Radionuclide activities and elemental concentrations in sediments from a polluted marine environment (Saronikos Gulf-Greece)

The levels and depth distributions of the natural radionuclides ²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K and the man-made ¹³⁷Cs were analyzed by γ-ray spectrometry, while the concentrations of 26 chemical elements were measured by INAA in sediment samples collected from the organic mud layer that covers the Keratsini–Psitalia strait, Saronikos gulf (Greece). The average activity concentration values of ²²⁶Ra, ²³²Th and ⁴⁰K were lower when compared, whereas that of ²³⁸U was comparable to the average Greek and world values. The elemental contamination of the sediments was estimated on the basis of the calculated EF values. The results revealed high EF values of As, Br, Cr, Ni, Sb, Se, Zn ranging from 160 for Br to 10 for Cr, whose main sources are probable related to contaminated sewage outfall from the area of Athens and the Piraeus Harbour.

     

Major,trace, and natural radioactive elements in bituminous coal from Australia,Romania, Russia,South Africa and Ukraine: A comparative study

Summary Five samples of bituminous coal collected from different basins (Australia, Romania, Russia, South Africa and Ukraine) have been investigated by using different analytical techniques. Na, Mg, Al, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Mo, Sn, In, Sb, Cs, Ba, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Lu, Hf, Ta, W, Hg, Th and U have been determined by neutron activation analysis, ⁴⁰K, ²³⁸U, ²³⁵U and ²³² Th have been measured radiometricaly, H, C, O, N, and S have been dosed by dynamic flash combustion, while gravimetric methods have been used to measure moisture and ash content together with calorific power. Major mineralogical fractions have been investigated by means of X-ray diffraction. The results have shown significant positive correlations between radiometric and activation analysis results, between calorific power and carbon, nitrogen and hydrogen concentrations and negative significant correlations between calorific power and ash content. According to the Romanian Regulations, only Cr and Ni for Romanian coal exceeded the minimum threshold to be considered unpolluting elements. The distribution of rare earth elements, La to Th ratio, as well as of Sc, La and Th together with Co, Hf and Th have confirmed that, irrespective of sample sources, the mineral part of coal has a composition close to that of the upper continental crust.     

The leachability of some natural and man-made radionuclides from soil and sediments on acid attack

A radiotracer study was made of the leachability of some natural and man-made radionuclides from soils and sediments subjected to attack by various acid mixtures. Particular attention was paid to the nuclides²³⁸U,²³²Th, Pa (as²³³Pa) and Np (as²³⁹Np), since for these neutron activation can be used to study recoveries and/or to induce in situ radionuclides in samples. Thus conventional NAA allowed determination of total²³⁸U and²³²Th instrumentally, and also enabled analysis of leachates and residues by radiochemical or instrumental NAA. Activation of these nuclides produced samples endogenously labelled with²³³Pa and²³⁹Np whose behaviour on acid dissolution/leaching could be examined. Furthermore, comparison of neutron irradiated and non-irradiated samples allowed us to investigate the possibility of increased leachability induced by nuclear recoil reactions; however, this effect was negligible. We also investigated the acid leaching of americium adsorbed on the surface of sediment. In general, unsatisfactory leaching recoveries were found for²³³Pa,²³⁹Np and²³²Th for most materials, indicating the need for total dissolution procedures.     

Heavy elements concentrations,physiochemical characteristics and natural radionuclides levels along the Saudi coastline of the Gulf of Aqaba

This paper represents the first work on the concentrations of heavy elements, physiochemical characteristics and activity levels of the naturally occurring radionuclides in the Saudi Arabian coastline of the Gulf of Aqaba. Concentrations of 19 heavy elements were measured, namely: Ag, Al, As, Ba, Be, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, Se, V and Zn. The radioactivity levels of ²³⁸U, ²³²Th and ⁴⁰K were estimated to be: 17 ± 1.7, 22.5 ± 3.7 and 649.6 ± 64.2 Bq kg^?1, respectively. The measurements were carried out using inductively coupled plasma-mass spectrometry (ICP-MS). In addition, physiochemical characteristics of 19 sediment samples (i.e., saturation percentage, pH, electrical conductivity, organic matter, cation exchange capacity and content of clay, silt and sand) have been determined. Indications for high correlation between most heavy elements are found. The correlation between heavy elements and the radionuclides ²³⁸U, ²³²Th and ⁴⁰K was generally significant.     

Analysis of natural radionuclides from uranium and thorium series in briney groundwaters

Analytical procedures for measuring various radionuclides in the²³⁸U and²³²Th chains in briney waters are described. Using methods such as mass spectrometry, and alpha, beta and gamma spectrometry, the desired measurement sensitivity required for each of the radionuclides is achieved.²³³U,²²⁸Th,²⁰⁸Po,²¹²Pb, and¹³³Ba are used as tracers for chemical yield recoveries. Typical precision of the results range from 5–20%.     

