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For more than 70 years, the Canadian Armed Forces (CAF) have been using the plastic explosive Composition C-4 based mainly on the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) for various operational needs. Composition C-4 is used as donor charge for the blow-in-place destruction of unexploded ordnance (UXO) by Explosive Ordnance Disposal teams and, as well, mostly used as a demolition explosive by engineering units. RDX is very stable in the environment, somewhat water-soluble and moves relatively rapidly towards surface and groundwater bodies in Ranges and Training Areas (RTA). It is the key contaminant that triggered the closure of a major RTA in the USA and the use of C-4 was proven to contribute to its accumulation in demolition ranges. A study was conducted to measure the deposition of RDX generated from the use of Canadian C-4 blocks and two shaped charges for comparison purposes, as the shaped charge represents a possible alternative for C-4 as a donor charge in blow-in-place operations. The shaped charges studied were the Excalibur and two diameters of the SM-EOD suite from SAAB Bofors. These shaped charges were selected for their potential to destroy UXOs. The Excalibur shaped charge led to RDX deposition rates similar to those observed with C-4 blocks, whereas the SM-EOD showed forensic traces of RDX. Based on these results, SM-EOD shaped charges provide a possible alternative to using C-4 for blow-in-place (BIP) operations, as they generate only small quantities of critical contaminants (such as RDX). By eliminating the contamination from the donor charge, the BIP operation will necessarily be improved and cleaner.

Many nation’s armed forces are undertaking efforts to minimize the environmental impacts of live-fire military training. Based on this, the Canadian Department of National Defence has undertaken a project to examine potential alternatives to the use of Composition C4, an RDX-based plastic explosive. Plastic explosives are widely used by all armed forces for both military engineering tasks and explosive ordnance disposal and their use may lead to the deposition of explosives in the environment, namely RDX, in the case of C4. RDX is very stable in the environment, water soluble, and moves relatively rapidly towards surface and groundwater bodies. One option identified as a potential RDX-free formulation is a pentaerythritol tetranitrate (PETN) based plastic explosive, commercially available in Germany and referred to as Seismoplast. In order to measure the environmental impacts of this formulation, a deposition rate study was conducted. These tests consist of evaluating the detonation efficiencies of munitions during detonation scenarios representative of military training. Data generated from these tests are the deposition masses of the energetic components in the explosive filler, which in this case is PETN. To achieve this objective, seven blocks of Seismoplast were open detonated over a surface of pristine snow, and post-detonation surface samples were collected to measure residual PETN. The trial demonstrated that less than 1×10−7 % of PETN is deposited upon detonation of Seismoplast. The energetic material deposition rates obtained in this trial are much lower than rates obtained for the RDX-based C4 currently in-service within Canada. Switching from a RDX-based plastic explosive to one based on PETN may be an interesting option through which the Department of National Defence can reduce the environmental impact of its activities.

Nitroglycerin (NG) is often present in soils and sometimes in pore water at antitank firing positions due to incomplete combustion of propellants. Various degradation processes can contribute to the natural attenuation of NG in soils and pore water, thus reducing the risks of groundwater contamination. However, until now these processes have been sparsely documented. This study aimed at evaluating the ability of microorganisms from a legacy firing position to degrade dissolved NG, as well as NG trapped within propellant particles. Results from the shake-flask experiments showed that the isolated culture is capable of degrading dissolved NG but not the nitrocellulose matrix of propellant particles, so that the deeply embedded NG molecules cannot be degraded. Furthermore, the results from column experiments showed that in a nutrient-poor sand, degradation of dissolved NG may not be sufficiently rapid to prevent groundwater contamination. Therefore, the results from this study indicate that, under favorable soil conditions, biodegradation can be an important natural attenuation process for NG dissolving out of fresh propellant residues. In contrast, biodegradation does not contribute to the long-term attenuation of NG within old, weathered propellant residues. Although NG in these old residues no longer poses a threat to groundwater quality, if soil clean-up of a legacy site is required, active remediation approaches should be sought.

The development of insensitive munitions by NATO countries is an ongoing effort. Less-sensitive ingredients in both explosives and propellants will ensure the protection of deployed troops against an unwanted reaction to an external stimulus on the munitions stockpile. In the US Army, current efforts are directed towards the development of melt cast insensitive explosive formulations. Various formulations, mainly based on DNAN and NTO, have been developed and are now being fielded. Our research goal is to measure the deposition rate of energetics compounds from various insensitive munitions detonation scenarios. Our hypothesis is that the relative insensitiveness of these formulations leads to slightly higher deposition rates than conventional explosive formulations. This paper describes detonation residues research on mortar rounds containing IMX-104 explosive. Analyses indicate that high-order detonation residues are slightly greater for this formulation than for conventional munitions. However, blow-in-place detonations (BIPs) resulted in much higher residues deposition, indicating that a larger donor charge is required for efficient detonation. The highly soluble compound NTO was particularly problematic, with BIP deposition approaching 95 % of the original load. Toxicological studies of NTO are not finalized, leaving considerable uncertainty regarding the feasibility of approving these rounds for distribution.

The insensitive high-explosive PAX-21 was the first of its kind fielded in an artillery munition by the United States military. This formulation contains three main components: RDX, dinitroanisole, and ammonium perchlorate (AP). In March 2012, detonation tests were conducted on PAX-21 60mm mortar rounds to determine the energetic residues resulting from high-order and blow-in-place (BIP) detonations. Post-detonation residues were sampled and analyzed for the three main PAX-21 components. Concentrations of RDX and dinitroanisole in the samples were quite low, less than 0.1% of the munitions' original organic explosive filler mass, indicating high order or near high order detonations. However, disproportionately high concentrations of AP occurred in all residues. The residues averaged 15% of the original AP following high-order detonations and 38% of the original AP mass following the BIP operations. There was no correlation between AP residues and the RDX and dinitroanisole. Perchlorate readily leached from the detonation residues, with over 99% contained in the aqueous portion of the samples. Use of these rounds will result in billions of liters of water contaminated above drinking water perchlorate limits. As a result of this research, PAX-21 mortar rounds are currently restricted from use on US training ranges.

