Table 3 (cont'd). Results from sampling location 3, Monite site.
b. Statistical analysis of TNT concentrations (g/g)
for discrete and composite samples.
Discrete samples
On-site analysis
Laboratory total
Sample
Mean
Mean of logs
Mean
Mean of logs
4.1b†
1
0.610b
4.7b
0.670b
2
2.3b
0.346b
1.8b
0.243c
3
3.4b
0.524b
1.9b
0.278c
4
4.3b
0.628b
1.4b
0.146d
5
5.2b
0.716b
0.9b
0.072e
6
4.5b
0.653b
0.8b
0.126e
7
115a
2.043a
78.5a
1.894a
†
Numbers designated with the same letter are not significantly different at
the 95% confidence level.
ANOVA for log on-site analyses
ANOVA for log lab analyses
F ratio = 64.6***
F ratio = 911***
Error MS = 0.00991
Error MS = 0.00106
Least sign. diff. = 0.235
Least sign. diff. = 0.077
Linear correlation analysis for on-site analysis vs. lab analysis
(r = correlation coefficient)
Slope
Intercept
r
untransformed, non-zero intercept
1.447
1.23
0.999
untransformed, zero intercept
1.464
0
0.998
log-transformed data
0.715
0.479
0.879
Results of paired t-tests for on-site vs. lab results
Means of seven discrete samples, t = 1.40 (NS)
Means of log values for seven discrete samples, t = 2.87*
Composite samples
On-site analysis
Laboratory total
n
7
7
mean value
12.6
4.16
standard deviation
1.22
0.66
RSD
9.66%
15.9%
ANOVA comparing on-site and lab analyses
F ratio = 264***
* Significant at the 95% level
*** Significant at the 99.9% level
** Significant at the 99% level
NS Not significant at the 95% level
indicating differences among samples. LSD tests
unambiguously confirmed by the composite
analyses (mean 12.6 g/g for field and 4.16 g/g
confirmed the difference between sample 7 and
the other six. Analysis of the log-transformed lab
for lab). This bias may be caused by the presence
data showed some differences among other
of unspecified environmental transformation
samples as well.
products of TNT, which were not determined us-
Comparison of the on-site and lab results us-
ing the RP-HPLC conditions specified in Method
ing both correlation analysis and a paired t-test
8330, but which react with the EnSys reagent to
yielded somewhat contradictory results owing to
form a colored Janowsky complex.
the very large effect of one extremely high con-
The results for this sampling location show the
centration sample (Table 3b). The positive bias of
value of both compositing and on-site analysis
the field method for soils at this location was
for site characterization at explosives-contami-
16
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