2.)
Soil Samples
Some atolls, and islands within atolls, which may have to be evaluated as
possible residence or agriculture sites do not yet have growing terrestrial
subsistence food plants.
A predictive methodology is therefore required to
estimate the expected concentrations of radionuclides in local foods and the
subsequent radiological doses.
This methodology is developed by determining
the concentration ratio between the edible fruit and the soil (pCi/g
fruit/pCi/g soil) for each radionuclide.
These concentration ratios can then
be multiplied by the average soil concentrations of an island with no existing
crops to estimate radionuclide concentration in the foods.
Soil sampling is, therefore, required for two purposes:
1) soil profiles
to a depth of about 40 to 60 cm {this encompasses the active root zone of most
food plants observed at the atolls) must be collected through the root zone of
each sampled tree to develop additional concentration ratio data to confirm
and expand the previously established concentration ratio data base.
2) soil
profile samples to depths of 40-60 cm must be collected on islands that are to
be evaluated for residence or agriculture.
The data developed from these
samples, in conjunction with the concentration ratio data base, will form the
basis of the dose assessment for each island.
Profiles may have to be
collected on a 50 m grid in some areas to provide sufficient resolution to
evaluate changes in soil concentration across an island; all profiles should
be collected in the following increments:
cm, and 25-40cm.
O-5 cm, 5-10 cm, 10-15 cm, 15-25
A significant data base, developed from ongoing DOE
Programs, already exists for Enewetak Atoll but limited data are available for
most other atolls.
Supplemental data are necessary to expand the current
information base to provide more reliable values for parameters in the
predictive models.
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