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.     

The determination of radium-226 in human bone

A simple procedure is described for preparing 10-g samples of bone ash for measurement of ²²⁶Ra by the ²²²Rn emanation technique. In this case, the radon is measured in 2-litre ion chambers, but scintillation chambers could be used. Coprecipitation of ²²⁶Ra with BaSO₄ gives separation from bulk constituents, and the final precipitate is soluble in a few ml of 30% EDTA. Chemical recovery is measured with ¹³³Ba tracer.     

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.     

The determination of radium-226 and radium-228 in soils and plants,using radium-225 as a yield tracer

Recovery of²²⁶Ra in analysis is determined using²²⁵Ra separated by anion exchange from²²⁹Th and²³³U. Radium is coprecipitated with barium, and purified by ion exchange.²²⁶Ra and²¹⁷At (decay product of²²⁵Ra) are measured by α-spectrometry.²²⁸Ra is determined both by β-counting²²⁸Ac and²²⁵Ac separated from²²⁸Ra and²²⁵Ra, and by α-counting its daughters after the decay of²²⁵Ra. Sources for α-spectrometry are prepared by electrodeposition (molecular plating).     

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.     

Separation and determination of uranium and radium-226 in phosphorites and their industrial derivatives by extraction chromatography

An extraction chromatographic method based on microporous polyethylene (Microthene) supporting tri-n-octylphosphine oxide (TOPO) was used to separate uranium and²²⁶Ra from phosphorites and their industrial derivatives. Uranium was then determined by fluorimetry and by alpha-spectrometry after electroplating, and radium by precipitation as Ba(Ra)SO₄ and alpha counting with a ZnS(Ag) alpha detector. The method was checked by using an IAEA phosphorite sample having a certified uranium concentration. Some phosphorite, phosphoric acid and plaster samples supplied by an Italian industrial plant were analyzed; uranium isotopes always resulted in radioactive secular equilibrium.     

Ultratrace-level radium-226 determination in seawater samples by isotope dilution inductively coupled plasma mass spectrometry

An improved and novel sample preparation method for ²²⁶Ra determination in liquid samples by isotope dilution inductively coupled plasma sector field mass spectrometry using laboratory-prepared ²²⁸Ra tracer has been developed. The procedure involves a selective preconcentration achieved by applying laboratory-prepared MnO₂ resin followed by cation exchange chromatographic separation. In order to completely eliminate possible molecular interferences, medium mass resolution (R = 4,000) combined with chemical separation was found to be a good compromise that enhanced the reliability of the method. The detection limit of 0.084 fg g⁻¹ (3.1 mBq kg⁻¹) achieved is comparable to that of the emanation method or alpha spectrometry and is suitable for low-level environmental measurements. The chemical recovery of the sample preparation method ranged from 72 to 94%. The proposed method enables a rapid, accurate and less labor-intensive approach to routine environmental ²²⁶Ra determination than the radioanalytical techniques conventionally applied.     

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.     

Multielement determination in floor sediments of the Japan Sea by nondestructive photon activation analysis

A nondestructive photon activation analysis with 30 MeV bremsstrahlung has been applied to the multielement determination in the floor sediments in a region of the Japan Sea. The abundances for 5 major and 11 trace elements were measured in several terrigeous and pelagic deposits, discussion being given on the results. Enrichments in certain trace elements, such as Mn, Ni and Co, were observed in the samples of pelagic areas, but to less extent relative to those of the mid-Pacific areas.     

Measurement of lead-210, bismuth-210, and polonium-210 in environmental samples

Mathematical equations governing the ratio of²¹⁰Bi/²¹⁰Pb and²¹⁰Po/²¹⁰Pb activities are used to explain the ingrowth of²¹⁰Bi and²¹⁰Po in environmental samples during post collection. Procedures are described for radiochemical separation of²¹⁰Pb,²¹⁰Bi, and²¹⁰Po in a state of radioactive disequilibrium and quantification by alpha- and beta-counting. Also, the special case is considered where²¹⁰Bi is in equilibrium with²¹⁰Pb, but both are in disequilibrium with²¹⁰Po. In this case, the activities of both²¹⁰Pb and²¹⁰Po are computed by measuring²¹⁰Po activity twice, using alpha-counting.     

