Table 8 (cont'd).
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
3.589bc†
1
3,960
3,280
3.516d
2
30,800
4.479a
29,300
4.467a
3
23,200
4.365a
21,300
4.329b
4
1,830
3.246d
850
2.929f
5
580
2.763e
527
2.722g
6
6,780
3.829b
5,720
3.756c
7
2,320
3.365cd
1,300
3.115e
†
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 = 71.2***
F ratio = 1553***
Error MS = 0.01060
Error MS = 0.00059
Least sign. diff. = 0.244
Least sign. diff. = 0. 057
Linear correlation analysis for on-site analysis vs. lab analysis
(r = correlation coefficient)
Slope
Intercept
r
untransformed, non-zero intercept
1.038
686
0.999
untransformed, zero intercept
1.070
0
0.999
log-transformed data
0.991
0.062
0.960
Results of paired t-tests for on-site vs. lab results
Means of seven discrete samples, t = 4.71**
Means of log values for seven discrete samples, t = 2.60*
Composite samples
On-site analysis
Laboratory total
n
7
7
mean value
11,300
9,620
standard deviation
2,020
409
RSD
17.9%
4.3%
ANOVA comparing on-site and lab analyses
F ratio = 4.54 (NS)
* Significant at the 95% level
*** Significant at the 99.9% level
** Significant at the 99% level
NS Not significant at the 95% level
tions were produced, indicative of the probable
wise, the mean RSD for lab analysis of the dis-
presence of TNT. This site was located in an area
crete samples was 5.0% and the RSD from repli-
that was thought to be free of contamination by
cate analysis of the composite was 2.8%.
personnel at Volunteer AAP. Laboratory analyses
Like sampling locations 4, 5 and 7, results from
confirmed the presence of TNT in these soils at
location 9 appeared to be sufficiently normally
concentrations ranging from 7 to 40 g/g.
distributed to conduct ANOVA without log-trans-
Analytical precision for both the field and lab
formation. When this was done, F ratios of 217
analyses for samples from location 9 was excel-
and 321 were obtained for field and lab results,
lent. The mean RSD for the field analyses was
respectively, indicating highly significant differ-
4.1% for the discrete samples and the RSD from
ences among discrete samples (Table 9b). LSD
replicate analysis of the composite was 9.0%. Like-
tests showed that nearly all of the discrete samples
29
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