Water masses labeled with global fallout 137Cs formed by subduction in the North Pacific

被引:49
作者
Aoyama, Michio [1 ]
Hirose, Katsumi [1 ]
Nemoto, Kazuhiro [2 ]
Takatsuki, Yasushi [3 ]
Tsumune, Daisuke [4 ]
机构
[1] Meteorol Res Inst, Geochem Res Dept, Tsukuba, Ibaraki 3050052, Japan
[2] Maizuru Marine Observ, Adm Div, Kyoto 6240946, Japan
[3] Japan Meteorolog Agcy, Global Environm & Marine Dept, Tokyo 1008122, Japan
[4] Cent Res Inst Elect Power Ind, Environm Sci Res Lab, Tokyo 1008126, Japan
关键词
D O I
10.1029/2007GL031964
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
We provide a first cross section of the Cs-137 concentration along 165 degrees E longitude in the western North Pacific. The Cs-137 profile is characterized by several subsurface cores with high Cs-137, including two Cs-137 concentration maxima at 20 degrees N, one at 250 m (sigma(theta) approximate to 25.5) and one at 400-500 m (sigma(theta) approximate to 26.0) depths. The shallower maximum is in the density range of North Pacific Subtropical Mode Water (NPSTMW) and the deeper one is in the density range of Lighter Central Mode Water (LCMW). The main Cs-137 cores, therefore, were formed by movements of NPSTMW and LCMW in the interior ocean during the past four decades. The Cs-137 has been transported from subarctic region to subtropics and tropics as a result of subduction.
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