29 results on '"Skrbić B"'
Search Results
2. Temporal trend of perfluorinated compounds in untreated wastewater and surface water in the middle part of the Danube River belonging to the northern part of Serbia
- Author
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Buljovčić Maja B., Antić Igor S., Kadokami Kiwao, and Škrbić Biljana D.
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emerging contaminants ,pfcs occurrence ,pfos ,pfoa ,environmental pollution ,Chemistry ,QD1-999 - Abstract
The occurrence and temporal variation of selected priority substances and contaminants of emerging concerns, i.e., eleven perfluorinated compounds (PFCs, belonging to perfluorosulphonates, perfluorocarboxylic acids, and perfluorinated sulphonamides) have been investigated in composite surface water samples of the Danube River at the upstream and downstream locations from the discharge point of wastewater. Among the analyzed compounds, six PFCs (PFOA, PFOS, PFHxA, PFNA, PFDA and PFUnA) were quantified. Overall, the detection frequency for most quantified compounds was very high (>90 %), only PFDA and PFUnA were quantified with less frequency, 33 and 67 %, respectively. The highest quantified concentrations of PFOA and PFOS were 14.9 ng/L (average 12.1 ng/L) and 14.2 ng/L (average 6.11 ng/L), respectively. These ones together with PFHxA (average 10.0 ng/L) were quantified at the highest concentrations in comparison to the other investigated compounds. However, the determined levels of PFOS during investigated sampling period, for all samples analyzed, were always lower than the maximum allowable concentration set for inland river waters but always higher than the environmental quality standard threshold value-AA-EQS of 0.65 ng/L sets by the Directive of European Parliament. Moreover, the levels of PFOA were always several times lower than the set AA-EQS value.
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- 2022
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3. Levels and risk assessment of selected persistent organic compounds in dust samples from Tianjin, China
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Škrbić Biljana D., Antić Igor, and Yaqin Ji
- Subjects
polychlorinated biphenyls ,organochlorine pesticides ,street dust ,principal component analysis ,Technology (General) ,T1-995 - Abstract
The aim of this paper was to determine spatial variation of 6 indicator polychlorinated biphenyls (PCBs) and 18 organochlorine pesticides (OCPs) in street dust samples (n=49) collected during summer season from suburban/urban zones of Tianjin, China. Sample preparation was performed by using accelerated solvent extraction with simultaneous extraction and clean-up of PCBs and OCPs, while quantification was carried out using gas chromatography coupled with microelectro absorption detector and gas chromatography coupled with mass spectrometry. The total concentrations of studied PCBs varied from
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- 2019
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4. Comparative analysis of reactive power definitions in the presence of harmonics
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Škrbić Bojana P. and Mikulović Jovan Č.
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reactive power ,power definition ,harmonics ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
In this paper, the most significant definitions of reactive power in single-phase and three-phase three-wire systems with non-sinusoidal voltages and currents are presented. Comparative analysis of these definitions has been performed. Fundamental principles on which these definitions rely are stated, and the application of these definitions to solving the problems of compensation is explained. Contrary to single-phase or three-phase symmetrical systems operating under sinusoidal conditions, reactive power compensation in systems operating under non-sinusoidal conditions does not result in maximal efficiency of electric energy delivery. Less efficiency in comparison to the theoretical maximum is being explained by the presence of harmonics and asymmetries in the system. Therefore, in the context of the reduction of losses during electric energy delivery to the load, the possibilities of nonactive power reduction should be contemplated instead of the possibilities of reactive power reduction.
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- 2017
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5. Application of principal component and hierarchical cluster analyses in the classification of Serbian bottled waters and a comparison with waters from some European countries
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Cvejanov Jelena Đ. and Škrbić Biljana D.
