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

作者：Kaeriyama Hideki^*; Shimizu Yugo; Ambe Daisuke; Masujima Masachika; Shigenobu Yuya; Fujimoto Ken; Ono Tsuneo; Nishiuchi Kou; Taneda Takeshi; Kurogi Hiroaki; Setou Takashi; Sugisaki Hiroya; Ichikawa Tadafumi; Hidaka Kiyotaka; Hiroe Yutaka; Kusaka Akira; Kodama Taketoshi; Kuriyama Mikiko; Morita Hiroshi; Nakata Kaoru; Morinaga Kenji; Morita Takami; Watanabe Tomowo

来源：Environmental Science & Technology, 2014, 48(6): 3120-3127.

DOI：10.1021/es403686v

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 Cs-134 (1.5-6.8 Bq m(-3)) was 18 degrees N, 135 degrees E, in September 2012. The potential density at the subsurface peaks of Cs-134 (100-500 m) and the increased water column inventories of Cs-137 between 0 and 500 m after the winter of 2011-2012 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 Cs-134 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 Cs-134 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.

• 出版日期2014-3-18