4 Results and Discussion
In our evaluation of the results for the metals concentrations, we chose to compare
values for each parameter to values encountered in the background samples. By doing
so, we can evaluate if the concentrations of a particular contaminant is anthropogenic
or not. GPS locations for each background samples can be found in Table I. For the
management point of view, this approach can be valuable, but the site owners want to
know if there are problems, at which extent and what can be done to solve them.
Scientifically, comparison with the background values is important since it allows the
understanding of the first effects of the training activities on the environment and
gives us plenty of time to react and possibly eliminate the effects of such activity by
applying mitigation methods. Our approach consisted in comparing all the results to
background values first then to the agricultural soils quality guideline (ASQG) and
finally to the Industrial Soil Quality Guideline (ISQG) established by the Canadian
Council of Ministers of Environments (CCME) (see www.ccme.ca or in the file
annexed in Appendix B on compact disk). Even if DND properties are not dedicated
to agriculture, the ASQG represents the first official threshold value and the fact of
having concentrations of a particular parameter higher than the ASQG can raise
important questions for the management of the sites. This is particularly true for sites
such as WATC Wainright where cows are allowed to graze in the DND properties
during summer. The same rationale can applied to the ISQG since the DND properties
are not industries, but having concentrations higher than the ISQG can urge the
Department to find and apply solutions for due diligence.
In our evaluation of the results, the mean values for background samples were the
mean of all collected backgrounds for each parameter measured. When results lower
than detection limits were encountered for specific parameters, half of the detection
limit for that parameter was used for calculation of the mean value. The results
obtained in training areas were compared to the mean value of the background to
which was added twice the standard deviation. This allowed the selection of results
having values greater than the background means, while being representative. Results
are presented for each parameter instead of per sample to facilitate the analysis of
trends for each parameter. Backgrounds were always tabulated first with mean,
standard deviation, mean plus twice the deviation standard, and CCME threshold
criteria values for each metal. Then, results for samples collected in the training areas
were tabulated. As mentioned in the first paragraph, surface soil samples were
compared to the background values and to the most stringent agricultural CCME
threshold levels for metals that were included in the latest published CCME quality
guideline. For metals that were not included in the CCME list, results were compared
to the mean values added to twice the standard deviation of all soil background
samples. Such results exceeding this value were highlighted in blue in Table II. Even
if not applicable to DND sites, the CCME agricultural soil criterion is the most
stringent reference, and, therefore, shows where contamination should be looked at
first and monitored. When metal concentrations were above the agricultural criteria
(green), they were also compared to the industrial soil criterion, which is the most
permissive criterion. These results were highlighted in red in the tables. For
vegetation, there are no CCME criteria. Results higher than the mean values added to
twice the standard deviation were highlighted in blue in Table III. Metals
11
DRDC Valcartier TR 2004-204
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