Factors Contributing to Accumulation of 210 Po in Freshwater Fishes in Dong Thai Lake, Vietnam and Radiological Hazard Assessment.

210 Po (polonium), one of the most toxic naturally occurring radionuclides, is well-known as a common natural radionuclide in fish species. Human consumption of 210 Po-contaminated fish could result in a significant internal dose. This study determined by alpha spectrometry the 210 Po activity in sixteen selected fish species with different living behaviors (pelagic, demersal), trophic positions (herbivores, carnivores, omnivorous), and masses in Dong Thai Lake, Hanoi, Vietnam. The min, max, and average of the 210 Po concentration of sixteen fish species were 0.80 ± 0.44, 12.7 ± 0.20, and 3.54 ± 0.31 Bq kg-1 , respectively. Regarding the different living behaviors, trophic positions, and masses, the results showed trending of 210 Popelagic  > 210 Podemersal ; 210 Poherbivores  < 210 Pocarnivores  < 210 Poomnivorous and 210 Po<0.2 kg  > 210 Po0.2-1 kg  > 210 Po>1 kg , respectively. The 210 Po concentrations in muscle tissue were greater in fish species with a small mass, omnivorous trophic position, and pelagic living behavior relative to demersal fish with a larger mass that were herbivores or carnivores. In addition, the results showed an uneven distribution of 210 Po activities in atmospheric aerosols, terrestrial soils, surface waters, and lake sediments in the study area. The primary source of 210 Po could be supplied from atmospheric aerosols and/or terrestrial soils in the study area. The 210 Po annual effective dose for adults due to fish consumption has been calculated with a range from 20 to 400 µSv y-1 and 111 µSv. y-1 on average, and it is far below the allowable limits of 1000 µSv y-1 .