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a National Scientific Research Inst. (INRS-ETE), 490 de la Couronne, Québec, QC G1K 9A9, Canada
b Defense Research and Development Canada (DRDC-Valcartier), 2459 Pie-XI Blvd. North, Québec, QC G3J 1X5, Canada
* Corresponding author (genevieve_bordeleau{at}ete.inrs.ca).
Received for publication April 19, 2007.
ABSTRACT
Within Canada, it has been recognized in the last decade that military training activities may have impacts on the environmental quality of training ranges. However, impacts of activities specific to Air Force Bases have not yet been intensely documented. A hydrogeological study was accomplished at the Cold Lake Air Weapons Range, Alberta, to evaluate the environmental impacts of using bombs, rockets, strafing, and open burning/open detonation (OB/OD) on the quality of soil, ground water, surface water, and lake sediments. Samples were analyzed for metals, anions, ammonium perchlorate (NH4ClO4), and energetic materials (EM). It was found that training activities did not result in measured values being exceeded on the basis of guidance values for surface water and lake sediments. Contamination by metals was mostly limited to soils, and some metals may be related to the use of bombs (Cd, Cu, Pb), strafe (Cu), and rockets (As, Ba, Cd, Cr, Cu, Fe, Ni, Pb, U, V, Zn). TNT (2,4,6-trinitrotoluene) was the main EM found in soils, while RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) was more common in ground water. Both are related to live bombing, while nitroglycerine (NG) is related to rocket use and was detected in soils only. Aluminum, nitrate, and ammonium perchlorate detected in ground water may be related to live bombing or rockets. OB/OD operations resulted in the presence of various EM in soils, and of perchlorate and nitrate in ground water. Contamination by metals and explosives in soils was localized around the targets and varied significantly in time; however, in ground water it was more constant and may persist for a period of several years after a target has been removed.
Abbreviations: BGL, background level • CLAWR, Cold Lake Air Weapons Range • EM, energetic material • HMX, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine • NG, nitroglycerine • OB/OD, open burning/open detonation • PLER, Primrose Lake Evaluation Range • RDX, hexahydro-1,3,5-trinitro-1,3,5-triazine • TNT, 2,4,6-trinitrotoluene • UXO, unexploded ordnance
IN the last decade an increased environmental awareness has led the Canadian Forces to complete studies to evaluate the impacts of various military activities on the quality of soil, ground water, and surface water. A better understanding of such environmental impacts is important to ensure sustainability and long-term availability of training ranges. Environmental impacts assessment studies have been performed on various army bases (Ampleman et al., 1998, 2000, 2003a, 2004; Thiboutot et al., 1998; 2001; Brochu et al., 2005; Martel et al., 2007) and a protocol concerning the methods of sampling and chemical analyses was developed (Thiboutot et al., 2002, 2003). However, until now no air force base within or outside Canada had been subjected to such an evaluation. Even though the chemical compounds used in army munitions and air weapons are similar, the size and compound combination of the munitions are different. On army ranges, munitions are smaller and many unexploded ordnances (UXOs) can be present in one location before a substantial contaminant plume develops in the ground water. On air force ranges, UXOs are much larger (especially for 500 to 2000 lb air-dropped bombs), and may penetrate the ground to depths greater than 10 m. Within this context, an environmental characterization and hydrogeological study of the Cold Lake Air Weapons Range (CLAWR), Alberta, was accomplished. CLAWR is the largest air weapons range in Canada, and the one most intensively used.
