 It slowly falls to earth as global fallout and is not soluble, and as a result it is difficult for this plutonium to be incorporated into an organism if ingested.Much of this plutonium is absorbed into sediments of lakes, rivers and oceans.However, about 66% of the plutonium from a bomb explosion is formed by the neutron capture of uranium-238; this plutonium is not converted by the bomb into a high fired oxide as it is formed more slowly.