-31oactivity approxiunhstohed embryos contained levels of radi . tely one-half that found in bird muscle (Appendix Table VIII) Dankto The Rongelap plankton collection consisted of a single tow March 26, paired tows on July 16, December 8 and December 18, ‘954, and four paired tows January 26-30, 1955. A Michael Sars pe net, 4-meter in diameter and with either No. 6 or No. 20 ilk mesh was used. Tows were taken at the surface during day- light hours. | Radioactivity of the Rongelap plankton samples was more than one hundred times greater than that of plankton samples Bollected from the open ocean waters of the Western Pacific vith the USCac "Taney" during Operation Troll. On the cruise: bf the "Taney" during March and April, 1955, 85 plenkton pamples were taken along the route from Kwajalein to the gee cilippines to Japan. i The average activity of these samples yas .015 x 1073 uc/g of wet sample, the highest values being p50 x 1073 uc/g. For the eight January 1955 Rongelap plankton samples the average value was 2.0 x 1073 uc/g, the lowest value peing 0.41 x 1073 uc/g, ) Other conclusions which may be drawn from analysis of the pongelap plankton samples are (1) that the radioactivity per gait weight 1s greater than for most other biological samples, $2) the decay rate is Similar to that for the soil sample, and ; N3) there is considerable variation in the radi oactivity of sam- ples from paired tows.

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