ae a eae cee meRS ee aeen eeeed er em CHAPTER V at tS ge ee photo! 15S] a ee bite ty Ogee egies utara tif sacha A a 2 RIE sates iaitga8d viteadete A ie a Ti Reiae ee coca ae Residual Activity in Pacific Ocean During February-May 1955, a survey was made by the Health and Safety Laboratory of the U.S. Atomic Energy Commission and the Office of Naval Research (Operation Troll) of the Pacific Ocean extending from the Marshall Islands westward across the Pacific, northward to Japan, then east to SanFrancisco. The chart, on page 40 represents data on activity found in sea water and plankton. Table 41 shows some representative data on activity versus depth of watersample.!? Tables 42 and 43 show representative data for marine life.” 4 igs hy ra he Miah ay r ' .tak : og Below is a summary of some of their conclusions: 1. Sea water and plankton samples show the existence of wide-spread low-level activity in the Pacific Ocean. Water activity ranged from 0-570 d/min/liter and plankton from 3-140 d/min/g wet weight. 2. There is some concentration of the activity in the main current streams, such as the North Equatorial Current. The highest activity was off the coast of Luzon, averaging 190 d/min/liter down to 600 m (April 1, 1955). 3. Analyses of fish indicate no activity approaching the maximum permissible level for foods. The highest activity in tuna fish was 3.5 d/min/g ash, less than 1 percent of the permissible level.* 4. Measurements of plankton activity offer a Sensitive indication of activity in the ocean. On June 11-21, 1956 another survey of radioactivity in the sea was conducted near Bikini and Eniwetok Atolls by the AFL. Since this survey was conducted during the Spring 1956 test series of detonations, temporarily relatively higher activities might be expected. Table 44 summarizes someof the data." *Based on 1/10 m.p.c. of that for atomie energy workers.