Insensitive high explosives are being used in military munitions to counteract unintended detonations during storage and transportation. These formulations contain compounds such as 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO), which are less sensitive to shock and heat than conventional explosives. We conducted a series of four tests on snow-covered ice utilizing 60-mm mortar cartridges filled with 358 g of PAX-21, a mixture of RDX, DNAN, and ammonium perchlorate. Rounds were detonated high- and low-order using a fuze simulator to initiate detonation. Blow-in-place (BIP) operations were conducted on fuzed rounds using an external donor charge or a shaped-charge initiator. Results indicate that 0.001 % of the original mass of RDX and DNAN were deposited during high-order detonations, but up to 28 % of the perchlorate remained. For the donor block BIPs, 1 % of the RDX and DNAN remained. Residues masses for these operations were significantly higher than for conventional munitions. Low-order detonations deposited 10–15 % of their original explosive filler in friable chunks up to 5.2 g in mass. Shaped-charge BIPs scattered 15 % of the filler and produced chunks up to 15 g. Ammonium perchlorate residue masses were extremely high because of the presence of large AP crystals, up to 400 μm in the recovered particles.

Training with live munitions is an integral component of preparing the modern military for warfare. Energetic compounds, such as propellants and explosives, are consumed during the use of these munitions. These compounds are never fully consumed, however, and the deposition and accumulation of energetic residue on training ranges is the result. This paper summarizes 10 years of research into propellant deposition rates for common military munitions used in the USA and Canada. Research indicates that the firing of howitzers and tanks leave very little residue, the firing of mortars can result in moderate deposition of propellant residue, small-arms firing positions have the potential for significant residue accumulation, and training with shoulder-fired rockets and 40 mm machine guns can result in dangerous quantities of unburned propellants. Residue rates vary widely for the weapon systems tested, from 10−6 % for large rocket systems to over 70 % for shoulder-fired rockets.

a b s t r a c t The expedient field disposal of excess gun propellants on the ground is an integral part of live-fire train- ing in many countries. However, burning excess propellant in the field will leave significant quantities of energetic residues and heavy metals in the environment. Compounds such as dinitrotoluene and nitro- glycerin and metals such as lead will leach into the soil column, eventually migrating to groundwater. Contamination of the environment will lead to high remediation costs and the possible loss of the training facility. After investigating the contamination at several propellant disposal sites, a portable propellant burn pan was developed and tested. The pan was transported to training sites where excess propellant was loaded and burned in a controlled manner. Up to 120 kg of excess single-base propellant charges have been burned during two series of tests at a consumption rate of greater than 99.9%. Less than 0.03% of the energetic material was recovered outside the burn pan. Recovered lead is largely contained within the pan. The turnover rate for burns is 15 min. The residues can be collected following cool-down for proper disposal. Published by Elsevier B.V.

For years, DRDC Valcartier has invested efforts at developing energetic thermoplastic elastomers (ETPEs) based on linear glycidyl azide polymers to serve as energetic binders and replacing the thermoset matrix in insensitive explosives. It was first observed that introducing ETPEs in their melted form was not an easy task because high and nonpractical viscosities were encountered in the process. It was discovered that 2,4,6-trinitrotoluene (TNT) could be used in its melted form as an organic solvent to dissolve the ETPE and allow its incorporation into the insensitive formulations. Using these ETPEs led to the development of a greener insensitive melt-cast explosive named green insensitive munitions (GIM). This new explosive was intensely studied. The mechanical properties and proportions of ETPE in the formulations were optimized to obtain a melt cast with low viscosity while leading to an insensitive explosive formulation. Work was conducted on GIM explosives to test their performance and sensitivity, fate and behavior with regard to the environment, their recycling capability, and toxicity. This paper describes the results of all experiments conducted so far to test these aspects of GIM explosives. The preparation of the ETPEs and the GIM explosives will also be briefly described.

The presence of energetic materials (used as explosives and propellants) at contaminated sites is a growing international issue, particularly with respect to military base closures and demilitarization policies. Improved understanding of the ecotoxicological effects of these materials is needed in order to accurately assess the potential exposure risks and impacts on the environment and its ecosystems. We studied the toxicity of the nitroaromatic energetic material 2,4-dinitrotoluene (2,4-DNT) on alfalfa (Medicago sativa L.), barnyard grass (Echinochloa crusgalli L. Beauv.), and perennial ryegrass (Lolium perenne L.) using four natural soils varying in properties (organic matter, clay content, and pH) that were hypothesized to affect chemical bioavailability and toxicity. Amended soils were subjected to natural light conditions, and wetting and drying cycles in a greenhouse for 13 weeks prior to toxicity testing to approximate field exposure conditions in terms of bioavailability, transformation, and degradation of 2,4-DNT. Definitive toxicity tests were performed according to standard protocols. The median effective concentration (EC50) values for shoot dry mass ranged from 8 to 229 mg kg- 1, depending on the plant species and soil type. Data indicated that 2,4-DNT was most toxic in the Sassafras (SSL) and Teller (TSL) sandy loam soils, with EC50 values for shoot dry mass ranging between 8 to 44 mg kg- 1, and least toxic in the Webster clay loam soil, with EC50 values for shoot dry mass ranging between 40 to 229 mg kg- 1. The toxicity of 2,4-DNT for each of the plant species was significantly (p ? 0.05) and inversely correlated with the soil organic matter content. Toxicity benchmark values determined in the present studies for 2,4-DNT weathered-and-aged in SSL or TSL soils will contribute to development of an Ecological Soil Screening Level for terrestrial plants that can be used for ecological risk assessment at contaminated sites. Crown Copyright © 2010.

