Abstract  A fast and accurate procedure has been developed for the determination of uranium at mu g L-1 level in tap and mineral water. The method is based on the direct introduction of samples, without any chemical pre-treatment, into an inductively coupled plasma mass spectrometer (ICP-MS). Uranium was determined at the mass number 238 using Rh as internal standard. The method provides a limit of detection of 2 ng L-1 and a good repeatability with relative standard deviation values (RSD) about 3% for five independent analyses of samples containing 73 mu g L-1 of uranium. Recovery percentage values found for the determination of uranium in spiked natural samples varied between 91% and 106%. Results obtained are comparable with those found by radiochemical methods for natural samples and of the same order for the certified content of a reference material, thus indicating the accuracy of the ICP-MS procedure without the need of using isotope dilution. A series of mineral and tap waters from different pants of Spain and Morocco were analysed.

Abstract  Globally, rivers supply uranium to the oceans with excess U-234 relative to secular equilibrium and U-234 taken-up by corals can be used for dating. In addition, the U-234 abundance in sea water, at the time the coral was growing, can be measured independently. The veracity of U-series ages used in determining past sea-level variations is dependent on selecting pristine corals free from diagenetic alteration. A quantitative test for alteration assumes invariant U-234 abundances in the oceans for at least the past half a million years and results from samples outside of a narrow range in modern ocean U-234 abundance are excluded from data sets. Here, we have used previously published data to show that U-234 in the oceans appears to be variable and directly related to changes in sea-level, not only over long glacial-interglacial timescales but also at very short, centennial timescales. Most of the previously discarded data can be used to provide valuable additional sea-level information. The process permits a unique insight into the interplay between sources and sinks of uranium in the oceans mediated by sea-level changes at rates far faster than previously thought possible. Similar, rapid sea-level, forcing of other trace element abundances in the oceans is likely. Crown copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.

Abstract  Cultured rabbit kidney cells were exposed to uranyl acetate. This produced single-membrane-bound presumably lysosomal bodies (called 'uraniosomes') containing electron-dense crystals in the cultured cells. Similar crystalline deposits were seen in extracellular locations also. All uraniosomes and extracellular uranium deposits analyzed by electron-probe x-ray analysis were found to contain uranium, potassium, calcium and phosphorus. Traces of sulphur were detected in some but not all uraniosomes and extracellular uranium deposits.

Abstract  The Senonian phosphorites in the Arad basin contain significant amounts of uranium. The average uranium concentrations in the Ghareb Formation, and the phosphate-lean and phosphate-rich beds of the Mishash Formation are 22,47 and 106 ppm, respectively, and the average uranium/phosphate ratios in these units are 7.4, 5.5 and 4.5. It is estimated that the Mishash and Ghareb Formations contains about 3,900 and 350 tons of uranium per square kilometre, respectively The abundance of uranium and its relations to the concentration of phosphate is examined in various subpopulations defined by stratigraphic position and/or phosphate content There exists a high positive correlation between the concentrations of uranium and phosphate (R=0.9 for individual samples and R=0.98 for means). The regression line between the two variables is Uppm=9.0+4.0 (phosphate%). The positive intercept indicates the existence of excessive amounts of uranium, over and above the concentrations which can be attributed to the uranium which is incorporated in francolite. Since independent uranium minerals are found in association with the phosphorites, the extra uranium is most likely due to secondary uranium minerals, formed by the leaching of uranium from the phosphorites. The possible remobilization of uranium out of phosphorites poses obvious potential environmental hazards for land use and the toxic contamination of groundwater resources.