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chemometrics ,anions in bottled water ,cations in bottled water ,total dissolved solids ,Chemistry ,QD1-999 - Abstract
The contents of major ions in bottled waters were analyzed by principal component (PCA) and hierarchical cluster (HCA) analysis in order to investigate if these techniques could provide the information necessary for classifications of the water brands marketed in Serbia. Data on the contents of Ca2+, Mg2+, Na+, K+, Cl-, SO4 2-, HCO3 - and total dissolved solids (TDS) of 33 bottled waters was used as the input data set. The waters were separated into three main clusters according to their levels of TDS, Na+ and HCO3 -; sub-clustering revealed a group of soft waters with the lowest total hardness. Based on the determined chemical parameters, the Serbian waters were further compared with available literature data on bottled waters from some other European countries. To the best of our knowledge, this is the first report applying chemometric classification of bottled waters from different European countries, thereby representing a unique attempt in contrast to previous studies reporting the results primarily on a country-to-country scale. The diverse character of Serbian bottled waters was demonstrated as well as the usefulness of PCA and HCA in the fast classification of the water brands based on their main chemical parameters. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172050]
- Published
- 2017
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6. Ecological value orientations and readiness for activism in Serbia
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Petrović Nebojša and Škrbić Branka
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ecology ,new ecological paradigm ,ecological awareness ,ecological values ,Geography. Anthropology. Recreation - Abstract
The global environmental crisis, caused by the unreasonable behavior of human beings and their economic activities that affect nature and its resources, has created a basis for the development of new environmental paradigm, which emphasizes the intrinsic value of nature, the close connection between society and the environment and the importance of their mutual influence. Changing the view of the world becomes a necessary step in establishing the optimum of the interplay between humans and the natural environment. Environmental knowledge is the most primary element of environmental awareness. The indispensable outcome of environmental awareness is ecological behavior that should be developed and encouraged. The formation of desirable behavior affect environmental objective and subjective factors. Objective factors are, for example, environmental conditions (degree of degradation of eco-system), socio-ecological infrastructure, the level of technological development. The subjective factors important for ecological behavior includes attitudes, expectations, political affiliation, personal and social values. For psychology, of particular importance are the values that support the behavior oriented towards environmental protection. This research examined the ecological value orientation and willingness to ecological involvement of students from the three groups of faculties: for mining and geology, for geography (environmental department), and faculties of social orientation (economic, law, philosophy . . . ). The results showed that the respondents have a well-developed environmental values that are a prerequisite for pro-environmental behavior and activities that leads to protection of the environment. Thus, the students were pretty much willing to engage in activities such as recycling various materials, use of public transportation and take other measures that contribute to a sustainable lifestyle.
- Published
- 2016
7. Conventional and advanced liquid biofuels
- Author
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Đurišić-Mladenović Nataša L., Predojević Zlatica J., and Škrbić Biljana D.
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biomass ,conversion ,bioethanol ,biodiesel ,celulozic ethanol ,sinthetic diesel ,green diesel ,Chemical technology ,TP1-1185 - Abstract
Energy security and independence, increase and fluctuation of the oil price, fossil fuel resources depletion and global climate change are some of the greatest challanges facing societies today and in incoming decades. Sustainable economic and industrial growth of every country and the world in general requires safe and renewable resources of energy. It has been expected that re-arrangement of economies towards biofuels would mitigate at least partially problems arised from fossil fuel consumption and create more sustainable development. Of the renewable energy sources, bioenergy draws major and particular development endeavors, primarily due to the extensive availability of biomass, already-existence of biomass production technologies and infrastructure, and biomass being the sole feedstock for liquid fuels. The evolution of biofuels is classified into four generations (from 1st to 4th) in accordance to the feedstock origin; if the technologies of feedstock processing are taken into account, than there are two classes of biofuels - conventional and advanced. The conventional biofuels, also known as the 1st generation biofuels, are those produced currently in large quantities using well known, commercially-practiced technologies. The major feedstocks for these biofuels are cereals or oleaginous plants, used also in the food or feed production. Thus, viability of the 1st generation biofuels is questionable due to the conflict with food supply and high feedstocks’ cost. This limitation favoured the search for non-edible biomass for the production of the advanced biofuels. In a general and comparative way, this paper discusses about various definitions of biomass, classification of biofuels, and brief overview of the biomass conversion routes to liquid biofuels depending on the main constituents of the biomass. Liquid biofuels covered by this paper are those compatible with existing infrastructure for gasoline and diesel and ready to be used in mixture with them as „drop-in“ fuels: bioethanol, celullosic ethanol, biodiesel, renewable diesel and BtL diesel; their major advantages and drawbacks are compared. [Projekat Ministarstva nauke Republike Srbije, br. 172050]
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- 2016
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8. Transesterification of linoleic and oleic sunflower oils to biodiesel using CaO as a solid base catalyst
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Predojević Zlatica, Škrbić Biljana, and Đurišić-Mladenović Nataša
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biodiesel ,calcium oxide ,heterogeneous catalysis ,transesterification ,linoleic and oleic sunflower oils ,Chemistry ,QD1-999 - Abstract
The purpose of this work is to characterize biodiesel (i.e. methyl esters, MEs) produced from linoleic and oleic sunflower oils (LSO and OSO, respectively) by alkali transesterification with methanol and CaO as a heterogeneous catalyst under different reaction parameters. The parameters investigated were the methanol/oil molar ratio (4.5:1, 6:1, 7.5:1, 9:1 and 12:1) and the mass ratio of CaO to oil (2% and 3%). The physical and chemical properties of the feedstocks and MEs, like density at 15oC, kinematic viscosity at 40oC, acid value, iodine value, saponification value, cetane index, fatty acid (methyl ester) composition, were determined in order to investigate the effects of LSO and OSO properties and reaction parameters on the product characteristics, yields and purity. The properties of feedstock had decisive effect on the physical and chemical properties of MEs as majority of them did not differ significantly under studied reaction conditions. The MEs produced generally met the criteria required for commercial biodiesel; in fact, the only exception was in the case of iodine value of ME produced from LSO. The product yields only slightly changed with the applied conditions; the highest yield (99.22%) was obtained for ME-LSO produced at 6 mol% methanol to oil ratio, while the lowest one (93.20%) was for ME-OSO produced under the lowest methanol/oil molar ratio (4.5:1). The applied catalyst amounts had similar influence on the oil conversion to biodiesel. The yields of ME-LSOs were in general somewhat higher than those obtained for ME-OSOs under the same conditions, which was attributed to the influence of the respective feedstocks' acid value and viscosity.
