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  • Author or Editor: T. Honda x
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Abstract  

Trace elements such as Sc, lanthanoids, Th and U were determined by means of instrumental neutron activation analysis (INAA) in marine sediment core samples collected from 5 coastal areas in western Japan mainly facing the Pacific. The origin of the coastal sediments and the sedimentary environment are discussed in terms of such parameters as the La*/Lu* and Ce*/La* ratios, the Th/Sc ratios and the Th/U-Ce/U plot obtained from the analytical data. In particular, it was confirmed that the Th/U-Ce/U plot introduced in this work is extremely useful for estimating the sedimentary environment, including redox conditions.

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Abstract  

A total of 19 elements in the samples of atmospheric deposition collected in Kawasaki, Japan, were determined by neutron activation analysis, ICPAES and flame photometry. The amounts of soil dust depositions were larger in springs and those of Sb and Zn depositions were larger in summers than in the other seasons. The values of the enrichment factors were higher for Sb and Zn than for the other elements determined throughout the sampling period. A factor analysis showed that the two elements were characterized as industrial components. Rubber products like tires that contain noncombustibles and rubber accelerators were a possible origin of high concentrations of Sb and Zn in the present samples.

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Abstract  

Concentration of lanthanides (Lns) in alunite group mineral samples from the Kusatsu-Shirane volcano area, Gunma, Japan, were determined by neutron activation analysis. Their Ln abundance patterns showed enrichment of light Lns relative to their original rocks and GSJ geochemical reference samples of feldspars. It was found that the concentration of light Lns increased with increasing concentration of K and P. The positive correlation between the light Lns and P concentration suggested the formation of florencite, whereas the positive correlation between the concentration of light Lns and K may reflect the difference between the solubility of double salts of K and Ln sulfates of light Lns and heavy Lns, respectively.

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Abstract  

Hot spring water and crater lake water samples were analyzed for their rare earth elements: (REE's) by neutron activation method, which, in the irradiation, sample preparation, incorporated a coprecipitation process in which aluminium was used as a collector. Ten REE's, La, Ce, Sm, Eu, Gd, Tb, Dy, Tm, Yb and Lu, were consequently detected and determined at the ppb level with satisfactory precision. It was shown that the aluminium coprecipitation is effective in enhancing concentrations of the REE's and reducing the amounts of interfering nuclides before neutron irradiation.

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Abstract  

Determination of the rare earth elements (REE's) in acidic hot spring and crater lake waters by neutron activation analysis (NAA), in which activation was performed mostly by epithermal neutrons (epithermal NAA) was investigated. Nine REE's, La, Ce, Sm, Eu, Tb, Ho, Tm, Yb and Lu, out of fourteen naturally existing REE's were determined at ppb levels with satisfactory precision. The epithermal NAA was found to be more effective in the determination of Sm, Tb, Ho and Yb than normal NAA, in which activation was performed mainly by thermal neutrons. Combined use of the epithermal and normal NAA's enabled the determination of eleven REE's, La, Ce, Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb and Lu.

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Abstract  

Previously undetermined three rare earth elements (REE's), Pr, Nd and Er, in acidic hot spring and crater lake waters were determined at ppb levels by neutron actavation analysis with the standard addition technique. Errors on final detemined values were 7.1–56%. Combining the present results and the results previously obtained amounts to the determination of all 14 naturally occuring REE's in the waters.

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Abstract  

Hot spring water samples have been analyzed for their rare earth elements (REE's) determination by the nondestructive neutron activation method. Five REE's, La, Ce, Sm, Eu and Yb, have consequently been detected and determined with satisfactory precision. The method has been found to be simple and suited for the simultaneous analyses of several samples. To determine all the REE's, however, some pretreatment of the samples will be necessary.

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Abstract  

Determination of Th and U in acidic hot spring and crater lake waters was investigated by neutron activation analysis (NAA). Before neutron irradiation, Th and U were preconcentrated and separated from interfering nuclides such as alkali metals and halogens by coprecipitation with aluminium. Irradiation was carried out in two ways, viz., irradiation with Cd foil wrapping (epithermal NAA) and irradiation without Cd foil wrapping (normal NAA). The final determined values of Th and U were at ppb levels. Higher reliability of the determined values was obtained for Th than for U. It was found that epithermal NAA was more effective for the determination of these two actinides than normal NAA and was more effective for the determination of U than that of Th.

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Abstract  

Contents of lanthanoids (Ln's) of rock salts have been measured by neutron activation analysis. Original salt samples were treated in advance of neutron irradiation so that Ln's were enriched and amounts of interfering nuclides were reduced. The contents of Ln's were at ppt-sub ppb levels and were comparable with or slightly lower than those of solar salts. The Ln abundance patterns of the salts were those with relative depletion in the heavy Ln's, thus having negative slopes. It was indicated that, when salt deposit was formed, Ln's were taken up by anhydrite more preferentially than by halite.

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Abstract  

Uranium and thorium contents of solar salts were measured by neutron activation analysis. In advance of neutron irradiation, U and Th were concentrated and separated from some interfering elements by neutralization in which they were precipitated with aluminium hydroxide from solutions obtained by dissolving the salts in water or dilute nitric acid solution. The uranium and thorium concentrations determined were from several hundred ppt to 10 ppb. It was strongly indicated that uranium tends to remain in the solution (brine from seawater) phase in the process of solar salt production while thorium tends to transfer to the solid (solar salt) phase.

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