Concentrations atmospheriques de85Kr dans les hemispheres nord et sud

The evolution of⁸⁵Kr concentrations in the atmosphere has been followed in the Northern hemisphere (France) from June 1966 to February 1979 and in the Southern hemisphere from March 1968 to October 1977 (Tahiti and Terre Adélie). The growth observed during the years 1966–1968 (1.8 pCi·m⁻³ per year) in the Northern hemisphere did not continue in 1969, 1970, 1971, during which period a constant level at 14.8 pCi·m⁻³ per year and even a decrease (12.9 pCi·m⁻³ in 1971) were noticed; this was followed by a new increase of about 0.9 pCi·m⁻³ per year. In the Southern hemisphere, a regular groth from 1968 to 1974 (0.9 pCi·m⁻³ per year) was followed by values stabilized around 14.5 pCi·m⁻³. The curve illustrating the evolution of the Krypton specific activity in the Northern hemisphere from 1954 to February 1979 shows that this increased in a discontinuous way from 1 to 40 disintegrations per minute; nevertheless the present atmospheric activity is very low with a value of only 8·10⁻⁵ MPC.      

Determination of radium isotopes in soil samples by alpha-spectrometry

A sensitive and accurate method for determination of radium isotopes in soil samples by α-spectrometry has been developed ²²⁵Ra, which is in equilibrium with its mother ²²⁹Th, was used as a yield tracer. Radium in soil samples was fused together with Na₂CO₃ and Na₂O₂ at 600 °C, leached with HNO₃, HCl and HF, preconcentrated by coprecipitation with BaSO₄, separated from uranium, thorium and iron using a Microthene-TOPO chromatographic column, isolated from barium in a cation-exchange resin column using 0.05M 1,2-cyclohexylene-dinitrilo-tetraacetic acid monohydrate as an eluant, electrodeposited on a stainless steel disc, and counted by α-spectrometry. The detection limit of the method is 0.43 Bq·kg⁻¹ for ²²⁶Ra, ²²⁸Ra and ²²⁴Ra if 0.50 g of soil sample are analyzed. The method was checked with two certified reference materials supplied by the IAEA, and reliable results were obtained Fourteen soil samples collected from the refractory industry in Italy were also analyzed. The mean radiochemical yields for radium were 85.7±4.3%, and the obtained radium concentrations in the soil samples were in the range of 8.08–3878 Bq·kg⁻¹ for ²²⁶Ra, of 1.60–678 Bq·kg⁻¹ for ²²⁸Ra and 1.25–550 Bq·kg⁻¹ for ²²⁴Ra, with ²²⁸Ra/²²⁶Ra and ²²⁴Ra/²²⁶Ra ratios ranged from 0.159–0.821 and from 0.142 to 0.525, respectively.     

Concentration of radionuclides in building and ceramic materials of Bangladesh and evaluation of radiation hazard

The concentration of radioactive²²⁶Ra,²³²Th and⁴⁰K in building and ceramic materials of Bangladesh was investigated by γ-spectrometry with two HPGe detectors. Radium equivalent activities, representative level index values, criterion formula, emanation coefficients and²²²Rn mass exhalation rates were estimated for the radiation hazard of the natural radioactivity in the materials. The activity concentrations of the natural radionuclides, radium equivalent activities, emanation coefficients and²²²Rn mass exhalation rates are compared with the corresponding values for building and ceramic materials of different countries. The radium equivalent activities in the samples varied between 30.9 (mosaic stone) and 328.0 Bq·kg⁻¹ (gypsum). The emanation coefficient of the materials ranged from 7.83 (cement) to 33.0% (soil) and the²²²Rn mass exhalation rate ranged from 2.31 (stone chips) to 118.0 μBq·kg⁻¹·s⁻¹ (gypsum).     

