Accumulation and cellular distribution of ^ ~ m , 2 1 0 ~ o , and ' l 0 Pb in two marine algae

Accumulation and cellular distribution of '̂Am, 2'0Po, and "Opb were studied in the marine diatom Thalassiosira pseudonana and the marine green alga Dunaliella tertiolecta, Both species concentrated Am, Po, and Pb from artificially spiked cultures, resulting in wet weight concentration factors of approximately 1 to 4 X lo5 for '̂Am, 3 to 7 X lo4 for 210Po, and 5 to 17 X lo3 for "OPb. These concentration factors are comparable to those based on analyses of natural plankton assemblages. In contrast to 2'0Po, ̂ Am and "OPb appeared to associate almost exclusively with structural components (cell walls and plasmalemmae) and showed no evidence of protein association. The data, together with field evidence, suggest that '̂Am and "OPb are not bound to cell material easily assimilated by herbivorous zooplankton, while "'Po associates with cellular organic compounds and is assimilated in animals. This may lead to high "OPo turnover rates in surface waters.