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The purpose of the study is to define the level of combined radiological and chemical contamination from the activities of soil and moss samples collected from the Eastern Black Sea region in Turkey and to assess the risk caused by the environmental radioactivity and chemical pollutants. The gamma, gross beta and gross alpha activities were measured in the soil and moss samples. The 238U, 232Th, 40K and 137Cs activity concentrations in the soil samples were measured in the range of 7.0 and 72 Bq kg-1 for 238U, 8.1 and 86 Bq kg-1 for 232Th, 203 and 1190 Bq kg-1 for 40K and 0.71 to 66 Bq kg-1 for 137Cs. In the moss samples, the 137Cs, 40K, 232Th, and 238U activity concentrations were found in the range of 1.03±0.27-24.23±1.39, 137±7-1340±68, 3.58±0.32-5.93±0.44 and 0.88±0.09-2.25±0.23 Bq kg-1, respectively. Contamination from toxic metals in the soils is categorized into enrichment factor, geoaccumulation risk, potential ecological risk and pollution load index. Co, Ni, As and Pb enrichments were determined in the extreme category in the 6 sampling sites. The pollution load index for the selected metals was found to be greater than 1. The geo-accumulation index in one sampling site showed contamination from heavy to severe levels of arsenic and lead. [ABSTRACT FROM AUTHOR]

The objective of this work was to study the sorption of uranium (VI) ions on magnesium oxide (MgO) from aqueous solutions. The MgO has been prepared via hydroxide precipitation followed by thermal decomposition of the hydroxide. MgO was characterized by X-ray powder diffraction, scanning electron microscope, and multipoint Brunauer, Emmett, and Teller. The relative importance of test parameters such concentration of adsorbate, pH, contact time, and temperature on adsorption performance of MgO for U(VI) ion were studied and the optimum sorption efficiency was found as 87.61 ± 3.10%. Desorption tests were also carried out and desorption efficiency was found as 100% with NH4Cl and NaNO3 solutions containing 0.1 M on a single step. Typical sorption isotherms (Freundlich and Dubinin-Raduskevich) were determined for the mechanism of sorption process and thermodynamic constants (Δ H°, Δ S°, and Δ G°) were calculated as −8.738 kJ mol−1, −21.68 kJ mol−1, and 0.102 kJ mol−1 K−1, respectively. © 2011 American Institute of Chemical Engineers Environ Prog, 2011 [ABSTRACT FROM AUTHOR]

Abstract: Lead borate based glass formulations with high chemical durability and lower melting temperatures compared to the currently used glasses were developed as candidates for the vitrification of radioactive waste. Properties including chemical durability, glass transformation temperature, and melting temperature were analyzed. The chemical durability of PbO–B2O3 glasses with PbO contents ranging from 30 to 80mol% was determined. An average dissolution rate of 0.2gm−2 day−1 was obtained for the composition 80PbO⋅20B2O3. These glasses were studied under simulation conditions and showed good potential as a vitrification matrix for radioactive waste management. Clear vitrified waste products containing up to 30mol% SrO and 25mol% Cs2O could be obtained. Leaching rates are about hundred times higher in low PbO glasses compared to high PbO glasses. These results are encouraging since they open up new horizons in the development of low melting temperature lead borate glass for waste immobilization applications. [Copyright &y& Elsevier]