Trophic Transfer and Radiation Dose Assessment of Radionuclides in Biota from Southeastern Coastal China

To understand the bioaccumulation characteristics of radionuclides and assess radiation dose to marine organisms, this study investigated the activity distribution and bioaccumulation characteristics of five key radionuclides, Tritium, Carbon-14, Strontium-90, Cesium-137, and Radium-226 (³H, ¹⁴C, ⁹⁰Sr, ¹³⁷Cs and ²²⁶Ra), in seawater and marine organisms in the coastal regions of Ningde, southeastern China. The radiation dose to five categories of marine organisms (fish, crustaceans, mollusks, bivalves, and macroalgae) from these radionuclides was assessed with the ERICA (Environmental Risk from Ionising Contaminants: Assessment and Management) tool 2.0. The results showed that ¹⁴C exhibited enrichment (Trophic Magnification Factor, TMF=1.18) with increasing trophic levels, which can be attributed to its active incorporation into biomolecules through metabolic processes. In contrast, ⁹⁰Sr showed a dilution effect (TMF=0.58), likely due to its regulation as a calcium analogue rather than active assimilation. Other radionuclides showed no significant variation across trophic levels. Additionally, crustaceans showed the highest bioaccumulation capacity for ²²⁶Ra (bioaccumulation factor, BAF=261.03-307.29 L/kg). Radiation dose of the five radionuclides to organisms ranged from 3.08 × 10^-7 to 0.13 µGy/h, with an average of 9.10 × 10^-3 µGy/h. This was far below the ERICA ecosystem screening limit of 10 μGy/h.