-412- Lagoon studies of transuranics will continue, providing adequate ship support is available. The atoll seems to have reached a chemical steady-state condition with respect to the partitioning of 239*240py between solution and solid phases of the environment. Using an experimentally determined Ky for 239»240py, the dissolved quantity predicted in equilibrium with the concentrations in sediment agrees well with recently average measured concentrations In water at both Enewetak and Bikini Atolls. characteristics. The remobilized 239924°py has solution-like Over the next 250 y, an estimated 50% of the present 233,240py sediment inventory will be remobilized to solution and discharged to the north equatorial! Pacific. It has yet to be determined if biological components of the sediments are an important link in the remobilization process. Additional temporal data are needed to verify our estimates of the rate of regenerated plutonium. Our evidence that plutonium is remobilized from the sediment to the water is substantial and leads to the conclusion that similar processes must be occurring in coastal and other aquatic areas. We are now modeling our data to show the extent of remobilizatién that may be occurring in coastal and other waters contaminated only with global fallout. Less significant marine radiological pathways to man also require study. For example, the highest plutonium levels in fish were found, unexpectedly, in samples collected from the ocean reef of Sally tsland. The gut samples contained contents with 150 pCi/g of 2392240pu, However, the concentration of other radionuclides was among the lowest detected in fish at Enewetak Atol}. These are high isolated plutonium sources at the atoll! available for uptake by marine organisms. As another example, a particle high in plutonium was isolated from the gills of fish caught near Yvonne. Using mass spectrometry we determined the 241py and, with the measured 2*!am concentration, dated the particle. It originated in the 1958 test series from the non-nuclear test held at Yvonne. It is obvious that hot particles are still available to fish on the reef. If these nonedible parts of fish are recycled to the terrestrial environment by man, levels of plutonium of marine origin could be increased in village areas. An evaluation of the expected impacts from those less significant pathways will be made. MAJOR MATERIALS, EQUIPMENT, AND SUBCONTRACT ITEMS: Estimated Cost Equipment FY 1979 FY 1980 Groundwater sampling equipment (pumps, generators, and in situ conductivity meters) $ 4,000 $ 3,000 Air samplers and generators for reef work In-situ filtration-preconcentration system 5,000 . 5,000 Sere 7" 19,