Determination of 210Po in Reagent Samples by Alpha-Ray Spectrometry Using Extraction Chromatographic Resin

The determination of ²¹⁰Po in phosphoric acid reagent by alpha-ray spectrometry using extraction chromatographic resin is presented. The decontamination factors of interference elements were measured. It was observed that HCl, HNO₃, ascorbic acid, thioacetamide and Cu were free from ²¹⁰Po but Pb contain small amounts of ²¹⁰Po. ²¹⁰Po in phosphoric acid samples was ranged from <8 to 2.4 Bq/l. The detection limit of ²¹⁰Po in 50 ml of phosphoric acid is 8 mBq/l with a counting time of 1 day undercounting efficiency of 30%.     

Measurements of210Pb and210Po in Japanese human hair

²¹⁰Pb and²¹⁰Po 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. The²¹⁰Po 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 the²¹⁰Pb concentrations from 0.7 to 6.5 mBq/g with a mean (median) value of 2.3±1.1 (2.0) mBq/g. The²¹⁰Po/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 of²¹⁰Po in human hair of Japanese may be due to the ingestion of animal protein mainly in the form of seafood.     

Effective doses due to intake of radiotoxic radionuclides 226Ra, 210Po and 210Pb through drinking water of coastal Karnataka

The concentrations of ²²⁶Ra, ²¹⁰Po and ²¹⁰Pb have been measured, by high efficiency 5″ × 5″ NaI(Tl) gamma ray spectrometer and chemical deposition method, in surface water samples from major rivers Kali, Sharavathi and Netravathi of coastal Karnataka. Measurements of ²²⁶Ra, ²¹⁰Po and ²¹⁰Pb in surface water from these rivers are important because the river water is main source of potable water in this region due to inadequate supply of treated water. The mean activity of ²²⁶Ra, ²¹⁰Po and ²¹⁰Pb in the surface water of the river Kali was found to be 5.13 mBq L⁻¹, 1.28 and 1.37 Bq L⁻¹, for Sharavathi River the mean activity was found to be 3.37 mBq L⁻¹, 1.30 and 1.44 Bq L⁻¹. In Netravathi River the mean activity of ²²⁶Ra, ²¹⁰Po and ²¹⁰Pb was found to be 3.30 mBq L⁻¹, 1.00 and 1.20 Bq L⁻¹. From the measured concentration of ²²⁶Ra, ²¹⁰Po and ²¹⁰Pb, the Effective dose to the population of the region was computed. The results of these systematic studies are presented and discussed in the paper.     

Atmospheric deposition of 210Po and 210Pb in Malaysian waters during haze events

Biogenic burning as forest fire phenomena occurring from April to August each year in the Sumatra and Borneo islands are major sources of biogenic uranium–thorium decay series in marine systems. 30 samples were collected during the Ekspedisi Pelayaran Saintifik Perdana 2009 cruise (EPSP 2009 cruise) between 12th June and 1st August 2009 from the Straits of Malacca to the Sulu and Sulawesi Seas to study the effect of haze and the monsoon season on the deposition rate of ²¹⁰Po and ²¹⁰Pb in Malaysian waters. All samples were spiked with 1 ml of lead [Pb(NO₃)₂; 25 mg ml^?1] and 0.05 ml of Polonium-209 tracer (26.08 dpm ml^?1). ²¹⁰Po activity was determined by auto plating onto silver foil and counting using an alpha spectrometry system (Canberra model Alpha Analyst with a silicon-surface barrier detector). Lead that was collected via electrodeposition, formed lead sulphate (PbSO₄) precipitation. This precipitate was wrapped onto plastic discs and counted for ²¹⁰Pb beta activity using a gross alpha–beta counting system (Tennelec model LB-5100 low background gas-flowing anti-coincidence alpha/beta counter) after 1 month to allow bismuth ingrowths. The range of ²¹⁰Po activities varied between 51.08 ± 15.1 and 742.08 ± 220.34 Bq/kg, whereas the activity of ²¹⁰Pb ranged from 31.10 ± 4.20 to 880.23 ± 123.86 Bq/kg and ²¹⁰Po/²¹⁰Pb ratio value varied between sampling stations from 0.19 to 13.77. The contents of ²¹⁰Po were also statistically positively correlated with the amount of total suspended particulate especially those recorded during heavy haze period events.     

