pasania edulis forest. 相似文献
7.
Mathematical equations governing the ratio of 210Bi/ 210Pb and 210Po/ 210Pb activities are used to explain the ingrowth of 210Bi and 210Po in environmental samples during post collection. Procedures are described for radiochemical separation of 210Pb, 210Bi, and 210Po in a state of radioactive disequilibrium and quantification by alpha- and beta-counting. Also, the special case is considered where 210Bi is in equilibrium with 210Pb, but both are in disequilibrium with 210Po. In this case, the activities of both 210Pb and 210Po are computed by measuring 210Po activity twice, using alpha-counting. 相似文献
8.
A method for speciation and determination of 210Pb and 210Po in soil samples was developed. The speciation was carried out by fractionating the soil samples into five fractions which are water soluble or exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter and bound to residue. After mineralisation, 10% solution of each fraction was used to spontaneously deposit polonium on a silver disk at 85-90 °C and pH 1.5, and 210Po was measured by α-spectrometry; the remain solution was used to separate lead by anion-exchange resin and purified by precipitation as PbS and PbSO 4, and 210Pb was determined by a low background β-counter. The IAEA-327 reference material (soil) was studied for 210Pb and 210Po speciation. The results show that: (1) the average yields are 88.7 ± 6.4% for 210Pb and 93.8 ± 8.2% for 210Po; (2) if compared to the total 210Pb activity in the sample, 210Pb fractions are 0.95% in exchangeable form, 10.6% bound to carbonates, 14.3% bound to Fe-Mn oxides, 7.0% bound to organic matter and 67.2% bound to residue or acid soluble, and the corresponding values for 210Po are 0.17%, 0.97%, 21.0%, 0.47% and 77.4%, respectively; and (3) the obtained 210Pb concentration is in good agreement with the recommended value given by the IAEA. 相似文献
9.
To determine the levels of 210Pb and 210Po in human tissues of people in Japan, various tissue samples were obtained at autopsy from the cadavers of 22 oncologic cases, mainly in Niigata Prefecture in northern Japan, from 1986 to 1988.Wet ashing, followed by electrochemical deposition and alpha spectrometry were used to separate and determine the 210Pb and 210Po present. Among the tissues analyzed, the highest concentrations of 210Pb and 210Po were observed in bone (sternum), liver, and kidneys. The total body burden of 210Pb and 210Po was found to be approximately 427 pCi and 514 pCi, respectively. This estimated 210Po value did not differ significantly from values found in populations in the U.S.A. and European countries. 相似文献
10.
This research describes methods for the sequential determination of 210Pb and 210Po activity concentrations in Ca-rich ash samples collected from oil shale-fired power plants in Estonia. The procedure involves digestion of Ca-rich ash samples in a microwave digestion system, radiochemical separation of 210Pb and 210Po and their measurements. All samples, blanks and standards were measured by liquid scintillation counting (Quantulus 1220). The method was tested using IAEA (International Atomic Energy Agency) RGU-1 and IAEA-444 reference materials. Spectral calibration/peak identification which included the optimization of α/β discrimination system (pulse shape analyser), and recovery have been made by 209Po and 210Pb standard solutions. 相似文献
11.
A scheme of fractionation of 210Pb, 210Bi, 210Po forms present in air aerosols based on the combination of methods of radiochemical analysis and radiometric deteemination with leaching by different agents has been developed. The ratio between the 210Pb, 210Bi, 210Po present in the aerosol samples was determined experimentally. Carbonate of 210Pb, and 210Po and 210Bi forms connected with oxides prevai in the aerosol component of atmospheric air. 相似文献
12.
