However, the patterns repeat themselves regardless of the error associated with counting, indicating that the trends found for the different ratios among the tissues and gut-content samples of the fish are real. This pattern pointed to the possibility of discrimination between isotopes of plutonium, which is difficult to accept from a purely chemical viewpoint. The following steps were taken to analyze if discrimation between the isotopes of plutonium was taking place. Gizzard and intestinal contents were removed from samples of mullet collected from the more-contaminated equilibrated with seawater for 5 hours. the ingested material to pass regions of Bikini and (Five hours is the normal time for through the gut of mullet.) From this experiment, the 238py:239+240py activity ratio was determined in the solid phase and in solution. Five sets of results are shown in Table 11. In every case, more 238py relative to 239+240py is measured in solution, which indicates that 238pu in the material ingested by fish must be in a more readily. soluble form than 239+240py, _ | The concentrations of 239+240py and 241Am in fish from the lagoon differ markedly from organ to organ and species to species. Less than 20% of the samples showed the same relative amounts of 24]Am and 239+240py in the body parts analyzed. Concentrations of plutonium in most fish parts from. any location collected during different years have comparable concentrations, Showing that the fish maintain restricted feeding territories. The concentration ratio of @4lam to 239+240py in muscle, bone, skin, or liver was always either equivalent to or less than the ratio in the gut contents or Table 11. Activity ratios of 238py:239+240py in liquid and solid phases of gut contents after equilibration with seawater. Solid phase Liquid phase 0.0081 0.13 0.048 0.11 0.43 0.003 0.14 0.021 0.010 0.22 0.045 0.0034 0.27 0.13 S000 74 20 - Solid: liquid phase 0.062