3.1 DESCRIPTICN CF FALLOUT SAMPLES Upon delivery of the semplcs to the site laboratory, the exterior of all the sample bottles was decontaminated with dilute acid and rinsed in water after which a reading of each sample was taken with a survey meter in contact with the bottom of *he cleaned bottle. On Shots 2 and 4, much of the fallout activity was retained by the fumnel. In these cases, the exterior of the funnel was cleaned and the interior monitored by inverting the funnel carefully over the meter, The funnel wes then rinsed with dilute acid into the bottle until it had been sufficiently decontaminated. The inside of the tottle was similerly washed and the rinsings collected in a graduated cylinder and appropriately aliquoted for counting and other treatments. Semples of both Projects 2.5a and 2.6a which were not treated at the field leboretory were packed for shipment to USNRDL after the sample bottles had been decontaminated and the survey meter reading had been observed. The samples retained at the field latoratory were removed from the polyethylene tottles. For larger samples, the: bulk of the material was transferred to weighing bottles or graduated cylinders and the remainder rinsed into the cylinders with water or dilute acid. For smaller samples, the bottle was cut and the meterial colle-:ted by use of a large rubber policeman or brush depending on whether the material was wet or dry. After obteining the total weight or volume, the sample was aliquoted. Most of the samples were slurries, or mixtures of solid and liquid. These were subjected to vigoreus stirring and aliquoted with pipettes, the tips of which had teen removed. In numerous cases it was extremely difficult to alicuot the untreated material because of large coral par- ticles, organic debris, and other material. A number of experiments required samples just as they had been collected. As the samples generally were sme]i anc triplicate samples from ea given station were no? available as had been plenned, they had to be alinuoted by the best means available. In cases where the samples could be acidified the aliquo*ting was greatly simplified. 3.1.1 Samples from Shot 1 These samples, descrited in Table 3.1, were received by the field leboratory on B+5.3 days. Stations 250 were lagoon rafts and stations 251 were island positions. The lat*er were concrete pits at ground level Due to a short supply of bottles for refitting the stations for subsequent shots collecting teams were obliged to combine all three bottles from each collector or occasionally discard two of the three fallout samples. Conse- quently, a comparison of the collecting efficiency of three adjacent “ which permitted considerable coral to drift into the collectors. collectors at a given station could not be determined as had been planned. For lagoon staticns, samples from two bottles were rinsed into the third with sea water; samples from the island stations rere combined without rinsing. This procedure resulted in uncertainties in the total quantity _of fallout cellected per unit area. Furthermore, since the samples col- b. ¢ lected on the lagoon were ¢iluted withsea water their original compositions were difficult to determine.