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The village of Dubravica is partially located over the western lignite deposits of the Kostolac basin. The examination of the dry residue obtained from drinking water from two individual wells by X-ray diffraction analysis, based on a typical peak, showed the presence of uranium in drinking water. The indirect method by Rajković and associates showed that, in sample I, the concentration of uranium in drinking water was 85.5 percent higher (3.71 mg/L) and that the concentration of uranium in sample II was only 22 percent lower (1.56 mg/L) than the Maximum Allowable Concentration (MAC) values required by the Regulations (2 mg/L). Analysis of the result of the introduction of uranium in the human body has shown that this way brings 0.84 to 2 mg of uranium in the human organism per annum or 0.09 to 0.22 mg of uranium is deposited annually in the kidney. Assessment of the potential health risk due to the presence of uranium in drinking water indicated that the population using drinking water from wells will be threatened by uranium in a short time interval. Regarding the long-term risk, the calculation has indicated that in the first sample of drinking water, about 25 inhabitants, and in the case of the second sample of drinking water, 10 inhabitants out of 1000 inhabitants are endangered. As the kidney is the organ in which uranium is deposited (accumulated) to the greatest extent, its presence causes weakening and failure of kidney function, which can destroy 75 percent of kidney function until the manifestation of the first clinical symptoms. This phenomenon is observed among the population along the rivers the Kolubara, the Drina, the Sava and the Morava and is called endemic nephropathy. The elements found in trace amounts (Pb, Cd, Si), live agents (bacteria and viruses), fungal plant toxins, genetic factors and immune mechanism can be listed as possible causes. However, uranium in drinking water has not been listed so far. The tests performed in this study clearly show the role of uranium in the epidemic, endemic nephropathy, which is growing and which is not at the acute phase of the disease but has already progressed to renal failure and end-stage kidney disease. Official data on the rise of endemic nephropathy and diabetes and increasing their share in diseases, as well as overall mortality rates, which amount to 18.19%, clearly indicate that the role of uranium in the Braničevo district environment should not be ignored. Since there are settlements on the terrain to be investigated, uranium and its migration through the environment must be monitored as all conditions for its migration are unfortunately favourable.

This study aims at analysing physical, chemical and microbiological properties, and content of macro- and microelements in the water from the Požarevac city public water supply system. Analysis shows an increased content of Ca in drinking water, as a result of the position of Požarevac on the sediments of river terrace of accumulative character of t1 type, predominantly consisting of quartzite. The water from the public water supply is alkaline ('calcic', 'bicarbonate water') and very hard, due to the increased Ca content. Beside Ca, potassium and aluminium exceed the maximum contaminant level, while Pb and Cd are at the very limit. Calculated data show that there are no short-term health risks regarding elements exceeding allowed concentrations found in the public water supply system. Data analysis regarding long-term health risks shows that Cd present in drinking water poses the only relevant threat to human health. Cancer risk is present in 202 out of 1000 inhabitants using this water.

In order to verify the content of macro- and microelements in drinking water in the village of Dubravica in the Branicevo district, which has no centralized water supply system, an analysis of the water sampled from two individual wells was conducted using the indirect method recommended by Rajkovic and associates. Tests on the RDA and AAS showed that: Al, Fe, Cr, Pb and U were in concentrations higher than the values allowed by Regulations on the hygienic quality of drinking water. To determine the risk of the presence of toxic metals in the elevated concentrations, the assessment of short-term and long-term potential carcinogenic risks was conducted. Based on the results obtained in the tested water samples, it is noticed that the value of the coefficient of risk (CR) was less than 1 for all potentially toxic metals that were determined in drinking water, which implies that there is no short-term carcinogenic potential risk to human health. Based on the results of the long-term potential risk for the occurrence and development of cancer, the risk of getting cancer of Cr was identified in the inhabitants of the village that used potable water of the first sample. In case of Pb, a risk of developing cancer, concerning the first sample of drinking water, may occur in 44 out of 1000 people and regarding the second sample, in 183 out of 1000 people. Based on the calculated estimates of the long-term health risk related to the presence of U in drinking water, it can be seen that there is a health risk related to the use of both water samples. On the basis of the calculated estimates of the long-term health risk related to the presence of uranium in drinking water, it can be noticed that the use of both water samples may lead to the potential risk of developing cancer: in 24.5 inhabitants regarding the first water sample and in 10.3 out of 1000 inhabitants in the case of the second water sample. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 43009]

