Characterization and assessment of potential environmental risk of tailings stored in seven impoundments in the Aries river basin, Western Romania

BACKGROUND: The objective of this study was to examine the potential environmental risk of tailings resulted after precious and base metal ores processing, stored in seven impoundments located in the Aries river basin, Romania. The tailings were characterized by mineralogical and elemental composition, contamination indices, acid rock drainage generation potential and water leachability of hazardous/priority hazardous metals and ions. Multivariate statistical methods were used for data interpretation. RESULTS: Tailings were found to be highly contaminated with several hazardous/priority hazardous metals (As, Cu, Cd, Pb), and pose potential contamination risk for soil, sediments, surface and groundwater. Two out of the seven studied impoundments does not satisfy the criteria required for inert wastes, shows acid rock drainage potential and thus can contaminate the surface and groundwater. Three impoundments were found to be highly contaminated with As, Pb and Cd, two with As and other two with Cu. The tailings impoundments were grouped based on the enrichment factor, geoaccumulation index, contamination factor and contamination degree of 7 hazardous/priority hazardous metals (As, Cd, Cr, Cu, Ni, Pb, Zn) considered typical for the studied tailings. Principal component analysis showed that 47% of the elemental variability was attributable to alkaline silicate rocks, 31% to acidic S-containing minerals, 12% to carbonate minerals and 5% to biogenic elements. Leachability of metals and ions was ascribed in proportion of 61% to silicates, 11% to acidic minerals and 6% to the organic matter. A variability of 18% was attributed to leachability of biogenic elements (Na, K, Cl(-), NO(3)(-)) with no potential environmental risk. Pattern recognition by agglomerative hierarchical clustering emphasized the grouping of impoundments in agreement with their contamination degree and acid rock drainage generation potential. CONCLUSIONS: Tailings stored in the studied impoundments were found to be contaminated with some hazardous/ priority hazardous metals, fluoride and sulphate and thus presents different contamination risk for the environment. A long term monitoring program of these tailings impoundments and the expansion of the ecologization measures in the area is required

The influence of feed protein level on some productive indices in Barred Plymouth Rock reared in free range system

The purpose of this paper was to assess the possibility of grow mixed breed broilers in free range system fed according to the slow feeding rate, with nutritional requirements mainly consisting of feed concentrate mixtures starting from the premises that currently there are no nutritional standards especially created for maintenance alternative systems. The experiment for the quantification of impact of nutritional features and of the CM administration intake on bio productive and economic performances of Barred Plymouth Rock avian youth has been reared during 10 weeks on two experimental variants. The elaborated experimental design was intended to assess the effect of a good nutritional start in both variants, but with a different time. Considering the same start, both in Vi and V2, by administering an CM with 2960 kcal ME and 22.04% CP, for 14 days in V| and 21 days in V2.Vi received a tri-phase feeding by using an intermediary „growing" phase during 36 days when CM was administered with 2990 kcal ME/kg and 20.03% CP followed by a finishing phase after 50 days and continued until the end of experiment, when CM was administered with 3000 kcal ME/kg and 17.30% CP. V2 was intended to establish the effect of a bi-phase feeding, therefore phase II became the „growing-finishing" phase, respectively the administration of a feed concentrate mixture with an energy level of 3000 kcal ME and 17.30% CP. Broilers in V,, tri-phase fed, had a feed intake comparison with that of broilers in V2 (bi-phase fed), an average body weight of 1428.60 g with a total increase of 8.3% higher and a better feed conversion (2.66 kg/kg) considering the increased costs per kg of live mass with 1.87% comparing with V2. Regarding the CP intake, depending on ME intake, the registered values are close in both variants. Based on a mathematic model like: y = a/(l+bx+cx2 ), one can assess the fodder feeding costs. The correlation rate between the fodder feeding costs and the CP intake is strongly positive for both variants

Influence of heavy metal ions on the luminescence of zinc oxide-based compounds

Luminescent zinc hydroxide (ZH) and zinc carbonate (ZHC) compounds were prepared by precipitation with different precipitating agents. The effect of various heavy metal ions on the optical properties of samples was discussed

PHYSICOCHEMICAL INVESTIGATION OF SOME GEOTHERMAL WATERS FROM SĂLAJ COUNTY, ROMANIA

Geothermal waters solve minerals from the geological layers due to their increased temperature. These minerals affect water hardness and salinity. Therefore, thermal water samples were collected from spa pools springs in Sălaj County, Romania: Broscărie (Șimleul Silvaniei), Jibou and Boghis. The physicochemical measurement reveals that Jibou water has a higher electrical conductivity of 10580 µSi/cm, caused by the higher value of total dissolved solids (TDS) of 5264 mg/l. It is followed by the water collected from Broscărie, with an electrical conductivity of 1949 µSi/cm related to TDS of 1023 mg/l. The weaker mineralization was found in Boghis water, around 619 mg/l, corresponding to an electrical conductivity of 1200 µSi/cm. Water hardness is related to the amount of CaCO3. Boghis water is the hardest, containing 356 mg/l, followed by the samples collected from Broscărie, with 178 mg/l. The water collected from Jibou is the softest of all samples, with a CaCO3 amount of about 106.8 mg/l. The mineral distribution was assessed by mineralogical optical microscopy (MOM) and X ray diffraction (XRD). The results show that NaCl crystallized as halite is responsible for the samples’ salinity, while aragonite, magnesian calcite and calcite are the minerals which cause the water hardness. Hard thermal water containing Ca and Mg are effective for rheumatoid symptoms amelioration, while salted water is optimal for skin care