Using as eluent a sequence of 3M HCl, 12M HCl, and 8M HNO 3, a mixture of 210Pb, 210Bi, and 210Po may be clearly separated on a column of Dowex 1×2−100 anion exchange resin. A Cherenkov count in H 2O and the variation in count rate with time confirm that the nuclides emerge in the order 210Pb→ 210Bi→ 210Po. If 12M HCl is replaced by 1.5M H 2SO 4/2.3 M Na 2SO 4, a clean separation also results, but recovery of 210Po becomes considerably more difficult. All three nuclides are readily detectable by liquid scintillation counting, with the
efficiency for 210Pb in the 60–70% range. The Cherenkov aqueous counting efficiency for 210Bi is ∼14–15%. 相似文献
13.
Alpha-counting of filters used to sample large volumes of air provides a convenient way of determining atmospheric concentrations of 210Pb. Following decay of short-lived 222Rn and 220Rn progeny, alpha activity of the filters increases as 210Pb decays to 210Po. After transient equilibrium is reached at about 3 y, alpha activity diminishes with the 22.3 y halflife of 210Pb. The degree of equilibrium between 210Pb and 210Po can be calculated subsequent to sampling, and the average concentration of 210Pb in the air during the sampling period can be computed. Contributions to the total 210Pb from ambient short-lived radon progeny are small, typically 2–4%. Using high volume air samplers with collection rates of 1.1–1.7 m 3/min for 24 h periods, and using counting times of 2 h for 20 cm 2 filter sections, we measured alpha counts ranging from 0.0100±0.0050 to 0.200±0.0200 dps. Periodic measurements on 100 of these filters over a 4 y period yielded mean 210Pb levels with standard deviations less than ±15%. The method requires minimal sample preparation and can be used to determine past atmospheric 210Pb concentrations on filters stored for up to 20 y and more. 相似文献
14.
The concentrations of 210Po and 210Pb were determined in about 30 species of marine organisms collected mainly from the north-easterm region of Japan to know the levels and distributions of these radionuclides and to estimate their intake levels from marine foods. 210Po and 210Pb showed a wide range of concentration in species: 0.6–26 and 0.04–0.54 Bq/kg (wet wt) in fishes, 0.5–220 and 0.2–43 Bq/kg (wet wt) in molluscs, echinoderms and chordatas, and 2.8–4.3 and 0.4–1.3 Bq/kg (wet wt) in algae, respectively. Higher accumulation of 210Po relative to 210Pb was found in all of the samples analyzed. The intake levels of 210Po and 210Pb by marine foods consumption were roughly estimated to be 0.48–0.69 and 0.022–0.042 Bq/d per person, respectively, on the basis of the statistical data on the consumption of seafood and/or production rates of marine foods. 相似文献
16.
A convenient non-destructive method for the determination of low level 210Pb and 226Ra with an ordinary high-purity Ge-detector is presented. The ordinary Ge-detectors used in this work were available to measure 46.5 keV -rays of 210Pb. These detectors were also useful for the non-destructive analysis of low-level 226Ra in lime-stone and calcium chemicals when a stream of nitrogen gas was maintained around the detectors. By this method, measurements could be carried out not only for 210Pb and 226Ra but also for other -emitting radionuclides simultaneously, using the same detector. The detection limits of about 1 Bq per sample for 210Pb and about 0.05 Bq per sample for 226Ra, respectively, were estimated, when the samples were counted for 1–2 days. 相似文献
17.
A method is described for the determination of 228Th, 230Th, and 232Th in environmental samples from uranium mining and milling operations. The analytical procedure is based on the direct determination
of 228Th in the sample by high resolution γ-spectrometry followed by extraction and purification of the thorium fraction using high
molecular weight amines and an anion-exchange technique, respectively, prior to α-spectrometry to determine isotopic ratios.
The lowest level of detection for each thorium isotope is 0.01 pCi/g for solid samples and 20 pCi/l for aqueous samples. Replicate
analyses of a typical mine waste stream gave a standard deviation of ±3% for 228Th. Standard deviations of the 230Th and 232Th increased to ±11% apparently due to traces of 210Po interfering in the α-spectrometry. 相似文献
18.