- Published
- 2012
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9. Alkali-catalyzed production of biodiesel from waste frying oils
- Author
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Predojević Zlatica J. and Škrbić Biljana D.
- Subjects
biodiesel ,waste frying oil ,alkaline two-step transesterification ,Chemistry ,QD1-999 - Abstract
The effects of the transesterification parameters on the yield and quality of the methyl esters (MEs) produced from waste frying oil (WFO) were investigated. A two-step alkali transesterification reaction followed by silica gel purification step was applied. The investigated reaction parameters were the methanol/oil molar ratio (6:1 and 9:1), the catalyst/oil weight ratio (1.0 and 1.5 mass %) and the type of catalyst (NaOH and KOH). The physical and chemical properties of the employed feedstock and the obtained biodiesel were determined in order to investigate the effects of both the properties of the WFO and the reaction parameters on the characteristics and yields of the product. It was found that the properties of the feedstock had a determinant effect on the physical and chemical properties of the MEs, as the majority of them did not differ significantly under the studied reaction parameters. However, the reaction parameters influenced the yields of the product. Higher yields were obtained with a 1.0 than with a 1.5 mass % catalyst to oil ratio. The increasing yield with decreasing catalyst/oil ratio was more pronounced with NaOH (9.15-14.35 %) than with KOH (2.84-6.45 %). When KOH was used as the catalyst, the yields were always higher (the mean yield was 94.86 %) in comparison to those obtained with NaOH (the mean was 84.28 %). Furthermore, the efficiency of KOH in conversion of WFO to purified MEs in comparison to NaOH was even more pronounced in the case of the higher methanol/oil ratio, i.e., for the 9:1 methanol/ oil ratio, the yield increase with KOH was about 2 times higher than the yield with NaOH, regardless of the applied catalyst/oil ratio.
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- 2009
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10. Qualitative TLC determination of some polycyclic aromatic hydrocarbons in sugar-beet
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Lončar Eva S., Kolarov Ljiljana A., Malbaša Radomir V., and Škrbić Biljana D.
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pahs ,sugar-beet ,cyclohexane extracts ,tlc ,silica gel ,Chemistry ,QD1-999 - Abstract
The presence of polycyclic or polynuclear aromatic hydrocarbons (PAHs) were investigated in sugar-beet from a local sugar factory in the district of Vojvodina. The sugar-beet was cultivated on areas near roads with intensive traffic. The procedure for the preparation and determination of these compounds included saponification of the sample, several liquid–liquid extraction systems and a silica gel column clean-up. The purified sample solution was analysed by thin layer chromatography (TLC) on silica gel with cyclohexane as the developing solvent. Benzo(b)fluoranthene and benzo(a)anthracene and/or benzo(a)pyrene were detected at concentrations greater than the allowed limits in food.
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- 2005
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11. Artificial neural network prediction of quantitative structure: Retention relationships of polycyclic aromatic hydocarbons in gas chromatography
- Author
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Sremac Snežana, Škrbić Biljana D., and Onjia Antonije E.
- Subjects
retention index ,gc ,ann ,pahs ,qsrr ,molecular descriptors ,Chemistry ,QD1-999 - Abstract
A feed-forward artificial neural network (ANN) model was used to link molecular structures (boiling points, connectivity indices and molecular weights) and retention indices of polycyclic aromatic hydrocarbons (PAHs) in linear temperature- programmed gas chromatography. A randomly taken subset of PAH retention data reported by Lee et al. [Anal. Chem. 51 (1979) 768], containing retention index data for 30 PAHs, was used to make the ANN model. The prediction ability of the trained ANN was tested on unseen data for 18 PAHs from the same article, as well as on the retention data for 7 PAHs experimentally obtained in this work. In addition, two different data sets with known retention indices taken from the literature were analyzed by the same ANN model. It has been shown that the relative accuracy as the degree of agreement between the measured and the predicted retention indices in all testing sets, for most of the studied PAHs, were within the experimental error margins (+-3 %).
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- 2005
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12. Isolation and characterization of antagonistic Bacillus strains capable to degrade ethylenethiourea.
- Author
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Vágvölgyi C, Sajben-Nagy E, Bóka B, Vörös M, Berki A, Palágyi A, Krisch J, Skrbić B, Durišić-Mladenović N, and Manczinger L
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- Anti-Bacterial Agents biosynthesis, Bacillus classification, Bacillus genetics, Biodegradation, Environmental, DNA Gyrase genetics, Fungi metabolism, Solanum lycopersicum microbiology, Molecular Sequence Data, RNA, Ribosomal, 16S, Rhizosphere, Soil Microbiology, Antibiosis, Bacillus isolation & purification, Bacillus metabolism, Ethylenethiourea metabolism
- Abstract
In this study, more than 150 bacteria showing antagonistic properties against bacterial and fungal pathogens of the tomato plant were isolated and characterized. The most efficient agents against these phytopathogenic microorganisms belong to the genus Bacillus: the best biocontrol isolates were representatives of Bacillus subtilis, B. mojavensis and B. amyloliquefaciens species. They intensively produced fengycin or/and surfactin depsipeptide antibiotics and also proved to be excellent protease secretors. It was proved, that the selected strains were able to use ethylenethiourea (ETU) as sole nitrogen source. These antagonistic and ETU-degrading Bacillus strains can be applied as biocontrol and also as bioremediation agents.