This paper presents a study of the profile distribution of available micronutrients Fe, Mn, Cu and Zn and radionuclide 137Cs in cultivated soil at the experimental field "Radmilovac" (property of Agricultural Faculty, Belgrade University) in the vicinity of Vinĉa Institute of Nuclear Sciences. The soil belongs to the anthrosol class of anthropogenic soils according to FAO (2006). At first, the deep plowing was performed while preparing soil for planting peach trees followed by cultivation of soil for 12 years. All agricultural treatments at the experimental field ceased for three years. After that period, soil sampling was carried out. Contents of DTPA-extracted Fe, Mn, Cu and Zn were in the range of (mg kg-1): 5.8-41.6; 9.2-34.2; 1-7.6 and 0.2-1.3, respectively. Detected activity concentration (Bq kg-1) for 137Cs ranged from 1.8 to 35. It was noticed that distribution patterns of 137Cs radionuclide and available Cu and Zn along soil depth were very similar and they were analyzed by simple linear regression; mutual affinity for the soil organic matter might affect their distribution in soil. Contents of available Fe and Mn exhibited different, more constant distribution within a soil horizon.

In order to control the quality of beer and raw materials for production of beer in Belgrade Beer Industry (BIP), water is analyzed (city, technological and demineralized water). Measurements of pH values indicated the increased pH values in the sample of tehnological water, which had no impact on wort hopping, since the tested samples of wort, young beer and final product had a pH value within the expected range. After processing city water, a sample of tehnological water was found with increased carbonate hardness, which is caused by the increased content of sodium hydrogen carbonate. Analysing the titration alkalinity, titration acidity and buffering power, it was found that the alkalinity was decreasing which is in accordance with the determination of pH values of wort and beer samples (young beer and final product). Analyzing the content of anions and cations in the examined water samples, it has been shown that the concentration of these examinated anions (Cl-, NO3 -, SO4 2- and PO4 3-) and cations (NH4 +, Na+, K+, Ca2+, Mg2+) are within the limits prescribed by the Regulations on hygienic safety of drinking water, and thus by the Regulations of quality and other requirements for beer. The contents of anions in wort and beer samples (young beer and final product) were determined by ion chromatography method. The contents of sulphate and nitrate ions were within the recommended limits. The concentration of chloride ions was above 150 mg/dm3, which may have an impact on the sensory properties of beer, while changes in the content of phosphate ions were insignificant. [Projekat Ministarstva nauke Republike Srbije, br. III 43009]

It is estimated that all over the world there are more than 550 million road vehicles in everyday use. Annually, 1.3 billion used tyres are dismantled from these vehicles due to safety reasons. A small number of these tyres end up reused as second-hand tyres or, after being retreated, as new ones. The rest are end of life tyres which are recycled or used as tire derived fuels under controlled combustion conditions. Modern vehicle tyres are a high-technological product containing, on the average, 85% hydrocarbon, 10-15% steel, as well as some other chemical materials. Tyres belong to high caloric materials, with calorific value of a passenger car tyre of approx. 30.2 MJ/kg being more than of hard coal and comparable to calorific value of petrol-coke. Having this in mind many countries use end of life tyres as safe alternative fuel in cement works or power plants. Undeveloped countries dump end of life tyres on legal and illegal scrap stockpiles. End of life tyres, if deposed correctly, don’t endanger the environment because they are chemically inert. However, since they can easily be burnt there is a real possibility of tyre dump fires, which in effect can lead to harmful products emission that extremely pollute the environment. End of life tyres represent a very important secondary material, which when recycled is transformed into a number of raw materials used in rubber industry, for road construction, sports facilities, residential and business buildings, artificial fish habitats in shallow seas, sea walls, steel production, etc. By the industrial procedures of controlled degradation, which have been uneconomical up till now, gaseous and liquid fuel can be obtained by natural rubber, steel and soot recycling. The countries of the EU, together with Norway and Switzerland, were the world leaders in the field of effective end of life tyre management in the year 2009. Out of 2.62 million tonnes of end of life tyres, 95% were restored or used as energents, and 5% settled on dumps. About 26.000 t of used tyres are collected in Serbia each year. In accordance with adopted legal legislations, up to 30% can be used as tire derived fuels while 70% are being recycled. Serbia belongs to the group of countries which have solved the problem of used tyres in a modern way, and in accordance with EU Legislation practice.

