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Radioactivity of water and sediments from the Danube river in its course through Serbia during 2001-2003 years has been tested by alpha- and gamma-ray spectrometry. Except for cesium originating from Chernobyl, the radioactivity level of water and sediment coincide with the content of natural radionuclides in the environment of rivers basin. No increase in the radioactivity of sediments. due to slowing down of the water flow, was observed. The obtained results were analyzed in accordance with the model which considers only naturally occurring radionuclides originating in river sediment. The distribution coefficients for natural radionuclides are determined.

The radioactivity of water and sediments from the Sava river in the course through Serbia during 2001-2003 has been examined by alpha- and gamma-ray spectrometry. Except for cesium originating from Chernobyl, the radioactivity level of water and sediment coincide with the content of natural radionuclides in the environment of the river basin. Distribution coefficients as well as the runoff coefficient were determined for (137)pCs.

Matrix-assisted laser desorption/ionization (MALDI) coupled with reflectron time-off-light mass spectrometry was applied to the analysis of fullerenes (C-60 and C-70). This investigation included the screening of three different compounds regarding their suitability as MALDI matrices. It has been found that the performance of alpha-cyano-4-hydroxycinnamic acid (CHCA), currently one of the most universally used matrices in MALDI analyses, is exceeded by some of these materials. In the negative ion-mode, excellent performance has been achieved using 2-[(2E)-3-(4-tertbutylphenyl)-2-methylprop-2-enylidene] malonitrile (DCTB). These matrixes should efficiently absorb at commonly used laser wavelength (typically for a 337-nm nitrogen laser) and form homogeneous microcrystalline solids with analyte molecules. The soft ionization technique affords little to no fragmentation of analyte. Carbon nanotubes, prepared by an are discharge method, were investigated as the third matrix. It was observed that the carbon nanotube layer as a matrix provides high detection sensitivity and mass resolution of fullerenes with eliminating matrix ion interference.

The spatial and temporal distributions of tritium in precipitation, river water, atmospheric water vapor, and air were observed in the Belgrade area over the period 1988-1997. Significantly higher tritium levels were measured in samples in the vicinity of the Vinca Institute of Nuclear Sciences compared with off-site locations. Annual mean tritium concentrations in precipitation ranged from 2.2 to 35.4 Bq/1, decreasing with distance from the nuclear facilities. The annual mean release of tritium into the environment from heavy water reactor operations at the Vinca Institute based on precipitation measurements was estimated to be about 80 TBq. Data show a large variability of tritium concentration in the air, fluctuating in the ranges 0.27-60.8 Bq/m(3) air (16-2468 Bq/l-H2O) in atmospheric water vapor in which tritium occurs as HTO and 0.04-1.05 Bq/m(3) air hue to the tritium content in atmospheric hydrogen gas. Annual average concentrations observed for HTO and HT forms were 11.5-19.1 and 0.46-0.48 Bq/m(3) air respectively. The two data sets for HTO and HT are similar, suggesting a near steady state over the period of observation. (C) 2000 Elsevier Science Ltd. All rights reserved.

Radioisotopes of uranium, thorium and plutonium in water, soil and fertilizer samples, have been chemically separated and determined by alpha-spectrometry method. Radiochemical Procedure involving ion-exchange, enabled to determine these isotopes in very tow concentrations (under 50 mu Bg/g). U-232, Th-229 and Pu-238 were used as a tracers for radiochemical yield recoveries (up to 90%). Thin layer sources have been obtained by electrodeposition.