Southwest Intrusion of 134Cs and 137Cs Derived from the Fukushima Dai-ichi Nuclear Power Plant Accident in the Western North Pacific

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• 作者：Hideki Kaeriyama ; Yugo Shimizu ; Daisuke Ambe ; Masachika Masujima ; Yuya Shigenobu ; Ken Fujimoto ; Tsuneo Ono ; Kou Nishiuchi ; Takeshi Taneda ; Hiroaki Kurogi ; Takashi Setou ; Hiroya Sugisaki ; Tadafumi Ichikawa ; Kiyotaka Hidaka ; Yutaka Hiroe ; Akira Kusaka ; Taketoshi Kodama ; Mikiko Kuriyama ; Hiroshi Morita ; Kaoru Nakata ; Kenji Morinaga ; Takami Morita ; Tomowo Watanabe
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：March 18, 2014
• 年：2014
• 卷：48
• 期：6
• 页码：3120-3127
• 全文大小：532K
• 年卷期：v.48,no.6(March 18, 2014)
• ISSN：1520-5851

文摘

Enormous quantities of radionuclides were released into the ocean via both atmospheric deposition and direct release as a result of the Fukushima Dai-ichi Nuclear Power Plant (FNPP) accident. This study discusses the southward dispersion of FNPP-derived radioactive cesium (Cs) in subsurface waters. The southernmost point where we found the FNPP-derived ¹³⁴Cs (1.5鈥?.8 Bq m^鈥?) was 18掳N, 135掳E, in September 2012. The potential density at the subsurface peaks of ¹³⁴Cs (100鈥?00 m) and the increased water column inventories of ¹³⁷Cs between 0 and 500 m after the winter of 2011鈥?012 suggested that the main water mass containing FNPP-derived radioactive Cs was the North Pacific Subtropical Mode Water (NPSTMW), formed as a result of winter convection. We estimated the amount of ¹³⁴Cs in core waters of the western part of the NPSTMW to be 0.99 PBq (decay-corrected on 11 March 2011). This accounts for 9.0% of the ¹³⁴Cs released from the FNPP, with our estimation revealing that a considerable amount of FNPP-derived radioactive Cs has been transported to the subtropical region by the formation and circulation of the mode water.