酸素安定同位体比および希土類元素, トリウム, ウラン濃度から見た新潟県における降水の特徴

狩野 直樹; 菊池 武大; 坂本 信生; 今泉 洋; 村山 等; 家合 浩明; 大泉 毅

doi:10.3769/radioisotopes.55.307

Environmental Characteristics of Precipitations Based on Both Oxygen Stable Isotopic Ratio and Concentrations of Rare Earth Elements (REEs), Thorium (Th), Uranium (U) in Niigata Prefecture

Naoki KANO, Takehiro KIKUCHI, Nobuo SAKAMOTO, Hiroshi IMAIZUMI, Hitoshi MURAYAMA, Hiroaki YAGOH, Tsuyoshi OHIZUMI

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Keywords: oxygen stable isotopic ratio, rare earth element, thorium, uranium, precipitation, ICP-MS, stable isotope ratio mass spectrometer, Niigata Prefecture

JOURNAL FREE ACCESS

2006 Volume 55 Issue 6 Pages 307-317

DOI https://doi.org/10.3769/radioisotopes.55.307

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Abstract

In order to investigate the characteristics (or the sources) of Precipitations in Niigata Prefecture, oxygen stable isotopic ratios (i.e., δ¹⁸O) and the concentrations of rare earth elements (REEs), thorium (Th), and uranium (U) in the precipitation samples were measured. The precipitation samples were collected using a filtrating bulk sampler every two weeks at 3 points in Niigata Prefecture during the period from December 2003 to December 2004.
Consequently, the following matters have been mainly clarified. (1) In rainy season, δ¹⁸O value of Precipitations was the smallest. (2) In regard to δ¹⁸O value, “Continental effect” and “Amount effect” was generally observed in this work. On the other hand, “Temperature effect” was remarkably found only in winter. (3) The concentrations of trace metallic elements (REEs, Th, U) increased in spring. (4) REEs in precipitations might have been derived from a crustal source as well as oceanic source, while anthropogenic source was not negligible.

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