The main contaminants expected at CLAWR are metals and energetic materials (EM). Various metals such as Cr, Cu, Pb, Sb, and Zn are expected to be found, originating from the corrosion of munition casings (Brochu et al., 2005). EM residues may be found in the soil and ground water as a result of low order or nondetonation of bombs. These shells may break on landing or eventually will corrode, leading to the exposition of their contents that may leach to the water table by the infiltration of precipitation water. Nitroglycerine (NG), dinitrobenzene (DNB), and trinitrobenzene (TNB) are either major ingredients or impurities in various types of propellants, used particularly in rockets. Dinitrotoluene (DNT) is often used as a plasticizer in rocket propellants. High explosives used in Canada and the United States usually contain 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and in some older munitions, tetryl. In addition to the danger pertaining to their explosive nature, many EM and their degradation by-products are toxic and potentially carcinogenic (USEPA, 2003b). Ammonium perchlorate, which is used extensively as an oxidizer in rocket fuel, is also a common contaminant on military bases and has been linked to various health disorders, affecting primarily the thyroid gland (USEPA, 2003a).
To characterize the impacts of training activities on the environment at CLAWR, sampling of soils, lake sediments, ground water, and surface water was accomplished. All samples were analyzed for EM and metals, except sediment samples which were analyzed for metals only. Surface water and ground water samples were also analyzed for anions, nutrients, and ammonium perchlorate.
Site Description
CLAWR, the part of CFB Cold Lake where air-to-air and air-to-ground training takes place, is one of the most sophisticated facilities of this type in the world, and is the only tactical bombing range in Canada. It covers an area of 11,700 km2 straddling the Alberta-Saskatchewan border (most of the base being located in northeastern Alberta) (Ampleman et al., 2003b). The range has been used in the last 40 yr for the training of Canadian and Allied pilots. Every year, the area is intensively used by several NATO air forces during the 6-wk annual Maple Flag exercise. There are four main training ranges at CLAWR, divided into two areas (Fig. 1 ). The first area is Primrose Lake Evaluation Range (PLER), which houses Alpha and Bravo training ranges. Those ranges are used for air-to-ground operation including dummy and live weapons. Some rockets are also used, mainly on Alpha Range. The second area, Jimmy Lake Range (JLR), contains training ranges Jimmy Lake and Shaver. Shaver Range is intensively used for live bombing and live firing missiles, while Jimmy Lake is mostly used for strafe, dummy bomb drop and rockets. Obsolete munitions are also destroyed on Shaver Range at the open burning/open detonation (OB/OD) site. The topography on Shaver, Alpha, and Bravo ranges is relatively flat, and the soil is kept free of vegetation through tilling to avoid bush fires caused by detonations. Jimmy Lake Range, however, is mainly composed of a series of hills and more grass is present on the soil.
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The Lea Park Formation is the major bedrock aquitard in this region and the top of this marine clay-shale formation, located at 50- to 120-m depth, essentially marks the lower limit of ground water supplies in the area (Wallick, 1984). The Quaternary surficial sediments present on the site are subdivided into three units, i.e., two sandy aquifers separated by a clay till layer (Martel et al., 2007). Based on analyses performed on 15 soil samples, all three hydrostratigraphic units have a total inorganic carbon (TIC) content 
0.2%, and both aquifers have a total organic carbon (TOC) content 0.3%, while the clay till aquitard has a TOC content between 0.2 and 1.1%. The aquifers have a cation exchange capacity (CEC) between 0.6 and 2.4 cmol·kg–1, and the CEC for the aquitard is between 8.4 and 9.4 cmol·kg–1 (Martel et al., 2007). The conditions in both aquifers are oxygenated, with an average dissolved oxygen (DO) level of 5.03 mg L–1 for the unconfined aquifer and 3.55 mg L–1 for the confined aquifer. However, in a few areas the DO is below 1 mg L–1 in the aquitard and the confined aquifer. The average redox potential for all units is around 220 mV, and all values are between –92 and +385 mV. Based on slug tests and grain size analyses, the geometrical average hydraulic conductivity is 2.4E-04 m s–1 for the shallow aquifer, 5.0E-07 m s–1 for the clay aquitard, and 1.8E-05 m s–1 for the confined aquifer (Martel et al., 2007). The thickness of the surface aquifer varies from 0 to 8 m. The surface aquifer is recharged from precipitation, which amounts to 427 mm yr–1. Estimated aquifer recharge values vary between 22 and 83 mm yr–1, depending on the method used, with an average of 56 mm yr–1 (Martel et al., 2007).
