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Sima M.,Romanian Academy of Sciences | Dold B.,University of Lausanne | Frei L.,Ecole Polytechnique Federale de Lausanne | Senila M.,Research Institute for Analytical Instrumentation | And 2 more authors.
Journal of Hazardous Materials | Year: 2011

Sulfidic mine tailings have to be classified as one of the major source of hazardous materials leading to water contamination. This study highlights the processes leading to sulfide oxidation and acid mine drainage (AMD) formation in the active stage of two tailings impoundments located in the southern part of the Apuseni Mountains, in Romania, a well-known region for its long-term gold-silver and metal mining activity. Sampling was undertaken when both impoundments were still in operation in order to assess their actual stage of oxidation and long-term behavior in terms of the potential for acid mine drainage generation. Both tailings have high potential for AMD formation (2.5 and 3.7wt.% of pyrite equivalent, respectively) with lesser amount of carbonates (5.6 and 3.6wt.% of calcite equivalent) as neutralization potential (ABA=-55.6 and -85.1tCaCO3/1000t) and showed clear signs of sulfide oxidation yet during operation. Sequential extraction results indicate a stronger enrichment and mobility of elements in the oxidized tailings: Fe as Fe(III) oxy-hydroxides and oxides (transformation from sulfide minerals, leaching in oxidation zone), Ca mainly in water soluble and exchangeable form where gypsum and calcite are dissolved and higher mobility of Cu for Ribita and Pb for Mialu. Two processes leading to the formation of mine drainage at this stage could be highlighted (1) a neutral Fe(II) plume forming in the impoundment with ferrihydrite precipitation at its outcrop and (2) acid mine drainage seeping in the unsaturated zone of the active dam, leading to the formation of schwertmannite at its outcrop. © 2011 Elsevier B.V. Source

Talos F.,Babes - Bolyai University | Senila M.,Research Institute for Analytical Instrumentation | Frentiu T.,Babes - Bolyai University | Simon S.,Babes - Bolyai University
Corrosion Science | Year: 2013

The dissolution and surface layer changes of new xTiO2(100-x)[4SiO2·CaO·0.3P2O5] sol-gel derived xerogels (0≤x≤20mol%) have been investigated in Kokubo's simulated body fluid (SBF). The ionic leaching rate was analysed by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). ICP-AES results showed a relatively fast dissolution of titanium free sample, with a high release of phosphorous and calcium ions in the first hour of incubation while the release of silicon ions continuously increased up to 6h of immersion. The titanium dioxide addition up to 20mol% differently influences the release of phosphorus, calcium and silicon ions, i.e. TiO2 strongly stabilises the phosphorus ions, to a lesser extent the calcium ions, and has almost no effect on the silicon ions release. The structural changes were evaluated using X-ray powder diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The XRD results show that all samples remain mainly amorphous after immersion in SBF. The changes occurred in the surrounding of phosphorous and silicon ions are well reflected in FTIR spectra and they were correlated with the samples stability in SBF. © 2013 Elsevier Ltd. Source

Senila M.,Research Institute for Analytical Instrumentation
Journal of Environmental Health Science and Engineering | Year: 2014

Background Lead (Pb) is a toxic element that occurs in elevated concentrations in soils, mostly as a result of anthropogenic activities. This study assess the Pb bioavailability in soils from two areas with different contamination level using Diffusive Gradients in Thin-Films (DGT) technique, single extractions and metal contents of vegetables grown on contaminated soils. Results In the area situated far from mining and smelting activities, the pseudo total Pb concentration (12 - 51 mg kg-1 dw) was found to be comparable to that normally found in unpolluted areas. In the area from the vicinity of the Pb smelter very high concentrations of pseudo-total Pb (850 - 9300 mg kg-1 dw) were found. The average concentrations of Pb accumulated in onion, garlic, carrot, and parsley grown on this contaminated soils were 18, 48, 38 and 91 mg kg-1 dw, respectively, and represent a risk factor for the consumers. Conclusions The present study demonstrates the utility of DGT technique for the assessment of Pb bioavailability, since, generally, better correlations are obtained between the effective Pb concentration and Pb concentration in vegetables than for bioavailable Pb determined by chemical extractions and Pb concentration in vegetables. Source

Ardelean I.,Babes - Bolyai University | Lupsor S.,Babes - Bolyai University | Rusu D.,Research Institute for Analytical Instrumentation
Physica B: Condensed Matter | Year: 2010

xMnO·(100-x)[As2O3·TeO2] glass system, with 0≤x≤50 mol %, was prepared and investigated by FT-IR and Raman spectroscopies in order to determine its structure and the changes induced by the increasing of MnO content. The results offered by FT-IR and Raman spectroscopies suggest a structure formed by AsO3, TeO4 tbp and TeO3 tp units. The presence of MnO2 units was confirmed by FT-IR spectra only for high concentration of MnO. © 2010 Elsevier B.V. All rights reserved. Source

Torok Z.,Babes - Bolyai University | Ozunu A.,Babes - Bolyai University | Cordos E.,Research Institute for Analytical Instrumentation
Environmental Engineering and Management Journal | Year: 2011

Technological accidents caused the loss of many human lives, the major pollution of the environment and significant financial losses. These accidents can be categorized in three major classes: fires, explosions and toxic releases. The prevention of technological accidents can be made in two ways, on one hand with technological improvements, on the other hand with legislative regulations. According to EU legislation Land-Use Planning is necessary and essential study for Seveso-type sites. Four years after the adhesion of Romania to the EU there is still missing a common risk analysis methodology which could be used for Land-Use Planning purpose. This paper (part one) opens a series of three papers proposing a risk assessment methodology and guidance limits for the estimation of physical effects of fires (in part one), and calculation of safety distances for Land-Use Planning for Seveso-type sites. With this purpose, different case studies were considered with technological accidents involving flammable hazardous materials. In this first part heat radiations from different types of fires were studied and physical effects and safety distances were calculated. Several methodologies applied in the EU member states were approached, while the proposed methodology is based on the results of this research. Source

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