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- 2013
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13. The influence of essential oil of aniseed (Pimpinella anisum, L.) on drug effects on the central nervous system.
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Samojlik I, Mijatović V, Petković S, Skrbić B, and Božin B
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- Animals, Central Nervous System Agents chemistry, Male, Mice, Plant Oils chemistry, Seeds chemistry, Central Nervous System Agents pharmacokinetics, Herb-Drug Interactions, Oils, Volatile chemistry, Oils, Volatile pharmacokinetics, Pimpinella chemistry, Plant Oils pharmacokinetics
- Abstract
Anise (Pimpinella anisum L.; Apiaceae) and its essential oil have been widely used in folk medicine, pharmacy and food industry. Since there are some data about the impact of anise on functions of central nervous system (CNS), the issue of possible interactions with drugs acting in CNS should be considered. This survey aimed to examine the influence of aniseed essential oil (EO) intake on the effects of drugs that act in CNS. The chemical profile of essential oil determined by GC-MS revealed as the main components: trans-anethole (88.49%), γ-himachalene (3.13%), cis-isoeugenol (1.99%), and linalool (1.79%). The effects of codeine, diazepam, midazolam, pentobarbital, imipramine and fluoxetine were tested in mice after 5days of peroral pretreatment with human equivalent dose of aniseed EO (0.3mg/kg). The intake of EO led to significant increase of analgesic effect of codeine. The motor impairment caused by midazolam was enhanced in the group treated by EO. The application of diazepam decreased the number and percentage of entries in open arm in elevated maze plus test in the group pretreated with EO indicating augmented effect of drug on motor activity. EO pretreatment caused significant shortage of pentobarbital induced sleeping time when compared to control. The decrease in antidepressant effect of imipramine and fluoxetine was diminished by the pretreatment with aniseed EO. Based on the results of this study we conclude that concomitant intake of aniseed EO preparations and drugs that act on CNS should be avoided due to potential herb-drug interactions, which also need further clinical confirmation., (Copyright © 2012 Elsevier B.V. All rights reserved.)
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- 2012
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14. Ranking and similarity for quantitative structure-retention relationship models in predicting Lee retention indices of polycyclic aromatic hydrocarbons.
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Héberger K and Skrbić B
- Subjects
- Cluster Analysis, Principal Component Analysis, Polycyclic Aromatic Hydrocarbons chemistry, Quantitative Structure-Activity Relationship
- Abstract
Quantitative structure-(chromatographic) retention relationship (QSRR) models for prediction of Lee retention indices for polycyclic aromatic hydrocarbons (PAHs) were gathered from the literature and the predictive performances of models were compared. Numerous Lee retention indices (46) were served as a reliable basis for ranking by a recently developed novel method of ordering based on the sum of ranking differences (SRD) [TrAC, Trends Anal. Chem. 29 (2010) 101-109], by which the best model can be selected easily. Two kinds of references for ranking were accepted, average (consensus) and the experimental retention indices. Leave-many-out cross validation of the SRD procedure provides an easy way to group similar models. Significant differences among models can be revealed by using Wilcoxon's matched pair test. Principal component analysis (PCA) and cluster analysis (CA) arranged the models in three groups, i.e. similarities among models are manifested. The classical exploratory techniques and cross-validation (CV) justified the findings based on SRD ranking, i.e. the seven fold CV can be applied for pattern recognition. Generalized pair correlation method (GCPM) provided very similar grouping pattern to the procedures based of sum of ranking differences. The two methods (SRD and GPCM) exert astonishingly similar grouping (pattern recognition) though their background philosophy and way of calculation are totally different., (Copyright © 2011 Elsevier B.V. All rights reserved.)
- Published
- 2012
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15. Principal component analysis of indicator PCB profiles in breast milk from Poland.
