著者

JIAN ZHENG TATSUO AONO SHIGEO UCHIDA JING ZHANG MAKIO C. HONDA

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.46, no.4, pp.361-369, 2012-08-20 (Released:2013-11-08)

参考文献数

52

被引用文献数

59 24

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The Fukushima Dai-ichi Nuclear Power Plant (DNPP) accident has caused serious contamination of the marine environment from atmospheric fallout deposition and the direct discharges of highly radioactive liquid wastes. In contrast to the immediate intensive studies on the distributions of released fission products, such as 131I, 134Cs and 137Cs, information on the possible contamination by actinides in the marine environment is quite limited. In this study, we report the first data-set on the distribution of Pu isotopes in surface sediments in the Pacific 30 km off Fukushima after the Fukushima DNPP accident. Activities of 239+240Pu and 241Pu, and atom ratios of 240Pu/239Pu and 241Pu/239Pu in surface sediments collected in July-August, 2011 were analyzed to make a quick assessment on the environmental impact of the possible Pu contamination. The observed 239+240Pu activities and 240Pu/239Pu atom ratios are comparable to those previously reported in marine sediments in the western North Pacific and its marginal seas, and in Japanese estuaries before the accident. The Pu contamination from the Fukushima DNPP accident was not observed in marine sediments outside the 30 km zone.

著者

AYA SAKAGUCHI AKINOBU KADOKURA PETER STEIER KAZUYA TANAKA YOSHIO TAKAHASHI HARUKA CHIGA AKIHITO MATSUSHIMA SATORU NAKASHIMA YUICHI ONDA

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.46, no.4, pp.355-360, 2012-08-20 (Released:2013-11-08)

参考文献数

26

被引用文献数

90 27

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Concentrations of the radionuclides, U, Pu, and Cs were measured in water samples (10-20 L) to study analyte dispersion and migration following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. A total of 8 water samples including oceanic water and paddy-field water were collected in the vicinity of the plant. Determinations of U, Pu and Cs isotopes were performed by accelerator mass spectrometry (AMS), inductively coupled plasma mass spectrometry (ICP-MS), and γ-ray spectrometry. The 236U/238U atom ratio was in the range 1.83-8.20 × 10-9 for fresh water and around 0.57 × 10-9 for seawater while the concentration of 236U was about 104-105 and 106 atoms/kg, respectively. Plutonium (239,240Pu) was detected in one riverine sample and the marine samples at very low levels and with large uncertainty. The concentrations of 137Cs in fresh riverine samples were 0.02-0.46 Bq/kg which are more than three orders of magnitude larger than the global fallout level. As for seawater samples within 80 km offshore of the FDNPP, the concentrations of 137Cs were 10-20 times higher than that of the Japan Sea water. Also 134Cs and 137Cs were of similar concentrations in all samples. The results show that volatile and refractory nuclides such as Cs, U and Pu exist in the dissolved phase, which can be readily assimilated by plants/humans. However the environmental impact of Pu and U in the vicinity of the FDNPP is considered to be low in comparison to that of the volatile radionuclide Cs.