著者

Isao Sano Takumi Saito Jun-Ichi Miyazaki Akihisa Shirai Takeru Uechi Takaki Kondo Satoshi Chiba

出版者

The Plankton Society of Japan, The Japanese Association of Benthology

雑誌

Plankton and Benthos Research (ISSN:18808247)

巻号頁・発行日

vol.15, no.2, pp.97-111, 2020-05-27 (Released:2020-05-30)

参考文献数

81

被引用文献数

7

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The evolutionary history and diversity of unionoid mussels in East Asia need to be clarified and would shed light on the formation process of the unique fauna of Japan. Unionoid mussels (Mollusca: Bivalvia) are unique models for understanding the process by which organisms have diversified before and after the formation of the Japanese archipelago. Unionoid mussels have poor dispersal ability, so it is thought that they would have been strongly influenced by the archipelago’s formation. Therefore, the speciation and diversification processes of mussels before and after the archipelago’s formation were investigated by analyzing the nuclear and mitochondrial DNA of a wide range of species, particularly those inhabiting East Asia. The evolutionary history and divergence time of these mussels were examined. Unionoid mussels were found to have higher endemicity than other freshwater organisms. Although most of the endemic unionoid mussels of Japan are likely to have diverged before the formation of the Japanese archipelago, some other Japanese unionoid mussel species, including species endemic to Lake Biwa, an ancient lake in Japan, potentially diverged after the Japanese archipelago began to separate from the continent. This suggest that adaptation to the unique habitat of the ancient lake has caused diversification in the mussels endemic to it.

著者

Kojiro SHIMOJO Noboru AOYAGI Takumi SAITO Hiroyuki OKAMURA Fukiko KUBOTA Masahiro GOTO Hirochika NAGANAWA

出版者

The Japan Society for Analytical Chemistry

雑誌

Analytical Sciences (ISSN:09106340)

巻号頁・発行日

vol.30, no.2, pp.263-269, 2014-02-10 (Released:2014-02-10)

参考文献数

39

被引用文献数

23 51

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Liquid–liquid extraction of lanthanide ions (Ln3+) using N,N-dioctyldiglycolamic acid (DODGAA) was comprehensively investigated, together with fluorescence spectroscopic characterization of the resulting extracted complexes in the organic phase. DODGAA enables the quantitative partitioning of all Ln3+ ions from moderately acidic solutions, while showing selectivity for heavier lanthanides, and provides remarkably high extraction separation performance for Ln3+ compared with typical carboxylic acid extractants. Furthermore, the mutual separation abilities of DODGAA for light lanthanides are higher than those of organophosphorus extractants. Slope analysis, loading tests, and electrospray ionization mass spectrometry measurements demonstrated that the transfer of Ln3+ with DODGAA proceeded through a proton-exchange reaction, forming a 1:3 complex, Ln(DODGAA)3. The stripping of Ln3+ from the extracting phase was successfully achieved under acidic conditions. Time-resolved laser-induced fluorescence spectroscopy revealed that the extracted Eu3+ ions were completely dehydrated by complexation with DODGAA.

著者

YASUTO MIYAKE HIROYUKI MATSUZAKI TAKESHI FUJIWARA TAKUMI SAITO TAKEYASU YAMAGATA MAKI HONDA YASUYUKI MURAMATSU

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.46, no.4, pp.327-333, 2012-08-20 (Released:2013-11-08)

参考文献数

28

被引用文献数

1 92

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In March 2011, there was an accident at the Fukushima Daiichi Nuclear Power Plant (NPP) and a discharge of radionuclides resulting from a powerful earthquake. Considering the impact on human health, the radiation dosimetry is the most important for 131I among radionuclides in the initial stage immediately following the release of radionuclides. Since 131I cannot be detected after several months owing to its short half-life (8 days), the reconstruction by 129I (half-life: 1.57 × 107 yrs) analysis is important. For this reconstruction, it is necessary to know the isotopic ratio of 129I/131I of radioactive iodine released from the NPP. In this study, the 129I concentration was measured in several surface soil samples collected around the Fukushima Daiichi NPP for which the 131I level had already been determined. The surface deposition amount of 129I was between 15.6 and 6.06 × 103 mBq/m2 within the region 3.6 to 59.0 km distant from the NPP. 129I and 131I data had good linear correlation and the average isotopic ratio was estimated to be 129I/131I = 31.6 ± 8.9 as of March 15, 2011.