Nitroglycerin (NG), a nitrate ester, is widely used in the pharmaceutical industry and as an explosive in dynamite and as propellant. Currently NG is considered as a key environmental contaminant due to the discharge of wastewater tainted with the chemical from the military and pharmaceutical industry. The present study describes hydrolytic degradation of NG (200 μM) at pH 9 using either conventional or microwave-assisted heating at 50 °C. We found that hydrolytic degradation of NG inside the microwave chamber was much higher than its degradation using conventional heating. Products distributions in both heating systems were closely related and included nitrite, nitrate, formic acid, and the novel intermediates 2-hydroxypropanedial (O CHCH(OH)HC O) and glycolic acid (CH2(OH)COOH). Two other intermediates glycolaldehyde (CH2(OH)CHO) and glyoxylic acid (CHOCOOH) were only detected in the microwave treated samples. The molar ratio of nitrite to nitrate in the presence and absence of microwave heating was 2.5 and 2.8, respectively. In both microwave assisted and conventional heating a nitrogen mass balance of 96% and 98% and a carbon mass balance of 58% and 78%, respectively, were obtained. The lower C mass recovery might be attributed to further unknown reactions, e.g., polymerization of the aldehydes CH2(OH)CHO, CHOCOOH and O CHCH(OH)HC O. A hydrolytic degradation pathway for NG was proposed involving denitration (loss of 2 NO 2 - ) from the two primary carbons and the loss of one nitrate from the secondary carbon to produce 2-hydroxypropanedial.

An environmental issue has arisen with M-72 malfunction on anti-tank ranges because many of these rockets break into pieces without exploding on impact, dispersing their energetic materials content on the ground surface and exposing them to transport by infiltration of rainfall and snowmelt. A case study (1998--2005) at Arnhem Anti-Tank Range (Garrison Valcartier, Canada, in operation since the 1970s) revealed octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) contamination and traces of 1,3,5-trinitro-1,3,5-triazine (RDX) and 2,4,6-trinitrotoluene (TNT) in ground water at varying concentrations, with all detected HMX concentrations below the USEPA guideline for drinking water of 400 microg L(-1). An HMX mass balance on a transect perpendicular to ground water flow, about 300 m downgradient of the impact area, indicated an HMX flux of about 3 g d(-1) (0.7-1 kg yr(-1), 2005). The HMX mass in the impact area on the sand terrace was estimated at 7 to 10 kg (in 2005). The annual dissolved HMX flux represents about 10% of the source. The dissolved HMX plume in ground water consisted of a series of slugs, generated at each significant infiltration event. HMX is weakly retarded by sorption and is neither biotransformed nor mineralized under the aerobic conditions of the aquifer. TNT and RDX exceeded the USEPA guideline (2 microg L(-1) RDX and 1 microg L(-1) TNT) in three and two samples, respectively. The TNT plume was discontinuous because this compound was not always present at the ground surface. TNT is biotransformed, weakly sorbed, and not mineralized. In two wells, perchlorate associated with the propellant was found at concentrations above the Health Canada preliminary guideline of 6 microg L(-1) near the firing position.

Hexanitrohexaazaisowurtzitane (CL-20) is an emerging explosive that may replace the currently used explosives such as RDX and HMX, but little is known about its fate in soil. The present study was conducted to determine degradation products of CL-20 in two sandy soils under abiotic and biotic anaerobic conditions. Biotic degradation was prevalent in the slightly acidic VT soil, which contained a greater organic C content, while the slightly alkaline SAC soil favored hydrolysis. CL-20 degradation was accompanied by the formation of formate, glyoxal, nitrite, ammonium, and nitrous oxide. Biotic degradation of CL-20 occurred through the formation of its denitrohydrogenated derivative (m/z 393 Da) while hydrolysis occurred through the formation of a ring cleavage product (m/z 156 Da) that was tentatively identified as CH(2)=N-C(=N-NO(2))-CH=N-CHO or its isomer N(NO(2))=CH-CH=N-CO-CH=NH. Due to their chemical specificity, these two intermediates may be considered as markers of in situ attenuation of CL-20 in soil.

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) are cyclic nitramines used as explosives. Their ecotoxicities have been characterized incompletely and little is known about their accumulation potential in soil organisms. We assessed the toxicity and uptake of these explosives in perennial ryegrass Lolium perenne L. exposed in a Sassafras sandy loam (SSL) or in a sandy soil (DRDC, CL-20 only) containing contrasting clay contents (11% and 0.3%, respectively). A 21-d exposure to RDX, HMX or CL-20 in either soil had no adverse effects on ryegrass growth. RDX and HMX were translocated to ryegrass shoots, with bioconcentration factors (BCF) of up to 15 and 11, respectively. In contrast, CL-20 was taken up by the roots (BCF up to 19) with no translocation to the shoots. These studies showed that RDX, HMX, and CL-20 can accumulate in plants and may potentially pose a risk of biomagnification across the food chain.

The Arnhem Anti-Tank Range (Canadian Forces Base [CFB] Valcartier, Canada, in operation since the 1970s) has been characterized, including the drilling, installation, and characterization of 25 wells and a ground-penetrating radar survey. The observed particular features of this site include highly variable flow velocities (from < 3 to 1200 m/yr) and transient flow regime in the regional aquifer below the contaminant source zone of the impact area, sharp flow direction shifts, discontinuous stratigraphy and a local perched aquifer. A transient ground water flow model permitted us to understand how the complex hydrogeological setting shapes contaminant transport in the regional aquifer. The model explains the highly variable energetic material (EM) concentrations measured in the plume with peaks associated to spring and to a lesser extent to fall recharge events. As a conclusion from this work, the authors suggest that the characterization of contaminant sources on slopes should extend over all seasons to be sure to detect potential transient flow conditions and variable contaminant concentrations.

