94
appear.
Similar to the radionuclide distributions found in the B-2 sediment
core, increased concentrations were measured in the lowest section of this
core.
As in both other cores from this region of. the lagoon, the 23942405,
ratios measured with deptn in the core showed only a sliyghtincrease with depth.
In the 8-16 cm region of the core, the ordering sequence of radionuclide
concentrations changed from those found in surface sediments (Fig. 19} to the
order Pu > Eu > Am > Co > Bi > Cs.
This sequence is the same as that observed
below the 6 cm section at Station B-2 and in surface sediments in the far
western region of the atoll.
5.3-3
Central and Eastern Lagoon Sediment Cores
The four sediment cores collected from the central and
eastern regions of the atoll (stations B-27, B-16, B-15, B-30) were similar in
three respects.
First, there was no significant net increase or decrease in
the concentration of radionuclides measured betyvieen the upper and lower sec-
tions in any of these four cores.
2394240
24) am, T55,
Pu,
V3? 66, 207
Second, the distribution profiles of
Bi and 696, concentrations are roughly
similar with depth in the individual cores. Third, the
2394240 pu/?*8pu
ratios
measured in all but the Tower section of the cores from Station B-27 were
Similar to the ratio in the surface sediment section.
Because of the very
short (6 cm) length of the station B-16 and B-30 cores, no further interpretation of the observed radionuclide profiles is warranted.
ordering of
Except for the
24) Am in one section, and 239+240 Pu in the 10-12 cm section immedi-
ately below, the ordering sequence of radionuclide concentrations in the 16 cm
core from Station B-15 is the same as in surface sediments (Fig. 19).
In
the 10-cm core collected from Station R-27, the sequence of 60¢9, 2073; and
13766 concentrations measured did not change with depth from that shown in
Fig. 19.
However, in the 4-8 cm region, 241 a was higher in concentration