Seven REEs in the deep sea sediments from various regions /19 sites/ of the Pacific Ocean and the Japan Sea were determined with INAA. Regional variations of La/Yb ratio and Ce anomaly may reflect the relative contribution of the source materials in the formation of the deep sea sediments.
Tris(1,10-phenanthroline) iron(II) ([Fe(phen)3]2+) ion synthesized in the supercage of zeolite Y has been characterized by Mössbauer, UV-VIS reflectance, and X-ray diffraction methods. The complex in the supercage may be significantly distorted by interaction between the complex and the supercage wall. Pyrolysis mechanism under air of the complex in the supercage was studied on the basis of Mössbauer spectra.
By means of INAA, REEs in the dredged rocks from a seamount /KH73-4-2/ in the East Mariana Basin were determined. Based on the REE patterns, the rocks are classified into two groups despite of alteration: highly altered palagonite of oceanic-island tholeiitic nature, and relatively fresh basaltic-andesitic rocks of alkaline rock nature.
Line-broadening due to paramagnetic relaxation was observed in Mössbauer spectra of Eu2+ in glassy frozen solutions; such broadening may be used as an indicator of the state of dispersion of europium. It was demonstrated by the Mössbauer technique that Eu2+ was oxidized to Eu3+ by photoirradiation at >300 nm and that this oxidation reaction was induced by photoexcitation of the 320-nm band of Eu2+.
Authors:Y. Takahashi, Y. Minai, Y. Meguro, S. Toyoda, and T. Tominaga
Binding constants of Eu(III)- and Am(III)-complexes with soil-derived humic acid were determined by solvent extraction at various pH and ionic strength. Based on the dependence of binding constants on pH and ionic strength, stabilities of the humate complexes in land water and seawater were estimated. Speciation calculation based on the binding constants indicated that Am(III) could combine with humic substances in natural water system.
Authors:Y. Takahashi, T. Kimura, Y. Kato, Y. Minai, and T. Tominaga
Luminescence lifetime of Eu(III) in polyacrylate and polymaleate complexes has been measured to evaluate the number of water molecules bound to the ion. The number of residual water molecules hydrated to Eu(III) in the polyacrylate and polymaleate complexes ranged from 3.5 to 4.5 when the supporting electrolyte concentration was 0.01. The residual hydration number decreased with the addition of supporting electrolyte. These results indicate that Eu(III) is surrounded by polymolecular ligands in these complexes.
Authors:Y. Takahashi, Y. Minai, T. Kimura, and T. Tominaga
Distribution of trace amount of Eu(III), or Am(III), in the aqueous/solid system containing humic acid and kaolinite, or montmorillonite,
was studied by batch experiments. Humic acid was also adsorbed on the clay minerals and its adsorption isotherm can be regarded
as a Langmuir type. It is shown that Eu(III), or Am(III), exists as humate complex either in the aqueous or on solid phase
in the system including kaolinite, or montmorillonite. These results suggest that the organic-inorganic complex like clay
minerals coated with humic substances is important as metal reservoir in the environment.
Authors:Y. Minai, T. Ishii, Y. Nakamura, H. Wakita, and T. Tominaga
Lanthanides in altered oceanic tholeiite were determined by means of instrumental neutron activation analysis. Potassium content was employed as a measure of degree of alteration. Lanthanide concentrations in moderately altered parts of tholeiite (K2O content below 1%) were identical with those in'unaltered parts while light lanthanide concentrations in more altered parts (K2O content above 1%) increased with degree of alteration.
Authors:T. Ozaki, S. Ambe, S. Enomoto, Y. Minai, and Y. Makide
The effect of ZnCl2 on the uptake of Be, Na, Mn, Co, Zn, Se, Rb, Sr, Rh, Cs and lanthanoids (Ce, Pm, Gd and Lu) by carrot (Daucas carota cv. U.S. harumakigosun) was investigated. Uptake was measured using a multitracer technique which enables to acquire information
about various elements under identical conditions. The amount of uptake of Rb, Cs, Sr, Mn and Co, into roots decreased with
increasing concentration of ZnCl2. On the other hand, little effect was observed for the uptake of Be, Se, Rh and lanthanoids. These results suggest that Rb,
Cs, Sr, Mn and Co competed antagonistically with Zn for the binding sites of carriers in the roots, while there was no influence
on the uptake of the other elements. Uptake of Se was not influenced by Cl added as ZnCl2. It is concluded, therefore, that carrot can distinguish Se from Cl based on the physicochemical differences between these
two anion species.
Authors:Y. Yamada, Y. Minai, H. Sato, and T. Tominaga
The UV photolysis of pentacarbonyliron isolated in low temperature nitrogen matrix was studied by the Mössbauer Technique.
Besides stable compounds /Fe2/CO/9 and Fe3/CO/12/ unstable species such as Fe/Co/4 and Fe2/CO/8 were produced by UV irradiation. Furthermore, the unstable species were found to react with nitrogen matrix, leading to the
formation of Fe/CO/4N2. Mössbauer parameters of the products were obtained.