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  • Author: Jaroslav Švehla x
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Abstract

Pectinatella magnifica is an invasive freshwater bryozoan with ability to produce large colonies reaching a capacity of up to several tens dm3. In the Protected Landscape Area and Biosphere reserve Třeboňsko the bryozoan was first found in 2003 in one mesotrophic sandpit. The species gradually spread to many other sites around the Třeboň area and at most of these locations its occurrence has invasion properties. Pectinatella expanded to some other sandpits, fishponds without intensive pisciculture. Pectinatella colonies are found mainly on submerged branches of willow trees. The differences between biomass in transects with the occurrence of shrub willow and biomass in transects without their presence were statistically significant in the total biomass weight and the number of colonies. The average weight of several colonies did not differ. The most important parameter affecting the occurrence was the low trophy of water. The water temperature is evidently an important factor affecting the seasonal dynamics of occurence. Differences in nitrogen and phosphorous content between the water outside and inside the colonies were statistically significant. The colonies also accumulate other elements, including microelements.

Abstract

The highly selective nitrogen donor ligand CyMe4BTBP for An(III) separation by solvent extraction was irradiated in a 60Co γ-source under varying conditions. Organic solutions of 10 mmol/L ligand in 1-octanol were contacted with different concentrations of nitric acid to observe the influence of an aqueous phase during irradiation. In subsequent liquid-liquid extraction experiments, distribution ratios of 241Am and 152Eu were determined. Distribution ratios decreased with increasing absorbed dose when irradiation was performed in the absence of nitric acid. With addition of nitric acid, initial distribution ratios remained constant over the whole examined dose range up to 300 kGy. For qualitative determination of radiolysis products, HPLC-MS measurements were performed. The protective effect of nitric acid was confirmed, since in samples irradiated with acid contact, no degradation products were observed, but only addition products of the 1-octanol molecule to the CyMe4BTBP molecule.

Abstract

Radiation stability of CyMe4-BTPhen was examined in systems with three selected cyclohexanone-based diluents. Accelerated electrons were used as a source of ionizing radiation. The CyMe4-BTPhen radiation degradation identification and characterization of the degradation products were performed by high performance liquid chromatography (HPLC) and mass spectrometry (MS) analyses. Residual concentrations of tested ligand were determined. Moreover, extraction properties of the solvents irradiated at two different doses were compared with the extraction properties of non-irradiated solvents to estimate the influence of the presence of degradation products in the organic phase.