Determination de quelques elements traces dans le charbon,d'une maniere non destructive,par photoactivation nucleaire

Photonuclear activation and high resolution gamma spectrometry have been used to determine nondestructively 28 trace elements in coal. The samples and synthetic multielement standards were simultaneously irradiated in the bremsstrahlung beam at 18 and 30 MeV maximum energies. Taking into account the contribution of the main possible interferences, limits of detection between 0.2 and 125 μg·g⁻¹ were obtained.

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Stagiaire Etranger au C. E. A.     

Extractive-spectrophotometric determination of manganese(II) using 3-bromobenzohydroxamic acid as chelating agent

Summary A new extractive spectrophotometric method is described for determining trace amounts of Mn(II) based on its reaction at pH 10.2 with 3-bromobenzohydroxamic acid (3BrHA) and subsequent extraction into Adogen 464 in toluene. The apparent molar absorptivity of the 1:3:1 (Mn:3BrHA:Adogen 464) complex is 8.7×10³ l·mol⁻¹ cm⁻¹ at 450 nm. Beer's law is obeyed from 0.5 to 6.0 mg·1⁻¹ of Mn(II) in the aqueous phase with a C.V. of 1.2%. The detection limit is 0.18 mg·1⁻¹. The method has been successfully applied to the determination of manganese in standard steel samples, natural water samples and plant material.     

Natural radioactivity in bottled natural spring,mineral and therapeutic waters in Poland

Activities of ²³⁸U, ²³⁴U, ²²⁸Ra, ²²⁶Ra, and ²²⁴Ra as well as total α- and β-activities of 23 bottled spring, mineral and therapeutic waters produced and distributed in southern and central Poland are presented. The activities vary from a few tenth to a few mBq·L⁻¹ for uranium and to several hundred mBq·L⁻¹ for radium isotopes. The activities of ⁴⁰K were calculated from chemical analyses of potassium and checked for several mineral waters by gamma-spectrometer coupled with an HPGe detector. Positive correlation between water mineralization and activities of ⁴⁰K, ²²⁶Ra, as well as total alpha- and total beta-activities were observed. The radiological annual doses were calculated for all investigated waters and for different human age groups assuming the consumption of 1 liter of water per day. The calculated committed effective dose rate from uranium and radium isotopes resulting from consumption of the investigated waters exceeds the recommended value of 0.1 mSv per year in seventeen cases for infants and in one case for adults.     

Concentration of natural radionuclides in and around Padubidri on the coastal Karnataka,India

The activity concentrations of natural radionuclides viz. ²³²Th, ²²⁶Ra and ⁴⁰K were measured in soil samples of Padubidri on the coastal Karnataka, the site for the proposed coal based thermal power station, using gamma-ray spectrometry to establish a baseline data on radioactivity levels in the environment of the region. The activity concentration of ²³²Th varies in the range of 38.5–115.5 Bq·kg⁻¹ with a mean value of 66.0 Bq·kg⁻¹, the activity concentration of ²²⁶Ra varies in the range 35.3–72.5 Bq·kg⁻¹ with a mean value of 53.5 Bq·kg⁻¹ and that of ⁴⁰K varies in the range of 307.5–550.9 Bq·kg⁻¹ with a mean value of 419.3 Bq·kg⁻¹. The radium equivalent activity varies in the range of 140.0–242.9 Bq·kg⁻¹ with a mean value of 180.2 Bq·kg⁻¹. The correlation between ²²⁶Ra and ⁴⁰K, ²³²Th and ⁴⁰K and ²²⁶Ra and ²³²Th was studied from the results of the concentration of these naturally occurring radionuclides. The calculated dose rates in air due to these naturally occurring radionuclides varies in the range of 66.0–110.0 nGy·h⁻¹ with a mean dose rate of 83.1 nGy·h⁻¹.     

