We also take this opportunity to review the field sampling design used at the
safety-shot sites to estimate the inventory of plutonium in soil and vegetation.
Our experience analyzing these data obtained using stratified random sampling
(sampling at random locations within strata) suggests that the use of a systemmatic (grid) pattern in conjunction with random sampling may result in better
estimates of the geographical distribution of plutonium than we have obtained
thus far, while still providing data suitable for estimating inventory. We
also display some recent results from our continuing effort to experiment with
estimating plutonium concentration contours using SURFACE II, a computer
contouring package under continuing development by the Kansas Geological
Survey (Sampson, 1973). These results were presented orally at the above-men—
tioned IAEA/ERDA Symposium, but most could not be published in the proceedings
due to space limitations.
SUMMARIZATION OF 239°240py DATA FOR AREA 13
Background Information
Figures 1 and 2 show the soil and vegetation sample locations for the Area 13
(Project 57) study site.
These were chosen at random within each stratum
discussed by Gilbert and Eberhardt (1974).
Figure 3 gives the AM, SE,°? and
range for soil, vegetation, small vertebrates, and beef cattle.
The soil and
vegetation data are in units of nCi/g dry weight for comparison purposes.
These data were taken from Gilbert et al. (1975, Table 14) and Romney et ail.
(1975, Table 2). The vegetation data are also given in units of nCi/g ash
(from Romney et al., 1975, Table 3) for comparison with the small vertebrate
and cattle tissue results which are in units of nCi/g ash. The soil and
vegetation data are given separately for each of the six activity strata.
The
results for pelt, GI tract, and carcass for the 11 Dipodomys microps taken
from strata 1 through 4 within the inner fence (inner compound) were pooled
together since the data presently available do not indicate consistent differences in Pu concentrations with increasing soil activity strata. The center
of activity of each small vertebrate collected thus far in Area 13 (of which
the 11 here are a subset) is given in Figure 4. Most of the rodent data used
here were reported by Moor and Bradley (1974, Table 9). Bradley and Moor
(1975) emphasize that about half of the radioanalysis data on rodents were not
available at that time.
The data given in Figure 3 for beef cattle have been discussed in part by
Smith et al. (1976a). The design of this cattle study is also discussed in
Smith (1974, 1975). Note that the number of samples varies from 1 to 3 so
that estimates of precision are either impossible to obtain or are extremely
unreliable.
More data will soon be available.
The cattle data discussed here
may be divided into three groups based on length of grazing:
{2, 3, 8},
4, 6}, {5}, where the numbers in brackets are identifying cattle numbers.
3SE = s/Yn = (standard deviation)/vn.
239
{1,