Investigation of Ferrous Conglomerate Particles Found in Carwash Slurry and Their Environmental Implications

Ferrous particles are usually found in atmospheric particulate matters due to the cars chassis oxidation. These particles are able forming conglomerates with the other mineral particles. Thus, the investigated carwash slurry (CS) reveals a high mineralized composition dominated by Quartz, Calcite and clay minerals with significant amount of iron hydroxides. We found some unusual bigger particles of ferrous conglomerate (FC) into the CS sample. XRD and mineralogical microscopy (MOM) reveal that FC sample is formed by a nanostructured mixture of 56 wt.% Calcite and 44 wt.% Goethite. SEM images and EDS spectra reveal submicron particles within the FC structure with a dense mixture of Ca and Fe. FTIR investigation reveal strong absorption bands for goethite and very weak ones for Lepidocrocite within the FC sample. The results indicates that the conglomerate weas formed on the car chassis rust by wet partial dissolution of calcite that locally forms Ca(OH)2 which further is re-crystallized as calcite due to the CO2 from the combustion gases. Fine crystallites of iron hydroxides are embedded into the re-crystallized calcite. In conclusion, the magnetic selection is recommended for the ferrous conglomerate particles removal from CS to be used as natural coverage for of urban dump sites rehabilitation

Porous chalcogenide based on zinc sulfide with enhanced adsorption properties

We report the preparation of porous zinc indium sulfide (ZIS) with high ability to adsorb organic dyes such as methyl orange (MO). The influence of reaction temperature and zinc concentration on the morpho-structural characteristics of ZIS were investigated

COPPER(II) COMPLEXES WITH NEW N-SUBSTITUTED SULFONAMIDES – SYNTHESIS, CRYSTAL STRUCTURE AND EVALUATION OF THE NUCLEASE ACTIVITY

Binary Cu(II) complexes of two new N-substituted sulfonamides, N-(pyridin-2-yl-methyl)biphenyl-4-sulfonamide (HL1) and N-bis-(pyridin-2-yl-methyl)biphenyl-4-4’-sulfonamide (H2L2), have been synthesized and characterized by X-ray diffraction, spectroscopic and electrochemical techniques. The structure of complex [Cu(L1)2] consists of a discrete monomeric Cu(II) species stabilized by π-π stacking interactions involving the pyridyl and phenyl rings of the coordinated ligands. In contrast, in the case of complex [Cu(L2)]n, each symmetrical  sulfonamide structure coordinates two Cu(II) ions, giving rise to a polymeric chain. Upon coordination, CuN4 chromophores with the N-pyrydil atoms in trans position are generated, and the coordination geometry of both complexes can be best described as highly distorted square-planar. The ability of complex [Cu(L1)2] to promote DNA cleavage with ascorbate activation was also evaluated; the complex has a moderate nuclease activity, being able to partially cleave supercoiled DNA to nicked circular and linear DNA. We herein also report the evaluation of the nuclease activity of complex Cu2(N-(pyridin-2-yl)biphenyl-4-sulfonamidate)4, previously characterized in terms of structure by our group

Template and template-free preparation of one-dimensional metallic nanostructures

In this article, we have studied and developed two approaches for organizing metallic nanoparticles into one-dimensional assemblies. The first uses DNA as a \u27template\u27 and allows the preparation of various silver nanostructures (\u27beads-on-a-string\u27 or rod-like wires). The conductance of such nanostructures was demonstrated by employing a powerful technique, Electrostatic Force Microscopy (EFM). This technique gave us \u27contactless\u27 information about the electrical properties of silver nanostructures, aligned on a SiO2/Si surface. Additionally, I-V characteristics of a single silver nanowire crossing two microelectrodes were recorded. The nanowire resistivity was estimated at 1.46 x 10(-7) Omega m (at 300 K), which is one order of magnitude higher than that of bulk silver (1.6 x 10(-8) Omega m). The second approach is a \u27template-free\u27 one, and exploits the binding ability of l-arginine, which favours the self-assembling of capped gold nanoparticles into gold nanochains. The results suggest that gold nanochains were formed due to dipole-dipole interaction between adjacent nanoparticles, which fuse together through an oriented attachment mechanism. Atomic force microscopy, TEM, UV-vis spectroscopy and X-ray diffraction were used to characterize the morphological, optical and structural properties of these metallic nanostructures

Electrochemical detection of lead at zinc oxide nanostructure based modified electrode

A modified glassy carbon electrode (ZnO-Nafion/GCE) prepared by drop-casting technique, was investigated by square wave anodic stripping voltammetry (SWASV) for the detection of Pb2+ in synthetic and reals water samples

INFLUENCE OF THE THERMAL TREATMENT ON THE COLOUR OF RO٠Al₂O₃ (R=Co, Ni) TYPE SPINEL PIGMENTS PREPARED BY A MODIFIED SOL – GEL METHOD

This paper presents the results obtained through the synthesis of spinel-structured, ceramic pigment nanopowders (CoAl2O4 si NiAl2O4), using a modified sol-gel method. This study focuses on the influence of the thermal treatment, applied during gel calcination, on the properties of the obtained powders. The behavior of the dried gels during calcination was studied by differential thermal analysis. The formation of the spinel structure after the thermal treatment, was analyzed using X-ray diffraction. The colour of the powders was characterized by UV–VIS spectroscopy, determining the absorption spectra. Additionally, the trichromatic coordinates were determined, and the corresponding pigment positions were fixed on the chromaticity diagram