Radiocaesium derived from the TEPCO Fukushima accident in the North Pacific Ocean: Surface transport processes until 2017
Radiocaesium derived from the TEPCO Fukushima accident in the North Pacific Ocean: Surface transport processes until 2017
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DOI：
10.1016/j.jenvrad.2018.03.014
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发表时间：
2018-09-01
影响因子：
2.3
通讯作者：
Tsumune, Daisuke
中科院分区：
文献类型：
--
作者：
Aoyama, Michio;Hamajima, Yasunori;Tsumune, Daisuke
利用1264个已发表的数据和42个新数据，对2011-2017年北太平洋西部和中部6个区域表层沃茨中Cs-137活度浓度的时间变化进行了研究。在北纬30-42度、东经140 - 160度的北太平洋西部和中部，放射性铯的东向输送明显。2015/2016年，地表水中的Cs-137活度浓度迅速下降至2-3 Bq m（-3），仍略高于FNPP 1事故前的Cs-137活度浓度（1.5-2 Bq m（-3））。铯-134/铯-137的放射性比率，经衰变校正至2011年3月11日，近似为0.5-0.8。2011/2012年，在北纬30度以南、东经130度和西经160度之间的西太平洋和中太平洋海域，Cs-137活度浓度在1-7 Bq m（-3）左右，但随后一直稳定在几Bq m（-3），直至2017年。经衰变校正至2011年3月11日的Cs-134/Cs-137放射性比为0.3-0.5。模型模拟的Cs-137活性浓度的时间变化在感兴趣的区域的地表水表现出良好的协议与观测，除了在西北太平洋。
We report temporal variations of Cs-137 activity concentrations in surface waters of six regions of the western and central North Pacific Ocean during 2011-2017 using a combination of 1264 previously published data and 42 new data. In the western and central North Pacific Ocean at latitudes of 30-42 degrees N and longitudes of 140 degrees E to 160 degrees W, eastward transport of radiocaesium was clearly apparent. Cs-137 activity concentrations in surface water decreased rapidly to similar to 2-3 Bq m(-3) in 2015/2016, still a bit higher than Cs-137 activity concentrations before the FNPP1 accident (1.5-2 Bq m(-3)). Cs-134/Cs-137 activity ratios decay-corrected to 11 March 2011 were similar to 0.5-0.8. To the south of 30 degrees N and between 130 degrees E and 160 degrees W in the western and central Pacific Ocean, Cs-137 activity concentrations were around 1-7 Bq m(-3) in 2011/2012 but then stabilized at a few Bq m(-3) up to 2017.Cs-134 activity concentrations were detected at levels of 0.1-0.9 Bq m(-3), and Cs-134/Cs-137 activity ratios decay-corrected to 11 March 2011 were similar to 0.3-0.5. Temporal variations of model-simulated Cs-137 activity concentrations in surface water in the region of interest showed good agreement with observations, except in the southwestern North Pacific Ocean.