Since the activity was messured on the samples
which were biolovically unclassified, 10 wos difficult
to point out the difference in degree of radiation
contamination among the different types of organisms.
Miological comp
However, if anythings, the activity in samples 1,°?,4,9.
Doliolum sp. were predominant, seemed to be generally
lower than those found in the samples consisting
mainly of Crustacea and Salpa sp.
Gamma spectrometry was made on the ash from the
fresh samples or from the samples placed in the preser-
arr
and 10, in which larval fish, Medusae, Sagitta sp. and
iT
“ Da.
Spey
Copepe
metic Copepoda
> Siphonophor
a?
4
Sp.
i
Hecusae( 203)
vative. The low level gamma spectrometer used
consisted of a heavily shielded scintillation detector
ppepoda
Electric Co.).
.
Mi cularia,Sagit
with a 256-channel pulse height analyzer (Toshiba
the cetector, fittedwith a 7.5emg x
7.5em solid NaI(TL) crystal,-was housed inside a special
shielding composed of mercury (2.5em thick) and lead
(10cm thick).
Miopepoda, Pterx
i tal 20%) yoiphe
(i.e. 0.82 for 137Cs
HOt) , Euphausi:
@hausiacea(10mt) ,Siphonophc
Mes sp.(10-20/
Muphausiacea(]
Pagitta sp.(]
480%) ,Copepod:
60Co and 144ce-l4Pr were presumed from the gamma
>phorae(10%) .
of 252r-95Nb were measured by referring to a standard
source of 137Cs (Nuclear Chicago Corp. Model RS 137)
with corrections for the difference in the number of
photons per disintegration.
and 1.0 for 95Zr-95Nb.) The results are shown in
Table 2. In addition to 95Zr-7 Nb, the presence of
energy Spectrum.
Some of the data pertaining to
concentrations
95Zr~9 Nb ain plankton were
of
found to
be on the same level as those found in spinach samples
measured in Tokyo. It mav be of interest to mention
that the concentration of nuclides, such as 90Sr, in the
marine organisms, amounts to not more than onehundredth of the concentration found in terrestrial
plants.
m,Sagitta sp.(
Modusae
ree
Mm ,Salpa sp.(]
elpa sp.(10%,
Mergestes sp.
ma Sergestes ¢
Hee, Medusae
mi sp., Pteroy
ore
Since the predominance of *7Zyr-95Np was observed,
attention was paid to these nuciides.
Concentrations
3 Megalopa ]
—~52—
—50-
CSR ee
eee
eee
Ne,