- Author
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Skrbić B, Szyrwińska K, Durišić-Mladenović N, Nowicki P, and Lulek J
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- Adolescent, Adult, Female, Humans, Life Style, Poland, Principal Component Analysis, Surveys and Questionnaires, Young Adult, Environmental Exposure, Environmental Pollutants analysis, Milk, Human chemistry, Mutagens analysis, Polychlorinated Biphenyls analysis
- Abstract
Principal component analysis (PCA) was applied to a data set containing the levels of indicator polychlorinated biphenyls (PCBs) in human milk of mothers living in the Wielkopolska region, Poland, in order to investigate the information captured in the PCB patterns and to elucidate the relationship between PCB concentrations in milk and donor characteristics. According to the obtained PCA results milk fat content was the most influential factor affecting the PCB levels in milk of the Wielkopolska cohort. The lifestyle data collected from the questionnaire completed by the donors appeared to have no influence on PCB concentrations in breast milk. The score plots revealed the PCB contents of milk were quite low and uniform with a few outliers, without discrimination observed either between the primipareous and secundipareous females or between donors from the urban and rural areas. Comparison of the PCB levels and profiles of human milk from the Wielkopolska region and from various European and Asian locations made by PCA reflected a generally low background exposure and indicated the possible reasons for the outlying of some samples. In order to enhance the chances of observing the relationship between donor habits and PCB levels in breast milk it was suggested that the questionnaire be redesigned to gather information about vegetable product consumption and indoor air exposure., (Copyright © 2009 Elsevier Ltd. All rights reserved.)
- Published
- 2010
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16. Chemometric interpretation of heavy metal patterns in soils worldwide.
- Author
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Skrbić B and Durisić-Mladenović N
- Subjects
- Kinetics, Metals, Heavy chemistry, Soil Pollutants chemistry, Environmental Monitoring methods, Environmental Pollution statistics & numerical data, Metals, Heavy analysis, Soil analysis, Soil Pollutants analysis
- Abstract
Principal component analysis (PCA) was applied on data sets containing levels of six heavy metals (Pb, Cu, Zn, Cd, Ni, Cr) in soils from different parts of the world in order to investigate the information captured in the global heavy metal patterns. Data used in this study consisted of the heavy metal contents determined in 23 soil samples from and around the Novi Sad city area in the Vojvodina Province, northern part of Serbia, together with those from the city of Banja Luka, the second largest city in Bosnia and Herzegovina, and the ones reported previously in the relevant literature in order to evaluate heavy metal distribution pattern in soils of different land-use types, as well as spatial and temporal differences in the patterns. The chemometric analysis was applied on the following input data sets: the overall set with all data gathered in this study containing 264 samples, and two sub sets obtained after dividing the overall set in accordance to the soil metal index, SMI, calculated here, i.e. the set of unpolluted soils having SMIs<100%, and the set of polluted soils with SMIs>100%. Additionally, univariate descriptive statistics and the Spearman's non-parametric rank correlation coefficients were calculated for these three sets. A Box-Cox transformation was used as a data pretreatment before the statistical methods applied. According to the results, it was seen that anthropogenic and background sources had different impact on the data variability in the case of polluted and unpolluted soils. The sample discrimination regarding the land-use types was more evident for the unpolluted soils than for the polluted ones. Using linear discriminant analysis, content of Cu was determined as a variable with a major discriminant capacity. The correct classification of 73.3% was achieved for predefined land-use types. Classification of the samples in accordance to the pollution level expressed as SMI was necessary in order to avoid the "masking" effect of the polluted soil patterns over the non-polluted ones., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)
- Published
- 2010
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17. Removal of water turbidity by natural coagulants obtained from chestnut and acorn.
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Sćiban M, Klasnja M, Antov M, and Skrbić B
- Subjects
- Hydrogen-Ion Concentration drug effects, Nephelometry and Turbidimetry, Organic Chemicals analysis, Plant Extracts pharmacology, Plant Proteins analysis, Seeds chemistry, Water chemistry, Aesculus chemistry, Coagulants pharmacology, Quercus chemistry, Water Purification
- Abstract
The ability of seed extracts of several species of chestnut and acorn to act as natural coagulants was tested using a synthetic turbid water. Active components were extracted from ground seeds of Horse chestnut and acorns of some species of family Fagaceae: Common oak, Turkey oak, Northern red oak and European chestnut. All investigated extracts had coagulation capabilities and their amounts depended on pH values and initial turbidities. The seed extracts from European chestnut and Common oak acorn were the most efficient expressing the highest coagulation activities, about 80% and 70%, respectively, in both low and medium investigated water turbidities at the lowest coagulant dose 0.5 ml/L.
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- 2009
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18. Levels of organochlorine pesticides in crops and related products from Vojvodina, Serbia: estimated dietary intake.
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Skrbić B and Predojević Z
- Subjects
- Beta vulgaris chemistry, Crops, Agricultural standards, DDT analysis, Diet, Eating, European Union, Flour analysis, Food Analysis methods, Food Contamination legislation & jurisprudence, Molasses analysis, Plant Oils chemistry, Quality Control, Risk Assessment, Sucrose chemistry, Sunflower Oil, Triticum chemistry, Yugoslavia, Crops, Agricultural chemistry, Environmental Monitoring methods, Food Contamination analysis, Hydrocarbons, Chlorinated analysis, Pesticides analysis
- Abstract
Levels of 16 organochlorine pesticides (OCPs) were investigated in 39 composite samples of agricultural crops, related by-products, and foodstuffs collected in Vojvodina, Serbia, in 2002 through 2004. After extraction and cleanup, OCPs were determined by capillary gas chromatography using electron-capture detection. The highest mean level of 0.971 ng/g whole weight (ww) was found for alpha-HCH in wheat flour samples. OCPs levels were well lower than the respective maximum residue limits set by current European and Serbian regulations. Mean OCP levels were low (<1 ng/g ww) for all sample types. The most frequently determined residue was 4,4'-DDT (identified in 76.9% of all samples analyzed), followed by gamma-HCH (66.7%), beta-HCH (48.7%), and endosulfan II (41.0%). OCP levels were compared with data from other international surveys. Calculated daily intakes of OCPs by way of consumption of the crop products included in this study according to data of the Serbian National Institute for Statistics were compared with the acceptable daily intakes established by the Food and Agriculture Organization/World Health Organization. The average level of contamination of the Vojvodina diet was believed to be harmless regarding the studied food commodities.