The content of NaCl (weight fraction of Cl-ions, in %) was analysed in different cheeses, which were bought in supermarkets, and made by domestic manufacturers. Sodium chloride in cheese samples was analysed after the extraction of chloride by nitric acid solution. Concentration of chloride ions was potentiometricly determined, with the chloride selective electrode and titrimetricly by Volhard method. According to the results in the analysis of the content of NaCl in %, by different methods it was determined that the share of NaCl in % ranged from 0.66 to 4.43% (determined by potentiometric route) that is from 0.97 to 4.72% (determined by titrimetric route by Volhard method). The difference in received results in different methods is less if the share of NaCl, in % is higher than 3%. If the share is less than 3%, the difference in results rapidly increases, and the biggest difference is when the share is less than 1%. This analysis was done according to the results received by Volhard method, which is accepted as a standard method. As Volhard method is in connection with cheese resolving by intense oxidation means, azotic acid and potassium permanganate, obligatory in fume board (hood), it is not a practical method. On the other hand, the potentiometric method with usage of the chloride-selective electrode is very simple and gives reliable and reproductive results. In case of a small content of NaCl, in %, higher precision and accuracy of determination by chloride-selective electrode can be obtained by indirect measurement of chloride-ions (by standard addition method).

Selenium is a trace mineral chemically related to sulfur and tellurium. In the body selenium combines with protein molecules to form selenoproteins and it is distributed in low concentrations and unequally in air, soil and water all over the world. Edible mushrooms are known to be selenium accumulators. Since mushrooms contain relatively high protein levels, and they can accumulate large amounts of selenium, it is reasonable to expect that selenium could be incorporated into proteins. The growth of mycelia and fruit body formation of different medicinal mushroom strains of Pleurotus ostreatus (Hk-35 and P70) over the wide range of concentrations of inorganic form of selenium were examined. Mushrooms were cultivated on agar base media and on substrates based on sawdust. Vegetative growths of mycelium were measured as colony diameter in pure cultures supplemented with inorganic form of Se supplements, prepared as Na2SeO4 and Na2SeO3 in concentrations of: 1, 10, 25, 50, 75, 100 and 150 mg/l. Inorganic form of Se supplements, showed stimulation effects (in concentration of 1-50 mg/l) and toxic effects in higher concentration. On the standard industrial sawdust based substrate, supplemented with 100 mg/kg Na2SeO4 and Na2SeO3, accumulation of Se in fruit bodies was determined by the method of flameless atomic absorption spectrophotometer. The readings were performed on Varian SpectrAA-10 spectrophotometer equipped with VGA-76. Se as Na2SeO4 and Na2SeO3 was effectively taken up from substrates and accumulated in fruit bodies. Mushrooms accumulated selenium between 120 and 250 mg/kg dry weight. In mushrooms cultivated without Se supplement, Se contents were only about 1 mg/kg and in substrate about 0.1 mg/kg.

Titration acidity and content of total tannins in mass-market red wines are analyzed in this paper. The content of total acids in wine, expressed through wine acid, was analyzed by potentiometric titration on 7.00 pH value. According to titratable acidity in analyzed wines, all wines (only) with analyzed parameters according to Regulations about wine quality. The analysis of differential potentiometric curves shows that these curves can give the answer to the question if non organic substances, amino groups and phenols are present in wine in large quantity, as they are always present in wine. However it doesn't give the clear answer which substances are present in analyzed samples. The answer to this question can be received only by the method of ionic chromatography. The content of total tannins shows short time of storage in wine cellars so wine wasn't stored long enough, i.e. they are commercial wines made for mass market production and consumption. Although they have less content of total tannin materials of given values, wine taste gives the correlation with other polyphenol materials that only give odour, aroma and 'bouquet' to wine. The relative error of mean value is very low which indicates the reproduction of results and reliability of the method of determination of total tannins in red wine.