Ein Rotationsviskosimeter zur Bestimmung des Viskositätsverlaufes bei sehr kleinen Geschwindigkeitsgefällen

Zusammenfassung Ein vonZimm undCrothers auf ein rotierendes System angewandtes Me?prinzip zur Bestimmung der Viskosit?t im Bereich kleiner Geschwindigkeitsgef?lle wurde so modifiziert, da? ohne direkte Ver?nderung am Rotationsviskosimeter (z. B. Wechsel des Rotors) die relative Viskosit?t in Abh?ngigkeit vom Geschwindig-keitsgef?lle untersucht werden konnte. Die Messungen erstreckten sich über einen Geschwindigkeitsgef?llebereich von 0,2 bis 2[s⁻¹] und einen Schubspannungsbereich von 1,1·10⁻³ bis 13,2·10⁻³[dyn cm⁻²]. Testmessungen an einem anionisch polymerisierten Polystyrol (M _n =81200) in Benzol bei 25 °C stimmten mit den Daten aus Vergleichsuntersuchungen der IUPAC überein. Beim Polyvinylcarbazol (M _w =6,85·10⁶) in Benzol konnten die im Kapillarviskosimeter erzielten Werte für die relative Viskosit?t im Rotationsviskosimeter best?tigt werden. Au?erdem wurde keine Abh?ngigkeit der Viskosit?t vom Gesohwindigkeitsgef?lle bei den Messungen im Rotationsviskosimeter festgestellt.

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Summary The rotating viscosimeter developed byZimm-Crothers for viscosity measurements under low stress rate was so modified that without any direct change in the viscosimeter (e.g. change of rotors) the dependence of relative viscosity on shear rate could be investigated. The measurements spanned a range of 0,2–2 [s⁻¹] for the rate of shear and a stress range of 1,1·10⁻³ to 13,2·10⁻³ [dyne·cm⁻²]. Test measurements on an anionic polymerized polystyreneM _n=81200) in benzene at 25 °C were in agreement with reference measurements of IUPAC. For polyvinylcarbazole (M _w=6,85·10⁶) the data obtained by rotating viscosimeter agreed with measurements by the capillary viscosimeter. Furthermore the data obtained by the rotating viscosimeter did not show any dependence of the viscosity on the rate of shear.

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Herrn Prof. Dr.K. Ueberreiter danke ich für sein Interesse an dieser Arbeit. HerrnD. Ziegler danke ich für die Unterstützung beim Aufbau des Rotationsviskosimeters.

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Diese Arbeit wurde von der Deutschen Forschungs-gemeinschaft finanziert, wofür ich meinen Dank ausspreche.     

Natural radioactivity and indoor radiation measurements in buildings and building materials in Gobichettipalayam town

Samples of natural and manufactured building materials used by the people of Gobichettipalayam town have been analyzed for ²²⁶Ra, ²³²Th and ⁴⁰K using gamma-ray spectrometry. Radium equivalent activity of the materials has been measured using the formula given by OECD and the geometric mean value of sand, clay and cements are found to be 53.53 Bq·kg⁻¹, 89.09 Bq·kg⁻¹ and 72.25 Bq·kg⁻¹, respectively. The radium equivalent activities obtained in the building materials are all well below the acceptable limit. The indoor gamma-dose has been measured using thermoluminescence dosimeters and it was found in the range of 1051.2–3946.0 μGy/year. The annual effective indoor gamma radiation dose to the people of Gobichettipalayam town has been found to be 0.8 mSv/y.     

Spectrophotometric determination of trace amounts of iodide-ions in form of ionic associate with brilliant green using electrochemical oxidation

A combined method involving electrochemical oxidation of iodide to iodate at a platinum electrode followed by extraction in CCl₄ of ionic associates of iodine-iodide complexes with brilliant green, formed in excess of iodide, was developed for the spectrophotometric quantification of iodide. The slope of the calibration curve yields a molar extinction coefficient of ɛ = 3·10⁵ L mol⁻¹cm⁻¹. This method can be used for the quantification of iodide in the concentration range of 3·10⁻⁷ − 3·10⁻⁶ mol L⁻¹ with a detection limit of 5·10⁻⁸ mol L⁻¹. The interfering effect of other ions on the determination of the iodide concentration was also investigated. The method was successfully applied for the determination of iodide in real samples of NaCl and spring water. Relative standard deviation is 1–2%.     

