410717 346.211 On the Distribution of Radioactivity in the Sea around Bikini Atoll in June, 1954. , oe Tf-O72) by Box 3. Y Po FFAS KEDwine— ene en _Fatcout- Resarts. Miyake, Y. Sugiura and K. Kameda Meteorological Researvh institute a Recevsed accvare ( 1955 Abstract Bx Beer ge ‘ the ' atmut radioactivity in the air and sea water caused by the US ‘ests in tne area of Boxin: Eniwetok Atolls, 1954, The + ortamination to fishes and fishing boats were brought The observation of the actua, state of the radioactivity around Bikim-Eriwet: k Atolis was carried out aboard the survey boat © Shun kotsu mary’ The maximum radivactiv ty in sea water was 7025 cpm / at S7G km west of Bikin and the rdrence re ognized a3 far as about JOO «wm trot. wtaptic discussions on the hor zontal of Bikini the radioactivity Atoll was Some oceano «s well as vertical; distributions of tne radjoactivity in tne sea are give 1 Introduction Leaving Tokvo Harbour on 15th Mav until 4th July aboard the survey boat i354 the the observation were carried out © Shunkotsu-maru” belonging to the Ministry of Agriculture and Forestry in tm sea area near Bikim Atoll where H.bomb test3 hac been done by U.S Atomic Energy Commission, to make clear the state of the rad oactive contaminatio: tu ].ving matter, sea water, the air etc. The purpose of this ' Japanese Birkin. Expedition” was to obtain a counter-plan against the serious damage fell on the Japane-e pelagic fisheries due to the radio- activity carelessly scattered in this sea area since the unfortunate affair of the fishing boat the ‘‘ Fuku-ryu-maru”. the ' Lucky Dragon” on lat March, 1954. In this expedition the present authors took charge of making a plan and ob- servations on the radioactive contaminaticn of sea water and the air. Two of the authors (Suc:ura and KaMepa participated in the expedition as observers. The fairly strong radioactivity was dete.ted .n wide area around Bikim Atoll, though U.S. Aric Energy Commission had daclared that the presence of the radioactiv.ty in the area was negligipie | | In this paper the authers intend to report the resu':s of observations and sune oceanographic discussions regarding the distributions of the radioactivity near Bikim Atcl! 2. vity in sea water The method of measurement of radioactivity WNRG It is dificul- to measure the radivactivity in sea water directly by simple evap- oration srethod owing to its high salinity, therefore, the carrier method has been adopted. After adding 2 gr of solid ammon.um chioride, 1 m/ of the aqueous solution of iron alum 1% 3 gr) and 1m of barium chloride solution (17.8 gr/d) to 1 litre of sea water water is heated to 50~70°C stirring well. A few drops of an alcoholic solution of phenol.phthalein 11% are added as an indicator, then ammonium BEST OPPY AVAILABLE 792% 27