Investigation on the radioactivity levels of seawater, sediments, and biota in Daya Bay, China

Objective:To investigate the radioactivity levels of seawater,sediments,and biota in the Daya Bay sea area,China,in order to establish the radioactivity baseline values,and provide basic data for the assessment of potential radiological risks that might result from the application of nuclear technology or human activities. Methods:Samples of seawater,sediments,and biota were collected from the Daya Bay sea area and analyzed.Their radioactivity baseline data were then compared with information from other regions in China and around the world reported in related literature. Results:For the seawater samples,the activity concentrations of natural radionuclide 40K were 9.9-10.4 Bq/L,while 238U,226Ra,210Pb,137Cs,and 110Agm were below the minimum detectable activity(MDA).Regarding the sediment samples,the activity concentrations of 238U,228Ra,226Ra,210Pb,40K,and 137Cs were 38.1-40.4,49.1-53.7,32.6-38.6,59-95,590-650,and 0.48-0.88 Bq/(kg dry weight),respectively,while 110Agm was below the MDA.For the marine shrimps in the biota samples,the activity concentrations of228Ra,226Ra,40K,and 137Cs were 1.14-2.75,0.17-0.43,63-76,and 0.038-0.045 Bq/(kg wet weight),respectively,while 238U,210Pb,and 110Agm were all below the MDA.Furthermore,for the marine fishes in the biota samples,the activity con-centrations of 228Ra,226Ra,210Pb,40K,and 137Cs were 2.1-19.7,0.32-3.78,＜2.2-2.8,59-70,and＜0.007-0.026 Bq/(kg wet weight),respectively,while 238U and 110Agm were all below the MDA.228Ra was found to be concentrated in Osteomugil ophuyseni with 19.7 Bq/(kg wet weight). Conclusions:The radioactivity levels of seawater and marine sediments in the Daya Bay sea area are within the range of the normal background values.osteomugil ophuyseni exhibited higher concentrations of 228Ra than other species in this study,while the other species in the biota show no significant difference in the radioactivity levels from data in relevant literature.