Natural radioactivity in Zambian building materials collected from Lusaka

Samples of natural and manufactures building materials collected around Lusaka have been analyzed for natural radionuclides using -spectrometry. A simple comparison of the specific radioactivities of primordial radionuclides in these materials to the world averages for soil (25 Bq kg^{–1 238}U, 25 Bg kg^{–1 232}Th, 370 Bq kg^{–1 40}K and 89 Bq kg^–1 Ra_eq) shows that, of the nine types of samples analyzed, only burnt clay bricks (for²³⁸U,²³²Th and⁴⁰K), cement roofing tiles (for²³⁸U), building and river sands (for²³²Th and⁴⁰K) have greater activities than does soil. Radiological evaluation of specific radioactivities in these materials indicates that all materials meet the external -ray dose limitation of 1.5 mSv y^–1, that is, all samples have a radium equivalent activity of less than 370 Bq kg^–1.     

Interlaboratory comoparison of analytical methods for the determination of natural series uranium and thorium isotopes in rock samples

Results are repoerted for²³⁸U,²³⁴U,²³²Th, and²³⁰Th determinations in 19 rock samples from a uranium mine, performed independently, byb three different laboratories. Uranium and thorium isotopoic activities were determkined by alpha spectrometry, after different pre-concentration and counting sample preparation techniques., Additionally, total concentrations of uranium were determined by fluorimetry and gamma spectreometry. the folloing conclusions could be drawn from this intercomparison test: (1) The results for²³⁸U specific activity agreed with the amjority of results within 10%. Lincar correlation coefficients between the three data sets were 0.999. However, for a few samples of much higher uranium concentrations, large deviations were observed, indicating problems of, sample heterogencity. (2) For the²³⁴U/²³⁸U activity ratio data, a still closer agreement was obtained (5%), as computation of the activity ratios did not, require information on the yield of the used tracer spike (²³²U). (3) The results for²³²Th specific activities and²³⁰Th/²³⁴U activity ratios showed larger deviastions between the three laboratories (typically up to 15%, in some cases still ore). Different Th-isotopes (²²⁸Th,²³⁴Th and²²⁹Th) have been used as yield tracers. The data indicates, however, that the observed deviations are not simply a consequence of a systematic difference in the calibration of the different spikes, but, probably cased by other errors such as incomplete sample dissolution, sample heterogencity, tec. The limitations of alpha spectrometry will be discussed and an application of the developed methods shown.     

Determination of trace elements in food by neutron activation analysis

Neutron activation analysis (NAA) methods have been developed for the determination of major, minor and trace elements in duplicate diets and individual food items. These include a cyclic instrumental NAA (CINAA) method for measuring Se content through its short-lived nuclide^77mSe; epithermal INAA (EINAA) for I and As; conventional INAA for Br, Ca, Cl, Co, Cr, Fe, K, Mg, Mn, Na, Rb, Sb, Sc, Sn and Zn; combination of EINAA and INAA for Al; radiochemical NAA (RNAA) for As, Au, Co, Cu, Fe, Hg, Mo, Sb, Se and Zn; and preconcentration NAA (PNAA) for U and Th. Accuracy of measurements have been evaluated by analyzing a number of biological and diet reference materials. Multielement concentrations of diets and foods have been measured by these methods.     

Multi-element analysis of 18 food groups using semi-quantitative ICP-MS

Fifteen radionuclides and stable elements in 18 food groups, which have been obtained by a market basket method, were determined by semiquantitative ICP-MS. Strontium, Cs,²³²Th, and²³⁸U were also determined by quantitative analytical ICP-MS or ICP-AES. For Sr,²³²Th, and²³⁸U, results of the semi-quantitative ICP-MS and the quantitative approaches were found to be in a good agreement, within ±10%. The other eleven elements (Li, V, Cr, Mn, Co, Ni, Cu, Rb, Mo, Cd, and Ba were determined with in 30% errors at the sub-ppb (ng/ml) level. More elements could be measured by the semi-quantitative mode if concentrations were at least at the sub-ppb level.     

