and/or narrow islands,

however, a correction is required for the aerial

measurement and uncertainty is introduced in the final average concentration
from the aerial measurement (Tipton and Meibaum, 1981).

The maximum difference observed between the two methods is about a factor
of 3 or 4 for smaller islands, and, because of the uncertainties in the two

methods, it is reasonable to assume that the average !3’Cs surface soil
concentration is somewhere between the results listed for the two methods.
more

soil

profile

samples

are

collected

and

analyzed,

the

As

average

concentration will probably approachwthe average concentration determined by
the aerial measurement.

,

Listed in Appendix B (Tables B-1 to B-14) are the comparative results of
the

individual

soil

profiles

for

each island on Bikini Atoll

corresponding aerial activity contour.
how well

the soil

and the

This comparison gives a better idea of

profile data match the aerial

data because each sample is

compared with the associated aerial contour in which it is located rather than
the island average.

Thus,

the error introduced by looking at island averages

where no soil profiles were taken in the center of the island is eliminated.
It does not,

of course,

improve in any way the resolution of the aerial

System, so there is still an averaging effect within a contour.
Also,

|

an uncertainty still exists in the precise location of the soil

profile sample and the small size of the soil

profile.

The sample locations

were marked on maps carried by the field teams but they are approximate
'

locations (see Appendix A).

The exact location of the soil profile sample

could easily be several meters from where we have it recorded on the maps.

Thus, when the location is near the boundary of two or more contour regions,
the true soil profile location could fall in any of the nearby aerial contour
regions.
We would

expect, therefore,

that the correlations would not always be

exact because of the uncertainty in the soil profile location and also because
the soil profile analysis involves a very small area of the soil surface,
while the aerial measurement integrates a much larger surface area. Overall,
the correlation between the soil profile and aerial results are reasonably
good.

The median and mean radionuclide concentrations for '37cs, 99sr,
239+240py and 24lam for each island for each soil increment to a depth of
60 cm are

5000325.

given

in

Tables

5

to 30.

Data are also given for. the average

19

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