Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA.
Proc Natl Acad Sci U S A. 2012 Jun 12;109(24):9483-6. doi: 10.1073/pnas.1204859109. Epub 2012 May 29.
The Fukushima Dai-ichi release of radionuclides into ocean waters caused significant local and global concern regarding the spread of radioactive material. We report unequivocal evidence that Pacific bluefin tuna, Thunnus orientalis, transported Fukushima-derived radionuclides across the entire North Pacific Ocean. We measured γ-emitting radionuclides in California-caught tunas and found (134)Cs (4.0 ± 1.4 Bq kg(-1)) and elevated (137)Cs (6.3 ± 1.5 Bq kg(-1)) in 15 Pacific bluefin tuna sampled in August 2011. We found no (134)Cs and background concentrations (~1 Bq kg(-1)) of (137)Cs in pre-Fukushima bluefin and post-Fukushima yellowfin tunas, ruling out elevated radiocesium uptake before 2011 or in California waters post-Fukushima. These findings indicate that Pacific bluefin tuna can rapidly transport radionuclides from a point source in Japan to distant ecoregions and demonstrate the importance of migratory animals as transport vectors of radionuclides. Other large, highly migratory marine animals make extensive use of waters around Japan, and these animals may also be transport vectors of Fukushima-derived radionuclides to distant regions of the North and South Pacific Oceans. These results reveal tools to trace migration origin (using the presence of (134)Cs) and potentially migration timing (using (134)Cs:(137)Cs ratios) in highly migratory marine species in the Pacific Ocean.
福岛第一核电站的放射性核素释放到海洋水中，引起了人们对放射性物质传播的极大关注。我们报告了确凿的证据，表明太平洋蓝鳍金枪鱼（Thunnus orientalis）将福岛放射性核素运送到整个北太平洋。我们测量了加利福尼亚捕获的金枪鱼中的γ放射性核素，发现 2011 年 8 月 15 个太平洋蓝鳍金枪鱼样本中的（134）Cs（4.0 ± 1.4 Bq kg（-1））和（137）Cs 含量升高（6.3 ± 1.5 Bq kg（-1））。我们在福岛之前的蓝鳍金枪鱼和福岛之后的黄鳍金枪鱼中没有发现（134）Cs 和背景浓度（~1 Bq kg（-1））的（137）Cs，排除了 2011 年之前或福岛之后加利福尼亚水域中放射性铯的吸收增加。这些发现表明，太平洋蓝鳍金枪鱼可以迅速将放射性核素从日本的一个点源运送到遥远的生态区，并证明了洄游动物作为放射性核素运输载体的重要性。其他大型、高度洄游的海洋动物在日本周围广泛使用水域，这些动物也可能是福岛放射性核素运送到北太平洋和南太平洋遥远地区的运输载体。这些结果揭示了在太平洋高度洄游海洋物种中追踪迁移起源（使用（134）Cs 的存在）和潜在迁移时间（使用（134）Cs：（137）Cs 比值）的工具。