The water table varies from being at or near the soil surface in some areas, to deeper than 10 m in others. On all training ranges, the ground water flows eastward, toward Primrose Lake. However, on the northern side of Shaver Range, ground water flows in the direction of the Shaver River (Fig. 2 ). Ground water velocities in the shallow aquifer have been calculated to be 5 m yr–1 on Jimmy Lake Range, 29 m yr–1 on Bravo Range, and 37 m yr–1 on Shaver Range (Martel et al., 2007). No hydraulic conductivity measurements were taken in the surface aquifer on Alpha Range.
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Sample Collection and Handling
Throughout the study 119 ground water samples and 40 surface water samples were collected and analyzed for metals, nutrients, anions, ammonium perchlorate, and EM (Table 1
). Ground water sampling was done using various methods, depending on the weather conditions. When the temperature was warm enough, low-flow sampling (Puls and Barcelona, 1996) was performed. In colder weather sampling was achieved with a mechanical pump or with a bailer. In all cases dedicated sampling systems were used to avoid cross-contamination between wells. Physiochemical properties were always measured using a multiparameter probe capable of recording DO, conductivity, temperature, pH, and oxygen redox potential (ORP). Surface water sampling was made by grabbing samples manually, directly with the sampling bottles. For surface water and ground water collected with the mechanical pump or with a bailer, samples for metal analyses were filtered. In addition, all samples for metal analyses were acidified to pH 2.0 by addition of HNO3, and samples for nutrients were preserved with H2SO4. For EM, 2 g of sodium bisulfate were added to the 1-L samples to ensure the stability of samples with respect to microbial degradation, and amber glass bottles were used to prevent photodegradation. Quality control was attained by collection of duplicates for 15% of the samples. In addition, many field blanks and trip blanks were gathered to detect any contamination coming from the field manipulations, the sample transportation, or the lab distilled water.
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Chemical Analyses
Dissolved metal concentrations were analytically determined by inductively coupled plasma/mass spectrometry (ICP/MS), according to USEPA standard methods 6020 and 200.7 (USEPA, 2003b), by three external laboratories. No digestion was required for water samples, and USEPA method 3050 (USEPA, 2003b) was used for soil samples. Anions, nutrients, and physiochemical parameters were analytically determined by the same laboratories in ground water and surface water samples. Analyses were performed according to standard methods 3120B-ICP–OES, 4110B- Ion Chromatography, 4500H, 2510, 2320 from the American Public Health Association (APHA) (APHA, 2005). EM concentrations were analytically determined at DRDC-Valcartier using two different methods. Soil samples from Phase I (except for linear samples on Shaver Range) were analyzed using the gas chromatography/electron capture detector (GC/ECD). A detection limit between 0.7 and 26 µg kg–1 was obtained, depending on the analyte. This method was based on Walsh and Ranney (1998) and Walsh (2001). For linear soil samples collected on Shaver Range in Phase I, and for all samples in Phase II, the EPA 8330 HPLC method (USEPA, 1994) using high pressure liquid chromatography, which is good for higher explosive concentrations, was used. The detection limit for different analytes was between 16 and 600 µg kg–1. This method was also used for all analytical determination of EM in ground water and surface water, and in this case a detection limit between 0.05 and 0.5 µg L–1 was achieved, depending on the analyte. Water samples for ammonium perchlorate were analyzed by Environment Canada in Burlington, Ontario. Concentrations were analytically determined using ion chromatography coupled to a tandem mass spectrometer (Martel et al., 2007). The detection limit was 0.011 µg L–1 and the practical quantitation limit was 0.05 µg L–1.