Abstract  In the Vromos Bay area, Southeastern Bulgaria, near the Black Sea coast, drainage waters from flotation tailings ponds and piles of low-grade polymetallic ores are heavily contaminated with radioactive elements (U, Ra, Th) and some toxic heavy metals (mainly Cu, Cd, Pb, Mn). Some of these waters were treated by a natural wetland characterized by a plant community in which Phragmites communis was the dominant species. Different species of Scirpus, Juncus, Carer and Poa as well as some algae were also present. However, Typha latifolia and Typha angustifolia were very rare and were present as single plants in this wetland. The pH of the waters being treated was in the slightly alkaline range (from 7.5 to 8) and flow rate varied from 0.2 - I l/s. The watercourse in the wetland was about 80 m long and water depth varied in the range of about 5 - 30 cm. The water treatment was started in March 1998 and until now (May 1999) the wetland effluents were characterized by pollutant concentrations decreased below the relevant permissible levels for waters intended for use in agricultural and/or industry. The removal of pollutants was due to different processes but the microbial dissimilatory sulphate reduction and biosorption played the main role. Uranium was precipitate mainly as uraninite (UO2), the heavy metals were precipitated mainly as the relevant insoluble sulphide, and the largest portion of radium was absorbed by the organic matter (both viable and dead) and clay minerals present in the wetland. Negative effects of the pollutants on the growth and activity of the indigenous plant and microbial communities were not observed. The efficiency of the water clean up markedly depended on the ambient temperature. However, excellent results were achieved even in the cold winter months (December - February) at temperatures about 0 degrees C.

Abstract  Two experimental plots of an agricultural land contaminated with radioactive elements (uranium, radium thorium) and toxic heavy metals (copper, zinc, cadmium) were treated by two different biotechnological in situ methods. The soil in this land was characterized by a negative net neutralization potential, and the soil pH was in a slightly acidic pH range (from 4 to 5). The contaminants were located mainly in the upper soil layers (mainly in the horizon A). Both methods were connected with the initial solubilization of the contaminants. Water acidified with sulphuric acid was used as a leach solution. The solubilization was mainly a result of the activity of the indigenous soil microflora. This activity was enhanced by suitable changes in the levels of some essential environmental factors, such as water, oxygen and nutrient content of the soil. The first method was then connected with the removal of the dissolved contaminants from the soil through the soil effluents. The second method was based on the transfer of the contaminants into the deeply located soil horizon B-2, where they were immobilized mainly as a result of the activity of the indigenous sulphate- reducing bacteria. Their activity was enhanced by injecting water solutions of organic compounds into the horizon B-2 through boreholes located in the relevant experimental plot. (C) 2001 Elsevier Science B.V. All rights reserved.

Abstract  The Gas Test Loop (GTL)-1 irradiation experiment was conducted in the Advanced Test Reactor (ATR) to assess corrosion performance of proposed booster fuel at heat flux levels similar to 30% above the design operating condition. Sixteen miniplates fabricated from 25% enriched, high-density (4.8 g U/cm(3)) U3Si2/Al dispersion fuel with 6061 aluminum cladding were subjected to peak beginning of cycle (BOC) heat fluxes ranging from 411 to 593 W/cm(2). No adverse impacts to the miniplates were observed at these high heat flux levels. A detailed finite element model was constructed to calculate temperatures and heat flux for an as- run cycle average effective ATR south lobe power of 25.4 MW(t). Miniplate heat flux levels and fuel, cladding, hydroxide, and coolant-hydroxide interface temperatures were calculated using the average hydroxide thickness on each miniplate measured during post-irradiation examination. The purpose of this study was to obtain a best estimate of the as-run experiment temperatures to aid in establishing acceptable heat flux levels and designing fuel qualification experiments for this fuel type. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  Fuel cycle analyses are performed to evaluate the impacts of further transmutation of spent nuclear fuel on high-level and low-level waste mass flows into repositories, on the composition and toxicity of the high-level waste, on the capacity of high- level waste repositories, and on the proliferation resistance of the high-level waste. Storage intact of light water reactor (LWR) spent nuclear fuel, a single recycle in a LWR of the plutonium as mixed-oxide fuel, and the repeated recycle of the transuranics in critical and subcritical fast reactors are compared with the focus on the waste management performance of these systems. Other considerations such as cost and technological challenges were beyond the scope of this study. The overall conclusion of the studies is that repeated recycling of the transuranics from spent nuclear fuel would significantly increase the capacity of high-level waste repositories per unit of nuclear energy produced, significantly increase the nuclear energy production per unit mass of uranium ore mined, significantly reduce the radiotoxicity of the waste streams per unit of nuclear energy produced, and significantly enhance the proliferation resistance of the material stored in high-level waste repositories.

