RESULTS AND DISCUSSION

North-South Transect Samples
In the earlier report

samples were given.

(Tamura,

1975a),

results of analyses of nine

In addition, the locations of three additional

samples along the north-south transect in Area 13 were given.

Analyses

of 10-g subsamples of the three additional samples (labeled 6A, 6B,
6C) showed the plutonium concentrations to be 296,

136, and 145

disintegrations per minute per gram (dpm/g), respectively.

The

analyzed samples excluded gravel (greater than 2-mm particles),
because the assumption was made that the plutonium contribution from
gravel is negligible.

Calculated concentrations of plutonium, however,

did include the weight contributed by gravel in order to maintain
consistency with other investigators on the project who normally
grind the total soil sample prior to analysis.
In Fig.

1,

the log of the plutonium activity is plotted against the

log of the distance from GZ.

The best-fit equation for the relation-

ship was found to be the logarithmic relationship:

Y = 1.26 + E+

-2.07) where Y is the activity in dpm/g and X is the distance in
feet; the term E + 9 is 107.

In addition to the original nine samples

along the transect and the three additional samples located from
1,900 to 3,600 ft from GZ,

the mean concentration of plutonium in the

samples taken near Site 2 for comparison of vegetated versus nonvegetated conditions is plotted.

Note that Sample 6C contained 145

dpm/g, which is higher than anticipated; however, this type of anomaly
is to be expected in large-scale field situations under variable
atmospheric conditions.
=

-

Results of the particle size distribution of 6A,

in Table 1.

6B,

and 6C are given

The particle size distribution of all three samples

appears to be more closely related to that in the surface soil of
Site 6 than of Site 7, which were previously reported (Tamura, 1975a).
The plutonium distribution in size fractions less than 2 mm is given
in Table 2.
The activity (dpm/g) for each size fraction is presented
in Row A.
As in previously reported samples of the north-south
transect, the 53-20 um size contains the highest concentration of

Plutonium.

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