DISTRIBUTION OF RADIOACTIVITY IN SEA WATER AND MARINE ORGANISMS FOLLOWING AN UNDERWATER NUCLEAR DETONATION AT THE ENIWETOK TEST SITE IN 1958 INTRODUCTION (3) Studies were made by the United States in 1955 (19) and by Japan in 1954 (17) and 1956 (2, 14) and 1956 to determine the extent of the re- sidual radioactive contamination in the western Pacific Ocean resulting from the nuclear tests at the Eniwetok Test Site. These studies were concerned with radioactive fallout material produced by the detonation of nuclear devices on land or in very shallow water. The present investigation was conducted during the 1958 test series (Hardtack) and was designed primarily to determine the uptake of the short-lived isotopes by marine organisms and to outline the mass of radioactive water immediately following the underwater detonation of a nuclear device (Wahoo) The survey was divided into two phases: the first, a predetonation survey, was designed to evaluate the radioactivity contributed by the earlier tests of the series; the second, a post detonation survey, covered the four-day period immediately following the Wahoo detonation. The Hydrographic Office of the U 5S. Navy assigned the USS Rehoboth (AGS-50) to assist the Office of Naval Research in a research ey © uA cus pe Ao