Determination of lead-210 in bottom sediments via bismuth-210

Determination of lead-210 in bottom sediments is applied for evaluation of sedimentation rates and sediments ages by concentration profiles of disequilibrated lead-210 from atmospheric sources. Advences in low level liquid scintillation spectrometry (LS) fitted for natural radioactivity measurements, permit to combine the possibility of immediate bismuth-210 separation with its radioactivity registration using LS spectrometer Quantulus (LKB-1220, Wallak, Finland). The method was tested on bottom sediment samples from Baltic Sea shelf, collected during the 76th cruise of RV Academician S. Vavilov. The proposed method of separation, purification and chemical yield determination is characterized by simplicity, rapidity and may be used in routine analysis.     

A simultaneous determination of lead-210 and polonium-210 in sea water

A new radiochemical procedure is described for the determination of lead-210 and polonium-210 in sea water. These nuclides are concentrated by coprecipitation with calcium carbonate from a sea water sample of large volume and then separated from calcium by formation of the hydroxides. Polonium-210 is deposited spontaneously onto a silver disc and determined by an α-counting technique. Lead-210 is also determined by counting the activity of polonium-210 produced during storage for 3 months.     

Radiochemical determination of lead-210 in environmental water samples using Cerenkov counting

A relatively simple method has been developed for the determination of²¹⁰Pb via its -emitting daughter,²¹⁰Bi. Lead-210 was separated from interfering elements as lead sulphate. The precipitate was dissolved in an alkaline solution of EDTA and the Cerenkov signal produced by the build-up of²¹⁰Bi was counted 30 days after storage using tritium channel of a liquid scintillation counter. Cerenkov counting efficiency was found to be approximately 20%. A lower limit of detection of 5.1 mBq/1 (based on 3 of the background with 500 minute counting time) was achieved. Chemical recoveries in the range of 70–100% were determined gravimetrically. Interference associated with currently used methods is avoided. Data from from both spiked samples and natural samples are presented.     

The determination of low levels of polonium-210 in environmental materials

A method is presented for the determination of polonium-210 at very low levels in the presence of many different ions. Essentially quantitative recoveries were obtained in 60 min by deposition on to a silver plate in a special holder from 50 ml solution at 85–90° with sodium citrate present.     

Activity concentration of polonium-210 and lead-210 in tobacco products and annual committed effective dose to tobacco users in Tiruchirappalli District (Tamil Nadu,India)

The present study has carried out with an objective of determining the activity concentrations of two radionuclides namely polonium-210 (²¹⁰Po) and lead-210 (²¹⁰Pb) in smoke tobacco products (cigarette, bidi and cigar) and smokeless tobacco products (chewing tobacco and snuff) consumed in Tiruchirappalli District, Tamil Nadu (India) and their annual committed effective dose to tobacco consumers. The concentration of ²¹⁰Po was always higher than that of ²¹⁰Pb in all the analyzed tobacco products. It also revealed that 79% of Annual committed effective dose comes from ²¹⁰Po and about 21% from ²¹⁰Pb. Maximum concentration (13.2 mBq g^?1) of ²¹⁰Po recorded in cigarette and lowest concentration was observed in snuff (6.4 mBq g^?1). The highest mean committed effective dose of ²¹⁰Po and ²¹⁰Pb in various tobacco products were found in cigarette followed by bidi, cigar, chewing tobacco and snuff. The study revealed that the tobacco products available in Tiruchirappalli District contain a relatively lower concentration of radionuclides when compared to other regional studies. Since this kind of study in India is fragmentary, the present study has generated a base data for the first time for entire Tiruchirappalli District.

     

Improved technique for recovery and measurement of polonium-210 from environmental materials

Polonium-210 obtained in acidic solution by digestion of sediment or tissue samples is efficiently plated onto one side of a silver disc for measurement of α-activity. Optimum conditions for solutions obtained from environmental samples are pH 1.5–2 in the presence of citrate and ascorbic acid, with the solution at 80°C and the silver disc rotated at 100–150 radian s^?1. Observed recoveries using a polonium-208 tracer are 97.5 ± 2.5% for sediments and 99.3 ± 1.3% for tissues.     

Determination of 210Pb in environmental samples

Summary Measurement of ²¹⁰Pb has gained a highly scientific attention due to its wide range of environmental applications. The most commonly used analytical techniques: gamma-spectrometry, beta-counting and alpha-spectrometry were used to measure environmental samples (geological, soil, sediment). Our paper is aiming at comparing the capabilities and limits of application of these three different analytical techniques for ²¹⁰Pb measurement in various environmental samples. In addition, analytical data of ²¹⁰Pb measurements with the three different techniques (gamma-spectrometry, beta-counting and alpha-spectrometry) are discussed to highlight the degree of comparability and the most probable sources of discrepancies and errors. Based on the demanded investigation, one analytical technique will be chosen for routine analysis, while the other techniques, if they are available, could be used for analytical quality assurance measures. It was essential to compare the analytical efficacy of each technique, which differ concerning the detection limit (MDA), sensitivity, analytical effort, the duration of analysis and waiting time before analysis.     