The samples of table salt bought in Belgrade supermarkets are analysed in this paper. The method of indirect iodometry was used in the process of the analysis, and received results were converted into the content of KI in mg/kg of salt. Beside the content of KI, the content of NaCl was also determined, counted to dry meter and water content, and received results were compared with the requests determined by Regulations of Table Salt Quality Meant for Human Diet and by manufacturers' declaration. Received results show that the volumetric method of indirect iodometry, applied in this analysis, is very reliable for determination of potassium iodine in table salt, because of its high precision and reproducibility of the analysis results. All received results show that the samples of table salt which can be bought in supermarkets are according to the demands given by Regulations. Only one sample (evaporated salt) has significantly less mass of KI than it is determined by Regulations, but also by manufacturer's declaration. Measured humidity in the samples of table salt received from sea salt (sample 1) is higher than humidity in the samples received from rock salt as the result of magnesium presence in sea salt, which is hygroscopic material. Although samples 5 and 6 also originate from sea salt, their smaller humidity is the result of additional heating and salt processing. .

Distribution of natural gamma-emitting radionuclides 238U and 40K were determined in the soil profiles from the peach-trees field on experimental farm Radmilovac, southeast Belgrade. Internal soil morphology has been changed in 1992. when soil rigosol type with deep Ap-horizon (0-80 cm) has been formed by special treatment of parent soil, chernozem type. Gamma-spectrometry method is applied in measurement of radionuclide activities in soil samples by using hyperpure coaxial gamma-ray detector, Canberra type. Investigation results has been shown that the natural activity contents obtained in the experiment are within the range of normal background activity according to UNSCEAR (2000) and that radionuclide activity decreased in the plant root zone. .

This paper presents the experimental results of the extraction of lead and silver from a lead-silver waste cake obtained in the process of hydrometallurgical zinc production. While controlling the pH value, the lead-silver cake was leached at a temperature close to boiling point in different concentrations of aqueous calcium chloride solutions. The experiments were performed applying different ratios between the mass of cake and the volume of the leaching agent under different durations of the process. It was concluded that at the optimal process parameters (pH 2.0-2.5; CaCl2 concentration, 3.6 mol dm-3; temperature, 95°C; solid/liquid ratio, 1:5), the leaching efficiency of lead and silver could reach the approximate value of 94 %. Applying the same optimal process parameters, the method was applied to the leaching of a lead-silver cake in a magnesium chloride solution, but with significantly lower efficiencies. The results show that leaching of lead and silver in a calcium chloride solution could be a prospective method for increasing the recovery of lead and silver during hydrometallurgical zinc production.

Potentiometric analysis of fluoride content (as F- ion) in solutions by using fluoride ion-selective electrode is simple, reliable and cheap. Very small concentrations of fluoride-ions (to 10-6 mol/dm3) can be determined by fluoride selective electrode, with regulation of ion strength of a solution and control of concentration of hydroxide ions and interfering ions of metals. The influence of pH and complexing ions of metals can be successfully regulated by the TISAB solution and by preserving pH value in the range from 5.00 to 7.00. The content of fluorides in the samples can be determined by the method of direct potentiometer, and in the case of very low concentration by standard addition method. In this paper it was analyzed the determination of fluoride ions concentration in bottled mineral waters and water from Belgrade plumbing in two Belgrade districts (Palilula and Novi Beograd) and in tea, by using the fluoride selective electrode. It was determined that the content of fluoride ions in bottled mineral water significantly differs from values given on declaration, and that content of fluoride ions varies over a period of time. The content of fluoride ions in water from plumbing in two Belgrade districts at the time of analysis was significantly increased and exceeded values given in Regulation for drinking water quality. The received results from the analysis of fluorides in teas show that fluorides exist in teas in different concentrations. There are also differences between the same kinds of tea, which is noted with mint (Mentha piperitae folium), as a consequence of differences between soils where it was planted. As taking of fluorides, according to World Health Organisation recommendation (WHO), is limited in the range from 2 to 4 mg per day, it is necessary to give the content of fluorides on all products that are used in human consumption.