- Published
- 2008
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19. Principal component analysis for soil contamination with organochlorine compounds.
- Author
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Skrbić B and Durisić-Mladenović N
- Subjects
- Environmental Monitoring, Hydrocarbons, Chlorinated analysis, Hydrocarbons, Chlorinated chemistry, Principal Component Analysis, Soil analysis, Soil Pollutants analysis, Soil Pollutants chemistry
- Abstract
In order to investigate the distribution pattern of individual organochlorine compounds in soil samples collected from the sites (Canary Island - Spain, China, Germany, India, Romania, Russia, Serbia, Swiss, UK) affected by industrial activities to the more remote areas, principal component analysis was performed on the data taken from literature. Loading plots pointed out the strong correlation among the variables. Score plots revealed similar PCB- and OCP-soil patterns for majority of the investigated sites. Nevertheless, the temporal differences of PCB-soil loads have been identified: the late 1990s and early 2000s concentrations are similar to those of the early 1940s, and they are below the levels existed in 1980. The most pronounced PCB concentrations characterized the soil from 1966. For OCPs the influence of sites location on the detected concentration has been revealed: China and India were characterized by comparably higher loads of DDX (DDT and its metabolites) and of HCH-isomers, respectively.
- Published
- 2007
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20. Organochlorine and organophosphate pesticide residues in wheat varieties from Serbia.
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Skrbić B
- Subjects
- Food Analysis methods, Gas Chromatography-Mass Spectrometry methods, Yugoslavia, Edible Grain chemistry, Food Contamination, Hydrocarbons, Chlorinated analysis, Organophosphates analysis, Pesticide Residues analysis
- Abstract
A survey was carried out to assess the levels of 20 organochlorine and 15 organophosphate pesticides in wheat grown in two regions of the Vojvodina Province in Serbia. A total of 49 samples of seven wheat varieties were collected during the 2004 harvest. In addition, a composite sample of cultivated wheat varieties was prepared from 36 samples coming from the same regions harvested in 2003 for comparison. Official method of analysis AOAC 970.52 was applied for the determination of pesticide residues. The ranges of mean values for organochlorine residues were 32-47 ng g(-1) for beta-HCH; 28-41 ng g(-1) for gamma-HCH; <1-61 ng g(-1) for aldrin; 5-132 ng g(-1) for dieldrin; 15-111 ng g(-1) for endrin ketone; and <1-77 ng g(-1) for endrin aldehyde. For organophosphate residues the ranges were: 7-27 ng g(-1) for thionazin; <5-35 ng g(-1) for disulphoton; 42-79 ng g(-1) for parathion methyl; 422-1336 ng g(-1) for chlorpyriphos; and <5-281 ng g(-1) for parathion. The mean levels of residues were compared with the regulated maximum levels according to the European Commission and Serbian national regulation, and the average intake of residues from wheat-based products was estimated for the Serbian population.
- Published
- 2007
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21. Distribution of chlorinated organic pollutants in a wide variety of soils from Europe and Asia: a multivariate statistical approach.
- Author
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Skrbić B and Durisić-Mladenović N
- Subjects
- Adsorption, Aluminum Silicates analysis, Asia, Clay, Environmental Monitoring statistics & numerical data, Europe, Humic Substances, Hydrogen-Ion Concentration, Multivariate Analysis, Principal Component Analysis, Hydrocarbons, Chlorinated analysis, Pesticides analysis, Soil Pollutants analysis
- Abstract
Principal component analysis was used to interpret the levels of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) previously determined in a wide variety of soils from Europe and Asia to (1) examine the interdependencies among them and chosen soil charaeteristics and (2) reveal PCB- and OCP-soil patterns throughout Europe and Asia. Loading values suggested correlations between the levels of certain compounds and soil characteristics, revealing the underlying structure of analyzed data; humus content, pH, and density correlated with the contents of p,p'-DDT, beta-hexachlorocyclohexane (HCH) and gamma-HCH, and clay content correlated with the concentrations of alpha-HCH and PCB 28. Component scores reflected relatively low concentrations of six "marker" PCBs in most of the soils, pointing out the outliers in the proximity of the local PCB sources. PCB loads in the 1990s and early 2000s were lower than the ones in 1980 and 1956, and they coincided with the soil levels in 1944. PCBs 138, 153, and 180 had the greatest influence of the six investigated congeners on soil-pattern differences. In relation to the OCP soil loads, the score plot revealed regions with recent and/or enhanced application of DDT and HCH.
