Sophia University, Department of Materials and Life Sciences, Tokyo, Japan.
Comenius University, Department of Nuclear Physics and Biophysics, Bratislava, Slovakia.
J Environ Radioact. 2020 May;216:106179. doi: 10.1016/j.jenvrad.2020.106179. Epub 2020 Feb 10.
Vertical distributions of Sr and Cs in Sea of Japan/East Sea (SOJ/ES) water in the period of 1977-2010 exhibited a typical diffusion shape with surface/subsurface maxima and decreasing values with increasing depth. Apparent vertical diffusion coefficients (AVDCs) and apparent initial surface fluxes (AIFs) of Sr and Cs, which were estimated using a curve-fitting method from a vertical diffusion model, showed temporal and spatial variability. A diffusion depth introduced for understanding of vertical movements of Sr and Cs in the SOJ/ES well correlated with corresponding AIFs, suggesting that spatial variations of the Sr and Cs inventories have been governed by oceanic conditions such as changes in AVDCs, which may be related with eddy field, characterizing the SOJ/ES. The temporal changes of the AVDCs suggest that the production of eddies increased during the 2000s comparing with that in the 1990s. These observations represent the first applications of radionuclides as tracers in production of oceanic eddies.
1977 年至 2010 年期间，日本海/东海（SOJ/ES）水中 Sr 和 Cs 的垂直分布呈现出典型的扩散形状，具有表面/次表面最大值，随着深度的增加而逐渐减小。使用垂直扩散模型的曲线拟合方法估算的 Sr 和 Cs 的表观垂直扩散系数（AVDC）和表观初始表面通量（AIF）表现出时空可变性。为了理解 Sr 和 Cs 在 SOJ/ES 中的垂直运动而引入的扩散深度与相应的 AIF 很好地相关，这表明 Sr 和 Cs 储量的空间变化受海洋条件的控制，例如 AVDC 的变化，这可能与 eddy 场有关，SOJ/ES 的特征。AVDC 的时间变化表明，与 20 世纪 90 年代相比，21 世纪 00 年代期间，涡旋的产生有所增加。这些观察结果代表了放射性核素首次作为海洋涡旋产生的示踪剂的应用。