The amount of titration acid in must is in the largest number of cases with in the range 5.0-8.0 g/dm3. Wines, as a rule, contain less acids than must, and according to Regulations, titratable acidity is in the range of 4.0-8.0 g/dm3 expressed in tartaric acid, because a part of tartaric acid is deposited in the form of salts (tartar or argol) during alcohol fermentation. For wines that contain less than 4 g/dm3 of titratable acids there arises a suspicion about their origin, that is, that during the preparation some illegal acts were done. Because of that, the aim of this paper is to determine titratable acidity in white wine, using standard methods of determination, which are compared with the results received by potentiometric titration using ion-selective electrode. According to the received results it can be seen that wine titration with indicator gives sufficient reliable values of wine titration acidity. However, as potentiometric titration at pH value 7.00 is more reliable and objective method, the values of titratable acids content in wine, expressed through tartaric acid, are given according to this result. The analysis of differential potentiometric curves shows that these curves can give us an answer to the question of the presence of a larger amount of other nonorganic substances, which have already existed in wine. However, none of the used methods gives absolutely reliable answer what substances are present in analysed samples.

Sulfuric acid is an important industrial and strategic raw material, the production of which is developing on all continents, in many factories in the world and with an annual production of over 160 million tons. On the other hand, the production, transport and usage are very dangerous and demand measures of precaution because the consequences could be catastrophic, and not only at the local level where the accident would happen. Accidents that have been publicly recorded during the last eighteen years (from 1988 till the beginning of 2006) are analyzed in this paper. It is very alarming data that, according to all the recorded accidents, over 1.6 million tons of sulfuric acid were exuded. Although water transport is the safest (only 16.38% of the total amount of accidents) in that way 98.88% of the total amount of sulfuric acid was exuded into the environment. Human factor was the common factor in all the accidents, whether there was enough control of the production process, of reservoirs or transportation tanks or the transport was done by inadequate (old) tanks, or the accidents arose from human factor (inadequate speed, lock of caution etc). The fact is that huge energy, sacrifice and courage were involved in the recovery from accidents where rescue teams and fire brigades showed great courage to prevent real environmental catastrophes and very often they lost their lives during the events. So, the phrase that sulfuric acid is a real "environmental bomb" has become clearer.

In this paper the analysis of strontium and uranium content in drinking water has been done, indirectly, according to the scale which originates from drinking water in water-supply system of the city of Belgrade. Gamaspectrometric analysis showed the presence of free natural radionuclide in low activities. The activity of 90Sr in scale which is 0.72±0.11 Bq/kg was determined by radiochemical. Because of the small quantities of fur in the house heater this activity can be considered as irrelevant, but the accumulation of scale can have intensified influence. In this paper, the analysis of effects of the radioactive isotopes presence (first of all 238U and 235U) in drinking water on human health has been done. .

Chemistry is in its nature a fundamental science, but nowadays its results are increasingly used in practice. In such a way, many syntheses of important nutrition and industrial compounds (chemical technology), or destruction of harmful substances (chemical ecology) have been developed. The analytic part of chemistry (analytical chemistry) has found a significant usage even in optimization of technological processes of food technology. One of the oldest ways of food preservation is drying (dehydration). The basis of this process of preservation is to vaporize water, to dry enough the product, in order to stop the activity of enzymes and possibility of microorganisms’ development. Water in agricultural products is not free but bound to dry matter. Therefore, for its vaporizing it is necessary to bring enough heat. The part of the brought heat is used for vaporizing water, but one part of it becomes the energy for activation of several chemical reactions that decrease the nutritive values and the quality of future food. Therefore, the important engineering problem emerges: determination of optimal conditions for drying. For optimization of technological process of drying, it is necessary to do mathematical modeling of dependence of water vaporizing speed from environmental conditions beforehand. The aim of this paper is to determine potato pieces drying kinetics in laboratory dryer, in order to determine the optimal conditions for its industrial dehydration. It was established that in the first quarter of the time of drying evaporated 28.3% of total evaporation of water, and then in order by quarters: 53%, 14.1% and 4.6%, respectively. The greatest speed of drying was realized at moisture of potatoes about 50%.

