Isotopic signature of plutonium at Bikini atoll.

Atom ratios of the isotopes (239)Pu, (240)Pu, (241)Pu and (244)Pu were determined in sediments and soils from Bikini atoll using low energy Accelerator Mass Spectrometry. All samples had been contaminated by local fallout from nuclear weapon testing between 1946 and 1958 and show significant variations in the isotopic composition, which are ascribed to the different yields of single tests and to the mixture of material from various devices. Differences in the (244)Pu/(239)Pu ratio (2.8-5.7x10(-4)) are more pronounced than in the (240)Pu/(239)Pu ratio of the same samples and provide complementary information to distinguish the sources of contamination.