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 ¹¹⁰Ag^m 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 ¹¹⁰Ag^m was below the MDA. For the marine shrimps in the biota samples, the activity concentrations of ²²⁸Ra, 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 ¹¹⁰Ag^m were all below the MDA. Furthermore, for the marine fishes in the biota samples, the activity concentrations 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 ¹¹⁰Ag^m 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.