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FURTHER CONTRIBUTIONS ON GROSS BETA RADIOACTIVITY OF
PLANKTON AND BOTTOM SAMPLES AT RONGELAP
cate
SECTION II
ATOLL
1954-1958
INTRODUCTION
Plankton in Rongelap lagoon took up large amounts of radioactivity
from fallout following the Bravo detonation at Bikini Atoll on March 1,
Since then,the radioactivity has declined with only relatively
slight additions from the two succeeding series of tests, Redwing in
1956 and Hardtack in 1958.
Since the last summary report on the
Rongelap surveys (UWFL-43) was written, plankton has been collected
four times, July 1956 and 1957, and March and August,
1958, and lagoon
bottom samples once, in August 1958.
The present report gives available data on plankton through 1958
including a reevaluation of 1954-1955 counts which were reported in
UWFL- 42:43; however, ash weight as well as wet weight is
used, with
a modification of results, and a comparison is made of activity yielded
by fine-meshed as contrasted with coarse-meshed plankton nets.
The rate of physical decay of early samples is compared with the rate of
change, herein termed decline, of successive samplings
up to more than four years after the original fallout.
at
later dates,
emery
1954.