Among all alcohol liqueurs, brandies from drupaceous plants are characterized with the highest level of hydro cyanic acid, benzaldehyde and ethylcarbamate. In fruit brandies ethylcarbamate mainly originates from hydro cyanic acid during the processes of alcohol fermentation of crushed fruit and its preservation, distillation and ripening of the brandy. Hydro cyanic acid and benzaldehyde arise from the hydrolysis of amygdaline that is found exist in the heart of fruit stones and seeds, as well as from the hydrolysis of prunasine from the skin and flesh of drupaceous plants. The content of amygdaline and prunazine depends on the type of fruit, which corresponds to the potential content of hydro cyanic acid and benzaldehyde in the brandy that corresponds the stoichiometric ratio 1:3.94. The content of the aldehydes: furfural and benzaldehyde in plum brandy, strong plum brandy, young brandy, of domestic production in the various regions of Serbia were analyzed in this paper.

Polarization techniques are used for testing the impact of different compounds (additives) on tinplate corrosion, using pieces of apricot dipped in syrup with and without nitrate addition as electrolyte solution, at the same time using filled cans as electrolytic cell and operating electrode. This procedure determined the intensity of inhibiting tin dissolving with some of the used additives like sodium-benzoate, potassium-sorbate sodium-lauril-sulphate and p-aminobenzoate acid. Adding these additives to canned pieces of apricot in syrup led to inhibiting of tin dissolving, which was experimentally proved.

The concept of fractional extraction from sediment — in our analyses it is scale, is based on the assumption that uranium with a solid substance conform bonds of different strength and that these bonds can be gradually fractionated by the action of reagents of increasing dissolving power whereby the separated phases of extraction are defined according to their function or the type of bond in that substance. The advantage of this analytical procedure is that it enables simultaneous observing of different forms of uranium emergence in sediment (solid substance), which cannot be achieved by using individual extraction methods. Using the method of fractional analysis, it has been found that uranium is mostly connected with mobile fraction - manganese and iron oxides (94.20 and 87.96 wt.%) which represents the fraction that is potentially accessible to human organism.

Phosphogypsum is primarily classified as a heavy waste. The classification of phosphogypsum as dangerous waste may be only maintained under the condition that phosphates with the highest content of radio nuclides are used in the production of H3PO4 by the so called "wet procedure" (Morocco, Florida), which, due to the great quantity of present radio nuclides, causes considerable environmental pollution by radon. The classification of phosphogypsum as a separate category of radioactive waste may be conditionally accepted, because phosphogypsum is not a radioactive waste. All the instructions about the collection, documentation and storage of phosphogypsum so far on disposal sites, and possible transport, also due to non-existing legal recommendations must comply with the classification of phosphogypsum as dangerous waste.

The results obtained by the analysis of the samples of coffee mostly consumed on our market showed that the coffee quality corresponds to the values as given in the Law of Health Food. It was not found that any of the parameters which determine food quality exceeded permitted values. Content of heavy metals and aflatoxines is below permitted values. The least content of caffeine was determined in a coffee sample roasted in the private roaster’s shop, and only in it the presence of coffee surrogates/substitutes was not proved. The obtained results of the coffee analysis showed that the coffees of most popular producers are very equal, and results of caffeine analysis are even more equal. This indicates the most probable fact that coffee is of the same origin, and that later, on during production, a different mixture was made, which affects the final product and gives aroma and taste to the liquid.

The analysis of scale originated from drinking water on the house water heater, showed that scale is basically calcium carbonate that crystallizes hexagonally in the form of calcite. Scale taken as a sample from different spots in Belgrade – upper town of Zemun (sample 1) and Pančevo (sample 2) showed different configuration although it came from the same waterworks. That indicates either that the water flowing through waterworks pipes in different parts of the city is not the same or the waterworks net is not the same (age, maintaining, etc). All the elements which are dominant in drinking water (Ca, Mg, K, and Na), and which could be found in water by natural processes, are by their content far below the values regulated by law. The analysis also showed the presence of many metals: Ti, Pb, Zn, Cu Li, Sr, Cd, and Cr in the first sample, which are not found in the scale taken near Pančevo. The results obtained by calculating the mass concentration in drinking water on the basis of scale content, showed that both waters belonged to the category of low mineral waters. Contents of inorganic substances in these waters (117.85 mg/dm3 for sample 1 or 80.83 mg/dm3 for sample 2) are twice lower than the values predicted by the legislation. Gammaspectrometric analysis indicates the presence of radioactive elements – uranium and strontium which can influence human health.