An attempt was made to introduce CL-20 in a TNT/energetic thermoplastic elastomer (ETPE)-based melt cast formulation, to obtain an insensitive composition with reduced adverse environmental properties. A loading limit of 42% w/w of CL-20 in melted TNT was observed, while it should have been around 70%. This paper describes the investigation that was undertaken to understand the observed phenomena. It was demonstrated that CL-20 undergoes structural alterations in melted TNT. The relative solubility of CL-20, RDX and HMX in melted TNT was determined and the α-, β-, γ- and e-CL-20 were prepared and characterized using Raman spectroscopy and DTA. CL-20 was mixed in melted TNT, as much as 4.2 g of CL-20 dissolved in 100 g of TNT. This allowed a transformation from e to β-CL-20 and a modification of CL-20 particle size and distribution. The later modification induced a raise in CL-20 specific surface and was responsible for the loading limit, while the transformation to β-CL-20 caused an increase in sensitivity and a decrease in density. This indicates that the use of CL-20 in TNT melt cast is not promising. Our study also showed that CL-20 is sensitive to morphological transformations, which should be taken into consideration in future processing using this compound.

Numerical modelling was done at the Cold Lake Air Weapons Range, Canada, to test whether the dissolved RDX and nitrate detected in groundwater come from the same sources, and to predict whether contamination poses a threat to the surface water receptors near the site. Military live fire training activities may indeed pose a risk of contamination to groundwater resources, however field investigations on military bases are quite recent, and little information is available on the long-term behaviour of munition residues related contaminants. Very limited information was available about the contaminant source zones, which were assigned based on our knowledge of current training activities. The RDX plume was well represented with the model, but the heterogeneous distribution of nitrate concentrations was more difficult to reproduce. It was nonetheless determined that both contaminants originate from the same areas. According to the model, both contaminants should reach the nearby river, but concentrations in the river should remain very low if the source zone concentration does not change. Finally, the model allowed the recommendation of a new location for the main bombing target, which would offer added protection to the river and the lake into which it flows.

Energetic materials contamination was investigated at the former Explosives Factory Maribyrnong, Victoria, Australia. Spectrophotometric/high performance liquid chromatography (HPLC) analysis was utilised to delineate a 5 tonne crystalline 2,4,6-trinitrotoluene (TNT) source in a former process waste lagoon that was found to be supplying contaminant leachate to the surficial clay aquitard with a maximum-recorded concentration of 7.0 ppm TNT. Groundwater within underlying sand and gravel aquifers was found to be uncontaminated due to upward hydraulic gradients resulting in slow plume development and propagation. Adsorption and microcosm test results from a parallel study were used as input parameters to simulate aqueous TNT transport in the clay aquitard using ATRANS20 software. The simulated TNT plume was localised within a few metres of the source, and at steady state, though leaching rate calculations suggest that without mitigation or other changes to the system, persistence of the source would be approximately 2,000 years. Remediation strategies may involve removal of the near surface source zone and infilling with an impermeable capping to impede leaching while facilitating ongoing natural attenuation by anaerobic degradation.

Natural attenuation processes affecting 2,4,6-trinitrotoluene (TNT) were determined within loams for two study areas at the former Explosives Factory Maribyrnong, Australia. TNT fate and transport was investigated through spectrophotometric/High Performance Liquid Chromatography (HPLC) analyses of soil and groundwater, adsorption and microcosm testwork. A five tonne crystalline TNT source zone delineated within near surface soils at the base of a TNT process waste lagoon was found to be supplying aqueous TNT loading (7 ppm) to subsurface soils and groundwater. The resultant plume was localized within the loam aquitard due to a combination of natural attenuation processes and hydrogeological constraints, including low hydraulic conductivity and upward hydraulic gradients. Freundlich described sorptive partitioning was the main TNT sink (KF = 29 mL/g), while transformation rates were moderate (1.01 × 10-4 h-1) under the aerobic conditions. Increasing 2-amino-4,6-dinitrotoluene predominance over 4-amino-2,6-...

Sublethal and chronic toxicities of 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) on earthworm Eisenia andrei in a sandy forest soil were assessed. Various reproduction parameters of fecundity (total and hatched number of cocoons, number of juveniles, and their biomass) were significantly decreased by TNT (or = 58.8 +/- 5.1 mg/kg dry soil), RDX (or = 46.7 +/- 2.6 mg/kg), and HMX (or = 15.6 +/- 4.6 mg/kg). These effects occurred at much lower concentrations than those reported earlier using artificial soil preparations. Growth of adults was significantly decreased in the TNT-spiked natural soils at 136.2 +/- 25.6 mg/kg dry soil, the highest concentration having no significant mortality. In contrast, survival and growth were not significantly reduced at relatively high measured concentrations of RDX (167.3 mg/kg) and HMX (711.0 mg/kg). Although TNT, RDX, and HMX share a common life-cycle response ( i.e., decreased juvenile counts), a number of differences related to other reproduction parameters (e.g., productivity of cocoons) was observed. These results indicate that the tested explosives do not support a common mechanism of toxicity, at least in the earthworm, probably due to differences in their physical-chemical properties as well as metabolites formed during exposure.

Polynitro organic explosives [hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and 2,4,6-trinitrotoluene (TNT)] are typical labile environmental pollutants that can biotransform with soil indigenous microorganisms, photodegrade by sunlight and migrate through subsurface soil to cause groundwater contamination. To be able to determine the type and concentration of explosives and their (bio)transformation products in different soil environments, a comprehensive analytical methodology of sample preparation, separation and detection is thus required. The present paper describes the use of supercritical carbon dioxide (SC-CO2), acetonitrile (MeCN) (US Environmental Protection Agency Method 8330) and solid-phase microextraction (SPME) for the extraction of explosives and their degradation products from various water, soil and plant tissue samples for subsequent analysis by either HPLC-UV, capillary electrophoresis (CE-UV) or GC-MS. Contaminated surface and subsurface soil and groundwater were collected from either a TNT manufacturing facility or an anti-tank firing range. Plant tissue samples were taken fromplants grown in anti-tank firing range soil in a greenhouse experiment. All tested soil and groundwater samples from the former TNT manufacturing plant were found to contain TNT and some of its amino reduced and partially denitrated products. Their concentrations as determined by SPME-GC-MS and LC-UV depended on the location of sampling at the site. In the case of plant tissues, SC-CO2 extraction followed by CE-UV analysis showed only the presence of HMX. The concentrations of HMX (300 mg/kg). Modifiers such as MeCN and water enhanced the SC-CO2 extractability of HMX from plant tissues.

