[en] Progress is reported on a study to evaluate the cycling of the transuranic radionuclides in the aquatic environment, their distribution within ecosystems, their uptake by biota and their sinks at Bikini. This year, the study has been to evaluate the Battelle large volume water sampler, BLVWS. Laboratory and field experiments on the collection efficiency for Pu, Am and other radionuclides using Al₂O₃ and Chelex-100 sorption beds in fresh and salt water have been completed. The sampler, with three or four sorption beds, has proven to be a reliable collector for Pu and Am, giving concentration values comparable to conventional sampling methods in laboratory studies with known radionuclide concentrations and in field studies where the concentrations were unknown. Possible speciation of Pu into colloidal, particulate, and soluble fractions has been indicated in both the tank and field collections. The larger volumes of water which were processed by the BLVWS method, (4 vs. 0.09 m³), in the near Washington Coastal waters, gave lower detection limits for Pu concentrations than those found by the conventional batch sample method. Interpretations of the Pu concentrations found in sediment and water samples collected at Bikini Atoll in 1972 and 1976 have been made