In drinking water, which is consumed daily, either directly, or with food there is a number of compounds, organic or inorganic, depending on the water type, origin and processing. The presence of these substances, due to their daily consumption, may exert a negative influence on human health and even lead to tragic outcomes.A list of inorganic substances and elements that may be found in water is presented in this paper, together with their permitted concentrations (MAC values) and the consequences they may cause, if present in concentrations higher than those permitted by regulations. Special emphasis is placed on heavy metals, because in most instances, they influence the human body unfavourably.

This paper presents the results of application of Scanning Electron Microscopy (SEM) to examinations of the samples of natural gypsum and phosphogypsum. Phosphogypsum has a well developed crystalline structure, and appear in two polymorphous forms, of rombic and hexagonal shape crystals. Natural gypsum has a poorly crystalline structure. The differences in crystalline structure influence the chemical behavior of these row materials.

This paper shows the results of investigations of corrosion resistance of different samples of chromium-nickel steels Č 4574 and Č 4583 in calcium-hypochlorite solution, by potentiodynamic method. The paper presents continuation of investigations on steels URANUS B6 and Č 4578 published in reference [1]. In this paper comparison of the obtained results is carried out, too, in order to detect steel, which quality is the best choice for calcium hypo chlorite solution requirements.

Corrosion resistance of Cr - Ni (special steels) specimen is tested by electrochemical methods, numerical method of linear polarization and polarization resistance method in calcium-hypochlorite (Ca(OCl)2) solutions. With increasing of Ca(OCl)2 concentration, pH value of the solution increases, as well as active chlorine concentration and corrosion activity of the medium. According to the quantitative method of the corrosion resistance determination it can be concluded that the steels tested in 1 wt % Ca(OCl)2 solution are resistant, in 10 wt % solution constant, and in 50 wt % suspension less resistant. URANUS B6 showed the best corrosion resistance of all tested chromium - nickel steels in all tested corrosion mediums.

A copper-selective electrode of the coated wire type based on sulphidized copper wire was applied successfully for determining Cu(II) ions by complexometric titration with the disodium salt of EDTA (complexon III). By the formation of internal complex compounds with the Cu(II) ion, the copper concentration in the solution decreases, and all this is followed by a change of potential of the indicator system Cu-DWISE (or Cu-EDWISE)/SCE. At the terminal point of titration, when all the Cu(II) ions are already utilized for the formation of the complex with EDTA, there occurs a steep rise of potential, thus enabling us, through the first or second derivative to note the quantity of copper that is present in the solution. Copper-selective electrode showed a responsivity towards titration with EDTA as a complexing agent, with the absence of "fatigue" due to a great number of repeated measurings. Errors occurring during quantitative measurements were more a characteristic of the overall procedure which involve, because of the impossibility of the complete absence of subjectivity, a constant error, and the reproducibility of the results confirmed this fact. The disodium salt of EDTA appeared as a very efficient titrant in all titrations and with various concentrations ot Cu(II) ions in the solution, with somewhat weaker response at lower concentrations in the solution.

It is possible to decompose starch into monosaccharides by the method of acid starch hydrolysis. By applying appropriate chemical procedure, a main solution is obtained, from which aliquots are taken after filtration to determine of the present glucose according to Luff-Shoorlu method. The analysed potatoes of cv. Desiree, grown on various sites in Serbia, have starch content that corresponds to available literature data. The highest starch content is found in potatoes from Ivanjica and Novi Pazar, i.e. from the areas where climate factors, air temperature, and land relief are favourable for potato growing. Lower starch contents are found in potatoes grown in flat areas with warmer climate and drier periods. Those are sites in PKB-Belgrade, Smederevo, Dobanovci and Mrčajevci areas, where the values obtained by experimental procedure are very similar. The lowest starch content is found in potatoes from Belegiš and Guča sites, where starch content is lower than normal from literature values, which may be explained by some special causes (climate, location, irrigation). On the basis of heavy metal contents in potato samples, it may be concluded that potatoes originating from sites famous for potato production are contaminated with Cd the content of which exceeds concentrations permitted by regulations. The presence of Cd in potato samples may also be explained by the application of phosphate fertilizers in higher (or recommended) rates. However, the soil itself should also be investigated, especially concerning the content of Cd and pH value. Thus, the influence of the soil itself should be established compared to fertilizer application in the current season. Presence of Cd in potatoes, on the other hand, is highly unfavourable because it prevents its utilization in nutrition, but also as a raw material for further processing of products based on potatoes: chips, etc. Also, Cd presence in foods is strictly controlled by EU, which prevents possible export of products based on potatoes containing Cd. Analyses of lindane and bensultap (Bancol) pesticides indicate that they are not within critical values, nor in such quantities to affect human health, so, from this aspect, the analysed potato samples from all sites are absolutely suitable for consumation.

