| Shenzhen is one of China’s three major nuclear power base, it owns China’s first large-scale commercial nuclear power plant—daya bay nuclear power plant, and later Ling’ao nuclear power plant. A comprehensive understanding of the current radionuclide level and its changes in the marine environment is helpful to evaluate the influence of nuclear power plant on the ambient environment. In this study, seawater,sediment and marine organisms were collected from the near-shore area of Shenzhen(mainly Daya Bay, Dapeng Bay, Deep Bay and Lingdingyang Estuary) during the September cruise in 2013 and April cruise in 2014, and were analyzed for gross alpha,gross beta, 226 Ra, 232 Th, 40 K, 137 Cs and 110 m Ag. In addition, the committed effective dose by ingestion of seafood were also estimated according to 《GB/T16148-1995》.The main results were:1) The activity concentration of gross alpha, gross beta, 226 Ra, 232 Th, 40 K, and137 Cs in seawater were in the range of 0.007~0.445 Bq/L, 0.016~0.084 Bq/L, 3.2~15.7Bq/m3, 12.8~42.6 Bq/m3, 529.7~974.1 Bq/m3, 0.8~4.5 Bq/m3; and the average were0.069±0.12 Bq/L, 0.045±0.01 Bq/L, 8.8±3.6 Bq/m3, 24.1±8.6 Bq/m3, 786.4±158.4Bq/m3, 2.6±0.4 Bq/m3. The activity concentrations of 110 m Ag were below the detection limit for all the samples. The level of these radionuclides fall in the range of those obtained from other near-shore areas of China, which were similar to the natural background levels.2) The activity concentration of gross alpha, gross beta, 226 Ra, 232 Th, 40 K, and137 Cs in sediment were in the range of 207~663 Bq/kg, 505~1263 Bq/kg, 32.9~59.8Bq/kg, 17.9~35.0 Bq/kg, 326.2~415.3 Bq/kg, 0.9~3.5 Bq/kg; and the average were445±97 Bq/kg, 783±182 Bq/kg, 43.2 ±8.9 Bq/kg, 26.5±4.4 Bq/kg, 364.2±82.7 Bq/kg,1.8±0.1 Bq/kg. The activity concentrations of 110 m Ag were below the detection limitfor all the samples. The level of these radionuclides were similar to those from other near-shore areas of China, which were belong to the normal range.3) The activity concentration of gross alpha, gross beta, 232 Th, 226 Ra, 137 Cs,110mAg in marine organisms were in the range of 1.3~43.8 Bq/kg, 7.0~237.1 Bq/kg,1.0~7.6 Bq/kg, 1.0~9.3 Bq/kg, 0.03~0.71 Bq/kg, 0.2~0.3 Bq/kg(fresh weight); and the average were 10.8±11.3 Bq/kg, 39.3±54.4 Bq/kg, 2.48±2.1 Bq/kg, 2.41±2.2 Bq/kg,0.14±0.2 Bq/kg, 0.25±0.1 Bq/kg(fresh weight). The radioactive contents in shellfish of Shenzhen were similar to those reported from other countries or regions, and were far below the limit of our country’s food radioactive standard. The internal radiation dose due to the ingestion of shellfish was 14.77 ?Sv?a-1 for Shenzhen residents, which was much lower than the individual dose limits to the public in China, 232 Th and 226 Ra was the mainly radionuclide that contribute to the internal radiation exposure via ingestion. |
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