Radionuclides in marine food web along China's coastal waters: Activity, distribution and trophic level...

This study investigated the occurrence, activity, distribution, and trophic level bio-magnification of 4 radionuclides (polonium(²¹⁰Po), strontium(⁹⁰Sr), cesium(¹³⁷Cs), and plutonium (^239,240Pu)) in 16 kinds of marine organism along China's coastal waters: the Bohai Sea, Yellow Sea, East China Sea, and South China Sea. Results showed that none of radionuclides was detected at the level exceeding the established regulatory limits, with the highest measured activities of ²¹⁰Po = 13.9 Bq/kg, ⁹⁰Sr = 0.22 Bq/kg, ¹³⁷Cs = 0.242 Bq/kg, ^239,240Pu = 3.28 mBq/kg. In the sampled organisms, mollusks were found higher levels of activities of radionuclides, with ²¹⁰Po activity reaching up to 11 Bq/kg. Stable isotope analysis revealed a significant positive correlation of radionuclide activities with the δ¹⁵N values (p < 0.001), It could be indicated that radionuclides are transferred through trophic levels rather than being influenced by food sources. Based on the δ¹⁵N values, a food web was constructed, and the consequently Trophic Magnification Factor (TMF) showed a bio-dilution effect of radionuclides. Significant difference of the values of δ¹³C and δ¹⁵N among marine organisms from China and from Japan was obtained, which means no migratory species from Japan was found. This study provides crucial data to support the safety of seafoods and informs risk assessment and management strategies in coastal regions.