Activity concentration of radium-226 in agricultural soils

Both Indian mustard and sunflower were grown in a hydroponic solution treated with different concentration activities of ¹³⁴Cs or with different amounts of copper or with both in order to investigate the interaction between copper and radiocesium. It was found that ¹³⁴Cs activity concentration applied in the nutrient solution exerted more influence on the uptake and translocation of copper by Indian mustard than by sunflower. Indian mustard grown in hydroponic solution containing certain levels of copper and being treated with higher ¹³⁴Cs activity concentration showed higher uptake of copper than sunflower. However, in the case of root copper concentrations, sunflower showed significantly higher copper immobilization by roots than Indian mustard. It was also found that the presence of copper in the hydroponic solution did modify radiocesium uptake by both species. The application of 1 mg/l in the growth medium could greatly increase the uptake of ¹³⁴Cs by both species. With 3 mg/l concentration of copper amended to the solution, the accumulation of ¹³⁴Cs by both species was decreased compared to the 1 mg/l copper treatment. These lines of evidence show that there is stronger interaction between copper and radiocesium in Indian mustard than in sunflower during the root uptake through nutrient solution.     

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.     

Scintillation emanometric determination of radium-226 in waters using a new method of radium preconcentration

A modified method of scintillation emanometry for radium determination is described which uses a simple and effective preconcentration of dissolved radium by coprecipitation with a ternary complex of calcium phosphomolybdate and polyethylene glycol. After dissolution of the voluminous precipitate in an alkaline solution of ethylenediamine-tetraacetic acid and deemanation of radon by a simplified procedure, the activity of radon is measured in a scintillation cell. The accuracy and precision of the method are very good as shown by determination of radium-226 in standard solutions and in natural water samples distributed by IAEA in the frame of interlaboratory comparison program. Easy construction of a simple scintillation cell is described, yielding cells with reproducible parameters and sufficient sensitivity for radium analysis in natural waters.     

The use of radium-226 in calibrating HpGe detectors

A technique is described for the production of sealed²²⁶Ra sources for use in efficiency and energy calibration of hyperfine germanium -radiation detectors.     

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.     

Fast,selective and sensitive methods for the determination of lead-210 in phosphogypsum and phosphate ore

Two methods are presented for a fast, accurate and precise determination of²¹⁰Pb in industrial samples with a calcium-phosphate and-sulphate matrix. One method combinessolid-liquid extraction on a Pb-selective column Sr^*Spec (Eichrom) with gamma-ray spectrometry of²¹⁰Pb and can be applied to samples >10 g for aselective ²¹⁰Pb determination. The yield is determined gravimetrically. The detection limit is 380 mBq for a 24 h counting period. The other method combineschromatography on Sr^*Spec with liquid scintillation counting of²¹⁰Pb for asensitive ²¹⁰Pb determination and can be applied to samples of up to 1 g. The yield is determined on-line by the UV signal of PbEDTA. The detection limit is 70 mBq for a 2 h counting period. Aspects of accuracy, precision, selectivity, sensitivity and the application of both methods to phosphogypsum and phosphate ores are presented.     

Determination of atmospheric lead-210 by alpha-scintillation counting of air filters

Alpha-counting of filters used to sample large volumes of air provides a convenient way of determining atmospheric concentrations of²¹⁰Pb. Following decay of short-lived²²²Rn and²²⁰Rn progeny, alpha activity of the filters increases as²¹⁰Pb decays to²¹⁰Po. After transient equilibrium is reached at about 3 y, alpha activity diminishes with the 22.3 y halflife of²¹⁰Pb. The degree of equilibrium between²¹⁰Pb and²¹⁰Po can be calculated subsequent to sampling, and the average concentration of²¹⁰Pb in the air during the sampling period can be computed. Contributions to the total²¹⁰Pb from ambient short-lived radon progeny are small, typically 2–4%. Using high volume air samplers with collection rates of 1.1–1.7 m³/min for 24 h periods, and using counting times of 2 h for 20 cm² 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 mean²¹⁰Pb levels with standard deviations less than ±15%. The method requires minimal sample preparation and can be used to determine past atmospheric²¹⁰Pb concentrations on filters stored for up to 20 y and more.     

The determination of134Cs,137Cs,210Pb,226Ra and228Ra concentrations in nearshore marine sediments and seawater

Multi-radionuclide analyses of coastal marine sediments and seawater can be of considerable value in defining rates and mechanisms of nearshore processes. A preliminary study of¹³⁴Cs,¹³⁷Cs,²¹⁰Pb,²²⁶Ra and²²⁸Ra in the Clyde Sea Area has been performed. A summary of the marine geochemistries of these species and a detailed account of methods involved in their routine analysis are described.