Factors Controlling Natural Radionuclides Migration in Sedimentary Rock Samples,Gabal Um‐Hamd,Southwestern Sinai,Egypt

The activity concentrations of some radionuclides (²³⁸U, ²³⁴U, ²³⁰Th, ²²⁶Ra, ²³²Th, ⁴⁰K and ²³⁵U) were measured by γ‐ray spectrometry in order to study their behavior and the relation between them in Carboniferous rock samples collected from Gabal (mountain) Um‐Hamd, southwestern Sinai, Egypt. The whole samples are located in the two limbs and trough of a synclinal form structure to identify the radionuclides migration processes which have occurred in these rock samples. The average activity concentrations of ²³⁸U, ²³²Th, ²²⁶Ra, and ⁴⁰K measured in the all samples except sandy dolostone sample are higher than the worldwide average values as reported by UNSCEAR 2008. The activity ratios (²³⁴U/²³⁸U) for half of the samples are in equilibrium, while the other half samples are below unity indicates migration‐out of uranium. The hazard indices were also calculated. The variations in lithologic types and the configuration of the structural synform played its roles beside the physical and chemical properties of different radionuclides in their fractionations.     

A critical review of bioassay techniques for actinides in light of ICRP recommendations for monitoring workers

A critical review is presented of bioassay techniques for actinides in light of ICRP recommendations for monitoring workers. It is obvious that very sensitive techniques are required to meet these recommendations. Alpha spectrometry, the most commonly employed technique for measuring actinides in bioassay samples, has limited sensitivity. There are, however, certain techniques which are sensitive enough to meet the recommendations of ICRP, such as, fission track analysis for²³⁹Pu and²³⁵U, neutron activation analysis for²³²Th, mass spectrometry for a number of radionuclides, and many techniques for uranium. ICP-mass spectrometry does not have enough sensitivity to be implemented as a method of choice for the bioassay of actinides at present, however, it is quite promising.     

Natural and Artificial Radionuclides in Selected Lignites from Istanbul

The radioactivity levels of Istanbul environs lignites were determined. The gamma-spectrometric technique has been used for the determination of activity levels of naturally occurring radionuclides ^235+238U, ^228+232Th, ⁴⁰K, ²²⁶Ra and fallout radionuclides ¹³⁷Cs in lignites taken from 7 different parts of Istanbul. Concentration of ²³⁸U, ^228+232Th, ⁴⁰K, ²²⁶Ra ¹³⁷Cs and ²³⁵U were found up to 1.6 ppm, 1.7 ppm, 4.9 ppm, 56.8 Bq/kg, 34 Bq/kg, 1.8 Bq/kg, 1.6 Bq/kg, respectively. In addition total alpha- and beta-activity levels in lignite samples were found to be 7.6 and 15 eps, respectively.     

Traceability in the amount-of-substance analysis of natural potassium, thorium and uranium by the method of passive gamma-ray spectrometry

 This paper describes the amount-of-substance analysis of the long-lived naturally occurring radionuclides ⁴⁰K, ²³²Th, ²³⁵U and ²³⁸U by the method of non-destructive passive gamma-ray spectrometry. Calibrands used were standard reference materials and high-purity analytical grade chemicals. Traceability of the measured results to reference materials was established. The emission probabilities of several high-energy gamma-rays were determined. High-energy gammas were measured to decrease the effect of gamma self-attenuation. Received: 31 August 1996 Accepted: 9 November 1996     

Prediction of the activity concentrations of 232Th, 238U and 40K in geological materials using radial basis function neural network

In this paper, three individual models and one generalized radial basis function neural network (RBFNN) model were developed for the prediction of the activity concentrations of primordial radionuclides, namely, ²³²Th, ²³⁸U and ⁴⁰K. To achieve this, gamma spectrometry measurements of 126 different geological materials were used in the development of the RBFNN models. The results indicated that individual and generalized RBFNN models are quite efficient in predicting the activity concentrations of ²³²Th, ²³⁸U and ⁴⁰K of geological materials.

     

Measurement of the radioactivity of238U,232Th,226Ra,137Cs and40K in soil using direct Ge(Li) γ-ray spectrometry

Radioactivity of the nuclides²³⁸U(²³⁵U),²³²Th,²²⁶Ra,¹³⁷Cs and⁴⁰K was measured in soil by direct -ray spectrometry using Ge(Li) detector. Relative laboratory method was used. Soil was dired, powdered, sieved and put into hemetically sealed container. CCRMP certified reference materials and compounds of the above nuclides mixed with fine quartz sand were used as references. Five and four -lines were used for the determination of²³²Th and²²⁶Ra, respectively, to obtain more accurate results. The most significant interferences, caused by the limited energy resolution of the detector, were resolved. In the case of ordinary soils, using one day duration of measurement and 1 kg mass of soil,²³²Th,²²⁶Ra and⁴⁰K can be determined with less than 10% relative random error. Elevated concentrations of²³⁸U(²³⁵U) and²²⁶Ra were observed in soil samples collected around a coal-fired power plant in Ajka town, Hungary.     

