87
and in seven of the nine sections a unique concentration sequence of the
ode
- 2394240, Pu 155e, 5 238, 806, , 137.6, 24a 5207p: was found.
A long core of entirely pulverized sediment was collected from the center
of the Bravo Crater.
Three seqments of this 56-cm core (the 0-12, 26-34 and
48-56 cm segments) were cut into 2-cm sections for the radionuclide measurements.
The concentrations of radionuclides (Fig. 22) measured in the two
lower segments of the core were similar to the uniform concentrations measured
in the Zuni Crater core.
In the surface 12 cm, however, a well-defined layer
of high radionuclide concentrations was centered at the 6-8 cm depth.
Elevated
concentrations of all radionuclides were measured in this section, which con-
tained the highest concentrations of 2385, (8.3 pCi/q), 2075 5 (432 pCi/g) and
606 (306 pCi/g) measured in any Bikini sediments, except for the one higher
2385, concentration (19.0 pCi/g) found in Zuni Crater sediments.
The ordering
sequence of radionuclide concentrations in different regions in the core
differed greatly.
The sequence in the 0-2 cm section of the core differed
from the sequence in lower sections and from the sequence found in any of the
three other grab samples collected across the crater, which individually also
differed from each other.
In the 2-12 cm region of the core the order in the
sections was Bi >Co >Eu >Am >Cs.
In the 26-34 region, three of four sections
had the order Co > Bi > Eu > Am > Cs and in the 48-56 cm region of the core,
the sequence was Co > Am > Eu > Bi > Cs or Co > Am> Bi > Eu > Cs.
Since
plutonium was only measured in one section in each region, its placement is
not included as characteristic of larger regions.
The low 2394240, 2385,
ratios found in the upper 12 cm of this core, however, illustrates that the
origin of these radionuclides was different from those found in the lower
regions.
The radionuclides measured in the uppermost layers may be remnants
from one of the smaller post-Bravo tests conducted in this area.
The