-41-
conditions are known to cause nutrient deficiencies which
can sometimes be identified by the appearance of the plant.
For example,
nitrogen deficiency is often accompanied by
yellowing and drying of the leaves and calcium deficiency
is often followed by blackening and death of the plant
(die-back).
removed
In coral atolls where the top soil has been
the retention of rain water in the surface layer
of soil would be slight,
resulting in the curling,
and ultimate death of the shallow-rooted plants.
drying,
On the
basis of these observations it may be concluded that some
of the abnormalities observed could have been caused by
factors other than radiation.
Therefore, it would be im-
possible to ascertain all of the causes of damage to plants
in an area where radiation and nutrient deficiencies both
exist.
In areas of high radiation levels, much of this
damage could be attributed to the radiation,because it has
been shown in controlled field experiments, with several
plants,
that chronic doses of gamma radiation of 13 to 37 r
per day for two to five months can cause plant abnormalities
of various kinds (12) | Similar to those found at the Eniwetok
Proving Ground.
The total gamma dose delivered in these ex~-
periments ranged from 780 r to 5550 r.
In more recent studies