Water Quality Survey of Streams from Retezat Mountains (Romania)

The Retezat Mountains, located in the Southern Carpathians, are one of the highest massifs in Romania and home of the Retezat National Park, which possesses an important biological value. This study aimed at the investigation of water quality in creeks of the Southern Retezat (Piule-Iorgovanul Mountains) in order to provide information on pollutants of both natural and anthropogenic origin, which could pose a threat for the human health. Heavy metal and other inorganic ion contents of samples were analyzed with on-site and laboratory measurements to estimate water quality. The samples were investigated using microwave plasma - atomic emission spectrometry to quantify specific elements, namely aluminium, cadmium, cobalt, chromium, copper, iron, magnesium, manganese, molybdenum, nickel, lead and zinc. The results were compared with the European Union and Romanian standards regarding drinking water and surface water quality. The studied heavy metals have been found to be in very low concentrations or under the method’s detection limit. Thus, in the microbasin corresponding to the sampling points, there seems to be no heavy metal pollution and, from this point of view, the samples comply as drinking water according to the European Union and Romanian recommendations. Our findings confirm that the Retezat Mountains are still among the least contaminated regions in Europe and that the ecosystem and the human health is not negatively influenced by water quality problems

Optical properties of SnO2 film

A SnO2 epitaxial thin film with thicknes of 25 nm is grown by the PLD technique on a (111) orientated SrTiO3 (STO) substrate. The effects of epitaxial growth on the lattice structure, microstructure and optical properties of oxide thin film has been studied. The film is out-of-plane epitaxial oriented to the substrate. The XRD difractograms show only tin dioxide peaks which can be assigned to the (002) and (004) reflexes of the tin dioxide phase. The thickness of the film is calculated from the distance of X-ray reflectivity oscillations. The observation of clear thickness fringes is an indication for a low surface roughness of the film. Atomic force microscopy (AFM) was also used to investigate the surface of the films. AFM images reveal a film surface that shows a flat film surface. Variable angle spectroscopic ellipsometry (VASE) has been used to determine the optical properties of the SnO2 film

Electrodeposition and corrosion behavior of hydroxyapatite onto titanium

The present study includes the results of the hydroxyapatite electrochemical deposition on titanium substrate from 3 solutions of different concentrations of precursors. The deposited HA layers and the substrate were studied by means of x-ray diffraction and scanning electron microscopy, and also corrosion resistance tests have been performed. Results confirmed the formation of low crystallinity hydroxyapatite coatings, displaying fine layers of feathery crystals and other structures resulted from agglomeration phenomena. Corrosion tests, performed in artificial saliva solution, showed that the corrosion resistance of the hydroxyapatite coated Ti sample obtained from 0.875M Ca and 0.525M P precursors solutions was higher than that of the other samples

Ecological survey of Padiș area, Romania

A couple of stream water samples from the Padiș tourist area (Romania) were analyzed using the chemical methods stipulated in the Romanian Pharmacopoeia in order to establish their content of heavy metals and other ions, both cations and anions. Additionally, the samples were investigated using microwave plasma – atomic emission spectrometry (MPAES) to quantify specific elements, namely aluminium, barium, cobalt, chromium, copper, manganese, molybdenum, nickel, lead, strontium and zinc. The cation levels found were compared with the Romanian and international standards regarding surface and drinking water quality

Electrochemical behaviour of LaMnO3-modified graphite electrodes

The electrochemical behaviour of LaMnO3-modified graphite electrodes was studied using cyclic voltammetry. Potassium ferricyanide was employed as a probe to determine the electroactive surface area of LaMnO3 modified electrodes and their diffusion coefficient. The electroactive surface area and the diffusion coefficient were calculated using the RandlesSevcik equation

Water quality survey of streams from Retezat mountains (Romania)

The Retezat Mountains, located in the Southern Carpathians, are one of the highest massifs in Romania and home of the Retezat National Park, which possesses an important biological value. This study aimed at the investigation of water quality in creeks of the Southern Retezat (Piule-Iorgovanul Mountains) in order to provide information on pollutants of both natural and anthropogenic origin, which could pose a threat for the human health. Heavy metal and other inorganic ion contents of samples were analyzed with on-site and laboratory measurements to estimate water quality. The samples were investigated using microwave plasma - atomic emission spectrometry to quantify specific elements, namely aluminium, cadmium, cobalt, chromium, copper, iron, magnesium, manganese, molybdenum, nickel, lead and zinc. The results were compared with the European Union and Romanian standards regarding drinking water and surface water quality. The studied heavy metals have been found to be in very low concentrations or under the method’s detection limit. Thus, in the microbasin corresponding to the sampling points, there seems to be no heavy metal pollution and, from this point of view, the samples comply as drinking water according to the European Union and Romanian recommendations. Our findings confirm that the Retezat Mountains are still among the least contaminated regions in Europe and that the ecosystem and the human health is not negatively influenced by water quality problems

Electro-oxidation of ascorbic acid on perovskite-modified electrodes

The main purpose of this research was to obtain LaMnO3 perovskite-modified graphite electrodes, to characterise them and to observe their electrochemical behaviour in the presence of ascorbic acid. The morphology of the perovskite films were studied by scanning electron microscopy (SEM) and their double-layer capacitance was determined using cyclic voltammetry. The results are promising, but the electrocatalytic activity of the films for the oxidation of ascorbic acid needs to be improved