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) can be efficiently mineralized with anaerobic domestic sludge, but the initial enzymatic processes involved in its transformation are unknown. To test the hypothesis that the initial reaction involves reduction of nitro group(s), we designed experiments to test the ability of a nitrate reductase (EC 1.6.6.2) to catalyze the initial reaction leading to ring cleavage and subsequent decomposition. A nitrate reductase from Aspergillus niger catalyzed the biotransformation of RDX most effectively at pH 7.0 and 30 degrees C under anaerobic conditions using NADPH as electron donor. LC/MS (ES-) chromatograms showed the formation of hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) and methylenedinitramine as key initial products of RDX, but neither the dinitroso neither (DNX) nor trinitroso (TNX) derivatives were observed. None of the above detected products persisted, and their disappearance was accompanied by the accumulation of nitrous oxide (N20), formaldehyde (HCHO), and ammonium ion (NH4+). Stoichiometric studies showed that three NADPH molecules were consumed, and one molecule of methylenedinitramine was produced per RDX molecule. The carbon and nitrogen mass balances were 96.14% and 82.10%, respectively. The stoichiometries and mass balance measurements supported a mechanism involving initial transformation of RDX to MNX via a two-electron reduction mechanism. Subsequent reduction of MNX followed by rapid ring cleavage gave methylenedinitramine which in turn decomposed in water to produce quantitatively N2O and HCHO. The results clearly indicate that an initial reduction of a nitro group by nitrate reductase is sufficient for the decomposition of RDX.

The lysosomal neutral red retention time (NRRT) assay, a biomarker for lysosomal membrane stability, and the total immune activity (TIA) assay, a measure of non-specific immune system activity, were used in laboratory studies to assess the toxic effects of 2,4,6-trinitrotoluene (TNT) on earthworms (Eisenia andrei) in vivo. The results were compared with the concentration of TNT and its metabolites in earthworm tissue, as well as standard sublethal toxicity endpoints including growth (i.e. weight change) and reproduction effects from previously published studies. Filter paper experiments indicated a significant decrease in NRRT at gtoreq1.8 mug TNT cm-2, whereas sublethal (weight loss) and lethal effects to earthworms were detected at gtoreq3.5 and 7.1 mug TNT cm-2, respectively. Experiments in artificial soil showed that NRRT effects could be detected at lower TNT concentrations (gtoreq55 mg TNT kg-1 soil dry weight) compared with other sublethal endpoints (effects on growth and reproduction). The TIA biomarker did not significantly respond to TNT. Cooper (as CuSO4, filter paper contact tests) and 2-chloroacetamide (soil tests), which were used as reference toxicants, also decreased the NRRT. The use of the NRRT assay linked with tissue concentrations of TNT metabolites in earthworms was identified as a potentially appropriate biomarker approach for TNT exposure assessment under laboratory conditions and a novel tool for effects-based risk assessment. (c) Biosciences Information Services.

Several defense departments intend to replace 2,4,6-trinitrotoluene (TNT) in munitions formulations by the less sensitive 2,4-dinitroanisole (DNAN). To help understand environmental behavior and ecological risk associated with DNAN we investigated its key initial abiotic and biotic reaction routes and determined relevant physicochemical parameters (pKa, log Kow, aqueous solubility (Sw), partition coefficient (Kd)) for the chemical and its products. Reduction of DNAN with either zero valent iron or bacteria regioselectively produced 2-amino-4-nitroanisole (2-ANAN) which, under strict anaerobic conditions, gave 2,4-diaminoanisole (DAAN). Hydrolysis under environmental conditions was insignificant whereas photolysis gave photodegradable intermediates 2-hydroxy-4-nitroanisole and 2,4-dinitrophenol. Physicochemical properties of DNAN and its amino products drastically depended on the type and position of substituent(s) on the aromatic ring. Sw followed the order (TNT < DNAN < 2-ANAN < 4-ANAN < DAAN) whereas log Kow followed the order (DAAN < 4-ANAN < 2-ANAN < DNAN < TNT). In soil, successive replacement of single bondNO2 by single bondNH2 in DNAN enhanced irreversible sorption and reduced bioavailability under oxic conditions. Although DNAN is more soluble than TNT, its lower hydrophobicity and its tendency to form aminoderivatives that sorb irreversibly to soil contribute to make it less toxic than the traditional explosive TNT.

The revolutionary insensitive, green, and healthier training technology with reduced adverse contamination (RIGHTTRAC) program is a 5-year technology demonstration program (TDP) aimed at showing that green and insensitive munitions have better properties than current munitions, and that it is feasible to implement safer weapon solutions that would ease the environmental pressure on ranges and training areas and decrease the health hazards for the users. The goals of this TDP are to reach a near-zero dud rate and to eliminate the potential for research development explosive (RDX) contamination as well as the use of toxic and carcinogenic compounds. This will be done by performing significant improvements to the fuzing system, the main explosive charge and the gun propellant. The vehicle used for this demonstration is a 105-mm army artillery munition (high-explosive M1), currently filled with Composition B (a 60:40 RDX:TNT mix) and using a single-base gun propellant (M1 formulation). The aim of this communication is to provide an overview of the project and to describe the steps taken to evaluate the environmental properties of the chosen propellant and explosive formulations. At its completion, it is believed that this project will have provided the required data to assess the long-term effects of the munitions on the environment right at an early stage of the weapon development cycle, and that this can be cost effective in the long run. This will help sustain military training while preserving our resources, as well as shaping the future of weapon system development.

