Gabriele Wallner
University of Vienna
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Featured researches published by Gabriele Wallner.
Applied Radiation and Isotopes | 2009
M. Srncik; Daniel Kogelnig; Anja Stojanovic; Wilfried Körner; Regina Krachler; Gabriele Wallner
For determining natural levels of (236)U with its environmental abundance of 10(-16)% rather large sample volumes (approximately 30L) are necessary, therefore the conventional radiochemical uranium analysis (pre-concentration and column chromatography) is very time consuming. To speed up the procedure hydrophobic ionic liquids (ILs) were evaluated as a potential extraction agent for uranium from aqueous solutions. High selectivity and efficiency for uranium compared to calcium and magnesium in natural water was achieved with tricaprylmethylammonium thiosalicylate, [A336][TS]. Uranium was stripped successfully from the investigated ILs with 2M HNO(3).
Journal of Environmental Radioactivity | 2008
Gabriele Wallner; Rosmarie Wagner; Christian Katzlberger
Ten samples of Austrian mineral water were investigated with regard to the natural radionuclides (228)Ra, (226)Ra, (210)Pb, (210)Po, (238)U and (234)U. The radium isotopes as well as (210)Pb were measured by liquid scintillation counting (LSC) after separation on a membrane loaded with element-selective particles (Empore Radium Disks) and (210)Po was determined by alpha-spectroscopy after spontaneous deposition onto a copper planchette. Uranium was determined by ICP-MS as well as by alpha-spectroscopy after ion separation and microprecipitation with NdF(3). From the measured activity concentrations the committed effective doses for adults and babies were calculated and compared to the total indicative dose of 0.1 mSv/a given in the EC Drinking Water Directive as a maximum dose. The dominant portion of the committed effective dose was due to the radium isotopes; the dose from (228)Ra in most samples clearly exceeded the dose from (226)Ra.
Applied Radiation and Isotopes | 2009
Francesca Quinto; Peter Steier; Gabriele Wallner; A. Wallner; M. Srncik; Max Bichler; Walter Kutschera; F. Terrasi; A. Petraglia; C. Sabbarese
We present a first effort to investigate (236)U in the environment near a shutdown nuclear power plant far away from highly contaminated sites, by using accelerator mass spectrometry. The detection limit of about 1pg (236)U allowed us to identify a minimal increase of the (236)U/(238)U isotopic ratio correlated to a peak of (137)Cs in river sediments downstream of the nuclear power plant, and to detect anthropogenic (236)U also upstream, where it is probably not related to the power plant but to global fallout. The (236)U content shoved variations of the (236)U/(238)U isotopic ratio in relation to the chemical-physical characteristics of the sediments. This demonstrates the potential of (236)U as an environmental tracer, and as an indicator for releases from nuclear facilities.
Journal of Environmental Radioactivity | 2013
R. Eigl; M. Srncik; Peter Steier; Gabriele Wallner
Accelerator Mass Spectrometry (AMS) and alpha spectrometry were used to determine uranium ((236)U, (238)U, (234)U) and plutonium isotopes ((239)Pu, (240)Pu) in sea and river water samples. Plutonium was separated by Dowex(®) 1 × 8 resin and UTEVA(®) resin was used for uranium purification. The measured (236)U/(238)U isotopic ratios for surface water from the Atlantic Ocean, the Pacific Ocean and the Black Sea were in the order of 10(-9), while values for river water were in the order of 10(-8). These contaminations may be attributed to global fallout. A sample of the reference material IAEA-443, collected from the Irish Sea, showed, in accordance to the reference value, a ratio that was 10(3) times higher due to effluents from the reprocessing plant at Sellafield. These results underline the good suitability of (236)U/(238)U as a tracer for hydrology and oceanography, and show that relatively small water samples are sufficient for the determination of (236)U by AMS, which is not the case for plutonium with present techniques. The plutonium concentrations in our water samples could only be measured with large uncertainties and were in the order of 10(-3) mBq/L (with the exception of the Irish Sea sample).
Journal of Environmental Radioactivity | 2011
M. Srncik; Peter Steier; Gabriele Wallner
The vertical distribution of the 236U/238U isotopic ratio was investigated in soil samples from three different locations on La Palma (one of the seven Canary Islands, Spain). Additionally the 240Pu/239Pu atomic ratio, as it is a well establish tool for the source identification, was determined. The radiochemical procedure consisted of a U separation step by extraction chromatography using UTEVA® Resin (Eichrom Technologies, Inc.). Afterwards Pu was separated from Th and Np by anion exchange using Dowex 1x2 (Dow Chemical Co.). Furthermore a new chemical procedure with tandem columns to separate Pu and U from the matrix was tested. For the determination of the uranium and plutonium isotopes by alpha spectrometry thin sources were prepared by microprecipitation techniques. Additionally these fractions separated from the soil samples were measured by Accelerator Mass Spectrometry (AMS) to get information on the isotopic ratios 236U/238U, 240Pu/239Pu and 236U/239Pu, respectively. The 236U concentrations [atoms/g] in each surface layer (∼2 cm) were surprisingly high compared to deeper layers where values around two orders of magnitude smaller were found. Since the isotopic ratio 240Pu/239Pu indicated a global fallout signature we assume the same origin as the probable source for 236U. Our measured 236U/239Pu value of around 0.2 is within the expected range for this contamination source.
