-aane meme meee eee ee SSESeS
very appreciably with depth.
off of Eneu and Bikini
The results of recent studies down to 100 cm
appear to be showing a similar result and will
be
fully reported on in Appendices A and B.
“It is therefore anticipated that sediment dredged from
the
bottom
landfill
of
the
lagoon
offers
a
should plans require them.
convenient
source
of
backfill
and
The sandy bottom is generally flat and
thus suitable for dredging, but numerous coral
heads emerge, some of which
- may exceed 1 km in diameter and stand more than 30 m high (Appendix A).
2.2
Islands
The islands of the atoll
size and in contamination.
(Figure 2, Tables 1, 2) vary greatly in
Only two of them are larger than 1 km? ; Bikini
(2.4 km*) and Eneu (1.2 km¢).
2.2.1
Soil
Composition.
distribution in depth fall
into two major classes.
extractable potassium and of total
fall
off with
Table 3.
to
depth
to
The major elements
become
judged by their
The concentrations of
phosphorus, nitrogen, and organic matter |
small
below
50
cm
(20
in.)
as
shown
in
Cesium-137 follows this pattern (Tables 2 and 3) and is thought
be associated
concentrations
of
with
the
organic
nonradioactive
matter.
strontium
On
and
the
other
calcium
are
hand,
the
practically
constant, and that of magnesium rises with depth.
2.2.2
Radioactive
Contamination.
The
transuranic
plutonium-239, -240 and americium-241 contribute less than
the
30-year cumulative dose because
‘and their activity in the soil
on
Bikini
elements
.08 percent to
they are scarcely taken up by plants
is low (6).
Their combined surface activity
is about 17 pCi/g, on Eneu about 1.3 pCi/g, both well
below the
transuranic standard of 40 pCi/g employed at Enewetak (13N).
The
two
major
radioactive
cesium-137 and strontium-90, present in soil
5000018
|
19
contaminants
today
are
at roughly the same range of