Results
To distinguish between natural and anthropogenic metal concentrations, soil samples were compared to the average background concentration plus twice the standard deviation, which generates a threshold for natural values with a 2.28% level of uncertainty. Background samples were collected from uncontaminated areas on the base, away from training ranges. From this point on, this threshold will be referred to as BGL. Results were also compared to the guidelines for agricultural soils and industrial soils from the Canadian Council of Ministers of the Environment (CCME, 2006). Even though military sites are not subjected to either one of those regulations, it is useful in pointing out where contamination is observed and should be monitored. For sediments, results were compared to the most stringent interim sediment quality guideline (ISQG), and to the more permissive probable effect level (PEL), both from CCME (2002). Ground water results for metals and anions were compared to the drinking water quality guidelines from Health Canada (2004); however, it must be noted that ground water on the base is not used for drinking purposes. For surface water, the CCME (2003) guidelines for aquatic life were used.
The only official guidelines for EM in soils and ground water are from the USEPA (2003a). However, a study from the Biotechnology Research Institute (Robidoux et al., 2006) calculated preliminary guidelines for EM in soils and ground water. Some guidelines for surface water have also been proposed by various authors and government authorities (Table 2 ). For perchlorate, Health Canada (2006) has set a preliminary guideline of 6 µg L–1 for ground water (Table 2).
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The main EMs detected in ground water are RDX and TNT, and were detected almost exclusively on Shaver Range, downgradient from the current and former targets (Table 4 ). All detected concentrations came from within 300 m of the targets (Fig. 3 ). However, concentrations vary with time and space and can be sporadic. Concentrations were higher near the former target. While only RDX was detected downgradient from the former target and concentrations remained stable over time, RDX, TNT, and TNT degradation products were detected downgradient from the current target, and concentrations increased from the first to the last sampling campaign. RDX was also detected twice in wells on other training ranges: once near the target on Bravo Range and once at Jimmy Lake Range. Finally, TNT was detected in a surface water sample from Primrose Lake downgradient from Bravo Range in August 2004. The surface water of the crater created by a bomb on Shaver Range contained considerable amounts of TNT, NG, 1,3-DNB, 2,4-DNT, 2,6-DNT, and RDX compared to all other water samples (Table 4).
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Soils and Sediments
Several metals exceeded the BGL in the soils on each training range (Table 5
). The main ones may be related to rockets and bombing activities. Copper also exceeded the agricultural soil quality criterion in several samples. On Jimmy Lake Range, Cu even exceeded the more permissive industrial soil quality guideline in 13% of the samples collected near the bombing target. Copper is also the only metal detected above BGL in soil samples from the strafe line on Jimmy Lake Range, except for one sample where Pb exceeded the BGL. However, concentrations are higher near the bombing target than on the strafe line. For most parameters, concentrations are significantly higher on Jimmy Lake Range. Alpha Range is the second most impacted site with respect to metals in soils, followed by Bravo Range, and finally by Shaver Range.
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EMs were detected in the soils of all training ranges (Table 6 ). Concentrations vary in time and are related to the intensity and regularity of bombing activities, as observed on Jimmy Lake Range where TNT was detected in almost all circular samples from Phase I, but only one sample from Phase II. On Shaver Range, on the other hand, chunks of various EM were found on the soil surface. Also, tetryl was detected on Shaver Range in a few circular samples in Phase I only. Generally, EM concentrations are comparable on Alpha, Bravo, and Jimmy Lake Range, but are roughly two orders of magnitude higher on Shaver Range near the current target. The USEPA soil guideline for TNT was exceeded in circular samples on Shaver Range. Samples from this location and from the crater also exceeded BRI proposed criteria for TNT, based respectively on protection of the environment, human health, and aquatic life (BRIENV, BRIHH, BRIAL). Soil samples from the OB/OD site exceeded the BRIENV criterion for TNT. Soil samples from the circular approach on Shaver Range also exceeded the BRIENV criterion for RDX, and the BRIHH criterion for 2,4-DNT. Finally, NG exceeded the BRIAL criterion on Jimmy Lake Range in circular samples. Figure 3 shows the location of sampling on Shaver Range, and the two strategies of sampling (circular and linear). Generally, the samples with the highest concentrations of RDX do not correspond to the samples with the highest concentrations of TNT. HMX was seldom detected, and TNT degradation products were detected on all training ranges in samples where TNT levels were high.
