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The reduction of heavy metals (cadmium, lead and zinc) in the presence of long-chain fatty acids (lauric, oleic and linoleic) in 0.55 mol dm?3 NaCl and 0.03 mol dm?3 NaHCO3 at pH 8.7 has been studied by differential pulse polarography. The increase of the peak height of investigated metals by up to tenfold the value obtained in electrolyte without fatty acid is due to adsorption of metal ions at the electrode surface. The accumulation of metal increases with the increase of adsorption time (at potentials more positive than the reduction potential of the particular metal) and with increase of salinity. The heavy-metal adsorption depends on the concentrations of both metal ions and fatty acids. The interaction of heavy metals with the unsaturated fatty acids in the bulk and/or in the adsorbed layer at different natural interfaces could be of considerable importance in an understanding of the fate and distribution of heavy metals in the natural aquatic environment. 相似文献
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Palma Orlović-Leko Zlatica Kozarac Božena Ćosović Slađana Strmečki Marta Plavšić 《Journal of Atmospheric Chemistry》2010,66(1-2):11-26
Characterization of atmospheric surfactants in bulk precipitations was carried out by adsorption study at the mercury electrode/solution interface using phase sensitive AC voltammetry. The structure and permeability of the adsorbed organic films at the mercury electrode was tested using the redox processes of lead and cadmium ions as electrochemical tools. The effects of organic matter from the bulk precipitations (rainwater and melted snow) were compared to those obtained for aqueous solutions of model substances: aromatic hydrocarbon (naphtalene), anionic surfactant (sodium dodecylbenzene sulfonate, NDBS), protein (albumine) and selected model substances suggested to be representative of water soluble organic compounds (WSOC) in atmospheric water (monocarboxylic, dicarboxylic, and polyacidic compounds and levoglucosan). It was found that substances like humic acid and 3-hydroxybutanoic acid may play an important role in atmospheric heterogeneous chemistry because of their surface active potential. 相似文献
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Edgar Hiller Bronislava Lalinská Martin Chovan Ľubomír Jurkovič Tomáš Klimko Michal Jankulár Róbert Hovorič Peter Šottník Renáta Fľaková Zlatica Ženišová Ivana Ondrejková 《Applied Geochemistry》2012
Environmental contamination with As and Sb caused by past mining activities at Sb mines is a significant problem in Slovakia. This study is focused on the environmental effects of the 5 abandoned Sb mines on water, stream sediment and soil since the mines are situated in the close vicinity of residential areas. Samples of mine wastes, various types of waters, stream sediments, soils, and leachates of the mine wastes, stream sediments and selected soils were analyzed for As and Sb to evaluate their geochemical dispersion from the mines. Mine wastes collected at the mine sites contained up to 5166 mg/kg As and 9861 mg/kg Sb. Arsenic in mine wastes was associated mostly with Fe oxides, whereas Sb was present frequently in the form of individual Sb, Sb(Fe) and Fe(Sb) oxides. Waters of different types such as groundwater, surface waters and mine waters, all contained elevated concentrations of As and Sb, reaching up to 2150 μg/L As and 9300 μg/L Sb, and had circum-neutral pH values because of the buffering capacity of abundant Ca- and Mg-carbonates. The concentrations of Sb in several household wells are a cause for concern, exceeding the Sb drinking water limit of 5 μg/L by as much as 25 times. Some attenuation of the As and Sb concentrations in mine and impoundment waters was expected because of the deposition of metalloids onto hydrous ferric oxides built up below adit entrances and impoundment discharges. These HFOs contained >20 wt.% As and 1.5 wt.% Sb. Stream sediments and soils have also been contaminated by As and Sb with the peak concentrations generally found near open adits and mine wastes. In addition to the discharged waters from open adits, the significant source of As and Sb contamination are waste-rock dumps and tailings impoundments. Leachates from mine wastes contained as much as 8400 μg/L As and 4060 μg/L Sb, suggesting that the mine wastes would have a great potential to contaminate the downstream environment. Moreover, the results of water leaching tests showed that Sb was released from the solids more efficiently than As under oxidizing conditions. This might partly explain the predominance of Sb over As in most water samples. 相似文献
