Gordana Dević

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.

Evaluation of sediment contamination with heavy metals: the importance of determining appropriate background content and suitable element for normalization

In the present study, concentrations of heavy metals (Cd, Cu, Co, Mn, Cr, Ni, Pb, and Zn) were determined at 35 river sediments in Serbia. The anthropogenic heavy metals input and quantification of the metal enrichment degree in sediments were estimated by calculating geo-accumulation indices (Igeo) and enrichment factors (EF). These pollution indices have been calculated using different background values (continental crust and local background values) and different element used for normalization (Al and Fe), followed by result comparison. The EF values calculated with continental crust as background (minor to extremely severe enrichment) were higher than when regional background values were used (minor to moderate enrichment). Significant influence of background values on the Igeo values is observed. Values of geo-accumulation index (<2) revealed that studied river sediments are remaining unpolluted to moderately polluted with Co, Mn, Cr, and Ni. Significant pollution in the sediments was observed for Cd, Cu, Pb, and Zn elements. The results of this study confirm the relevance of precise and accurate determining of local background concentrations while assessing sediment pollution. The values of EFs for studied elements were more influenced by the choice of background values than selection of element used for normalization. Our recommendation would be to use the local and regional background content in quantification of metal contamination in sediments, since these values differ and are site and region dependent.

Risk assessment of trace element contamination in river sediments in Serbia using pollution indices and statistical methods: a pilot study

To effectively manage potential environmental and human health impacts of contaminated river sediments, it is important that information about the source (anthropogenic vs geogenic), variability and environmental risks associated with the contamination are well understood. The present study was carried out to assess the source and severity of contamination and to undertake a risk assessment for selected elements (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn) in river sediments in Serbia. The estimate of the anthropogenic component of contamination was derived by determining the total element content and the background values for elements in sediments, and the severity of pollution was assessed by calculating a number of pollution indices including the contamination factor, the enrichment factor, the index of geoaccumulation, the ecological risk factor, the potential ecological risk index, the pollution load index, the combined pollution index, the modified degree of contamination and the toxic unit factor. This analysis indicates that river sediments in Serbia are primarily polluted with Zn, Cu and Cd. The most contaminated river systems are the Ibar, Pek, West Morava and Great Morava rivers. Mining activities were found to have a significant influence on sediment. Multivariate analyses suggested anthropogenic origins for Pb, Zn, Cd, As, Ni and Cu, whilst Fe, V, Mn, Co and Cr appear to have a mixed origin (both lithogenic and anthropogenic sources). A geochemical approach, with a calculation of pollution indices and statistical methods, is recognised as useful for the risk management of trace elements in sediments around the world.

Characterization of eluted metal ions by sequential extraction from Krepoljin coal basin, Serbia: Mechanisms of metal interaction

ABSTRACT Eight samples of powdered brown coal (Krepoljin coal basin, Miocene age) were successively extracted by two extractants at room temperature: bidistilled water, Me1, and 2 M MgCl2 solution, Me2. Large amounts of Ni and Zn are leached from the coal deposit by water. On the contrary, no significant amounts of Pb and Cu are washed under normal conditions. Also, the mobility of Zn and Ni especially depends, to a high extent, on ionic strength. It can be assumed that the humic acids co-extracted during water leaching, Me1, and being a highly competitive ligand for metal ions, will act as a disturbing agent in metal speciation procedure in coals. This assumption is supported by the obtained significant correlation between the Me1:Me2 ratio and the humic acid complex stability constants.

An Assessment of the Chemical Characteristics of Early Diagenetic Processes in a Geologically Well-defined Brown Coal Basin

The characteristics of early diagenetic processes, which influenced the composition of the organic matter of coals from the Krepoljin coal basin, Serbia, Miocene age was assessed by statistical correlation analysis and multivariate principal component analysis. The complexity of processes in a coal-forming sedimentary environment has been paid special attention to obtain the most possible reliable interpretation of these early diagenetic processes and, therefore, this investigation was performed by applying principal component analysis. The principal components, which are defining the coals and promoting individual early diagenetic processes, were the precursor materials and environmental factor, respectively, represented by higher plants, algae, and molds—expressed by the relative contents of the Cs29-, Cs28-, Cs27-steranes, respectively, and the content of organic sulphur—Sorg, average content 166 ± 101 μmole/g. The main and highly interrelated effects of the higher plant material were as follows: (i) increase of the sulphur content of coal organic matter, (ii) promoter of sulphate reducing conditions, and (iii) establishment of the H/C- and N/C-ratios of organic matter. Pyrite formed by the participation of Sorg.

IR and UV/VIS Spectroscopic Characterization of the Higher Fullerene C76-D2 for Its Quantitative and Qualitative Determination

The only stable isomer of the higher fullerene C76 of D2 symmetry was isolated from carbon soot by the new and advanced extraction and chromatographic methods and processes. Characterization of the isolated C76-D2 was performed by the IR(KBr) and UV/VIS method in the absorption mode. All of the experimentally observed infrared and electronic absorption bands are in excellent agreement with the theoretical calculations for this fullerene. The molar absorptivity and the integrated molar absorptivity of the observed entire new series of various characteristic, both deconvoluted and convoluted IR absorption bands of the C76-D2 isomer, in different integration ranges were determined. In addition, the molar extinction coefficients of its UV/VIS absorption bands were determined. The obtained novel IR and UV/VIS spectroscopic parameters are significant for the quantitative assessment of C76-D2. All the presented data are important both for its qualitative and quantitative determination, either in natural resources on Earth and in space or in artificially synthesized materials, electronic and optical devices, optical limiters, sensors, polymers, solar cells, nanophotonic lenses, diagnostic and therapeutic agents, pharmaceutical substances, for targeted drug delivery, incorporation of metal atoms, in biomedical engineering, industry, applied optical science, batteries, catalysts and so forth.

Environmental Impacts of Reservoirs

The construction of reservoirs is one of the most important practices for the development and management of water resources. Many large reservoirs were built without a thorough or systematic evaluation of the long-term environmental, social, and economic interactions of different alternatives.