|Title:||Radiocesium in the Taiwan Strait and the Kuroshio east of Taiwan from 2018 to 2019||Authors:||Huang, Wei-Jen
Chen, Chen-Tung Arthur
|Issue Date:||17-Nov-2021||Publisher:||NATURE PORTFOLIO||Journal Volume:||11||Journal Issue:||1||Source:||SCIENTIFIC REPORTS||Abstract:||
The release of anthropogenic radiocesium to the North Pacific Ocean (NPO) has occurred in the past 60 years. Factors controlling Cs-137 (half-life, 30.2 year) and Cs-134 (half-life, 2.06 year) activity concentrations in the Kuroshio east of Taiwan and the Taiwan Strait (latitude 20 degrees N-27 degrees N, longitude 116 degrees E-123 degrees E) remain unclear. This study collected seawater samples throughout this region and analyzed Cs-134 and Cs-137 activity concentrations between 2018 and 2019. A principal component analysis (PCA) was performed to analyze the controlling factors of radiocesium. Results of all Cs-134 activity concentrations were below the detection limit (0.5 Bq m(-3)). Analyses of water column Cs-137 profiles revealed a primary concentration peak (2.1-2.2 Bq m(-3)) at a depth range of 200-400 m (potential density sigma(theta:) 25.3 to 26.1 kg m(-3)). The PCA result suggests that this primary peak was related to density layers in the water column. A secondary Cs-137 peak (1.90 Bq m(-3)) was observed in the near-surface waters (sigma(theta) = 18.8 to 21.4 kg m(-3)) and was possibly related to upwelling and river-to-sea mixing on the shelf. In the Taiwan Strait, Cs-137 activity concentrations in the near-surface waters were higher in the summer than in the winter. We suggest that upwelling facilitates the vertical transport of Cs-137 at the shelf break of the western NPO.
|Appears in Collections:||環境生物與漁業科學學系|
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