DRAFT ————— Studies of these physical aspects, ae well as mo2sure~ ments of the background of radioactivity, were conducted aboardthe Seripps vessel M. V. HORIZON during 5 April -~ 5 May 1956 in a rectangular area reaching 100 miles to the south, 200 miles to the west and north, and 250 miles to the cast of Bikini Atoll (Fig. 1A4).2 Particular attention was given to background radioactivity anc res neer Bikini end the most probable fallout areas (Fig. 1B), ckereune in and rate of eflux of water from Bikini Llageon, and fallout particles on the deep ocean bottom fron the CASTLE events. rediosetivity was Paar studied in Atlinginae Legcon. As vseG in this report, redioactivity Lackgercvnd is tke total amount duo to the combinetion of naturally cccurring radicactive elercnts and the radioactivity s remaining from eport was prepared in the field during and immedi-« ately following thc cata collecticns; it is for uso by Progran Ocsenogzreanher. _-_— 2e = ee ee wee Ail figures ere at the end of the rescert, 12 [2 Corier LAM Ro we ¢