Bedford Institute of Oceanography , Fisheries and Oceans Canada, Dartmouth, Nova Scotia B2Y 4A2, Canada.
Mediterranean Institute of Oceanography (UM 110, UMR 7294), CNRS, Aix Marseille Université , Université Toulon, IRD, 13288 Marseille, France.
Environ Sci Technol. 2017 Sep 19;51(18):10494-10502. doi: 10.1021/acs.est.7b02712. Epub 2017 Sep 6.
The large inventory of radioactivity released during the March, 2011 Fukushima Dai-ichi nuclear reactor accident in Japan spread rapidly across the North Pacific Ocean and was first observed at the westernmost station on Line P, an oceanographic sampling line extending 1500 km westward of British Columbia (BC), Canada in June 2012. Here, time series measurements of Cs and Cs in seawater on Line P and on the CLIVAR-P16N 152°W line reveal the recent transport history of the Fukushima radioactivity tracer plume through the northeast Pacific Ocean. During 2013 and 2014 the Fukushima plume spread onto the Canadian continental shelf and by 2015 and early 2016 it reached Cs values of 6-8 Bq/m in surface water along Line P. Ocean circulation model simulations that are consistent with the time series measurements of Fukushima Cs indicate that the 2015-2016 results represent maximum tracer levels on Line P and that they will begin to decline in 2017-2018. The current elevated Fukushima Cs levels in seawater in the eastern North Pacific are equivalent to fallout background levels of Cs that prevailed during the 1970s and do not represent a radiological threat to human health or the environment.
2011 年 3 月日本福岛第一核电站核反应堆事故期间释放的大量放射性物质迅速扩散到北太平洋，并于 2012 年 6 月首次在加拿大不列颠哥伦比亚省（BC）以西 1500 公里的海洋学采样线 P 线上最西端的站点观察到。在此，P 线上和 CLIVAR-P16N 152°W 线上海水 Cs 和 Cs 的时间序列测量结果揭示了福岛放射性示踪剂羽流通过东北太平洋的近期输运历史。2013 年和 2014 年，福岛羽流扩散到加拿大大陆架，到 2015 年和 2016 年初，P 线上的表层水中 Cs 值达到 6-8 Bq/m。与福岛 Cs 时间序列测量结果一致的海洋环流模型模拟表明，2015-2016 年的结果代表了 P 线上的最大示踪剂水平，它们将在 2017-2018 年开始下降。目前北太平洋东部海水中福岛 Cs 的升高水平相当于 20 世纪 70 年代盛行的 Cs 的沉降背景水平，不会对人类健康或环境构成放射性威胁。