Compounds forming very stable complexes - chelates, have a wide field of application in analytical chemistry. The most famous group of these compounds are complexons. Complexons represent organic polyaminocarbonic acids as for example ethylenediaminetetraacetic acid (EDTA) and its salts. The EDTA molecule has six coordinative sites. It is a hexadentate ligands i.e. it has two binding nitrogen atoms and four oxygen atoms from carboxyl groups and it forms complexes with almost all metal ions. EDTA as a tetraprotonic acid, H4Y disociates through four steps, yielding the ions HsY-, H2Y2-, HY3- and Y4-. Which of the EDTA forms will be encountered in a solution, depends on the pH. Due to the poor solubility of EDTA in pure water, as well as in most organic solvents, the disodium salt of EDTA Na2H2Y-2H2O, under the commercial name complexon III, is utilized for analytical determinations. In water, EDTA forms soluble, stabile chelate complexes with all cations, at the molar ratio 1:1, regardless of the charge of the metal ion. In contrast to other equilibria, which are mainly defined by Le Chatellier's principle, equilibria related to metal-EDTA complex formation are also dependent on the influence of the secondary equilibria of EDTA complex formation. Complexing reactions, which are equilibrium reactions, are simultaneously influenced by the following factors: solution pH and the presence of complexing agents which may also form a stabile complex with metal ions. The secondary reaction influence may be viewed and monitored through conditional stability constants. In the first part of the paper, the reaction of the formation of the Cu2+-ion complex with EDTA is analyzed beginning from the main reaction through various influences of secondary reactions on the complex Cu2+-EDTA: pH effect, complexation effect and hydrolysis effect. The equations are given for conditional stability constants, which include equilibrium reactions under actual conditions.

Phosphogypsum is a waste product in the manufacture of phosphoric acid from phosphorite and sulphuric acid by so-called "wet process" and represents a refuse that is as such simply thrown away. Phosphogypsum which is produced by "dihydrating procedure" contains not only various impurties but also radionuclides, which limits its construction use. Performed testings point to the complexity of phosphogypsum structure and composition while the electron microscope's pictures showed its different crystal composition compared to the natural gypsum. The calcined and refined phosphogypsum can be used for partition walls manufacture. To avoid the danger of the possible presence of radionuclides it is better to use the mixture of natural gypsum and phosphogypsum for this purpose. Substantial saving of materials and economic effect can be achieved in this way. The analyse performed in this work have shown significant presence of radionuclides in phosphogypsum. Gammaspectrometric measurements of radioactivity have determined substantial radioactivity of phosphogypsum. Using the maximum tolerated level values that are legally accepted, as well as equations to calculate indexes of tolerated radionuclide presence, an index of 2.23 has been determined for interiors and 1.13 for exteriors, i.e. 0.64 in case of roads. On the basis of the maximum tolerated level of radioactive building materials contamination (< 1), forbiden is the use of phosphogypsum in interiors, allowed (≈ 1) in exteriors and roads. The tests of heavy metal components in phosphogypsum have proved their presence in the amounts potentially producing consequences if present in closed spaces. That is conditioned by the phosphogypsum quantity, as well as by the area of space partitioned.

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Copyright of Journal of Agricultural Sciences, Belgrade is the property of University of Belgrade, Faculty of Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Archives of Industrial Hygiene & Toxicology / Arhiv za Higijenu Rada I Toksikologiju is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)