Abstract  Degradation of 4-chloro-2-methylphenol(PCOC), a refractory toxic chemical emitted to the environment from the industrial production of phenoxy herbicides was studied in aqueous solution. Electro-Fenton and photoelectro-Fenton processes were used as the degradation methods. H(2)O(2), produced by the reduction of oxygen at carbon cathode reacted with dissolved metal ions to form hydroxyl radicals, which in turn reacted with PCOC sequentially to degrade the aromatic ring. The effects of using different [Fe(2+)]/[PCOC](0) and the effect of replacing Fe(2+) by Mn(2+) ion have been examined. It was found that degradation rate was increased with increasing [Fe(2+)]/[PCOC](0) ratio from 2 to 4. However, the total charge utilized during the treatment was also increased. The efficiency of PCOC degradation was observed to be higher when Mn(2+) was used as the catalyst. The mineralization of aqueous solutions of PCOC, withdrawn from the reactor at certain time interval. has been followed by total organic carbon (TOC) decay and dechlorination. A fast and complete degradation of the aromatic ring was achieved in photoelectro-Fenton system. 41.7% charge during a 300 min photoelectron-Fenton TOC decay and complete dechlorination were observed by consuming only 141.4 C electrical char treatment. In the case of electro-Fenton system, 280.7 C electrical charge was consumed during 450 min of electrolysis to attain a similar degradation of PCOC. 14.9% TOC removal and 89.3% dechlorination have been obtained in this system under the applied conditions. (c) 2005 Elsevier B.V. All rights reserved.

Abstract  On the Kyrgyzstan territory there are 46 tailing dumps where stored more than 600 Mm(3) of tails. They are man-caused solids of fine-dispersed waste of reprocessing and contain radioactive nuclides, heavy metals Compounds and toxic substances used as reagents in extraction processes depending oil the reprocessed ore. Tailing dumps of radioactive waste are in the cities of Mailuu-Suu, Kadji-Sai, Min-Kush and Kara-Balta occupied nearly 3,600 m 2 of total area. In this connection we are confirmed that for rehabilitation of uranium tailing dumps, along with the engineering works, reconstruction of ecosystems and soil densification, it is necessary to conduct by means of phytomeliorative actions.

Abstract  Ion imprinted polymer (IIP) material of mesoporous nature was prepared in two steps: (i) by forming binary/ternary complexes of uranyl imprint ion with a suitable non-vinylated uranophile, formamidoxime and/or vinylated ligand, 4-vinyl pyridine (VP) and (ii) by thermally copolymerizing them with 2-hydroxy ethyl methacrylate (HEMA) as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the cross-linking monomer in presence of 2,2'-azobisisobutyronitrile as initiator and 2-methoxy ethanol as porogen. The IIP material formed was subsequently leached with 50% (v/v) HCl to obtain leached materials which then rebind uranyl ions selectively from aqueous solutions. Corresponding non-imprinted polymer (NIP) materials were also prepared under the same conditions exactly as the UP but in the absence of the uranyl ion template. Extensive characterization of IIP (both unleached and leached) and NIP materials were done using SEM, XPS, EDS, IR and BET-surface area and pore size analysis. The optimal pH for quantitative removal is 8.0-9.0 and the HIP materials offered either higher or comparable retention capacity 80.0 mu mol of uranyl ion per g of polymer with respect to most of the hitherto prepared uranyl IIP materials. In addition, the imprinting effect was noticed in all the experimental variables and selectivity characteristics. The applicability of IIP material for the removal of emerging toxic pollutant uranium from uranium mining industry feed simulant solution is successfully demonstrated. (C) 2008 Elsevier Inc. All rights reserved.

