TABLE IV
SOIL SAMPLING AND ANALYTICAL METHODOLOGY AT VARIOUS STUDY SITES
2
Sampling Area (cm )
Sampling Technique
Location
Amount Analyzed (2)
Sample Prertreatmenct
Los Alamces
Core
4.5
None
Whole sample ~ 25
Trinity
Core
4.5
None
Whole sample ~ 25
Eniwetok
Core
Thule, Greenland
Excavation
Rocky Flats
Excavation
10
Ball-milled
100-127
Core-excavation
Nevada Test Site
10-50
Bail-milled
~ 100
Remove > 0.6 cm
100
5 samples composited
5-10
Remove > 0.5 cm
TABLE V
238
SPATIAL RELATIONSHIPS OF
n
Within Plot
160 to 2550
9 to 160
Within Strata
160 to 2560
CG to 160
Overall
Coefficient of variation
Pu CONCENTRATION VARIABILITY IN MORTANDAD CANYON SOILS
1.2
0.79
0.94
27
5
12
relate variability to any specific factor.
The dif-
ficulties in comparing soil plutonium data between
0.85 (0.60)
0.75 (0.31)
4
5
The variability was considerably reduced by
examining the data from smaller spatial units as
sites can be appreciated by examining some of the
achieved through stratificarion.
potential components of variability at the various
CV was calculated as 1.2 when all the data from che
sites.
contaminated portion of the canyon were used, where-
Soil sampling and analytical methodology
The concentration
as the data from two segments of scream channel
employed at several sites are summarized in Table IV
reduced the CV to 0.79 and 0.94 for the respective
to emphasize the potential for these factors as
strata.
components of the total variability.
Although chem-
samples from each sampling location within che 2560-
Wichin-plot variability based on triplicate
ical procedures for plutonium analysis between sites
m segment averaged 0.75 and 0.85 for the two strata,
are similar in thac they involve HNO,-HF digestion,
indicating that closely spaced replicate samples
followed by column separation and alpha speccrometry,
did not greatly reduce the variabilicy as measured
considerable differences exist in sampling tech-
over much larger areas as represented by the two
niques,
strata.
3
sample preparation, and in the size of soil
The relationships between soil pluconium con-
aliquot analyzed for plucoaium,
One of che sources of tield sampling variability
for soil plutonium is
the heterogeneous distribution
of the element within the study areas.
An example
of the effect of spatial heterogeneicy on variabil-
centration variabiliry, soil particle size fraction,
and soil depth were investigated at those sites
where data were available
Recky Flats)
(i.e., Los Alamos and
to examine further the components of
ity is given in Table V for Mortandad Canyon at Los
plutonium concentration variability.
Alamos where a plutonium concentration gradient
Table VI illustrate che relationship of tne CY
exists with distance down the canyon.
with soil particle size fraction and soil depth for
Table V were calculated for all samples
The CVs in
(n = 27)
The data in
soils from Mortandad Canyon at Los Alamos.
There
collected within a 2560-m segment of stream channel,
were no significant relationships between CV and
for two strata (0 to 160 and 160 to 2560 a) within
soil particle size fractions
that segment,
as inferred by analysis of variance.
and for triplicate sampies taken at
each of 9 plots within that segment.
in either study area
However, in
all cases, there was a significant change (9 < 0.05)
in CV with soil depth.
63