[en] Reviewed is the transition period in the history of physics between 1895 and 1905, a decade which began 100 years ago and which is characterized by high scientific activity and creativity with significant results for the further development of natural science. A great number of outstanding scientists, especially physicists, worked in this period. Their important discoveries manifest the beginning of the history of isotopic research. 12 refs

[en] Three practical applications of the defined solid angle absolute β counting (DSAABC) method using end-window Geiger-Muller counter are presented. ⁹⁰Sr and ¹⁴⁷Pm nuclides were determined in filtered aerosol samples collected in Debrecen, Hungary, immediately after the Chernobyl accident. Development of an active method is in progress in order to determine radon and thoron daughters attached to airborne aerosols. Indoor concentrations were measured by this method in Ajka, Hungary, where radioactive industrial wastes were used as building materials. Determination of ⁹⁰Sr and ¹⁴⁷Pm in hot particles of Chernobyl origin, collected in Kiev, Ukraine, is in progress. The relation to the application of the DSAABC method is treated in detail and some results are presented. 1 fig., 3 tabs., 10 refs

[en] The migration of ¹⁵²Eu in a fine sand/water-system containing humic substances was tested under natural conditions in flow-through-column arrangements. In this system the trivalent Eu forms colloids (Eu-Humate); these are transported without retardation at the natural filter velocity, however, at recoveries clearly below 100%. 11 figs., 2 tabs., 7 refs

[en] This research deals with pollution impact on natural water resources in the industrial area of Belchatow, central Poland, where a large brown coal deposit is exploited and the coal is burned in an electric power plant. To trace the sources of groundwater pollutants the stable isotope analysis of oxygen and sulfur in sulfates was applied. The mass-spectrometric analysis was performed on SO₄^2- samples from numerous wells and piezometers in the excavation area. By repetitive sampling performed in November 1994, May 1995 and December 1996 significant changes of SO₄^2- concentration and sulfur and oxygen isotopic ratios in several sites were recorded. The interpretation of isotope ratios allowed the recognition of three groups of sulfates: (1) from the leaching of Permian salt dome; (2) produced by the leaching of soluble sulfates from an ash pool and (3) produced by oxidation of natural sulfides in water-bearing rocks. 28 refs., 4 figs., 2 tabs

[en] A concept for a site evaluation with respect to ground water protection is explained. In this concept isotope methods are used as a tool to verify and confirm the results. Two examples are described where tritium, stable isotopes, tritium-3He and radiocarbon are used to determine the infiltration rate, turnover time, mean residence time of aquifer systems. These results were compared with those obtained from classical hydrogeologic data. Assuming different scenarios for possible contaminant output from landfills, waste-management facilities or waste disposal sites possible consequences for the ground water quality are derived. It can be shown that the reliability and accuracy of the predictions can be increased considerably by the application of isotope methods. 4 figs., 2 tabs., 7 refs

[en] The author narrated on his personal experience of the past forty years of the development of isotope hydrology as an independent scientific branch. He started with the basic research work of for example Dansgaard and Libby and went on to the recent world-wide recording and interpreting isotopic data network. The IAEA organisation has accompanied the scientific development in an exemplary manner and, thus brought forward the isotope hydrological research activities to the high standard reached presently. This is documented by the great number of publications promoted by the IAEA throughout this time. 4 figs, 24 refs

[en] Defined solid angle absolute β counting of thick samples using end-window Geiger-Muller counter is shown to be a useful method in the field of environmental radio analysis. Some new proposals in connection with the possibility of the reduction and evaluation of the correction factors for the numerous effects responsible for losses and gains in the β counting rate are made on the basis of a comprehensive review of the literature on this topic. A new formula is proposed in order to evaluate correction factors for internal back scattering within thick samples. The case of the exponential decrease of activity as function of the thickness in filter-type samples is treated. 1 fig., 48 refs

[en] The Craig-Gordon model (C-G model) has been synonymous with the isotope effects associated with the evaporation of water from surface waters, soils, and vegetations, which in turn constitutes a critical component of the global water cycle. On the occasion of the four decades of its successful applications to isotope geochemistry and hydrology, an attempt is made to: (a) examine its physical background within the framework of modern evaporation models, (b) evaluate our current knowledge of the environmental parameters of the C-G model, and (c) comment on a general strategy for the use of these parameters in field applications. Despite its simplistic representation of evaporation processes at the water-air interface, the C-G model appears to be adequate to provide the isotopic composition of the evaporation flux. This is largely due to its nature for representing isotopic compositions (a ratio of two fluxes of different isotopic water molecules) under the same environmental conditions. Among many environmental parameters that are included in the C-G model, accurate description and calculations are still problematic of the kinetic isotope effects that occur in a diffusion-dominated thin layer of air next to the water-air interface. In field applications, it is of importance to accurately evaluate several environmental parameters, particularly the relative humidity and isotopic compositions of the 'free-atmosphere', for a system under investigation over a given time-scale of interest (e.g., hourly to daily to seasonally). With a growing interest in the studies of water cycles of different spatial and temporal scales, including paleoclimate and water resource studies, the importance and utility of the C-G model is also likely to grow in the future

[en] Reduction of perrhenate with stannous chloride at an excess of sodium gluconate in aqueous solution results in formation of rhenium(V) gluconate. The reaction proceeds slowly compared to that of pertechnetate. Aqueous solutions of rhenium(V) gluconate can be prepared down to a concentration level of at least 10 4 mol·^-1 within two hours. The usefulness of rhenium(V) gluconate to serve as a precursor for preparation of oxorhenium(V) complexes as potential radio therapeutic agents is revealed by subsequent ligand exchange reactions carried out with mercaptoacetyldiglycine, 3-thiapentane-dithiol-1,5/butanethiol and with 2-aminobenzenethiol. 5 figs., 14 refs

[en] An overview about shaking batch, diffusion and flow-through-column techniques for determination of sorption parameters of radionuclides in sediment/water systems is given. The evaluation of these processes makes evident, that only flowthrough-column process and recirculation-column process deliver sorption results close to nature. 13 figs; 4 tabs; 11 refs