Abstract  The strain Lysinibacillus sphaericus JG-A12, isolated from the uranium mining site at Haberland. Saxony (Germany) selectively and reversibly accumulates radionuclides and toxic metals. Metal binding occurs to its surface layer (S-layer) surrounding the cells. Here, we have studied by Fourier-transform infrared (FTIR) spectroscopy the protein structure and stability as a function of Au-III binding and the subsequent reductively induced formation of Au-nanoclusters. Similar to previously studied complexes with Pd-II. Au-treated S- layers become resistant to acid denaturation evidenced by little response of their amide I absorption frequency. However, the strong effect of Pd-II on the side chain carboxylate IR absorption intensity is not observed with gold. Particularly after reduction, the carboxyl absorption responds little to acidification and a fraction appears to be protonated already at neutral pH. We ascribe this to a hydrophobic environment of the carboxyl groups after formation of Au-nanoclusters. EXAFS spectra agree with the metallic Au-Au distance but the reduced coordination number indicates that the Au-nanoclusters do not exceed similar to 2 nm. Thus, the S-layer of L. sphaericus JG-A12 provides a biotemplate for efficient Au-nanocluster formation in an acid-resistant matrix and independently of cysteins.

Abstract  The effect of solvent/monomer (S/M) feed ratio on the structure and adsorption properties of copper(II)-imprinted microporous polymer particles was investigated. Copper(II) ion-imprinted microporous particles were prepared from two functional monomers, methacrylic acid (MAA) and vinyl pyridine (4-VP), by forming a complex with the template copper ion by ionic interactions. The self-assembled copper/monomer complex was polymerized in the presence of an ethylene glycol dimethacrylate (EGDMA) cross-linker by a suspension polymerization. The diameter of the prepared microparticles was 200-700 mu m. The chemical structure, morphology and adsorption capacity of the Cu(II)-imprinted microporous particles were analyzed using scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) test, atomic adsorption spectroscopy (AAS), furrier transform infrared spectroscopy (FTIR), and energy dispersive X-ray spectrometer (EDX). The adsorption capacity of the imprinted beads for the template ion, Cu(II), was significantly affected by the initial concentration and pH of the feed solution. The imprinted particles showed high selectivity for the copper ion, as the adsorption capacity for the Cu(II) ion was much higher than that of other metal ions such as Ni (II), Zn(II), and Cd(II). The adsorption capacity, adsorption kinetics, and selectivity of the imprinted particles prepared in this study, however, were not significantly affected by the S/M feed ratio. (C) 2010 Elsevier B.V. All rights reserved.

Abstract  Although essential for plants, copper can be toxic when present in supra-optimal concentrations. Metal polluted sites, due to their extreme conditions. can harbour tolerant species and/or ecotypes. In this work we aimed to compare the physiological responses to copper exposure and the uptake capacities of two species of duckweed, Lemna minor (Lm(EC1)) and Spirodela polyrrhiza (SP), from an abandoned uranium mine with an ecotype of L minor (Lm(EC2)) from a non-contaminated pond. From the lowest Cu concentration exposure (25 mu m) to the highest (100 mu M), Lm(EC2) accumulated higher amounts of copper than Lm(EC1) and SP. Dose-response curves showed that Cu content accumulated by Lm(EC2) increases linearly with Cu treatment concentrations (r(2) = 0.998) whereas quadratic models were more suitable for Lm(EC1) and SP (r(2) = 0.999 and r(2) = 0.998 for Lm(EC1) and SP, respectively). A significant concentration-dependent decline of chlorophyll a (chl a) and carotenoid occurred as a consequence of Cu exposure. These declines were significant for Lm(EC2) exposed to the lowest Cu concentration (25 mu M) whereas for Lm(EC1) and SP a significant decrease in chl a and carotenoids was observed only at 50 and 100 mu M-Cu. Electric conductivity (EC) and malondialdehyde (MDA) content increased after Cu exposure, indicating oxidative stress. Significant increase of EC was observed in Lm(EC2) for all Cu concentrations whereas the increase for Lm(EC1) and SP became significant only after an exposure to 50 mu M-Cu. On the contrary, for Lm(EC1), SP, and Lm(EC2), MDA content significantly increased even at the lowest concentration. Protein content and catalase (CAT) activity showed a decrease with an increase in Cu concentration. For the species Lm(EC1)and SP, a significant effect of copper on CAT activity was observed only at the highest concentration (100 mu M-Cu) whereas, for Lm(EC2), this effect started to be significant after an exposure to 50 mu M-Cu. Superoxide dismutase (SOD) activity increased with increasing concentrations of Cu, with a very similar trend between the three populations of duckweed. However, due to the facts that enzyme activity is expressed as units of activity per gram of protein and that protein content decreased with Cu exposure, the increase in SOD activity might partly result from a relative increase of this enzyme inside the pool of proteins. Consequently, the results obtained in our experimental conditions strongly suggest that duckweed species from the uranium-polluted area have developed mechanisms to cope with metal toxicity and that this tolerance is based on the existence of protective mechanism to limit the metal uptake rather than on an enhancement of the antioxidative metabolism. (c) 2008 Elsevier B.V. All rights reserved.