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%.     

Determination of 210Pb and 210Po in mineral and biological environmental samples

The paper deals with the determination of ²¹⁰ Pb and ²¹⁰ Po in mineral and biological environmental samples. ²¹⁰ Pb and ²¹⁰ Po were preconcentrated from filtered water samples by coprecipitation with iron(III) hydroxide at pH 9-10 using ammonia solution and the precipitate was dissolved with HCl and mineralized with H2O2. ²¹⁰ Pb and ²¹⁰ Po in soil or sediment, algae and mussel samples were sequentially leached out at 250 °C with HNO₃ +HF, HClO₄ and HCl. About 10-20% of the leaching solution was used for ²¹⁰ Po determination which was carried out at 85-90 °C for 4 hours by suspending a silver disk in a HCl solution of pH 1.5 and containing some hydroxylamine hydrochloride and sodium citrate. No preliminary separation was required and essentially quantitative recoveries were obtained by using standard ²⁰⁹ Po tracer. The remains of the leaching solution were used for the determination of ²¹⁰ Pb which was first separated by a BIO-RAD-AG 1-X4 resin column, then purified by using Na2S to precipitate as PbS and finally precipitated as PbSO₄ for source preparation. Starting from 3 g sediment (30 liter water), the lower limits of detection of the method were 0.73 Bq.kg^-1 (0.078 mBq.l^-1 ) for ²¹⁰ Pb and 0.25 Bq.kg^-1 (0.016 mBq.l^-1 ) for ²¹⁰ Po. The procedure has been checked with two certified samples supplied by the International Atomic Energy Agency (IAEA) and reliable results were obtained. Most of the analyzed samples were sediments, showing average yields of 84.2±5.2% for ²¹⁰ Pb and 96.4±4.1% for ²¹⁰ Po.     

Determination of polonium-210 in cigarettes from Syria

Various Syrian cigarettes /Hamra long filter, Oreidt, Granata, Palmyra, Hamra short filter/ were analyzed for their²¹⁰Po content.²¹⁰Po was precipitated on a silver plate after chemical separation and measured by -spectroscopy. The concentration values found for²¹⁰Po ranged between 0.02 and 0.08 pCi g^–1.     

Validation of the lead-210 dating method

²¹⁰Pb datings of sediments from open marine area, salt marsh area and estuary and of peat from a raised bog have been performed. Different methods of calculation are used. Net accumulation rates in the range of 0.0078–0.44 g·cm⁻²·year⁻¹ were obtained. The results are in good agreement with those obtained by other methods.     

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.     

Atmospheric residence times of strontium-90 and lead-210

The concentrations of⁸⁹Sr,⁹⁰Sr,²¹⁰Pb and²¹⁰Po were measured in a series of rain samples collected at Fayetteville (36°N, 94°W), Arkansas, after the 14th Chinese test of March 18, 1972, which occurred at Lop Nor (40°N, 90°E), China. Approximately concordant tropospheric residence times were obtained from the⁸⁹Sr/⁹⁰Sr and²¹⁰Po/²¹⁰Pb ratios in rain. The⁸⁹Sr/⁹⁰Sr ratios were also measured for the rain samples collected at Tokyo (36°N, 140°E), Japan, and at Ankara (40°N, 33°E), Turkey.     

Effects of polonium-210 on determination of atmospheric gross alpha-radioactivity

Ingrowth and decay of²¹⁰Po on air filters used for gross alpha-determination can lead to errors in estimation of long-lived airborne radioactivity. Interferences are present to some degree in all samples and change with time, making the gross alpha-technique quantitatively invalid. However, since the degree of equilibrium between²¹⁰Po and its parent²¹⁰Pb can be calculated at any time after filter collection, it should be possible to use the gross alpha-method to estimate past atmospheric concentrations of²¹⁰Pb. Measurements on filters after elapsed times of up to 15 years show that such determinations are feasible.     

The calculation of lead-210 dates for McKay Lake sediments

Lead-210 dates are assigned to a sediment core retrieved from McKay Lake, Ottawa, Canada. Sediment mixing is found to have little, but discernible, influence on the age/depth profile. Consideration of mixing yields lower estimates of the derived ages, in agreement with the prediction based on a mathematical model. The inferred dates support the previous assignments based on Ambrosia horizon and the known occurrence of a catastrophic event. The procedures used in the calculation of the age profiles are fully described.     

An example of situational radiological analysis: An incident with polonium-210

Data on the nuclear physical, chemical, and radiobiological characteristics of polonium-210 are generalized. The characteristics of the radionuclide intake by the human body, its transport, and deposition in different organs are considered. The formation of the α radiation dose has been analyzed using RBE = 3 for deterministic effects in terms of formal dosimetry of incorporated radionuclides. Radiological analysis of a case of polonium-210 poisoning in London has been performed. The activity of the radionuclide at which it is lethal upon a single peroral administration has been evaluated (0.012–0.36 GBq), and the formal possibility of detecting a carrier of polonium-210 on the basis of data on excreta and γ radiation measured using a whole-body counter (WBC).