30 29 of the inventory estimated to a l6-cm depth in the sediment column disturb large quantities of material and release large amounts of (Table 1). unassimilated material containing plutonium in their feces. The average quantities of soluble plutonium in the water are Moriarty in recent (Mo76) estimates that a 200-g mullet, a species common to Fnewetak, years only small fractions of the Atoll plutonium inventory is either which feeds by scooping up bottom material to sift and remove small remobllized to the solution phase or resuspended to the water column. algae, will pass 50 g of dry sediment through its gut per day. also small fractions of the sediment inventory. Therefore, During 1976 zooplankton samples contained less than 1% of the Bottom particles from the NW quadrant of the lagoon where highest 23942405, activity in the total material filtered from an equivalent piutonium concentrations in sediment are found usually have high volume of water (No78b). plutonium concentrations, indicating that a fraction of The remaining 2394240Pu in the particulate the plutoniua in material is therefore associated with other forms of suspended matter, the particulate phase may originate from turbulent resuspension of the Between 1960 and 1963 Johannes investigated the composition of the sediment components in deep suspended particles in the lagoon (Jo67). associated plutonium is probably not transported for any distance in the Progressing from the eastern (60 m) water. This resuspended material and reef toward the lagoon, suspended benthic alyae and sediment particles lagoon. became less abundant with depth of the water as they settle to the the same general area of its origin. bottom, and suspended macroscopic organic aggregates, consisting largely active processes capable of generating and moving particulate plutonium of mucus released by coral, increased progressively in size and number in the water mass have been considered, (Jo67). ether processes resuspend so little of the plutontum inventory. Often calcareous grains resuspended near the reef, Previous results indicate that the material is redeposited in Only a few of the vartety of It ds romarkable that these and barring microorganisms, copepod fecal pellets, and other undifferentiated catastrophic events, the present distribution and inventory of plutonitin material were incorporated with the aggregates. in the sediments will be only slightly altered durinp the years by These materials and other particles produced in the pelagic environment are the most important food components for lagoon zooplankton and certain plankton-feeding fish (Ge74). The small quantities of plutonium relocation of labelled material from other regions in the lapeon, Laboratory studies with contaminated sediments and soils from Enewetak show that plutonium is rapidly partitioned between the solid ingested with this particulate debris is dispersed over the lagoon by phase and solution, reaching equilibriur after severel days with an these organisms. average distribution coefficient for plutenium of 1.8 x 10", Herbivorous fish play a role in the generation of particles in the water column (5m73). These fish are not efficient assimilators; while satisfying their energetic requirements, they Table & shows this and some recent determinations of the distritution coefficlent for plutenium in laberatory and field experfinents using a Je are pac’ s