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Comparison of Training Ranges
The extent of contamination on training ranges differs greatly between the soils and ground water. Soils on Jimmy Lake Range are the most impacted by metals, followed by Alpha Range, Bravo Range, and finally Shaver Range. Metals detected above BGL which can be related to training activities include As, Ba, Cd, Cr, Cu, Fe, Pb, Ni, U, V, and Zn. It seems that the munitions most frequently used on Jimmy Lake Range (i.e., rockets and dummy bombs) may have resulted in greater soil contamination by metals than live bombing, which is the main activity on other training ranges. Not only did more metals exceed the BGL on Jimmy Lake Range, but the concentrations reached 24 times the BGL, while on other ranges it did not usually exceed five times the BGL. Metals detected above the BGL almost exclusively on Jimmy Lake Range include Ba, U, and Zn. Rockets are also fired on Alpha Range, although it is not the main activity. Metals detected above BGL on Jimmy Lake Range and Alpha Range only could also be related to rocket use, and include As, Cr, Fe, and Ni (Fig. 4
).
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For ground water the situation is different. The only metals detected above the guidelines which could be related to training activities are Al, Fe, and Mn. However, all three are naturally abundant in soils and their solubility in water depends greatly on factors such as pH and redox potential, although in this study no relationship was found between those parameters and metal concentrations. Although conditions are mainly oxidizing at CLAWR, wetlands are found upgradient of the training ranges, and conditions in wetlands are typically more reducing. It is thus possible that naturally-occurring Al, Fe, and Mn are solubilized in the wetlands and are intercepted in the wells on the training ranges. It is therefore difficult to clearly relate their presence in ground water to military training activities.
As opposed to soils, fewer metals exceeded the guidelines in ground water on Jimmy Lake Range than on other ranges. Only Al and Fe exceeded the guidelines on this training range; however, they did so in a larger proportion of samples than on the other ranges. Guidelines for Al and Fe were exceeded in fewer samples on Alpha, Bravo, and Shaver ranges, but additionally on both Alpha and Shaver ranges Mn exceeded the guideline in about half of the samples. Contaminant concentrations in samples exceeding the guidelines were generally comparable between ranges, but Al concentrations were higher on Jimmy Lake Range, where they reached seven times the background concentration. In addition to those metals, nitrate seems to be related to live bombing and munitions destruction (Fig. 4). Nitrate was detected above the BGL (1.75 mg L–1) in ground water from the shallow aquifer on Bravo and Shaver ranges, and from the deep aquifer on Alpha Range. Contamination is generally limited to the shallow aquifer, as is the case for ammonium perchlorate.
EMs were detected in the soils on all training ranges. The presence of explosives in soils is different depending whether the training range is used mainly for live bombing or for rocket firing (Fig. 4), and concentrations are related to the intensity and frequency of live bombing activities. Contrary to metals, Shaver Range is the most heavily impacted training range by explosives. Concentrations near the current target were up to 500 times higher than on Alpha Range, the second most impacted training range with respect to TNT. RDX concentrations on Shaver Range were up to 100 times the concentrations found on Alpha Range. HMX was detected in a few samples on Shaver Range, and concentrations were lower than for RDX. It is possible that the HMX comes from anti-tank weapons, which could have been fired at the tank target at some point in the past; it is also possible that HMX is present only because it is an impurity of RDX produced by the Bachman process (Ampleman et al., 2003a). Jimmy Lake Range is the least impacted training range by most explosives. This was expected, because it is supposed to be used mainly for strafe, rocket firing, and dummy bombs. Moreover, the widespread presence of NG, a compound used in propellants, corresponds to the firing of rockets (Fig. 4). NG concentrations on Jimmy Lake Range were higher than on Shaver Range.
