sion «Agtha chfa cdot ve stietlie so eft - Pe re re Ly METHODS Radioactivity of common substances and organisms at Eniwe- tok Atoll was evaluated in two ways, first by concentrated study involving many organisms collected frequently at one island, Belle, and second, by less intensive study at several islands around the atoll in order to elucidate the geographical distribution of the activity. Belle Island (Fig. 1) was the major collecting and observation site, except for rats, for which it was Janet Island. Collections cana (Sanitdefonse) as, EENikaS80 were made on April 15, 1954 at bette Cogembogy 56. Belle before the Nectar test, oFalts, almost daily for the week after, and at increasing intervals later. The second aspect of the study, at several islands, involved pre- Nectar collections in April and May, and nine to ten post-Nectar collections, usually expedited by helicopter, at intervals in- ° toreensies: oe “ on CKonre=\. ., | a > “yrteroy (Rigiti) creasing from one to nine months, _ at which time six islands, Henry, Os, Leroy, Alice, Olive, Vera, and enane . taniyaantS’ EF neuneat mites kil oe weney tated Bruce were visited. The remaining two islands, Janet and Elmer, were sampled at approximately the same times in connection with other studies. aise ip a af eo Fig. Atoll we ~ 1. Map of Eniwetok survey meter readings were taken frequently at Belle, but m only about half of the visits to other islands. The Juno meter was used for high (Table 2) levels of activity and the Geiger counter (Nuclear, MX-5) for low levels. Several spots were usually monitored with the instrument one inch from the ground and with the shield both open and closed. Similar readings three feet from the ground were taken less frequently and are not included. For the distributional study on the various islands a handful of island soil from the top inch, intertidal beach sand, a few milliliters of sea water, algae, and three sea cucumbers were taken. Periodic trips by M-boat around the periphery of the lagoon, a mile or two centrally from the islands, served for sampling sea water, plankton, and pelagic fish by rod and reel. Plankton tows usually lasted from 15 to 30 minutes at from one to two knots per hour using two 1/2-meter nets, fine (No.20 of 173 mesh/inch) and coarse (No.6 of 74 mesh/inch) towed simultane ously from either side of the M-boat. Large jellyfish. if present were removed and the samples preserved by adding formalin to make 5%. “_ 7a ag RRS