In this study, we measured the activity concentrations of Cs-137 and Sr-90 in surface seawater and surface sediments at the Tra Co, Bach Long Vi, and Ky Anh locations in the Gulf of Tonkin, Vietnam, from December 2018 to October 2019. The average activity at the selected locations was 1.22, 1.43, and 1.33 Bq/m3 for Cs-137 and 0.88, 1.17, and 1.09 Bq/m3 for Sr-90 in surface seawater samples and 0.74, 1.01, and 0.81 Bq/kg dry for Cs-137 and 0.49, 0.49, and 0.43 Bq/kg dry for Sr-90 in sediment samples. The ratio of the average activity concentration (Cs-137/Sr-90) in the surface seawater was 1.42, 1.22, and 1.22 at the Tra Co, Bach Long Vi, and Ky Anh locations, respectively. These are somewhat low compared to the global ratios (1.6 and 1.8). Meanwhile, Cs-137/Sr-90 ratios in the sediment samples at the selected locations were 1.51, 2.06, and 1.88, respectively, which is equal to or greater than the corresponding value for global sedimentation according to the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Correlations between Sr-90, Cs-137, and organic carbon content were detected in this study. The results showed that Cs-137 has a high correlation with the organic carbon content in sediment, while Sr-90 has a low correlation.

中文翻译：

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越南北部湾海水和沉积物中 Sr-90 和 Cs-137 的活性浓度

在这项研究中，我们测量了 2018 年 12 月至 2019 年 10 月越南北部湾 Tra Co、Bach Long Vi 和 Ky Anh 地区的表层海水和表层沉积物中 Cs-137 和 Sr-90 的活性浓度. 选定位置的平均活度为 Cs-137 的 1.22、1.43 和 1.33 Bq/m3 和表层海水样品中 Sr-90 的 0.88、1.17 和 1.09 Bq/m3 和 0.74、1.01 和 kg 0.81 Bq/m3对于沉积物样品中的 Cs-137 和 0.49、0.49 和 0.43 Bq/kg，对于 Sr-90 干燥。在 Tra Co、Bach Long Vi 和 Ky Anh 位置，表层海水中的平均活性浓度比 (Cs-137/Sr-90) 分别为 1.42、1.22 和 1.22。与全球比率（1.6 和 1.8）相比，这些数字略低。同时，选定位置沉积物样品中Cs-137/Sr-90的比率分别为1.51、2.06和1.88，分别等于或大于根据联合国原子辐射影响科学委员会 (UNSCEAR) 确定的全球沉积的相应值。本研究检测了 Sr-90、Cs-137 和有机碳含量之间的相关性。结果表明，Cs-137与沉积物中有机碳含量的相关性较高，而Sr-90的相关性较低。