Anomalously high activities of <Superscript>137</Superscript>Cs in soils and vegetation on and near a diabase outcrop in La Sierra de Lema,Venezuela

As a result of routine soil sampling to determine the ¹³⁷Cs background activities country-wide in Venezuela, it was decided to further investigate El Mirador (Lookout) area at the base of the Sierra de Lema mountain range. In April 2003 (A), soil samples were collected at eight sites on and around the edge of the diabase outcrop to confirm that this area had anomalously high ¹³⁷Cs activities. In July 2003 (B), not only soil samples were collected again, but also black mat, palm tree leaves and trunks, fruit bushes leaves and its fruit and fern leaves. The ¹³⁷Cs content was measured by high resolution gamma-ray spectroscopy by a comparative method with reference materials. The ¹³⁷Cs activity values range from 16.3 to 30.8 Bq·kg-1 in the soil samples collected in July 2003, 20.7–32.1 Bq·kg⁻¹ for the black mat, 26.3–38.4 Bq·kg⁻¹ for the palm leaves, 16.8–31.2 Bq·kg⁻¹ for the palm trunks and 17.6–27.3 Bq·kg⁻¹ for the fruit bush leaves, while, the ¹³⁷Cs activity values for the whole fruit were between 23.4 and 30.7 Bq·kg⁻¹; but, the value of the ¹³⁷Cs activity in the center of the fruit (the edible part) was 51.6 Bq·kg⁻¹, and the value of the ¹³⁷Cs activity for the fern leaves was 51.8 Bq·kg⁻¹. Thus, most of the ¹³⁷Cs activity values determined in the soil, black mat and vegetation samples from El Mirador (Lookout) were considered anomalously high with respect to those found near the equator and in other areas of Venezuela. Only the center of the fruit from the Clusia grandiflora bushes and the fern leaves had high activity ratios, about a factor of three and could be considered as biomonitors that concentrate and retain the ¹³⁷Cs. Finally, these anomalously high ¹³⁷Cs activities have been attributed not only to the rich organic soils, as sinks, but also due to the affect of the cloud forests.     

Assessment of Inorganic Fibre Burden in Biological Samples by Scanning Electron Microscopy – Energy Dispersive Spectroscopy

A method based on cloud point extraction (CPE) separation/preconcentration of trace cadmium as a prior step to its determination by graphite furnace atomic absorption spectrometry (GFAAS) has been developed. If the system temperature is higher than the cloud point temperature (CPT) of the nonionic surfactant of p-octyl polyethyleneglycolphenyether (Triton X-100), the complex of Cd²⁺ with 1-(2-pyridylazo)-2-naphthol (PAN) could be extracted into surfactant-rich phase. The chemical variables affecting CPE were evaluated and optimized. Under the optimum conditions, preconcentrating 10.0 mL of water samples permitted a limit of detection of 5.9 ng · L⁻¹ (3σ) for cadmium with an enhancement factor of 50 and a relative standard deviation of 2.1% (n = 11, c = 2.0 ng · mL⁻¹). The method was applied to the determination of cadmium in reference material and water samples with satisfactory results.     

Rare-earth elemental analysis of banded iron-formations by instrumental neutron activation analysis

Representative banded iron-formations (BIFs) from various locations of the eastern Indian geological belt were investigated by instrumental neutron activation analysis (INAA). After pre-concentration, irradiation was carried out using a neutron flux of 5.1·10¹⁶ m⁻²·s⁻¹, 1.0·10¹⁵ m⁻²·s⁻¹ and 3.7·10¹⁵ m⁻²s⁻¹, with thermal, epi-thermal and fast neutrons, respectively. The activities in these samples were measured by a HPGe detector. Ten rare-earth elements, such as La, Ce, Nd, Sm, Eu, Tb, Ho, Tm, Yb and Lu, have been qualitatively identified and quantitatively estimated in these samples. The present investigation is an example of employing a pre-concentration method for high iron-containing ores prior to neutron activation analysis.     

