Dragana Djordjevic

Liver, gills, and skin histopathology and heavy metal content of the Danube sterlet (Acipenser ruthenus Linnaeus, 1758).

The sterlet (Acipenser ruthenus L.) is a bottom-feeding fish species with a direct exposure to contaminants from water and sediments. Although heavy metal pollution is believed to be one of the main threats to the sterlet population in the Danube River basin, there is a lack of knowledge of the exact impact of heavy metals on their survival. In the present study, effects of heavy metal pollution on sterlet in the Danube basin were assessed as well as the utility of different sterlet organs and tissues as indicators of heavy metal contamination. The sterlet were sampled at three different sites in the Danube basin, in Hungary and Serbia, isolated from each other by dams. Heavy metal analysis included measurement of Cd, As, Pb, Cr, Hg, Cu, Ni, Fe, Mn, and Zn concentrations in sterlet gills, muscle, liver, and intestine, and histopathological analyses comprised assessment and scoring of the extent and intensity of alterations in skin, gills, and liver tissue. Analysis revealed a significant presence of sublethal histopathological changes that were most pronounced in the liver and skin and increased accumulation of heavy metals, with the highest concentrations in the liver. Canonical discriminant analysis showed significant differentiation among the three studied localities, suggesting that the heavy metal concentrations in sterlet populations were site specific. The present study concludes that the accumulation of heavy metals is a response to the presence of these pollutants in the environment, and, together with other pollutants, it affects the vital organs of natural sterlet populations.

Natural and anthropogenic factors affecting the groundwater quality in Serbia.

Various chemometric techniques were used to analyze the quality of groundwater data sets. Seventeen water quality parameters: the cations Na, K, Ca, Mg, the anions Cl, SO4, NO3, HCO3 and nine trace elements Pb, As, Mn, Ni, Cu, Cd, Fe, Zn and Cr were measured at 66 different key sampling sites in ten representative areas (low land-Northern Autonomous Province of Serbia, Vojvodina and central Serbia) for the summer period of 2009. HCA grouped the sample sites into four clusters based on the similarities of the characteristics of the groundwater quality. DA showed two parameters, HCO3 and Zn, affording more than 90% correct assignments in the spatial analysis of four/three different regions in Serbia. Factor analysis was applied on the log-transformed data sets and allowed the identification of a reduced number of factors with hydrochemical meaning. The results showed severe pollution with Mn, As, NO3, Ni, Pb whereby anthropogenic origin of these contaminants was indicated. The pollution comes from both scattered point sources (industrial and urban effluent) and diffuse source agricultural activity. These samples may not be suitable for human consumption; the water quality belongs to class III/IV (contaminated). The Fe anomalies (7.1mg/L) in the water from the Vetrnica site can be attributed to natural sources, such as the dissolution of rock masses and rock fragments. The serious groundwater contamination with As (25.7-137.8 μg/L) in the area of Banat (Northern Autonomous Province of Serbia, Vojvodina) and a sample No. 9 at the Great Morava River requires urgent attention.

Characterization of gelation process and drug release profile of thermosensitive liquid lecithin/poloxamer 407 based gels as carriers for percutaneous delivery of ibuprofen.

Suitability of liquid lecithin (i.e., solution of lecithin in soy bean oil with ∼ 60% w/w of phospholipids) for formation of gels, upon addition of water solution of poloxamer 407, was investigated, and formulated systems were evaluated as carriers for percutaneous delivery of ibuprofen. Formulation study of pseudo-ternary system liquid lecithin/poloxamer 407/water at constant liquid lecithin/poloxamer 407 mass ratio (2.0) revealed that minimum concentrations of liquid lecithin and poloxamer 407 required for formation of gel like systems were 15.75% w/w and 13.13% w/w, respectively, while the maximum content of water was 60.62% w/w. The systems comprising water concentrations in a range from 55 to 60.62% w/w were soft semisolids suitable for topical application, and they were selected for physicochemical and biopharmaceutical evaluation. Analysis of conductivity results and light microscopy examination revealed that investigated systems were water dilutable dispersions of spherical oligolamellar associates of phospholipids and triglyceride molecules in the copolymer water solution. Rheological behavior evaluation results indicated that the investigated gels were thermosensitive shear thinning systems. Ibuprofen (5% w/w) was incorporated by dispersing into the previously prepared carriers. Drug-loaded systems were physically stable at storage temperature from 5 ± 3°C to 40 ± 2°C, for 30 days. In vitro ibuprofen release was in accordance with the Higuchi model (rH>0.95) and sustained for 12h. The obtained results implicated that formulated LLPBGs, optimized regarding drug release and organoleptic properties, represent promising carriers for sustained percutaneous drug delivery of poorly soluble drugs.

pH-Dependent Leaching of Dump Coal Ash—Retrospective Environmental Analysis

Abstract Trace and major elements in coal ash particles from dump of “Nikola Tesla A” power plant in Obrenovac near Belgrade (Serbia) can cause pollution, due to leaching by atmospheric and surface waters. In order to assess this leaching potential, dump ash samples were subjected to extraction with solutions of decreasing pH values (8.50, 7.00, 5.50, and 4.00), imitating the reactions of the alkaline ash particles with the possible alkaline, neutral, and acidic (e.g., acid rain) waters. The most recently deposited ash represents the greatest environmental threat, while “aged” ash, because of permanent leaching on the dump, was shown to have already lost this pollution potential. On the basis of the determined leachability, it was possible to perform an estimation of the acidity of the regional rainfalls in the last decades.