Determination of 210Po and uranium in high salinity water samples

A method for the determination of uranium and ²¹⁰Po in high salinity water samples has been elaborated. Both radionuclides are preconcentrated from 0.5 dm³ saline media by co-precipitation with hydrated manganese dioxide, followed by dissolution of the precipitate in 200 mL of 1 M HCl. Uranium isotopes ²³⁵U and ²³⁸U can be directly determined by ICP MS method with a detection limit of 0.01 ppb for ²³⁸U. Prior to a selective determination of ²¹⁰Po, the majority of other naturally occurring α-emitting radionuclides (uranium, thorium and protactinium) can be stripped from this solution by their extraction with a 50% solution of HDEHP in toluene. Finally, ²¹⁰Po is simply separated by direct transfer to an extractive scintillator containing 5% of trioctylphosphine oxide in Ultima Gold F cocktail and determined by an α/β separation liquid scintillation technique with detection limit below 0.1 mBq/dm³.     

Polonium-210 and lead-210 in marine organisms: Intake levels for Japanese

The concentrations of²¹⁰Po and²¹⁰Pb 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 and²¹⁰Pb 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 of²¹⁰Po relative to²¹⁰Pb was found in all of the samples analyzed. The intake levels of²¹⁰Po and²¹⁰Pb 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.     

210Pb and210Po analysis in sediments and soils by microwave acid digestion

A microwave acid digestion method prior to the determination of²¹⁰Pb and²¹⁰Po in sediments and soils is described. It involves an acid (HNO₃, HCl, HF and H₃BO₃ 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 of²¹⁰Po and²¹⁰Pb, 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.     

Measurements of <Superscript>210</Superscript>Po and <Superscript>210</Superscript>Pb in total diet samples: Estimate of dietary intakes of <Superscript>210</Superscript>Po and <Superscript>210</Superscript>Pb for Japanese

To estimate the dietary intakes of ²¹⁰Pb and ²¹⁰Po for the Japanese adults and their annual effective doses, ²¹⁰Pb and ²¹⁰Po were measured for 240 daily diet samples collected at two locations of Ishikawa Prefecture in Japan over three years by duplicate portion studies. No appreciable differences in intake rates of ²¹⁰Pb and ²¹⁰Po and their ²¹⁰Po/²¹⁰Pb ratios were seen among the years in each district, and between the two districts. The intake rates evaluated using 240 diet samples were 0.20 Bq/d/p for ²¹⁰Pb and 0.61 Bq/d/p for ²¹⁰Po as a median, respectively. Annual effective doses of ²¹⁰Pb and ²¹⁰Po for Japanese adults were estimated to be 0.050 and 0.053 mSv/y, respectively.     

Levels of 210Po in blood, urine and hair of some Saudi smokers

Summary The activity concentration of ²¹⁰Po was investigated in blood, urine and hair samples of some non-smokers, cigarette-smokers (tobacco-smokers) and shisha smokers (jurak- and mehassel-smokers). The results indicated that ²¹⁰Po concentration was variable within each group of volunteers and fluctuated within certain range. The activity concentration in the blood of the non-smokers, the cigarette-smokers and the shisha-smokers was found to be ranged from 7-77, 17-86 and 22-92 mBq/l, respectively. These values were ranged from 1.5-10, 3.3-15.9 and 2.2-19.6 mBq/l in the urine samples of the same volunteers, respectively. The ²¹⁰Po activity concentration in their hair was found to be ranged from 1.9-4.8, 1.9-6.4 and 2-6.5 Bq/kg, respectively. The obtained results are discussed and some conclusions, based upon the average values, were drawn.     

