oute pho- 1.6.2 Lagoon Waters. The radioactivity of the waters enclosed within Bikini and Ailinginae Lagoons, as shown in Table 1.5, ranged from seven to fourteen times the natura] potassium gamma bseckground and from three to seven times the average radioactivity of the surface water surrounding the lagoons. No difference was detected between the lagoon water at Site Elmer, Eniwetok, and the surrounding ocean water, perhaps due to the exchange of water permitted by the wide, deep channel nearby. The radioactivity of the lagoon water, in contrast with the open otean water, was associated with the suspended particulate matter. The residue from 6 liters of filtered surface water, emitting a total of 4,860 y/min, showed 2,720 y/min, or 56 percent associated ”- re 7 OP an Spagna ram } ne TABLE 1.3 GAMMA RAYS EMITTED PER MINUTE PER LITER OF EPG OPEN SEA AREA WATERS The values of (y/min)/liter (0.075 to 1.5 Mev) have been corrected to account for a 22 percent efficiency and a 41 percent geometry of the scintillation counter when standardized with Co™ and Zn"*. The average back- ground due to instrument noise and cosmic rays has been subtracted from the reported values. The natural K” background of 74 (y/min) /liter of sea water bas not been subtracted and is included in the above figures. liorom ‘om a waer to ‘as d to . itted er adio1.5 ses. ion iter tu- four no ts m- omumnenerh ich — Depth meter —> 7 5 3 0 207 «237,838 so _ 1300 1000 _ 217-2150 12500 _ o — 130 = ~_ — _ 200 =O _ 170 «105 201285 — _ 300 00 — 500 1700 600 600427 1,000 1200 620 1,400 267 2,000 140 3,000 205 4,000 — — _ 4,300 4,600 4,200 Stations iz ié 35 7 26 siaTsKOC*«‘TIGM 30 90 115 OO — mol -=125 65 55 60 -8s — _ _— ~ — — _ — 170 80s 180 00 _ — ~ _ 3 — — ~_ _ ~ — 5,200 5,100 4,300 3,400 4,600 25 28302 90 — _~ 888 205 175 187 Salinity for ~—sBtation 29 pot 84.56 34.58 35.01 35.25 85,22 34.58 34.43 34.41 _ — 45 185 1260 205 «34.60 = — _ —~ — 1% 187 ~120 $4.58 _ _ _— a “5 0UC ~ — 170 34.59 870m e385 — 200 417° 34.58 190 435 280 eo — 325 — 185 260 ~—s84.59 — _— ~— ~ 2050 ~_ — 195 34.60 «290 o — oe — 2672217, 00—iBi«é8LwCC 290 0 _ — — _ — — ~ 187 180 — — _ — _ _ _ ~ 15 0CiaT — _ — ~— — — — Bottom Depth, meters 3,560 1,440 with the insoluble fraction. Subtracting the K*° contribution from the total, 62 percent of theartificial radioactivity was retained by particulate matter larger than 0.5 micron in diameter. An analysis of the particulate matter in the lagoon water showed 85 percent Ce! and 15 percent Ru'™ of the gamma-emitting isotopes. The soluble fraction was not identified. w Zn, of reover 1.6.3 Marine Organisms of the Open Sea. The assay of the oceanic fauna consistently showed the presenceof artificia] radioactive contamination. Zooplankton from water of an average activity of 173 + 85 (y/min)/kg (Table 1.3) showed an average of 18,000 + 4,000 (y/min)/kg (Table 1.4) or more than a one-hundredfold concentration over that of water. Neglecting the K*activity of the plankton (0.08 to 0.8 (y/min)/gm) and subtract- ing the K“° activity (74 (y/min)/liter) from the water, unsorted zooplankton, on the basis 21