Evaluation of strontium isotope abundance ratios in combination with multi-elemental analysis as a possible tool to study the geographical origin of ciders

In order to evaluate alternative analytical methodologies to study the geographical origin of ciders, both multi-elemental analysis and Sr isotope abundance ratios in combination with multivariate statistical analysis were estimated in 67 samples from England, Switzerland, France and two Spanish regions (Asturias and the Basque Country). A methodology for the precise and accurate determination of the ⁸⁷Sr/⁸⁶Sr isotope abundance ratio in ciders by multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) was developed. Major elements (Na, K, Ca and Mg) were measured by ICP-AES and minor and trace elements (Li, Be, B, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Y, Mo, Cd, Sn, Sb, Cs, Ba, La, Ce, W, Tl, Pb, Bi, Th and U) were measured by ICP-MS using a collision cell instrument operated in multitune mode. An analysis of variance (ANOVA test) indicated that group means for B, Cr, Fe, Ni, Cu, Se, Cd, Cs, Ce, W, Pb, Bi and U did not show any significant differences at the 95% confidence level, so these elements were rejected for further statistical analysis. Another group of elements (Li, Be, Sc, Co, Ga, Y, Sn, Sb, La, Tl, Th) was removed from the data set because concentrations were close to the limits of detection for many samples. Therefore, the remaining elements (Na, Mg, Al, K, Ca, Ti, V, Mn, Zn, As, Rb, Sr, Mo, Ba) together with ⁸⁷Sr/⁸⁶Sr isotope abundance ratio were considered for principal component analysis (PCA) and linear discriminant analysis (LDA). Finally, LDA was able to classify correctly 100% of cider samples coming from different Spanish regions, France, England and Switzerland when considering Na, Mg, Al, K, Ca, Ti, V, Mn, Zn, As, Rb, Sr, Mo, Ba and ⁸⁷Sr/⁸⁶Sr isotope abundance ratio as original variables.     

Distribution of137Cs,40K,238U and232Th in soils from Northern Venezuela

More than one hundred undisturbed soil samples from Northern Venezuela and the islands of Margarita and Los Roques have been analyzed for¹³⁷Cs,⁴⁰K,²³⁸U and²³²Th by -ray spectroscopy. The specimens were taken from between 5–10 cm below the earth's surface. Thus, they are valid not only for the¹³⁷Cs deposition studies but also for the estimation of the natural -ray dose from primordial radionuclides that form the terrestrial component. The concentration of⁴⁰K was directly determined from its 1461 keV -ray, while those of¹³⁷Cs,²³⁸U and²³²Th were performed using a -ray from one of their daughter radionuclides: the 661 keV -ray of^137mBa for¹³⁷Cs, the 1760 keV -ray of²¹⁴Bi for²³⁸U and the 2620 keV -ray of²⁰⁸Tl for²³²Th. Finally, the concentration values were compared with those of global estimates.     

Measuring activity of 235, 238U, 232Th and 40K in geological materials using neutron activation analysis

The radioactivity of the ^{235, 238}U and ²³²Th isotope decay chains for geological samples can usually be assumed to be in equilibrium due to their age. Similarly, one can assume that the isotopic mass proportions are equal to natural isotopic abundance. Current methods used to ascertain activity in these decay chains involve alpha particle spectrometry, ICP-MS or passive gamma-ray spectrometry, all of which can be laborious and time consuming. In this research, we have used thermal and epithermal neutron activation analysis (NAA) of small sample sizes of various geological materials in order to ascertain these activities. By using NAA, we aim to obviate cumbersome sample preparation, the need for large samples and extended counting time. In addition to the decay chains of uranium and thorium, ⁴⁰K was also determined using epithermal neutron activation analysis to determine total potassium content and then subtracting out its isotopic contribution.     

Dietary232Th and238U intakes for Japanese as obtained in a market basket study and contributions of imported foods to internal doses

Thorium-232 and²³⁸U contents in four food groups were measured by inductively coupled plasma mass spectrometry (ICP-MS). Daily intakes of²³²Th and²³⁸U for Japanese were estimated to 2.22 mBq and 15.5 mBq per person, respectively. Furthermore, preliminary estimations were made for the effects of imported foods on internal exposures for Japanese.     

Limitations of gamma-ray spectrometry in the quantification of 238U and 232Th in raw materials and by-products

The effect of interference and disequilibrium was evaluated in analyzing ²³⁸U and ²³²Th using gamma-ray spectrometry. The interference in ²³⁴Th as an indicator of ²³⁸U was considerably increased according to the activity level of ²³²Th compared with that of ²³⁸U. However, its correction was necessary to assume that the secular equilibrium in the thorium decay series must be secured in the material. In addition, the disequilibrium in the decay series can be easily shown in the chemical process for manufacturing materials. This makes the limitation in the indirect measurement of natural radionuclides using gamma-ray spectrometry, especially in chemically processed products.