Instrumental neutron activation analysis of monomineral fractions of sulfide minerals and quartzes

A method has been worked out of multi-elemental instrumental neutron-activation analysis INAA of small weights some mg of monomineral fractions of sulfide minerals pyrites, galenites, chalcopyrites, arsenopyrites, bornites, chalcosines and quartzes. The samples were irradiated in a nuclear reactor under a flux of 1.3·10¹³ n·cm⁻²·s⁻¹. For measuring the gamma radiation of the exposed samples Ge(Li) gamma-spectrometers with semiconductor detectors were used. Determined in sulfide monofractions were the elements: Co, Sc, Ag, Se, Sb, Cr, Fe, Zr; rare-earth elements: Ce, Sm, Eu and others at content levels of 10⁻¹−10⁻⁴%. In quartzes they were: Mn, Na, Sb, Cr, Sc, Fe, Co at content levels of 10⁻⁵−10⁻⁷% and Au to n×10⁻⁹%. A special method has been worked out for the determination of In in sulfides with the irradiation of samples in a cadmium screen. An example is cited of using the method for studying some peculiar features of the genetics of copper pyrite deposits. The data on the distribution of admixture elements in sulfide monofractions produced in this work made it possible to conclude that the oreformation in the deposits has a stage-by-stage character.     

Biosorptive behavior of mango (<Emphasis Type="Italic">Mangifera indica</Emphasis>) and neem (<Emphasis Type="Italic">Azadirachta indica</Emphasis>) barks for <Superscript>134</Superscript>Cs from aqueous solutions: A radiotracer study

The role of dead biomasses viz., mango (Mangifera indica) and neem (Azadirachta indica) bark samples are assessed in the removal behavior of, one of important fission fragments, Cs(I) from aqueous solutions employing a radiotracer technique. The batch type studies were carried out to obtain various physico-chemical data. It is to be noted that the increase in sorptive concentration (from 1.0·10⁻⁸ to 1.0·10⁻² mol·dm⁻³), temperature (from 298 to 328 K) and pH (2.6 to 10.3) apparently favor the uptake of Cs(I) by these two bark samples. The concentration dependence data obeyed Freundlich adsorption isotherm and the uptake follows first order rate law. Thermodynamic data evaluation and desorption experiments reveal the adsorption to be irreversible and endothermic in nature proceeding through ion-exchange and surface complexation for both dead biomasses. Both bark samples showed a fairly good radiation stability in respect of adsorption uptake of Cs(I) when irradiated with a 300 mCi (Ra-Be) neutron source having an integral neutron flux of ∼3.85·10⁶ n·cm⁻²·s⁻¹ and associated with a nominal γ-dose of ∼1.72 Gy·h⁻¹.     

The use of charcoal from agriculture waste in the speciation of iodine from well and river waters

The concentrations of iodine in fresh waters are known to be within the range of 0.5 to 35 ng·ml⁻¹, much lower than in oceanic waters. The iodine concentrations, particularly that of¹²⁹I which is significant from the radiation safety aspect, in public drinking waters have to be specified in order to verify the required level before distribution for domestic use. A modified version of an established method was used in the adsorption of iodine, iodate, total inorganic iodine and charcoal-adsorbable iodine using activated carbon prepared from oil palm kernel wastes. A thorough investigation of the physical properties of the activated carbon was carried out to determine its viability as an adsorbent for volatile species such as iodine. The iodine species were preconcentrated from water samples collected from wells in villages and from water intake points along rivers. The quantitative analysis of the species adsorbed was done by irradiating the activated charcoal loaded with the respective species in a neutron flux of 5.1·10¹² n·cm⁻²·s⁻¹ from a TRIGA MkII, nuclear reactor. Recovery experiments using spiked samples was done to provide quality assurance controls.     