In ground water, EMs have been detected almost exclusively on Shaver Range. However, while TNT was the main contaminant in soils, RDX was a more common contaminant in ground water. It is known that RDX is more mobile than TNT (Brannon and Myers, 1997; Brannon and Pennington, 2002), the latter being more easily degraded in amino DNTs that may react with organic matter of the soil to become covalently bonded to the soil, becoming nonlabile. It is therefore possible that RDX moves more rapidly to the water table, and creates a larger ground water plume. RDX was also detected once in one well on Bravo Range and one on the northern edge of Jimmy Lake Range. Explosives had been detected in soils near the target on Bravo Range, so the presence of RDX in ground water is not surprising. Contamination in the Jimmy Lake Range well was unexpected because no live firing is thought to take place there. However, it is possible that a UXO has fallen there at some point in time and is still contaminating the ground water. TNT was detected in surface water from Primrose Lake, 200 m south of the well where RDX was detected on Bravo Range. The presence of TNT in Primrose Lake might be due to the strong winds blowing contaminated soil from Bravo Range into the lake.
Contaminant Distribution on Training Ranges
Linear transect sampling and circular sampling around targets was done to evaluate the extent and patterns of contamination on training ranges. Results showed that not all metals are similarly distributed in soils. In most cases metal concentrations were significantly higher in the circular samples than in the linear samples, and no correlation could be found in the linear samples between concentrations and distance from target. Metals following this distribution pattern include Ba, Cd, Fe, Pb, Ni, U, V, and Zn. Among them, Cd and Pb were even more localized, with significantly higher concentrations found in the small and medium circles than in the large circle. The only metal which could directly be linked to strafing is Cu. Although no clear correlation could be established between concentration and distance from target, Cu was detected in linear samples on Jimmy Lake Range at higher concentrations than on other training ranges. Finally, As was detected in comparable amounts in linear and circular samples.
Among the parameters in ground water which could be related to military activities (Al, Fe, Mn, pH, nitrate, perchlorate), only Al, nitrate, and perchlorate seemed to be spatially related to targets, or the OB/OD site. On Shaver Range, ground water Al concentrations exceeding the guideline were found in the shallow aquifer at the OB/OD site and downgradient from it, as well as in a few locations downgradient from both the current and former targets. This may be related in part to the tritonal used in air bombs, which is a mixture of TNT and Al. However, on all other ranges, the location of samples with Al concentrations exceeding the guideline was not related to target location. Nitrate concentrations above the guideline, however, were always detected downgradient from the targets on Alpha, Bravo, and Shaver ranges, and at the OB/OD site on Shaver Range. On Jimmy Lake Range, nitrate concentrations were very low. The spatial distribution of nitrate suggested that high nitrate contents are related to live bombing and munitions destruction. Perchlorate distribution is similar to nitrate, except that it was detected in fewer wells. The OB/OD site is the only location where high nitrate and perchlorate concentrations were detected in the confined aquifer (except for Alpha Range), indicating a connectivity between the upper and lower aquifers. Although OB/OD activities are performed on the soil surface or in shallow pits, it is possible that EM residues have been buried deeper, or that some soil has been excavated in the past or removed by explosions, thus damaging the clay layer and allowing for contamination of the deep aquifer.
In the case of explosives, on Alpha, Bravo, and Jimmy Lake ranges no correlation could be established between contaminant concentration in soil and distance from target. However, TNT concentrations were significantly higher in the circular samples (near the targets) than in the linear transect samples. TNT degradation products were detected in samples where TNT levels were high, and RDX was almost always detected near the targets but seldom further away. In the case of Shaver Range, a progression of TNT concentrations was observed in the linear sampling, which was done over a distance of 700 m (Fig. 5 ). The highest TNT concentrations in the circular samples were found at a depth of 15 to 20 cm, which could be explained by the tilling performed to prevent plants from growing. NG, RDX, TNT, and TNT degradation products were detected in the soils from the OB/OD site. The presence of NG could be the result of the open burning of propellants, which is a dirty process (Ampleman et al., 2000).