A microwave acid digestion method prior to the determination of 210Pb and 210Po in sediments and soils is described. It involves an acid (HNO 3, HCl, HF and H 3BO 3 mixture) digestion with microwave heating in closed vessels at high pressures. Analyses carried out for various reference
materials showed that the results were statistically equal to certified values and reproducibility was also assured. The advantage
of the microwave technique compared to the traditional leaching procedures is that the solid materials are completely dissolved
and, therefore, ca. 100% efficiency is achieved in the extraction of 210Po and 210Pb, even though a fraction is associated to the silica net. Moreover, time of analysis is drastically reduced, as are the
risks associated to vapour inhalation and material corrosion. 相似文献
19.
210Pb and 210Po in human hair have been measured to serve as an aid in order to estimate the dietary intake and body burden of these radionuclides of Japanese. The 210Po concentrations found in 83 hair samples were ranging from 4.0 to 59.3 mBq/g with a mean (median) value of 18.2±12.2 (14.9) mBq/g as compared to the 210Pb concentrations from 0.7 to 6.5 mBq/g with a mean (median) value of 2.3±1.1 (2.0) mBq/g. The 210Po/ 210Pb activity ratios (mean: 8.7±5.1, median: 7.1) were surprisingly higher compared with the available literature value of about 2. The high concentration of 210Po in human hair of Japanese may be due to the ingestion of animal protein mainly in the form of seafood. 相似文献
20.
In order to evaluate the possible radiological impact to the local public and environment from a phosphogypsum stockpile, 210Po and 210Pb concentrations in river water, lagoon water, suspended matter, superficial sediment, algae and bivalves samples collected in Venice lagoon area have been investigated. The results show that the mean 210Po and 210Pb concentrations in river water are 1.42±0.36 mBq .l -1 and 1.46±0.39 mBq .l -1 with a mean 210Po/ 210Pb ratio of 0.98±0.17 and about 60% of them are associated with the particulate; 210Po and 210Pb contribution from the phosphogypsum stockpile to the river water is negligible. Higher 210Po (2.61-5.67 mBq .l -1) and 210Pb (1.31-3.62 mBq .l -1) concentrations in the lagoon waters have been observed if compared with the literature values. About 60% of 210Po and 210Pb are found in the soluble form with a mean 210Po/ 210Pb ratio of 1.79±1.47. 210Po and 210Pb concentrations in 28 out 37 sediment samples ranged from 26 to 45 Bq .kg -1 (dry weight), only 9 sediments with 210Po and 210Pb concentrations greater than 45 Bq .kg -1 are found and most of them are located 1-4 km near the phosphogypsum stockpile. The elevated 210Po and 210Pb concentrations in the sediments may be due to the contamination from the phosphogypsum stockpile. The mean 210Po/ 210Pb ratio (0.986±0.049) in the sediments shows that 210Po and 210Pb exist in nearly secular equilibrium. 210Po and 210Pb concentrations in algae vary with different species. The mean 210Po and 210Pb concentrations in Gracilaria compress and Ulva laetevirens which show a similar behavior, are 3.18±1.23 Bq .kg -1 and 2.42±1.26 Bq .kg -1 (fresh weight), respectively, with a mean 210Po/ 210Pb ratio of 1.45±0.34. The mean concentration factors with respect to the filtered water are 1096±424 for 210Po and 1299±680 for 210Pb. The mean 210Po and 210Pb concentrations in the soft part of Mytilus edulis are 23.2±9.7 Bq .kg -1 and 0.537±0.203 Bq .kg -1 (fresh weight), respectively, with a mean 210Po/ 210Pb ratio of 43.6±10.0. The mean concentration factors with respect to the filtered water are 8006±3351 for 210Po and 290±109 for 210Pb, showing a very high accumulation effect for 210Po. The accumulation behaviors of Cerastoderma glaucum and Tapes philippinarum for 210Po are similar to Mytilus edulis, but that for 210Pb seems less effective, corresponding to a relatively higher 210Po/ 210Pb ratio. The estimated committed effective doses from 210Po for the individual local public through ingestion of bivalves are in the range of 0.050-0.231 mSv .y -1. 相似文献
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