The determination of rare earth alloying additives in special steels by neutron activation analysis

A procedure for neutron-activation analysis of cerium, lanthanum, praseodymium and neodymium, tested on more than thirty samples of steels, is described. After irradiation for 20 hrs with a neutron flux of 1.2·10¹³ n·cm⁻²·sec⁻¹ the steel samples were dissolved in aqua regia and extraction separation of iron from 6N HCl by ether was employed. The REE were separated as a group by precipitation as fluorides and hydroxydes. The individual rare-earth elements were separated from each other using a KU-2 cation exchange resin and a solution of ammonium α-hydroxyisobutirate as eluant. The separated samples were counted on a NaI(T1) γ-spectrometer.     

Releases of radium from an abandoned uranium mine site: Žirovski Vrh uranium mine, Slovenia

Since the beginning of explorative uranium mining at the Žirovski Vrh uranium ore deposit area in 1968, a radioactivity monitoring programme has been carried out. The extent of the programme has varied according to the pre-operational, operational, and, finally, post-operational conditions. In this paper, our ten year results on the dissolved radium concentrations in surface waters, which have been contaminated and potentially affected by the uranium mining and milling activities, are reported. With the exception of waters drained from the hydrometallurgic waste site with radium content ranging from 2 to 9 kBqm⁻³, radium content is far below the drinking water limit of 1000 Bqm⁻³; in the Brebovŝčica stream, which collects all the waters affected by the mine, the present radium concentration does not exceed 10 Bqm⁻³.     

Improvement in the determination of traces of uranium in aqueous medium having high dissolved organic carbon and chloride ion by alpha-spectrometry

During this work the determination of uranium in the range of μg·L⁻¹ to tens of μg·L⁻¹ was done by alpha-spectrometry after electroplating the aliquots of water sample using (NH₄)₂SO₄ as an electrolyte. In general, the determination of uranium by alpha-spectrometry needs its separation from other transuranics specially thorium. The process described here does not involve any sample digestion and radiochemical separation of uranium from other transuranics. In this method an aliquot (1 to 3 mL) of the sample was dried and dissolve in (NH₄)₂SO₄ and thereafter the sample was electroplated on a stainless steel (SS) planchet by using an electrochemical cell of special design. The proposed techniques have a distinct advantage over the determination of uranium by adsorptive stripping voltammetry (AdSV) in which uranium-chloranilic (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone) acid complex was used for concentrating the uranium from the solution. Since in the case of AdSv, the determination of uranium was not possible for samples having dissolved organic carbon (DOC) more than 15 mg·L⁻¹ and Cl⁻ concentration is in the range of 40,000 μ·g⁻¹. In the case of spike experiments with ²³²U the recovery was observed in the range of 90–95% in aqueous medium having higher concentration of Cl⁻ and DOC as indicated above.     

Determination of Tannic Acid by Flow Injection Analysis with Inhibited Chemiluminescence Detection

A novel flow injection procedure has been developed for the determination of tannic acid based on the inhibition of the chemiluminescences in luminol-H₂O₂-Manganese tetrasulfonatophthalocyanine (MnTSPc) system by tannic acid. The method is simple, rapid and sensitive with a detection limit of 8 × 10⁻¹⁰ mol·L⁻¹ and a linear range of 7 × 10⁻⁹–5 × 10⁻⁶ mol·L⁻¹. The relative standard deviation is 1.9% for eleven measurements of 5 × 10⁻⁷ mol·L⁻¹ tannic acid. The method has been successfully applied to the determination of tannic acid in real Chinese gall and hop pellets samples.