Abstract  As a result of many years of research on environmental parameters in Kyrgyzstan, the main sources of radioactive and toxic matter contaminations have been established. The territory of Kyrgyzstan is constantly exposed to pollution by radionuclides caused by stratospheric, tropospheric, and local atmospheric fallouts. The other sources are the uranium tailings located at some places, which are a real threat for the environment and human health. Some methodological questions about the influence of geophysical conditions on the territorial distribution of contaminations have been considered. The tropospheric mechanism of contamination transfer for different seasons of the year has been suggested.

Abstract  Acid mine water from in situ chemical leaching of uranium (Straz pod Ralskem, Czech Republic) was treated in laboratory scale experiments by zero-valent iron nanoparticles (nZVI). For the first time, nZVI were applied for the treatment of the real acid water system containing the miscellaneous mixture of pollutants, where the various removal mechanisms occur simultaneously. Toxicity of the treated saline acid water is caused by major contaminants represented by aluminum and sulphates in a high concentration, as well as by microcontaminants like As, Be, Cd, Cr, Cu, Ni, U, V. and Zn. Laboratory batch experiments proved a significant decrease in concentrations of all the monitored pollutants due to an increase in pH and a decrease in oxidation-reduction potential related to an application of nZVI. The assumed mechanisms of contaminants removal include precipitation of cations in a lower oxidation state, precipitation caused by a simple pH increase and co-precipitation with the formed iron oxyhydroxides. The possibility to control the reaction kinetics through the nature of the surface stabilizing shell (polymer vs. FeO nano-layer) is discussed as an important practical aspect. (C) 2010 Elsevier Ltd. All rights reserved.

Abstract  This paper gives a general overview about bio distribution studies which are especially related to engineered nanoparticles (NPs) made of gold and silver. The analysis of biological materials from bio distribution studies plays a significant role in the application of atomic spectrometry to study NPs. Therefore, special focus is given to the generally applied strategy as well as the use of the inductively coupled plasma mass spectrometry (ICP-MS) technique for the determination of the NPs containing metals. An overview of the recent research applications on gold and silver NPs is also presented. While for gold NPs a large variety of very different sizes, shape and coating are known, they also provide many opportunities in imaging, diagnostics, and therapies of nanomedicine. Hence, their bio kinetics in the body are prerequisites for specific tailoring of nanomedicinal applications and for a comprehensive risk assessment. Silver NPs are applied in a lot of consumer products; therefore it is useful to get a better understanding of their in vivo distribution. (c) 2012 Elsevier B.V. All rights reserved.

Abstract  The feasibility of using sulfur-containing organophosphorus reagents for the chelation-supercritical fluid extraction (SFE) of toxic heavy metals and uranium from acidic media was investigated. The SFE experiments were conducted in a specially designed flow-through liquid extractor. Effective extraction of the metal ions from various acidic media was demonstrated. The effect of the ligand concentration in supercritical CO2 on the kinetics of metal extraction was studied. A simplified model is used to describe the extraction kinetics, and good agreement of experimental data with the equilibrium-based model is achieved.

