atgeeted tae Southern more wnan tne nortnern part of Rongelap Atoll. Samples tuf7o-77 of plankton collected July 1956 from the Rongelap Islan: vicinity of honselap Lagoon were more radioactive when first couns-C one insnta after collecting than the corresponding sample from the lagoon near Kecelle Island. (QU74) Island cumples (4077) was anor 2} One of tne Rongelap to 9 times more radioacthe than tue over two Sumples 410 ae teyeu most rapidly of those studied. Witain o wacks it wus less tian haif (.44) as actse as when first counte.., wilde tne ot.:er tvo Bultples CGecayed only to32.5 “:6 of their Origvini: vilues. When recounted as much as a year still later, this sa ole that had originally been tne highest of the three was leasu ruttoiuctive of all, Furthemear:*, tiucs verif,ing its earlier rapid decay. tne ctner hongelap Isiund sample, also, had decayed more tnan in.i cAtaer of the Kacelie Isiand samples. | Teeay Of Marsh 1359 samples was negligible during the two months Jeptemteor to November 1l,5c, from wnile August 1958. samples decayed duriin, 01 monta of Novemper 1353 fairly rapidly, Of atous 2.95 Gars, tnus supportin,: the assumption that the incressed were aturiuutebvie o . ‘ Levels with a half-life to the Harautack series of detonations. Tne rate of cecay Of tue samples collected in 1954 was less Stecp Cian the rave of deciine of rudiouctivity in Rongelap Lagoon Deaiuttin. Da Fissure > bie veeax olopes of curves 1 to 2 range from el. LO uw maxiinun Ol -c.4+, Give, ? Vo lle fa Pisgure €, even in tie steep portion from 060 to 1740 the ceeline slope shown by the dotted iine //0.