- Published
- 2007
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22. Modified softwood sawdust as adsorbent of heavy metal ions from water.
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Sćiban M, Klasnja M, and Skrbić B
- Subjects
- Adsorption, Sodium Hydroxide chemistry, Metals, Heavy chemistry, Water chemistry, Wood
- Abstract
The sawdust of deciduous softwood-poplar, and coniferous softwood-fir, have been found to possess some adsorption capacities for heavy metal ions. Their adsorption capacities can be increased by previous treatment with a sodium hydroxide solution. Adsorption capacities of alkali modified adsorbents were higher than for unmodified ones from 2.5 to 5 times for copper ions, and about 15 times for zinc ions. Also, for modification can be used solution of sodium carbonate, but that alkaline solution is less efficient than sodium hydroxide solution. The 1% sodium hydroxide solution is suggested for modification of softwood sawdust. It was established that the ion exchange is not only adsorption mechanism, than microprecipitation of metal-hydroxide in the pore liquid was happened, too. At the same time, the leaching of organic matters from modified softwood sawdust were less than from unmodified ones for about 7% for poplar and 23% for fir.
- Published
- 2006
- Full Text
- View/download PDF
23. Prediction of the Lee retention indices of polycyclic aromatic hydrocarbons by artificial neural network.
- Author
-
Skrbić B and Onjia A
- Subjects
- Temperature, Neural Networks, Computer, Polycyclic Compounds chemistry
- Abstract
A quantitative structure retention relationship technique using an artificial neural network (ANN) has been used for the prediction of the Lee retention indices for PAHs on SE-52 and DB-5 stationary phases. The selected descriptors that appear in the ANN model are the boiling point, molecular weight, connectivity index and the Schabron molecular size descriptor. The network was trained and optimized using a training and validation data sets. For the evaluation of the predictive power of the ANN, the optimized network was used to predict the temperature-programmed Lee retention indices of two unseen testing data sets. The results obtained showed that the mean of relative errors and the correlation coefficients between the calculated ANN and the experimental values of Lee retention indices for the validation and two testing sets are 1.42% and 0.9460 on SE-52; 1.32% and 0.9381; 1.43% and 0.8939 on DB-5 stationary phases, respectively. These values are in good agreement with the relative error obtained by experiment.
- Published
- 2006
- Full Text
- View/download PDF
24. Survey on some contaminants in white sugar from Serbian sugar beet refineries.
- Author
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Skrbić B and Gyura J
- Subjects
- Copper analysis, Dietary Sucrose standards, European Union, Food Analysis methods, Food Industry standards, Humans, Iron analysis, Quality Control, Yugoslavia, Zinc analysis, Dietary Sucrose chemistry, Food Contamination analysis
- Abstract
Refined white sugar is a very pure food product, even though it contains very small amounts of soluble and insoluble impurities. The content of these impurities has nutritional significance and determines the usefulness of sugar for various industrial applications. The main quality criteria used to indicate the content of these impurities are ash and colour. The aim of this paper was to evaluate the quality according to the EU sugar market regime and the content of iron, copper and zinc in white sugar samples from Serbian sugar beet refineries during the 2003 campaign. A total of 166 samples representative of the production of four Serbian sugar refineries were investigated. After wet digestion the concentrations of iron, copper and zinc were determined by flame atomic absorption spectrometry. The mean content of iron, copper and zinc in sugar samples was 0.37 mg/kg, 0.06 mg/kg and 0.02 mg/kg and was significantly different from the average content 0.28 mg/kg, 0.09 mg/kg and 0.07 mg/kg respectively in the analysed European sugar factories. The data were also compared with literature values for commercial white sugar samples from European sugar beet refineries and European legislation set for copper and zinc. Furthermore, the quality of produced sugar was evaluated according to the standards of the European Union indicating that 76% of all investigated Serbian samples belonged to the second sugar quality category.
- Published
- 2006
- Full Text
- View/download PDF
25. Principal component analysis of trace elements in Serbian wheat.
- Author
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Skrbić B, Durisić-Mladenović N, and Cvejanov J
- Subjects
- Seeds chemistry, Spectrophotometry, Atomic, Yugoslavia, Trace Elements analysis, Triticum chemistry
- Abstract
Trace elements (Cu, Fe, Pb, Hg, Cd, As, Mn, Zn) were analyzed quantitatively in 14 wheat samples collected from fields in all Serbian growing regions, harvested in 2002. Microelements were determined according to an atomic absorption spectrophotometric method. Principal component analyses (PCA) were performed on data matrices consisting of contents of trace elements in wheats (columns) and all Serbian wheat-growing regions (rows). It was found that four principal components account for 87.2% of the total variance in the data. The plot of component loadings showed significant groupings for concentration of some microelements. The component scores indicated the similarities among the Serbian wheat-growing regions. The loading plot reveals that there is no need to measure all of the variables to achieve the same classification. It is enough to measure one variable per group. Naturally, this conclusion is valid only within the limits of the present study of wheat grain samples from different parts of Serbia.