Abstract  The graft polymerization of acrylonitrile on crosslinked polyvinyl alcohol (CPVA) microspheres was performed by using cerium ammonium sulfate as initiator, and grafted microspheres CPVA-g-PAN were prepared. Subsequently, the grafted PAN was converted into poly (amidoxime) (PAO) via amidoximation reaction with hydroxylamine hydrochloride as reagent, resulting in the functional microspheres CPVA-g-PAO. The chemical structure and physicochemistry characters of CPVA-g-PAO microspheres were adequately characterized by infrared spectrum (FTIR), scanning electron microscope (SEM) and determining zeta potential. The effects of main factors on the amidoximation transform reaction of the grafted PAN were studied with emphasis, and the adsorption property of the functional microspheres CPVA-g-PAO for some biomolecules was examined preliminarily with uric acid as a model biomolecule. The experimental results show that in the a midoximation transform reaction of nitrile groups, medium pH and reaction temperature are two main factors. For this system, the adequate pH value and temperature are 6 similar to 7 and 70 degrees C. Under the fitting conditions, the conversion ratio of the nitrile group of the grafted PAN reaches 72% for 4 h. In a wider pH range, the zeta potential of the microspheres CPVA-g-PAO is a greater positive value. They exhibit strong adsorption ability for uric acid, a toxic endogenrsis molecule,and the adsorption capacity can get up to 95 mg/g.

Abstract  Uranium is one of the most toxic radionuclide contaminants and is progressively dispersing in the environment due to the exploration and utilization of nuclear energy. Uranium in the environment endangers both human and animal health, and thus proper management of uranium-contaminated environments has become an urgent need. For treatment of soils contaminated with uranium, traditionally employed chemical (extraction/washing, immobilization) and physical (excavation and disposal) treatment technologies are costly and have produced uncertain results and consequently, alternative pollution control techniques involving various strategies have been considered. Phytoremediation has been widely accepted as an economic, environment-friendly and efficient approach for management of soils contaminated by uranium. As uranium speciation and its bioavailability are closely related to soil properties, such as pH, organic matter, phosphates, carbonates, and iron oxides, they act as key factors influencing uranium uptake by plants. Based on the knowledge of these factors, various soil amendments such as citric acid, calcium carbonate, and phosphate to improve bioavailability of uranium have been proposed. In addition, inoculation of plants with biological amendments such as arbuscular mycorrhizal fungi has also emerged as an effective remediation strategy for uraniumcontaminated soils. In aquatic environments, rhizofiltration can be used as a suitable approach for uranium remediation. With the recent developments, phytoremediation has the potential to become an integral part of the management of uranium-contaminated environments.

Abstract  A highly Al-resistant dissimilatory sulphate-reducing bacteria community was isolated from sludge of the wetland of Urgeiriça mine (community W). This community showed excellent sulphate removal at the presence of Al³⁺. After 27 days of incubation, 73, 86 and 81% of sulphate was removed in the presence of 0.48, 0.90 and 1.30 mM of Al³⁺, respectively. Moreover, Al³⁺ was simultaneously removed: 55, 85 and 78% of metal was removed in the presence of 0.48, 0.90 and 1.30 mM of Al³⁺, respectively. The dissociation of aluminium-lactate soluble complexes due to lactate consumption by dissimilatory sulphate-reducing bacteria can be responsible for aluminum removal, which probably precipitates as insoluble aluminium hydroxide. Phylogenetic analysis of 16S rRNA gene showed that this community was mainly composed by bacteria closely related to Desulfovibrio desulfuricans. However, bacteria affiliated to Proteus and Ralstonia were also present in the community.

Abstract  Cadmium (Cd) and uranium (U) are potentially toxic metals added to soil via phosphate fertiliser. Measured Cd and U concentrations in archived soils of the Winchmore long-term fertiliser indicated annual accumulation rates increased with the rate of superphosphate (SSP) applied, up to 5 mg Cd kg(-1) and 7 mg U kg(-1) in plots receiving 376 kg SSP ha(-1) y(-1). At the same rate of application, Cd was enriched in dryland compared to irrigated topsoil, while sampling to 30 cm showed that Cd, and less so U, moved down the profile in proportion to the rate of SSP applied and irrigation frequency. Using data in a mass balance suggested that soil Cd enrichment may have recently reached a plateau. The current rates of Cd and SSP application at Winchmore are unlikely to further enrich topsoil beyond the soil trigger value in the planned New Zealand Cd management strategy of 1 mg Cd kg(-1).