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Sanja Frka Blaženka Gašparović Daniela Marić Jelena Godrijan Tamara Djakovac Vjeročka Vojvodić Jelena Dautović Zlatica Kozarac 《Estuarine, Coastal and Shelf Science》2011
The relationship between changes in lipid classes and phytoplankton composition and abundance in the northern Adriatic was studied during spring and summer 2008 at two stations with different nutrient levels, i.e. at the western mesotrophic and eastern oligotrophic areas. Changes in the phytoplankton community depended on temporal surface nutrient depletion and bottom accumulation; that is, microphytoplankton, mainly diatoms Pseudo-nitzschia sp., developed at nutrient richer surface layers of the mesotrophic area in spring and at deeper layers of the oligotrophic site in late summer. In other periods nanophytoplankton dominated. Dissolved organic carbon (DOC) and lipid content were comparable for the two stations, while particulate organic carbon (POC) was richer at the mesotrophic side. Total lipid concentrations varied in the range from 8.0 to 92.2 μg l−1 and from 16.9 to 76.9 μg l−1 in the dissolved and particulate fractions, respectively. DOC and POC contents were in the ranges from 0.77 to 1.58 mg l−1 and from 0.06 to 0.56 mg l−1, respectively. Lipid and organic carbon distribution did not follow phytoplankton progression, indicating decoupling between organic matter production and decomposition throughout the investigation period. The main sources of lipids were marine phytoplankton and bacteria. Low nutrient conditions caused increased biosynthesis of lipids. Also, increasing oligotrophy led to an increasing number of phytoplankton taxa. The synthesis and accumulation of glycolipids by the developed taxa were enhanced during nutrient exhaustion, contributing in late summer, on average, 20.2 and 22.0% at the mesotrophic and oligotrophic stations, respectively, in the particulate fraction. The distribution of bacterial lipids and lipid breakdown products implies that bacterial lipid degradation was significant in spring, while very probably lipid abiotic degradation took place during summer. 相似文献
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Marian Marschalko David Krčmář Isik Yilmaz Renáta Fľaková Zlatica Ženišová 《Environmental Earth Sciences》2018,77(3):95
The aim of the study is to evaluate the warming effect (thermal contamination) of city centres with high building density. This phenomenon has a number of scientific and practical implications. The case study was conducted in Bratislava (Slovakia), in the geological environment of alluvial gravels of the Danube River, where a permanent warming of the subsurface in the city centre is experienced, which is mainly affected by high building density and underground utilities. Thanks to this thermal contamination, the heat pumps efficiency is greater in winter, while in summer, their effectiveness is lower. Economically, this negative phenomenon in the case of heat pumps has a positive effect, since it increases energy efficiency during the heating period. This phenomenon is not universal and depends on the specific boundary conditions of the geological settings and hydrogeological conditions. 相似文献
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David Krcmar Renata Flakova Ivana Ondrejkova Kamila Hodasova Daniela Rusnakova Zlatica Zenisova Martin Zatlakovic 《Ground water》2020,58(3):406-412
Groundwater temperature is a useful hydrogeological parameter that is easy to measure and can provide much insight into groundwater flow systems, but can be difficult to interpret. For measuring temperature directly in the ground, dedicated specifically designed monitoring wells are recommended since conventional groundwater wells are not optimal for temperature monitoring. Multilevel monitoring of groundwater temperature is required to identify contributions of different possible heat inputs (sources) on measured temperature signals. Interpreting temperature data as a cosine function, including period, average temperature, amplitude, and phase offset, is helpful. Amplitude dampening and increasing phase shift with distance from a boundary can be used for estimation of transport parameters. Temperature measurements at different depths can be used for evaluation of unknown parameters of analytical functions by optimization of regression fits in Python. These estimated parameters can be used to calculate temperatures at known water table depths which can be applied as a fixed transient boundary condition in MT3DMS to overcome the limitations of MT3DMS heat transport modeling in the unsaturated zone. In this study, temperature monitoring and modeling was used to evaluate the influence of a department store's heated basement foundation on groundwater temperature within a green space (city park), with the main outcome that 17 years after construction, the department store foundation has increased the mean groundwater temperature by 3.2 °C. Heat input evaluated by the MT3DMS model varied from 0.1 W/m2 at a distance of 100 m up to 12 W/m2 next to the building. 相似文献
