Polonium (210Po) and lead (210Pb) in marine organisms and their transfer in marine food chains

The determination of Po-210 and Pb-210 was performed in marine organisms from the seashore to abyssal depths, encompassing a plethora of species from the microscopic plankton to the sperm whale. Concentrations of those radionuclides ranged from low values of about 5 x 10(-1) Bq kg(-1) (wet wt.) in jellyfish, to very high values of about of 3 x 1(0)4 Bq kg(-1) (wet wt.) in the gut walls of sardines, with a common pattern of Po-210 > Pb-210. These radionuclides are primarily absorbed from water and concentrated by phyto- and microzooplankton, and then are transferred to the next trophic level along marine food chains. Investigation in epipelagic, mesopelagic, bathypelagic and abyssobenthic organisms revealed that Po-210 is transferred in the marine food webs with transfer factors ranging from 0.1 to 0.7, and numerically similar to those of the energy transfer in the marine food chains. As Po-210 preferentially binds to amino acids and proteins, its transfer in food chains likely traces protein transfer and, thus, 210Po transfer factors are similar to ecotrophic coefficients. Pb-210 is transferred less efficiently in marine food chains and this contributes to increased Po-210:Pb-210 activity ratios in some trophic levels. (C) 2010 Elsevier Ltd. All rights reserved.