GOV e
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SAS Me aey
ny
STATUS OF RONGELAP INVERTEBRATE STUDIES,
K.
OCTOBER 26,
1960
Bonham
Three phases of endeavor may be mentioned.
1.
Facilities of the Research Computer Laboratory were
utilized for writing a program, with the aid of Dr. E. E.
Collias, oceanographer, to permit data processing of gross
beta using the IBM 650 computer.
Two subroutines, prepared
with the help of Dr. D. B. Dekker (Director, Computer Lab.)
compute, (a) the geometric mean plus and minus one standard
deviation, and, (b) the coefficient of variation for a selected group of values.
Since the first program yields the results in six types
of units, d/m/g and uc/kg, wet, dry, and ash (as well as the
counting error at the 95% confidence level and the three pos-
sible weight ratios),
the two subroutines may be used to se-
lect the unit that gives the least variability.
In this way
_the unit may be used that is appropriate to the nature of the
Sample.
For example, less variability resulted when radioactivity of plankton was expressed on an ash-, than on a wetweight basis.
2.
Gross beta radioactivity of invertebrates of Rongelap
waters in Sept. 1959 is summarized in the accompanying table.
The highest levels are in the northwestern portion of the
atoll (Naen I.) where clam kidney was lmicrocurie per kilogram
of wet tissue.
Samples showing most radioactivity were hermit
crab exoskeleton, snail liver, and kidney of tridacnid clams.
Through the courtesy of Dr. Douglas G. Chapman, statistician, it was shown that in our data no significant difference
existed between the tissue values of radioactivity for different
species of tridacnid clams at any particular locality, and, simi-
larly,
that values for the sea cucumbers Holothuria atra and H.
ideucospilota did not differ significantly.
Therefore, levels of
radioactivity for tridacnid clams may be calculated on the basis
of whichever species is available at that particular locality,
and either or both of the common black sea cucumbers may serve |
aS a monitoring species.
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