116 previously. This is due to the large concentration gradients exhibited by some radionuclides "within the Bravo Crater” and at “mid-Jagoon" which were reported as the collection sites for the previous collections. If mid-lagoon is taken as Station B-25, the concentrations of 65 and 2078; found in this work, and decay corrected to 1964, are well within the range of concentrations measured by Welander (1967) in 1964. The concentration of 137 Cs measured in this work, corrected for decay to 1964, however, is 100% higher than the upper range of 13764 concentrations reported by Welander; this could indicate that transport of 137 Cs may be occurring from higher concentration regions upstream. In the Bravo Crater (using the concentrations measured in surface sediments at Station C-3) the concentrations of 137¢6 (decay corrected), 2394240 Pu and 23854 are lower hy 34%, 18% and 24%, respectively, than those measured in samples collected in 1969 by Held (1971); this indicates that radionuclides may be leaving this area. Some care should be exercised in the application of these figures, however, because of the uncertainty in the collection sites and the possible differences in sample collection techniques. With respect to (3) above, some date (Nevissi and Schell, 1974; Schell, 1974a; Noshkin et al., 1974; Lowman, 1973) are presently available on the concentration of radionuclides in the waters of Bikini Atoll Lagoon. Although water samples were not collected at each of the sediment sampling stations reported herein, the numher of water samples collected are large and the interpretation of the water data encompasses a tremendous (and uncompleted) task. Such a treatment is outside of the scope of this work. However, in line with the interpretation of the radionuclide distributions in the sediments, the ratios of the radionuclides measured in bottom water and surface sediments were computed aS a measure of the possible differences between the fractionation of radionuclides between the sedimentary (source) and aqueous phases.