- Published
- 2005
- Full Text
- View/download PDF
26. Polycyclic aromatic hydrocarbons in surface soils of Novi Sad and bank sediment of the Danube River.
- Author
-
Skrbić B, Cvejanov J, and Durisić-Mladenović N
- Subjects
- Cities, Environmental Monitoring, Geologic Sediments analysis, Particle Size, Risk Assessment, Rivers, Yugoslavia, Carcinogens analysis, Polycyclic Aromatic Hydrocarbons analysis, Soil Pollutants analysis, Water Pollutants, Chemical analysis
- Abstract
Concentrations of 16 EPA polycyclic aromatic hydrocarbons (PAHs) in the surface soil samples of Novi Sad city urban area and in the Danube bank sediment sample were measured in 2001. The sampling sites were chosen in order to cover the whole city area and the results correspond to a network of six representative sampling sites. The total content of PAHs ranged from 307 to 1452 microg/kg with arithmetic mean value of 667 microg/kg and median of 382 microg/kg that represented typical PAH level of soils throughout Novi Sad urban area. Value of total PAHs content obtained in bank sediment sample along the Danube River was 975 microg/kg. Benzo(a)pyrene known to be carcinogenic formed 6-14% of the sum concentration of the identified PAHs for all investigated samples. Data were compared with the ones found for soils and river sediments throughout the world, and with target values set by Dutch authorities for unpolluted soil. The total carcinogenic potency for each sampling site was calculated and compared with the ones obtained on the base of the target concentrations. It was revealed only one sampling site with carcinogenic potency below the value calculated for unpolluted soil.
- Published
- 2005
27. Trace metal distribution in surface soils of Novi Sad and bank sediment of the Danube River.
- Author
-
Skrbić B and Cupić S
- Subjects
- Environmental Monitoring, Rivers, Spectrophotometry, Atomic, Yugoslavia, Geologic Sediments chemistry, Metals, Heavy analysis, Soil Pollutants analysis, Water Pollutants analysis
- Abstract
Concentration ofCu. Cd, Pb, Zn, As, Mn, and Fe in the Novi Sad city urban area surface soil samples and the Danube bank sediment sample were measured in 2001. The results correspond to a network of six representative sampling sites in which the main soil properties, organic matter, water content, pH, and particle size have also been determined. The geometric mean content of Zn, Cu, Cd, and Pb obtained from soil samples throughout the Novi Sad urban area (61.32, 28.39, 0.151, and 2.70 mg/kg, respectively) was compared with the geometric mean concentration in world soils. It was revealed only one site (sampling site No. 3) with Zn and Cu content higher than the allowed ones set by Dutch authorities used for investigation of a site for possible rehabilitation (Dutch A values).
- Published
- 2004
- Full Text
- View/download PDF
28. An evaluation of residues at an oil refinery site following fires.
- Author
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Skrbić B and Miljević N
- Subjects
- Environmental Monitoring, Environmental Pollutants analysis, Industrial Waste, Polychlorinated Biphenyls analysis, Polycyclic Aromatic Hydrocarbons analysis, Fires, Petroleum, Soil Pollutants analysis
- Abstract
Soil pollution at the oil refinery at Novi Sad following destruction of crude oil and its products in storage tanks during the Kosovo conflict was investigated. More than 100,000 t of crude oil and its products were destroyed, and about 90% of these were burnt off, 10% leached and 130 t recovered. The acute injection of polycyclic aromatic hydrocarbons (PAHs) to the air of the town was widespread depending on the weather conditions and ranged from 1-431,000 ng/m3. The presence of PAHs, polychlorinated biphenyls (PCBs), and elements in the surface zone and soil core samples taken from various sites were determined up to a depth of 100 cm. Concentrations of PAHs were in the range between 0.75 and 86.19 microg/g dry soil. The contaminated soil can be expected to act as a permanent pollution source, while the mobile constituents are likely to cause groundwater pollution.
- Published
- 2002
29. Mobility of heavy metals originating from bombing of industrial sites.
- Author
-
Skrbić B, Novaković J, and Miljević N
- Subjects
- Explosions, Hazardous Waste, Humans, Incineration, Petroleum, Public Health, Refuse Disposal, Risk Assessment, Industrial Waste, Metals, Heavy analysis, Soil Pollutants analysis
- Abstract
Surface soil samples from the "NIS Jugopetrol" fuel storage sites has been studied. The aim of this work has been the detection of heavy and inorganic metals including As, Pb, Cd, Ni, Zn, Cr, and Cu in soils after bombing present due to outflow, burning or leaking of crude oil and oil products at five chosen locations: Belgrade-Cukarica, Smederevo, Nis, Bor and Prahovo. In order to get information of the future environmental and health risks, sampling was repeated after several months at the same locations. Certain locations present a threat on environment because of the possible transport of contaminants during higher water levels.
- Published
- 2002
- Full Text
- View/download PDF
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