210Pb and 210Po radionuclides in the urban air of Lodz, Poland

The concentration of two important radionuclides: ²¹⁰Pb and its decay product ²¹⁰Po in the urban air in the center of the Polish city of Lodz were measured during the winter and spring seasons of 2008–2009. Urban airborne particulate matter was collected using two methods: an Anderson 9-stage impactor, and a high-volume aerosol sampler type ASS500 working in the frames of the aerosol sampling network in Poland, established for radionuclide monitoring. Average concentrations for 10 months sampling period for ²¹⁰Pb and ²¹⁰Po were 0.556 and 0.067 mBq/m³, respectively. However remarkable fluctuations due to meteorological condition were observed: from 0.010 to 0.431 mBq/m³ for ²¹⁰Po and from 0.167 to 1.847 mBq/m³ for ²¹⁰Pb. The highest concentrations, almost 60% of the total activities, of both radionuclides were found in the first two fine aerosol fractions with particle diameters below 0.36 μm. The aerosol residence times calculated from the ²¹⁰Po/²¹⁰Pb ratio ranged from 7 to 120 days.     

The role of Cherenkov and liquid scintilation counting in evaluating the anion-exchange separation of210Pb−210Bi−210Po

Using as eluent a sequence of 3M HCl, 12M HCl, and 8M HNO₃, a mixture of²¹⁰Pb,²¹⁰Bi, and²¹⁰Po may be clearly separated on a column of Dowex 1×2−100 anion exchange resin. A Cherenkov count in H₂O and the variation in count rate with time confirm that the nuclides emerge in the order²¹⁰Pb→²¹⁰Bi→²¹⁰Po. If 12M HCl is replaced by 1.5M H₂SO₄/2.3 M Na₂SO₄, a clean separation also results, but recovery of²¹⁰Po becomes considerably more difficult. All three nuclides are readily detectable by liquid scintillation counting, with the efficiency for²¹⁰Pb in the 60–70% range. The Cherenkov aqueous counting efficiency for²¹⁰Bi is ∼14–15%.     

Radiochemical determination of210Po and210Pb in water

A method for²¹⁰Po and²¹⁰Pb determination in water samples is described. The nuclides are concentrated, in presence of added²⁰⁸Po 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 PbSO₄ in citrate.²¹⁰Pb content is determined by measuring the activity of its daughter²¹⁰Bi. The critical steps in the isolation of lead have been examined and discussed.     

Presence and forms of210Pb,210Bi and210Po in ground level aerosols

A scheme of fractionation of²¹⁰Pb,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 the²¹⁰Pb,²¹⁰Bi,²¹⁰Po present in the aerosol samples was determined experimentally. Carbonate of²¹⁰Pb, and²¹⁰Po and²¹⁰Bi forms connected with oxides prevai in the aerosol component of atmospheric air.     

Simultaneous determination of210Bi and210Po on pine needles by solvent extraction and liquid scintillation counting

A determination procedure has been developed for²¹⁰Bi and²¹⁰Po in environmental samples and was applied for pine needles. Bismuth-210 and²¹⁰Po separated from the parent nuclide²¹⁰Pb as BiOCl precipitate were extracted simultaneously by TOPO/toluene containing PPO and POPOP. The separation of²¹⁰Bi and²¹⁰Po from²¹⁰Pb was almost satisfactory. The activity of²¹⁰Bi+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 ratio²¹⁰Po/²¹⁰Bi. The decreasing pattern of the activity was compared with theoretical patterns, and best estimates for²¹⁰Po and²¹⁰Bi were obtained by non-linear least-squares fitting. The activities of²¹⁰Bi and²¹⁰Po 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.     

210Pb and 210Po concentrations in the Venice lagoon ecosystem (Italy) and the potential radiological impact to the local public and environment

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.     

Determination of 210Pb, 210Bi and 210Po in natural drinking water

A new method for the radioanalytical determination of the ²²²Rn progenies ²¹⁰Pb, ²¹⁰Bi and ²¹⁰Powill be presented, which has been improved for analyses of water samples fromdifferent regions in Austria. 1–2 liter samples were taken in polyethylenebottles prefilled with conc. HNO₃ to obtain 0.2M acidic solutions,thus avoiding adsorption effects. After adding 1.6 mg of inactive lead carrier,the water sample was evaporated to dryness, converted to the chloride formand dissolved in 1M HCl.     