The sublethal and chronic effects of the environmental contaminant and explosive octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) in artificial soil were assessed using the earthworm ( Eisenia andrei ). Based on various reproduction parameters (total and hatched number of cocoons, number of juveniles and their biomass), fecundity was reduced at the different concentrations of HMX tested (from 280.0±12.3 to 2502.9±230.0 mg kg −1 dry soil) in spiked artificial soil (LOEC: 280.0±12.3 mg kg −1 dry soil). The growth of adult E. andrei was also reduced at the different concentrations tested, though no mortality occurred, even at the highest tested concentrations. The number of juveniles produced was correlated with the number of total and hatched cocoons, and the biomass of juveniles was correlated with the number of cocoons. Pooled results of these and earlier studies on explosives (TNT, RDX) using the E. andrei reproduction test confirm that effects of HMX on cocoon production are indicative of some reproductive consequences (number of juvenile and their biomass), whereas adult growth, in general, does not correlate strongly with change in reproduction capacity.

Long-term exposure to 2,4,6-trinitrotoluene (TNT) can induce changes in the structure and activities of soil microbial communities. Such changes may be associated with an elevated microbial tolerance. An in situ respirometry technique based on the analysis of the substrate-induced respiration response to freshly added TNT was used to examine soil microbial tolerance to TNT at the community level. The specific growth rate derived by fitting an exponential equation to respiration data was taken as the measurement endpoint. Microbial tolerance was evaluated using a tolerance index defined as the ratio of the specific growth rate at a spiking dose of 2000 μg TNT/g soil to that of the control with no spiked TNT. Three soils with long-term exposure histories (TNT level in soil: 1.5, 32, and 620 μg TNT/g, respectively) exhibited significantly higher microbial community tolerance to TNT than two uncontaminated control soils. A soil containing 29,000 μg TNT/g exhibited the highest tolerance. Findings from this study support the hypothesis that pollution-induced community tolerance can be used as a means of identifying those compounds that have exerted selective pressure on the community.

To monitor the biodegradation of explosives in microcosm experiments, carbon-14 labelled substrates such as 14C-HMX were needed. Many synthetic routes were evaluated to identify the best synthesis of 14C-HMX with high yield and minimal radioactive waste. To synthesize 14C-HMX, acetylation of labelled hexamethylenetetramine (14C-HMTA) was done yielding 3,7-diacetyl-1,3,5,7-tetraazabicyclo-[3.3.1]-nonane (14C-DAPT) which was nitrated to obtain 1,5-diacetyloctahydro-3,7-dinitro-1,3,5,7-tetrazocine (14C-DADN) in one step. Nitrolysis of 14C-DADN was achieved using a mixture of 100% nitric acid and phosphorus pentoxide to yield 14C-HMX. The synthesis of this carbon-14 labelled HMX was optimized first using cold starting materials and then conducted with labelled compounds. This synthesis represents the best way of preparing high purity 14C-HMX with a high yield. Copyright © 1999 John Wiley & Sons, Ltd.

2,4,6-Trinitrotoluene (TNT) is an worldwide recalcitrant environmental contaminant and is toxic to a number of organisms including humans. This study examines the acute effects (lethal and biomass changes) of TNT on the oligochaetes species Eisenia andrei, using the 3-day filter paper, and the 7- and 14-day direct contact spiked soil (OECD artificial and forest soil) toxicity tests. Studies using the filter paper test indicated that the lethality of TNT could be detected in the range 1.5 to 14.2 microg/cm(2), with significant biomass (body weight) changes occurring at the lowest concentration. Acute effects (lethality) could not be measured when earthworms were placed on filter paper containing a saturated aqueous solution of TNT. This may indicate that with these exposure conditions, TNT may have been adsorbed to the filter paper, and that this matrix should be saturated with TNT before becoming available to the earthworms. Spiked soil toxicity tests indicated that the E. andrei lethality by TNT was >1.5 times higher when earthworms were exposed to TNT-spiked forest soil (LOEC:260 mg/kg; LC(50) 14 days 222.4 mg/kg) than to spiked OECD artificial soil (LOEC:420 mg/kg; LC(50) 14 days: 364.9 mg/kg). The sublethal effect on biomass change at the selected TNT concentrations in soil was not significant compared to controls. Results indicate that the bioanalytical methods described in this article could be used as TNT toxicity assessment tools. This soil quality test method gives valuable information for the screening of soil toxicity.

The sorption−desorption characteristics of 2,4,6-trinitrotoluene (TNT), 4-amino-2,6-dinitrotoluene (4-ADNT), and 2,4-diamino-6-nitrotoluene (2,4-DANT) within a natural topsoil, an illite shale, and...

The acetonitrile-sonication extraction method (US EPA SW-846 Method 8330) and aquatic-based toxicity tests were used on laboratory and field samples, to characterize the ecotoxicity of soils contaminated with energetic substances. Spiked soil studies indicated that 2,4,6-trinitrotoluene (TNT)-dependent soil toxicity could be measured in organic extracts and aqueous leachates using the 15-min Microtox (Vibrio fischeri, IC50=0.27 to 0.94 mg TNT/liter incubation medium) and 96-h Selenastrum capricornutum growth inhibition (IC50=0.62 to 1.14 mg/liter) toxicity tests. Analyses of leachates of composite soil samples [containing TNT and some TNT metabolites, 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), and 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX)] from an explosives manufacturing facility, indicated toxicities similar to those found in the TNT-spiked soil studies and pure TNT in solution, and suggested that TNT was the major toxicant. Using TNT as a model toxicant in soils having different moisture contents (20% vs dry) and textures (sandy vs clayey–sandy) but similar organic matter content (3–4%), multi-factorial analyses of Microtox test data revealed that these soil factors significantly influenced the TNT extractability from soil and subsequent toxicity measurements. Taken together, data indicate that the modified Method 8330 may be used in conjunction with ecotoxicity tests to reflect the toxic potential of soils contaminated with energetic substances.

