18
Eniwetok Test Site have been due to radiation effects.
Indeed,
the same "abnormalities" have been found in areas not subject to
radioactive contamination.
Consequently,
studies aimed specifi-
cally at the determination of radiation effects can best be done
under controlled laboratory conditions.
The emphasis at Rongelap Atoll has therefore been on mineral
transport through the biota.
This requires evaluation of the stable
isotopes as well as the radioisotopes.
The efforts of the first
year have been concentrated on the land forms; however,
collection
and analysis of marine organisms have been made to provide a continuous record of radiation levels in different life forms.
The
Marine phase is to be expanded during the coming year to include
more extensive sampling of the
lagoon bottom and waters.
None of the studies can be considered complete now or for
some time to come.
Some of the points that stand out most clearly
thus far are as follows:
l.
The general levels of radioactivity continue to decline more
rapidly than would be expected from physical decay alone (there
are certain exceptions such as the levels of sr?? in coconut crabs).
2.
Extensive sampling of soils shows clearly that the radioiso-
topes remain concentrated in the top inch or less.
3.
Radioactive materials are found more uniformly mixed to a
depth of several inches in lagoon sediments.