A rapid method for the separation of 210 Po from 210 Pb by TIOA extraction

A rapid method for the separation of ²¹⁰ Po from ²¹⁰ Pb was developed utilizing extraction of triisooctylamine (TIOA)/xylenein HCl+H₂O₂ medium. Polonium in the form of PoCl ₆ ²– was extracted into TIOA phase and ²¹⁰Pb remains in the aqueous phase. Lead-²¹⁰ was determined by -countingof its granddaughter, ²¹⁰ Po ingrown from ²¹⁰ Pb forsome period of time. Distribution of ²¹⁰ Po and ²¹⁰Pb in TIOA and aqueous phases was investigated in various concentrations ofHCl media. Hydrogen peroxide was used to further decompose organic matterand to remove sulfur to prevent its deposition on the silver disc. The improvedprocedure resulted in a good chemical yield (80–95%) and a good á-resolution.     

Alpha and gamma spectrometry for determination of natural and artificial radionuclides in tea, herbal tea and camomile marketed in Italy

Several kinds of tea, camomile and herbal tea were analysed to determine natural and artificial radioactivity. The radionuclides were determined by alpha (²¹⁰Po) and gamma (²²⁸Ac, ²¹⁴Pb, ²¹⁴Bi, ²¹⁰Pb, ⁴⁰K and ¹³⁷Cs) spectrometry. ²²⁸Ac ranged between 0.6 and 9.0 Bq kg⁻¹_dry; ²¹⁰Po between 1.90 and 36.1 Bq kg⁻¹_dry; ²¹⁴Pb and ²¹⁴Bi between 0.7 and 4.9 Bq kg⁻¹_dry; ²¹⁰Pb between < 10.0 and 58.9 Bq kg⁻¹_dry; ⁴⁰K between 463 and 936 Bq kg⁻¹_dry; ¹³⁷Cs between < 0.3 and 2.6 Bq kg⁻¹_dry. The percentage of ²¹⁰Po extraction in infusion was also determined; the arithmetical mean value of percentage of ²¹⁰Po extraction resulted 20.7 ± 7.50.     

Determination of polonium-210 in phosphoric acid

Polonium-210 in phosphoric acid has been recognized as a significant source of alpha contamination of processed Si-wafers for memory devices of computer. In the present work, a convenient method was developed for the determination of trace²¹⁰Po in phosphoric acid of high purity. For the determination,²⁰⁹Po was used as a yield tracer. The present method consists of (1) addition of the tracer to 5 ml aliquot of phosphoric acid sample, (2) pH adjustment (to 2) of the sample solution to make up electrolytic solution, (3) electrodeposition for the simultaneous achievement of Po separation and preparation of counting source on stainless-steel disc, and (4) alpha-ray spectrometry. By the developed method, more than 95% of Po was separated from phosphoric acid sample onto counting disc. The minimum detectable radioactivity of²¹⁰Po in 5 ml of phosphoric acid was about 0.03 mBq by counting the electrodeposited alpha-activity for 10 days under a counting efficiency of ≈30%.     

Evaluation of measurement uncertainty in the determination of 210Pb and 210Po using beta counting and alpha spectrometry

 Measurement uncertainties in the determination of ²¹⁰Pb and ²¹⁰Po in Reference Material IAEA-300 (Baltic Sea Sediment) were evaluated. ²¹⁰Pb and ²¹⁰Po were separated from the matrix using an Sr resin column. The chemical yield of ²¹⁰Pb was determined gravimetrically in PbSO₄ form. Precipitation was followed by beta proportional counting after ²¹⁰Bi ingrowth. ²¹⁰Po was determined by alpha spectrometry after its spontaneous deposition on a Cu planchet. The major source of uncertainty was identified as the statistical counting uncertainty, which was also expected and is almost impossible to reduce without extension of the time required for an analysis. The expanded uncertainties were determined as 7.4% and 12.2% for ²¹⁰Pb and ²¹⁰Po, respectively. Received: 3 September 2002 Accepted: 3 December 2002 Acknowledgement This work was financially supported by Ministry of Education, Science and Sport, Republic of Slovenia (Project group PO-0106–0532). Presented at CERMM-3, Central European Reference Materials and Measurements Conference: The function of reference materials in the measurement process, May 30–June 1, 2002, Rogaška Slatina, Slovenia Correspondence to P. Vreˇcek