Short-range and mid-range (grid size) spatial heterogeneity in explosives concentrations within surface soils was studied at an active antitank firing range. Intensive sampling was conducted adjacent to two target tanks by establishing sixteen 6-m-square grids. Each grid was subdivided into four quadrants, and in each quadrant an area-integrated surface sample was formed into a pile that included about 10% of the top 5 cm of soil in the quadrant. After in situ homogenization, random aliquots were combined to form replicate representative samples. Grid composites were also prepared by combining equal portions of soil from the four quadrants for each grid. In nine of the quadrants, a second area-integrated sample was prepared. On-site analysis showed concentrations of HMX ranging from as high as 2160 mg/kg near one target to ≤1 mg/kg at a distance of 20 m from the target. TNT concentrations, ranging from ≤1 to 23 mg/kg, were much lower than would be expected based on the 70 : 30 composition ratio of HMX to TNT in the melt-cast explosive used on site. On-site concentration estimates for HMX and TNT were in excellent agreement with laboratory HPLC results; correlation coefficients were 0.992 and 0.975, respectively. Spatial heterogeneity of HMX concentrations was large on both short- and midrange scales, and this factor dominated the overall uncertainty associated with site characterization. Greater emphasis on sampling is urgently needed to improve the representativeness of explosives residue determinations in soil. ©1999 John Wiley & Sons, Inc. Field Analyt Chem Technol 3:19–28, 1999

The acetonitrile-sonication extraction method (US EPA Method 8330) associated with aquatic-based toxicity tests was examined to study the ecotoxicity of energetic substances in soil. Three studies were carried out: (1) toxicological characterization of different energetic substances to select a representative toxicant and to validate the choice of bioassays; (2) choice of an appropriate solvent to transfer acetonitrile extracts to the bioassay incubation media; and (3) optimization of Method 8330 using soil samples spiked with the toxicant. Initial studies indicated that pure 2,4,6-trinitrotoluene (TNT) was toxic to Vibrio fischeri [Microtox; IC50 (15 min) of 4.2 microM], whereas RDX was less toxic (IC20 = 181 microM) and HMX was not toxic up to its limit of water solubility (22 microM). Selected pure TNT metabolites were less toxic than TNT. Similar results were found using the 96-h Selenastrum capricornutum growth inhibition test. The toxicity of pure TNT in different solvents (acetonitrile, acetone, and DMSO) and that from Method 8330-extracted TNT-spiked soil samples were compared to TNT dissolved in water. Data indicated that DMSO was the most appropriate solvent to transfer the acetonitrile extracts. A modified Method 8330 may be used in conjunction with bioassays and chemical analyses to examine the ecotoxicity of soils contaminated with energetic substances.

A multidisciplinary approach involving chemistry, microbiology, ecotoxicology and environmental engineering was undertaken by the Defence Research Establishment of the Department of National Defence (DREV/DND) and the Biotechnology Research Institute of the National Research Council of Canada (BRI/NRC) to characterize and to optimize the biodegradation potential of TNT and RDX in pure form and in soil. The nature and level of contamination by RDX and TNT in various soils were determined in an interlaboratory study involving both organizations using EPA Method # 8330. Microorganisms were isolated from the native soils and found to be capable of mineralizing (¹⁴CO₂ liberation) RDX under aerobic conditions when the latter was used as sole nitrogen source. RDX disappearance was accompanied by the elimination of toxicity associated with RDX, as determined by the Microtox test. Studies are underway to use the isolated indigenous strain as a bioaugmentation agent for future site application. Thus far TNT showed more toxic effects than RDX and metabolic analysis showed that TNT was biotransformed into the more toxic amine metabolites. In soil these amine metabolites react with humic acids to give recalcitrant and intractable products. To eliminate problems associated with TNT mineralization in soil we thus undertook a study to first wash TNT out of the soil using several water additives and then treat the TNT washings. Preliminary data showed that mineralization of TNT using sewage sludge under both aerobic and anaerobic conditions was enhanced in the presence of cyclodextrins. Further enhancement in the mineralization rate of TNT was obtained after subjecting the soil extract to photolysis. In an integral study, soil heavily contaminated with RDX (2000 ppm) and TNT (1000 ppm) was treated in bioslurry reactors supplemented with sewage sludge under both aerobic and anaerobic conditions. The biological performance of these reactors was monitored using microcosms spiked with ¹⁴C-labelled TNT or RDX. Preliminary data showed that RDX was almost completely mineralized. TNT rapidly disappeared (biotransformation to amino derivatives) with little mineralization. The data obtained from the present aerobic, soil washing and bioslurry reactors studies will be used for the development of practical soil remediation technologies., Fourth International Symposium on Special Topics in Chemical Propulsion : Challenges in Propellants and Combustion 100 Years After Nobel (4-ISICP), May 27-31, 1996, Stockholm, Sweden

The presence of nitroglycerin (NG) has been reported in shallow soils and pore water of several military training ranges. In this context, NG concentrations can be reduced through various natural attenuation processes, but these have not been thoroughly documented. This study aimed at investigating the role of soil organic matter (SOM) in the natural attenuation of NG, under aerobic conditions typical of shallow soils. The role of SOM in NG degradation has already been documented under anoxic conditions, and was attributed to SOM-mediated electron transfer involving different reducing agents. However, unsaturated soils are usually well-oxygenated, and it was not clear whether SOM could participate in NG degradation under these conditions. Our results from batch- and column-type experiments clearly demonstrate that in presence of dissolved organic matter (DOM) leached from a natural soil, partial NG degradation can be achieved. In presence of particulate organic matter (POM) from the same soil, complete NG degradation was achieved. Furthermore, POM caused rapid sorption of NG, which should result in NG retention in the organic matter-rich shallow horizons of the soil profile, thus promoting degradation. Based on degradation products, the reaction pathway appears to be reductive, in spite of the aerobic conditions. The relatively rapid reaction rates suggest that this process could significantly participate in the natural attenuation of NG, both on military training ranges and in contaminated soil at production facilities.

