ik
rs
3
a)
fay
‘oo
B PLUTONIUMIN SI. WATERS. LTC
RK. M. wong
E concentration in the 10-12 cm section of the core + usually about | 10 the concentra-
ual
ab.. Richmond, 34
tion of the surface section.
cy
a
It was found that the addition of hvdrochloric acid in the leaching step 1s
one
B necessary only for sediment samples of lowsalinity. Most marine sediments contain
ates
mm”, 100-ym -
sufficient chloride for complete leaching of plutonium from the sample using only
‘nitric acid.
Weigh out a 100-g aliquot of dried sediment. transfer it to a 3-] beaker, wet the
t sample with water. and add 1 ml of standardized plutonium-236 tracer. Carefully
= add 200 ml of 16 M nitric acid and 100 ml of 12 M hydrochloric acid. slowly stir the
-ed in a chamber
od. No. 428), a.
o. 115), a linear
alyzer (Nuclear
inder (Canberra .
& sample and allow the mixture to react at room temperature. If foaming becomes
. appreciable, controlit with the addition ofa few drops of n-octanol. Whenthe reaction
: subsides, cover the beaker witha watchglass, heat gently, then to near boiling (90-100°)
. and digest the sample for about 2 h with occasionalstirring.
be used.
Add 300 ml of 1 M nitric acid and 25 ml of 30°hvdrogen peroxide and continue
from the North
ynvenient deter-
heating (90-100°) until the peroxide has decomposed. Cool the sample, filter through
= a glass fiber filter paper and wash the residue with ca. 50 ml of hot | M nitric acid.
transfer the sea
rinses and evaporate (90-100°) unul salts begin to form. Estimate the volume of the
so'ution, add an equal volume of 1 M nitric acid, dilute to 1 | with 8 M nitric acid.
and cool to room temperature. Add ca. 10 ¢ of solid sodium nitrite. mix and leave for
30 min before proceeding with the plutonium purification.
imples??,
etc.) of all dust,
* Transfer the residue back to the 3-1 beaker and repeat the entire process from the
; addition of concentrated nitric and hydrochloric acids. Combinethefiltrate and acid
‘cipitate to settle
Lay
ee Rigeet
ent
Tve any unusual
mation may be .
ul of 3 M hydro1 few times, and
tinse the empty
1¢ sample.
-236 (2-3 d.p.m.}
of 2 M sodium
second 100 miof
ml) to make the
a
300 | capacity).
Procedure for marine organisms
The concentration of fall-out plutonium in marine organisms1s quite variable:
a range from 0.004 d.p.m.kg in fish tissue to more than 10 d.p.m. kg7’ in certain
seaweeds has been observed'*. For optimal sample counting rate, the activity should
.. be about 0.5-5 d.p.m. Lower activity would require too long counting whereas higher
activity could unnecessarily increase the chance of cross-contamination between
* samples.
Table I, which may be used as a guidefor the selection of the proper sample
size, lists the average °7°Pu concentrations in some marine organismsof the Atlantic
Ocean collected in 1970'*. Similar ranges of 77°Pu concentration have also been
found in some Pacific organisms'*.
-nsfer the hydro-
jlastic wrap and
ate. Dissolve the
-e volume of the
ition to a 400-ml
TABLE |
AVERAGE PLUTONIUM-239 CONCENTRATION OF MARINE ORGANISMS IN THE ATLANTIC OCEAN!+
.dd 5 mi of 30%
Oruanisms
on a hot plate at
om temperature,
‘roceed with the .
Sargasso weed
Mixed Zooplankton
Starfish, Asterias forbesi
Mussels and clams. shell
13
3
2
0.6
meat
0.3
Milena, Saiiearea
er eS eee
PE
quot: the 77°Pu
2
Fish, guts
ufficient fall-out
sections of cores
*39 Py (dpm. per ky wet wt.)
90084282
bone
liver
meat
0.9
0.3
0.1
0.004
Anal. Chim. Acta, 56 (1971) 355-364