Optimizacija i primena gasno-difuzione protočne injekcione metode za određivanje hlorida

A selective and sensitive procedure for the fast and indirect determination of chloride by the gas-diffusion FIA method has been optimized and applied for the determination of chloride in water samples which contained different amounts of the analyte. The examined samples were: seawater, tap water and very pure water from the water-steam system of the power plant "Nikola Tesla B" in Obrenovac. Application of an amperometric detector (model LC-17A; BAS, West Lafayette, USA) enables the detection limit to be decreased down to 0.05 mu mol/dm(3) of chloride, which col responds to 35.5 pg, and adjustment of the acceptor flow rate and direction inside the gas-diffusion unit. In this way the optimized FIA system has excellent repeatability. For 5 mu mol/dm(3) it was found to be 1.11% (n = 5). The throughput of this method is 60 samples per hour.Selektivan i osetljiv postupak za brzo, indirektno određivanje hlorida gasno-difuzionom metodom otpimizovan je i primenjen za određivanje hlorida u uzorcima voda sa vrlo različitim sadržajem ove vrste: morskoj, vodi za piće i vrlo čistim vodama u sistemu voda-para TE "Nikola Tesna B" u Obrenovcu. Upotreba amperometrijskog detektora tipa LC-17A omogućava snižavanje granice detekcije na 0.05 μmol/dm3 hlorida (što za uzorak zapremine 0.2 cm3 iznosi 35.5 pg) i podešavanje brzine i smera toka u gasno-difuzionoj jedinici. Ovako optimizovan protočni sistem ima odličnu reproduktivnost. Za hloridni standard koncentracije 5 μmol/dm3 relativna standardna devijacija iznosi 1.11 % (n = 5)

Pretkoncentracija mikroelemenata iz vode koristeći 4-morfolin ditiokarbamat

The optimum conditions were found for the preconcentration of trace metals in natural waters and model samples with standard metals concentrations by using 4-morpholine dithiocarbamate. The formed complexes were extracted with chloroform. Different methods for recovering the metals from the organic solvent were studied and compared before AAS metal analysis. The developed preconcentration method was successfully applied to the determination of trace metals concentrations in water samples from the "Barje" lake (Leskovac. Yugoslavia).Nađeni su optimalni uslovi za pretkoncentraciju mikroelemenata iz vode koristeći 4-morfolin ditiokarbamat kao kompleksirajući agens. Nagrađeni kompleksi su ekstrahovani hloroformom. Upoređeni su različiti načini ekstrakcije metalnih jona iz organskog rastvarača pre analize atomskom apsorpcionom spektrofotometrijom. Razvijena metoda za pretkoncentraciju uspešno je primenjena za analizu uzoraka vode jezera Barje (Leskovac Jugoslavija)

Raspodela olova u vodi i njegova asocijacija sa elementima u sedimentu jezera "Barje" (Leskovac, Jugoslavija)

The lead concentrations in the water of the "Barje" lake are presented for the years 1995 to 1998. Sequential extraction was applied to estimate the chemical association of lead in the sediments of the "Barje" lake. Several lead fractions showed highly significant correlations with the corresponding substrate (step II: Mn-oxyhydroxides; step III: Fe-oxyhydroxides) suggesting that lead carbonates were incorporated with amorphous iron and manganese hydroxides. An explanation for this relation can be in the same anthropogenic source of these elements.Predstavljena je koncentracija olova za jezero "Barje" od 1995 do 1998. godine. Sekvenciona ekstrakcija je primenjena za proučavanje hemijskih asocijacija olova u sedimentima jezera "Barje". Visoko signifikantne korelacije pojedinih frakcija olova sa odgovarajućim supstratima (druga faza: Mn oksihidroksidima; treća faza: Fe oksihidroksidima) pokazuje da su olovo-karbonati inkorporirani sa amorfnim hidroksidima gvožđa i mangana. Objašnjenje se može potražiti u istom antropogenijskom izvoru

n-alkanes as a tool for estimation of the biodegradation of oil-type pollutants in alluvial sediments (Danube, Yugoslavia)

An attempt was made to assess the microbial degradation degree of an oil-type pollutant in an alluvial sediment on the basis of n-alkane abundance changes in saturated hydrocarbon fractions within a ten-month period. For that purpose, oil-contaminated alluvial ground waters were investigated, taken from three drill-holes (three depths), three times each (winter '97/'98, spring '98 and autumn '98) in the area of an oil refinery, in the immediate vicinity of the Danube (Yugoslavia). The results have unambiguously confirmed that depth-dependent, but obviously existing, biodegradation processes of oil-type pollutants occur in a very short time period

n-alkanes as a tool for estimation of the biodegradation of oil-type pollutants in alluvial sediments (Danube, Yugoslavia)

An attempt was made to assess the microbial degradation degree of an oil-type pollutant in an alluvial sediment on the basis of n-alkane abundance changes in saturated hydrocarbon fractions within a ten-month period. For that purpose, oil-contaminated alluvial ground waters were investigated, taken from three drill-holes (three depths), three times each (winter '97/'98, spring '98 and autumn '98) in the area of an oil refinery, in the immediate vicinity of the Danube (Yugoslavia). The results have unambiguously confirmed that depth-dependent, but obviously existing, biodegradation processes of oil-type pollutants occur in a very short time period

Leaching of Trace and Major Elements in Coal Ash Dumps

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