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Surface micro-layer (ML) samples were collected in different seasons over a long time period in the coastal area of the Middle Adriatic Sea including the seawater Rogoznica lake location and the semi-enclosed estuarine Martinska station. Natural surface micro-layers were studied as original samples and as ex-situ reconstructed films after previous extraction by organic solvents of different polarities (n-hexane and dichloromethane). Using alternating current (AC) voltammetry (out-of-phase mode) the concentration of surface active substances (SAS) in original ML of both locations was determined, and the enrichment factor (EF) in the ML was related to the underlayer water (ULW) samples collected at 0.5 m depth. Seasonal variability of SAS concentrations of the ML was observed at both locations. The ex-situ films were studied using a modified AC voltammetry method (out-of-phase mode) transferring an organic extract of natural micro-layers spread onto electrolyte from the air-water interface to the mercury electrode surface. The comparison of adsorption characteristics for model lipids of different polarities and those of transferred ex-situ reconstructed films has revealed that different types of lipid material were present in each ex-situ film of the same micro-layer. Additional characterization of the surface active material of natural MLs was carried out by AC voltammetry (in-phase mode) using cathodic reduction of cadmium ions as an indicator of permeability of different films adsorbed at the mercury electrode. The SAS of ML of both investigated locations induced an inhibition effect to the reduction of cadmium ions. Seasonal variations of inhibition have also been noticed. The electrochemical study contributed to the physicochemical characterization of the surface active matter of the surface micro-layer with the emphasis to the role of lipids which, although they represent a minor fraction of the total micro-layer organic material, contribute considerably to the micro-layer formation and stabilization at the air–water interface. 相似文献
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The behavior of arsenic and antimony at Pezinok mining site,southwestern part of the Slovak Republic
Renata Flakova Zlatica Zenisova Ondra Sracek David Krcmar Ivana Ondrejkova Martin Chovan Bronislava Lalinská Miriam Fendekova 《Environmental Earth Sciences》2012,66(4):1043-1057
Arsenic and antimony contamination is found at the Pezinok mining site in the southwest of the Slovak Republic. Investigation of this site included sampling and analysis of water, mineralogical analyses, sequential extraction, in addition to flow and geochemical modeling. The highest dissolved arsenic concentrations correspond to mine tailings (up to 90,000 μg/L) and the arsenic is present predominately as As(V). The primary source of the arsenic is the dissolution of arsenopyrite. Concentration of antimony reaches 7,500 μg/L and its primary source is the dissolution of stibnite. Pore water in mine tailings is well-buffered by the dissolution of carbonates (pH values between 6.6 and 7.0) and arsenopyrite grains are surrounded by reaction rims composed of ferric iron minerals. Based on sequential extraction results, most solid phase arsenic is in the reducible fraction (i.e. ferric oxyhydroxides), sulfidic fraction, and residual fraction. Distribution of antimony in the solid phase is similar, but contents are lower. The principal attenuation mechanism for As(V) is adsorption to ferric oxide and hydroxides, but the adsorption seems to be limited by the competition with Sb(V) produced by the oxidation of stibnite for adsorption sites. Water in mine tailings is at equilibrium with gypsum and calcite, but far from equilibrium with any arsenic and antimony minerals. The concentrations of arsenic and antimony in the surrounding aquifer are much lower, with maximum values of 215 and 426 μg/L, respectively. Arsenic and antimony are transported by ground water flow towards the Blatina Creek, but their loading from ground water to the creek is much lower compared with the input from the mine adits. In the Blatina Creek, arsenic and antimony are attenuated by dilution and by adsorption on ferric iron minerals in stream sediments with resulting respective concentrations of 93 and 45 μg/L at the site boundary south of mine tailing ponds. 相似文献
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