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Abstract  

In this paper, the sorption behavior of Cs+ and Sr2+ on column of fucoidic sands under dynamic flow conditions was investigated, and their sorption capacities (SC) towards these two cations were studied. The determination of SC is based on the construction of respective breakthrough curves using 137Cs and 85Sr radionuclides as isotopic indicators in laboratory experiments. The samples were taken from several parts of the borehole in the area of interest. Undisturbed cores of 5 cm in diameter and 10 cm long were put in the glass columns and the cores were perfectly tightened using acrylate resin. In this time-dependence study, the so-called cenoman background groundwater was used. A concentration of 10−6 mol/dm3 of Cs+ and Sr2+ in liquid phase individually was established using neutral salts of CsNO3 and Sr(NO3)2, respectively. The groundwater was introduced at the bottom of the columns by a multi-head peristaltic pump, at a constant flow-rate of about 4 cm3/h. The results show that the sorption capacity of the investigated fucoidic sands for 137Cs and 85Sr is 0.1–1.5 and 0.05–0.5 μmol/100 g, respectively, in dependence on the evaluation of corresponding breakthrough curves. Some differences in the behavior of the cores during the experiments have also been observed and explained.

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Summary  

The behavior of cadmium labeled with 109Cd in different depth horizons of arable and forest soils were studied under static (batch) conditions in three interconnected processes, which consist of sorption, desorption and extraction. In the sorption, Cd2+ was applied in the aqueous calcium nitrate solution. Both untreated soils and peroxide treated soils were used in order to remove organic matter from some of the soil samples used in parallel. The influence of the V/m ratio on the sorption coefficients was investigated in preliminary experiments with untreated soils. Contrary to the usually short-term sorption, a long-term sorption of cadmium was investigated in untreated and treated soil horizons, which lasted more than fortnight. Kinetic studies of sorption were carried out and cadmium concentration dependence in aqueous phase of the second order kinetic constants was observed. For evaluation of sorption and desorption processes Freundlich isotherms were used. It was found that the Freundlich adsorption intensity coefficient is more time dependent than the absorption capacity coefficient, and the sorption itself consists of rapid and slow processes according to the soil constituents. Desorption and extraction processes revealed the possibility of cadmium recovery from various soil horizons. Based on the obtained results two- or three-stage theory of cadmium retention in soils was proposed. Some new insight into the role of organic matter in the sorption/desorption process of cadmium is also presented.

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Abstract  

Possibilities of the determination by radioactivity measurements of3H,14C and131I are described for the individual nuclides and their mixtures, with the use of liquid scintillators. The changes in the counting efficiency have been determined as a function of the parameters of the measuring equipment, and parameters are suggested which make possible the determination of3H,14C and131I individually, or in the pairs3H−14C,3H−131I,14C−131I, and finally, in the triplet3H−14C−131I.

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Abstract  

The overall recovery of the separated113mCd with added Cd carrier from 50 samples of natural water was determined by a secondarysource tube excited energy dispersive X-ray fluorescence spectrometer measuring the amount of cadmium in the final CdS+CuS coprecipitate on a 25 mm diameter Millipore filter. The method enables to determine 1–20 g Cd in 100 sec. with a limit of detection of 0.8 g.

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Abstract  

Open-cell polyurethane foam cylinders have been used for collecting radioiodine in the vent of a labelled compound producing plant. The cylinders were unimpregnated or impregnated with Alamine 336 with or without stable elemental iodine dissolved. A collection efficiency of about 90% has been obtained for impregnated foam cylinders.

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Abstract  

In migration experiments, sorption of 137Cs and 152,154Eu in the columns of crushed crystalline rocks of 0.25–0.8 mm grain size under dynamic flow conditions from the synthetic groundwater (SGW) has been studied. Five samples of crystalline rocks from Cavernous Gas Reservoir near Příbram were taken. Plastic syringes of 8.8 cm length and 2.1 cm in diameter were used as columns. The water phase was pumped downward through the columns, using a multi-head peristaltic pump, with a seepage velocity of about 0.2 cm/min. The radioactive nuclides, containing chemical carriers, were added into the water stream individually in the form of a short pulse. Desorption experiments were carried out with 2:1 (v/v) mixture of H2SO4 and HNO3. In the columns the longitudinal distribution of the residual 137Cs and 152,154Eu activities was also determined. By the evaluation of respective breakthrough and displacement curves, the experimental and theoretical retardation factors, distribution coefficients and hydrodynamic dispersion coefficients were determined using the integrated analytical form of a simple advection-dispersion equation (ADE). Dynamic sorption experiments were also compared with the results of static sorption experiments.

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Automatic isotope gas analysis of tritium labelled organic materials

II. Determination of tritium in organic compounds with a pyrolytic sample decomposition method combined with isotope exchange

Journal of Radioanalytical and Nuclear Chemistry
Authors:
I. Gács
,
S. Mlinkó
,
K. Payer
,
D. Bánfi
, and
T. Palagyi

Abstract  

An analytical procedure and an automatic apparatus are described for the determination of tritium in organic compounds by gas counting. The sample is pyrolysed in hydrogen atmosphere at 1000°C, then, with hydrogen, the decomposition products are rinsed through a column of molecular sieve-5A heated to 550°C. Tritium in water, hydrogen sulphide, ammonia and hydrogen cyanide is transferred into the hydrogen stream by isotope exchange completed on the column. The inactive water vapor, hydrogen sulphide, ammonia and hydrogen cyanide as well as carbon dioxide are removed from the gas stream by appropriate absorbents, and the radioactive hydrogen together with tritiated methane, carbon monoxide and nitrogen included in the pyrolytic products is led into an internal proportional counter tube for radioactivity measurement. The method provides quantitative recovery, it is free of memory effect and suitable for the rapid assay of a wide variety of organic compounds containing C, H, N, O, S in addition to tritium.

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Automatic isotope gas analysis of tritium labelled organic materials

III. Determination of tritium in organic compounds and biological samples by a combustion method combined with isotope exchange

Journal of Radioanalytical and Nuclear Chemistry
Authors:
I. Gács
,
S. Mlinkó
,
K. Payer
,
Z. Vargay
,
L. Ötvös
,
D. Bánfi
, and
T. Palágyi

Abstract  

An isotope analytical procedure and an automatic instrument developed for the determination of tritium in organic compounds and biological materials by internal gas counting are described. The sample is burnt in a stream of oxygen and the combustion products including water vapour carrying the tritium are led onto a column of molecular sieve-5A heated to 550 °C. Tritium is retained temporarily on the column, then transferred into a stream of hydrogen by isotope exchange. After addition of butane, the tritiated hydrogen is led into an internal detector and enclosed there for radioactivity measurement. The procedure, providing quantitative recovery, is completed in five minutes. It is free of memory effect and suitable for the determination of tritium in a wide range of organic compounds and samples of biological origin.

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Acta Archaeologica Academiae Scientiarum Hungaricae
Authors:
S. Palágyi
,
O. Csirke
,
J. Futó
,
J. †Hlavay
,
B. Raucsik
,
A. Szabó
, and
I. Vassányi
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