"1. wee CHAPTER 5 CONCLUSIONS The radioactivity of the six groups of organisms by islands is summarized in Table 5.1. The individual counts for preshot samples ranged from 0 to 80,000 d/m/g of wet sample, and the distribution of counts was strongly skewed to the lect. A count of zero was obtained from samples collected at all islands and for most of the groups. For the posttest samples individuai counts ranged from 0 to 14,000,000 d/m/g, wet. The few zero counts were from Japtan or Igurin. Counts of 1,000,000 d/m/g or greater were obtained from all groups of living organisms other than land vertebrates. The distribution of posttest counts was also skewed tothe left. The average values (Table 5.1) are those of all samples prepared for counting and may include more than one sample from one specimen. A comparison of one group with another is limited by the differences between species and tissues as well as by the variations in sampling; however, the number of samples processed warrants the belief that trends are indicated. Although the range in values for one group of organisms at one station may be considerable, the order of magnitude of differences between islands and between groups is great enough to clearly indicate a constant order in the ranking of the groups and a definite pattern of distribution by stations. Ranking of the groups for both the pre- and postshot collections (1) by the station with the greatest activity, (2) by the three stations with the greatest activity, or (3) by ali stations gave the same order, with one exception, and was as follows: algae, invertebrates, plankton,fish, land plants, and land vertebrates. The exception was that of the postshot land plants, which ranked third. The pattern of distribution of activity of the preshot collections clearly indicates the areas of former test sites, Engebi, Aomon-Biljiri, and Runit. Pretest collections at other stations had considerably less activity, which decreased with distance from the test site in the following order: Bogombogo, Runit, Igurin, and Japtan. The activity at Japtan Island was not much greater than that which would be expected from naturally occurring isotopes. An exception was the counts of plankton samples, which were greatest on the western side of the Atoll. This distribution might be expected because of the movement of the surface currents from east to west. Forthe posttest collections the center of distribution was shifted toward the site of the Mike shot. For the outlying stations there was again a marked decrease in activity but with greater activity, as related to distance from Mike site, on the western side of the Atoll than on the eastern side. There was a slight but definite increase in activity at Japtan. The ratio of postshot to preshot activity as determined by the averages for each group of organisms was approximately 300 for the aquatic organisms and 1000 for the land plants and vertebrates. 82 UNCLASSIFIFN