- 69 The radioisotopes in the ocean are those that occur from natural sources, posal of radioactive waste. from fallout, or from dis- The radioactivity in sea water from naturally occurring radioisotopes is about 750 disintegrations per minute per liter, of which «40 contributes ninety-seven per cent of the activity. The greatest amount of radioactivity added to the ocean has been in the area of local fallout near Bikini-Eniwetok Atolls. The amount of radioactivity from fallout in a liter of sea water, immediately following a detonation may be thousands of times greater than the amount from x40; within one year, however, the amount is less than from KO, From the Bikini-Eniwetok area, fallout is carried westward by the North Equatorial Current system at a rate of seven to ten miles per day. Radioactive wastes may be the principal source of radioisotopes in the ocean in the near future but at the present time the contribution from this source has been negligible. Biological effects from radioisotopes in the ocean should be especially evident in the Bikini-kniwetok area; however, gross population changes or morphological abnormalities have not been observed in samples from the area,