Radioactive status of seawater and its assessment in the northeast South China Sea and the Luzon Strait and its adjacent areas from 2011 to 2014

Abstract

To understand the impact of the Fukushima nuclear accident (FNA), ¹³⁷Cs, ¹³⁴Cs, ⁹⁰Sr, and gross beta were analyzed in the northeast South China Sea (NSCS), the Luzon Strait (LS) and its adjacent areas. ¹³⁷Cs, ⁹⁰Sr, and gross beta values in the NSCS were similar to those prior to the FNA. ⁹⁰Sr and ¹³⁷Cs in the LS and its adjacent areas were consistent with those in the NSCS. The high ¹³⁷Cs-peak values occurred at depth of 150 m whereas the high ⁹⁰Sr-peak values occurred at depth of 0.5 m. The ¹³⁷Cs and gross beta mean values in Cruise I were higher than those in Cruise II whereas the ⁹⁰Sr mean value was just the reverse. ¹³⁴Cs in all seawater were below the minimum detectable activity. The past and present data since the 1970s suggested ¹³⁷Cs and ⁹⁰Sr in the study areas still originated from global fallout and the FNA influence were negligible.

Keywords: Fukushima nuclear accident (FNA); Radioactive monitoring; Seawater; The Luzon Strait and its adjacent areas; The northeast South China Sea.