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Progression of Contaminants over Time
In soils it was difficult to evaluate the progression of contaminant concentrations over time, because samples were only collected in two campaigns. Moreover, samples could not be collected at exactly the same place in both campaigns because precision of our GPS devices is typically ± 5–13m, and because soils on training ranges are regularly tilled. In ground water and surface water, however, such a comparison is possible because samples were collected in five campaigns. No progression of contaminant concentration was observed in ground water and surface water for metals. However, a progression of explosive contamination was observed on Shaver Range. First, at the old target area, only RDX was detected, contrary to the current target. Because the old target area has not been used for over 25 yr, it is possible that all of the TNT was already adsorbed or degraded, while RDX continues to contaminate the ground water. The explosive contamination at this site is not expected to increase, because the old target has been removed and the area is no longer used for bombing. However, it is possible that some UXOs are still buried and intact, and they may start contaminating the ground water in the future when they will crack open due to corrosion.
TNT was first detected downgradient from the current target in November 2004, and RDX in November 2005. TNT concentrations increased in the two subsequent sampling campaigns. At the moment, no explosives have been detected in the two wells located between the target and Shaver River, in the direction of flow from the target. However, perchlorate and nitrate were detected in those wells. Perchlorate concentration was stable, and nitrate concentration increased. Perchlorate is clearly related to training activities, and nitrate is a possible product of explosive degradation (Brill and James, 1993; Hawari et al., 2002; Son et al., 2004). Both compounds are very mobile, and in ground water it is possible that they are the leading edge of the contaminant plume, potentially followed by EM residues. For this reason, monitoring over the next several years will be very important.
Conclusions
Contamination by metals on the training ranges is mainly limited to soils, where rocket use causes contamination by As, Ba, Cr, Fe, Ni, U, and Zn; while Cd, Cu, and Pb may be related to both bombs and rockets. Strafing results in high levels of Cu in soils, but OB/OD operations do not cause metal contamination, probably because the OB/OD site is regularly cleared of debris. It is also possible that detonation results in pulverization of metals, which may be expelled far from the detonation site. In ground water, only Al could be related to live bombing, rockets, and munitions destruction. TNT is the main EM in soils and is mainly concentrated around the targets. Blow-in-place operations using C-4 result in high levels of RDX in soils. In ground water RDX is the main contaminant and is related to live bombing. The use of rockets causes mostly NG contamination in soils, and ammonium perchlorate in ground water (soils were not analyzed for perchlorate). Various EMs are found in the soil at the OB/OD site, but not in ground water. However, OB/OD operations result in significant concentrations of nitrate and ammonium perchlorate in ground water. Generally, contaminants are localized around targets, with very low concentrations at distances greater than 50 m from the target. The presence of contaminants in soils varies significantly over time; however, in ground water it is more stable. Because it may take a long time before buried UXOs becomes corroded, they represent a risk of ground water contamination for several years.
ACKNOWLEDGMENTS
The authors wish to thank CLAWR environmental officers Drew Craig and Sarah Richard, as well as all military personnel at CLAWR for their assistance in the study. We would also like to thank personnel at DCC for assisting in the research.
NOTES
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REFERENCES
This article has been cited by other articles:
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  R. Martel, M. Mailloux, U. Gabriel, R. Lefebvre, S. Thiboutot, and G. Ampleman Behavior of Energetic Materials in Ground Water at an Anti-Tank Range J. Environ. Qual., January 13, 2009; 38(1): 75 - 92. [Abstract] [Full Text] [PDF]
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