Association Forms Of Heavy Metals In Fly Ash From Power Plants

During coal combustion, the organic component becomes oxidised, while inorganic components mostly remain in the ash. All natural elements were found in coal, except some very rare ones, like polonium, francium, astatine, etc. (Finkelman 1993). The variability of inorganic constituents is influenced by biological, hydrological and geochemical factors and their association forms govern their behaviour and their technological and environmental impact. Emission and deposition of coal ash represent major environmental problems, due to the large amount of ash obtained. The environmental impact of ash has at least two aspects: a) emission and deposition of enormous amounts of ash particles, polluting air, water and soil; b) leaching of microelements (including toxic metals), but also major cations and anions from ash by atmospheric and surface waters.

Speciation of Trace and Major Elements from Coal Combustion Products of Serbian Power Plants (I)—“Kostolac A” Power Plant

Abstract In order to examine association patterns and pollution potential of trace and major elements from coal ash, six composite samples of fresh, filter fly, and aged dump coal ash from “Kostolac A” power plant located 100 km from Belgrade, the Serbian capital, were subjected to the sequential extraction procedure. Five extractants were applied (in the following order): distilled water, 1 M ammonium acetate, 0.2 M ammonium oxalate/0.2 M oxalic acid, an acidic solution of H2O2, and 6 M HCl. Obtained concentrations were statistically analyzed and associations of trace and major elements were established.

Leaching of trace and major elements from coal ash dumps

Coal ash samples taken from an active, currently filled cassette as well as samples taken from passive cassettes of the power plant in Obrenovac (Yugoslavia) were subjected to sequential leaching, comprising of extraction with distilled water, 1 M KC1 and 0.1 M HC1. Concentrations of trace and major elements found in extracts revealed that lead and cadmium are not present in significant concentrations, while other elements show different behavior: practically all absorbed trace elements and most of the major elements are partially leached during transport, while later, on the dump, only a slow release of most of the examined ion‐exchangeable elements occurs.

Trace and Major Elements in Ash of “Nikola Tesla A” Power Plant Dump (I)—Leached Concentrations and Environmental Implications

Eight samples each of coal ash taken from active, currently filled, and passive, previously filled cassettes of “Nikola Tesla A” power plant dump (Obrenovac near Belgrade, Serbia) were subjected to a sequential extraction, comprising of the following five phases: distilled water, 1 M ammonium acetate, 0.2 M ammonium oxalate/0.2 M oxalic acid, acidic solution of H2O2, and 6 M solution of HCl. Leached concentrations were discussed from the standpoint of their environmental significance, keeping in mind the processes occurring during and after coal ash transport to the dump, as well as the concentrations washed from the original filter lignite ash.

Distribution of Trace and Major Elements in Lignite and Products of Its Combustion-Leaching Experiments and Cluster Analysis

One of the strategic issues for contemporary manhood is production of a sufficient amount of energy for further technological development. Despite numerous attempts to use new, practically inexhaustible energy sources, such as solar energy (Li, 2002), wind energy (Belanger & Gagnon, 2002) and high and low tides (Omer, 2002), for example, instead of conventional sources, i.e., coal, petrol or gas, the latter ones, nevertheless, remain unavoidable factors in balancing the energy demands of most countries, including Serbia, at the beginning of the 21st century. On the basis of investigations of coal genesis, its composition, as well as general characteristics of coal deposits, coal can be defined as a combustible sedimentary rock, originating mainly (some coals are algal) from residues of terrestrial and aquatic plants, and of minerals (< 50 %) (Wood et al., 1983). Chemical and physical characteristics of coal are predetermined by the nature of precursor plants, the amount of inorganic material, and by the nature, intensity and duration of biochemical and geochemical processes that are responsible for coal formation. Almost all natural elements have been found in coal (Finkelman, 1993), in variety of forms (Eskenazy & Valceva, 2003; Yudovich & Kertis, 2005), which are responsible for the coal’s technological, economical but also ecological impact. Elements can be variously associated (Font et al., 2005). Further, association types may vary within the same deposit (Kuehn & Kurzbach, 1992; Vyazova & Kryukova, 1997). During coal combustion in power plants, practically only the organic part of coal burns, producing carbon dioxide and water, i.e. its vapor. The inorganic components of coal mainly do not burn, but remain in the ash, which is a by-product of combustion. Since coal, by definition, contains more than 50 % of organic substances, which are not found in the ash, or are found in the very low concentrations, it is clear that the main part of the inorganic components of coal, including trace elements, is concentrated in the ash. During combustion different processes occur, which influence the non-uniform distribution of the elements and phases in different fractions of the combustion products (Xu et al., 2004; Goodarzi, 2006; Ward & French, 2006). One of the basic mechanisms which are present is “evaporation-condensation” (Schultz et al., 1973). Namely, during coal combustion at high temperatures certain elements evaporate. At the lower temperatures, which are typical for the higher parts of the reactor in which the combustion occurs, part of the substances which

Trace and Major Elements in Ash of “Nikola Tesla A” Power Plant (III)—Associations of Elements in Passive Cassette Ash

Statistical analysis of concentrations of trace and major elements obtained by five-step sequential extraction of samples of dump ash taken from a passive, previously filled cassette of “Nikola Tesla A” power plant dump located near Belgrade, Serbia, revealed the existence of magnesium alumosilicates, mixed silicates of potassium and magnesium, alumosilicates not containing magnesium, and compounds of aluminium, not containing silicon or magnesium that were dissolved in the fifth phase of extraction. Intraphase associations of major elements dissolved in the third phase were not established. Preferential intraphase and interphase binding of matrix and adsorbed and ion-exchangeable fractions of elements were established and discussed.