Journal of Environmental Radioactivity | 2013
Tania Jabbar; Gabriele Wallner; Peter Steier
A review of literature focused on (129)I determination in air is provided. (129)I analysis in the environment represents a vital tool for tracing transport mechanisms, distribution pathways, safety assessment and its application as environmental tracer. To achieve that, specific chemical extraction methods and high sensitivity analytical techniques have been developed. This paper is intended to give an overview about the sample collection, extraction and distribution of (129)I in the air. Sensitivity of available measurement techniques for the determination of (129)I is compared. The article also provides the summary of current worldwide distribution of (129)I in air and respective radiation exposure of man.
Journal of Environmental Radioactivity | 2011
M. Srncik; Erich Hrnecek; Peter Steier; Gabriele Wallner
Samples from a marine sediment core from the Irish Sea (54.416 N, 3.563 W) were analyzed for the isotopic composition of uranium, plutonium and americium by a combination of radiometric methods and AMS. The radiochemical procedure consisted of a Pu separation step by anion exchange, subsequent U separation by extraction chromatography using UTEVA® and finally Am separation with TRU® Resin. Additionally to radiometric determination of these isotopes by alpha spectrometry, the separated samples were also used for the determination of (236)U/(238)U and plutonium isotope ratios by Accelerator Mass Spectrometry (AMS) at the VERA facility.
Radiochimica Acta | 2008
M.B. Froehlich; Erich Hrnecek; Peter Steier; A. Wallner; Gabriele Wallner; Peter Bossew
Abstract The occurrence of 238Pu, 239(40)Pu, 241Am, 90Sr and 137Cs in the region of Nassfeld (Salzburg, Austria) is discussed at four different locations by evaluating a depth profile for each radionuclide. Furthermore, the plutonium separated from the soil samples was measured by Accelerator Mass Spectrometry (AMS) to get information on the isotope ratio 240Pu/ 239Pu. The radiochemical procedure consisted of a Pu separation step from Am and Sr by anion exchange in 8 M HNO3 after oxidation state adjustment to Pu(IV). Am and Sr were coprecipitated with calcium oxalate. Am was separated from Sr by extraction chromatography using TRU-resin. The Sr separation was performed also by extraction chromatography using Sr-resin; after coprecipitation as oxalate, 90Sr was measured in a gas proportional counter. For the determination of 239(40)Pu and 241Am by α-spectrometry thin sources were prepared by microprecipitation with NdF3. With the respective Pu isotope ratios, it was possible to identify the global fallout as source of the contamination. This was confirmed by the ratio 241Am/239(40)Pu. From the activity ratio 90Sr/ 137Cs, it could be shown that most of these radionuclides stem from the reactor accident in Chernobyl.
Science of The Total Environment | 2016
Regina Krachler; Rudolf F. Krachler; Gabriele Wallner; Peter Steier; Yasin El Abiead; Hubert Wiesinger; Franz Jirsa; Bernhard K. Keppler
Iron is a micronutrient of particular interest as low levels of iron limit primary production of phytoplankton and carbon fluxes in extended regions of the worlds oceans. Sphagnum-peatland runoff is extraordinarily rich in dissolved humic-bound iron. Given that several of the worlds largest wetlands are Sphagnum-dominated peatlands, this ecosystem type may serve as one of the major sources of iron to the ocean. Here, we studied five near-coastal creeks in North Scotland using freshwater/seawater mixing experiments of natural creek water and synthetic seawater based on a (59)Fe radiotracer technique combined with isotopic characterization of dissolved organic carbon by Accelerator Mass Spectrometry. Three of the creeks meander through healthy Sphagnum-dominated peat bogs and the two others through modified peatlands which have been subject to artificial drainage for centuries. The results revealed that, at the time of sampling (August 16-24, 2014), the creeks that run through modified peatlands delivered 11-15μg iron per liter creek water to seawater, whereas the creeks that run through intact peatlands delivered 350-470μg iron per liter creek water to seawater. To find out whether this humic-bound iron is bio-available to marine algae, we performed algal growth tests using the unicellular flagellated marine prymnesiophyte Diacronema lutheri and the unicellular marine green alga Chlorella salina, respectively. In both cases, the riverine humic material provided a highly bio-available source of iron to the marine algae. These results add a new item to the list of ecosystem services of Sphagnum-peatlands.
Radiochimica Acta | 2011
M.B. Froehlich; Klaus Mayer; Erich Hrnecek; Maria Wallenius; Zsolt Varga; Peter Steier; Gabriele Wallner
Abstract Uranium ores and yellow cake samples of known geographic origin were investigated for their n(236U)/n(238U) isotope abundance ratio. Samples from four different uranium mines in Australia, Brazil and Canada were selected. Uranium was separated by UTEVA® Resin and was measured by Accelerator Mass Spectrometry (AMS) at the Vienna Environmental Research Accelerator (VERA). The measurement of the isotope abundance ratio n(236U)/n(238U) will be used to investigate possible correlations between the original mineral (uranium ore) and the intermediate product (yellow cake). Such correlations are useful indicators for nuclear forensic or for non-proliferation purposes.