The high explosive nitroaromatic 2,4-dinitroanisole (DNAN) is less shock sensitive than 2,4,6-trinitrotoluene (TNT), and is proposed as a TNT replacement for melt-cast formulations. Before using DNAN in munitions and potentially leading to environmental impact, the present study examines the ecotoxicity of DNAN using selected organisms. In water, DNAN decreased green algae Pseudokirchneriella subcapitata growth (EC50 = 4.0mg/L), and bacteria Vibrio fischeri bioluminescence (Microtox, EC50 = 60.3mg/L). In soil, DNAN decreased perennial ryegrass Lolium perenne growth (EC50 =7 mg/kg), and is lethal to earthworms Eisenia andrei (LC50 = 47 mg/kg). At sub-lethal concentrations, DNAN caused an avoidance response (EC50 = 31 mg/kg) by earthworms. The presence of DNAN and 2-amino-4-nitroanisole in earthworms and plants suggested a role of these compounds in DNAN toxicity. Toxicity of DNAN was compared to TNT, tested under the same experimental conditions. These analyses showed that DNAN was equally, or even less deleterious to organism health than TNT, depending on the species and toxicity test. The present studies provide baseline toxicity data to increase the understanding of the environmental impact of DNAN, and assist science-based decision makers for improved management of potential DNAN contaminated sites.

Nitroguanidine (NQ) is an energetic material that is used as a key ingredient of triple-base propellants and is currently being considered as a TNT replacement in explosive formulations. NQ was efficiently degraded in aerobic microcosms when a carbon source was added. NQ persisted in unamended microcosms or under anaerobic conditions. An aerobic NQ-degrading bacterium, Variovorax strain VC1, was isolated from soil microcosms containing NQ as the sole nitrogen source. NQ degradation was inhibited in the presence of a more favorable source of nitrogen. Resting cells of VC1 degraded NQ effectively (54 μmol h(-1) g(-1) protein) giving NH(3) (50.0%), nitrous oxide (N(2)O) (48.5%) and CO(2) (100%). Disappearance of NQ was accompanied by the formation of a key intermediate product that we identified as nitrourea by comparison with a reference material. Nitrourea is unstable in water and suffered both biotic and abiotic decomposition to eventually give NH(3), N(2)O, and CO(2). However, we were unable to detect urea. Based on products distribution and reaction stoichiometry, we suggested that degradation of NQ, O(2)NN═C(NH(2))(2), might involve initial enzymatic hydroxylation of the imine, -C═N- bond, leading first to the formation of the unstable α-hydroxynitroamine intermediate, O(2)NNHC(OH)(NH(2))(2), whose decomposition in water should lead to the formation of NH(3), N(2)O, and CO(2). NQ biodegradation was induced by nitroguanidine itself, L-arginine, and creatinine, all being iminic compounds containing a guanidine group. This first description of NQ mineralization by a bacterial isolate demonstrates the potential for efficient microbial remediation of NQ in soil.

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and nitroglycerin (NG) are two energetic materials commonly found in the environment on military training ranges. They are deposited on the ground in the form of solid particles, which can then dissolve in infiltration water or in surface water bodies. The objective of this study was to evaluate whether photolysis by sunlight can significantly contribute to the natural attenuation of RDX and NG (as solid particles or dissolved in surface water) at mid-northern latitudes, where training ranges of Canada and many European countries are located. Experiments conducted at 46.9°N show that both compounds are degraded by sunlight when dissolved in water, with half-lives between 1 and 120 d, depending on the compound and time of year. Numerical models may be useful in predicting such photolysis rates, but the models should take into account current ozone levels, as older radiation datasets, collected before the ozone depletion observed since the late 1970s, underestimate the RDX/NG photolysis rate. For solid RDX or NG-bearing particles, photolysis is slower (half-lives of 2–4 months), but the degradation rate is still rapid enough to make this process significant in a natural attenuation context. However, photolysis of NG embedded within solid propellant particles cannot proceed to completion, due to the stable nitrocellulose matrix of the propellant. Nonetheless, photolysis clearly constitutes an important attenuation mechanism that should be considered in conceptual models and included in numerical modeling efforts.

The environmental fate of nitroglycerin (NG) in the unsaturated zone was evaluated in the context of double-base propellant residue deposition at anti-tank training ranges. Fresh propellant residues were collected during live anti-tank training. Surface soils, sub-surface soils and water samples from the unsaturated zone were collected at an active anti-tank range, and at a legacy site where NG-based propellants have been used. Results show that the residues are composed of intact propellant particles, as well as small quantities of NG, dinitroglycerin (DNG) and nitrate which are rapidly dissolved by precipitation, resulting in sporadic pulses of those compounds in water from the unsaturated zone after rain/snow melt events. The dissolved NG and DNG can be progressively degraded in the unsaturated zone, releasing nitrate as an end-product. Over a period of several years, small propellant particles located at the soil surface can be carried downward through the soil pore system by infiltration water, which explains the presence of NG in sub-surface soils at the legacy site, more than 35 years after site closure. NG is no longer leached from these old particles, therefore the detection of NG in sub-surface soils does not signify that groundwater is at risk of contamination by NG.

The present study describes the use of two commercially available lignins, namely, alkali and organosolv lignin, for the removal of 2,4-dinitroanisole (DNAN), a chemical widely used by the military and the dye industry, from water. Sorption of DNAN on both lignins reached equilibrium within 10 hr and followed pseudo second-order kinetics with sorption being faster with alkali than with organosolv lignin, i.e. k2 10.3 and 0.3 g/(mg x hr), respectively. In a separate study we investigated sorption of DNAN between 10 and 40 degrees C and found that the removal of DNAN by organosolv lignin increased from 0.8 to 7.5 mg/g but reduced slightly from 8.5 to 7.6 mg/g in the case of alkali lignin. Sorption isotherms for either alkali or organosolv lignin best fitted Freundlich equation with enthalpy of formation, deltaH0 equaled to 14 or 80 kJ/mol. To help understand DNAN sorption mechanisms we characterized the two lignins by elemental analysis, BET nitrogen adsorption-desorption and 31P NMR. Variations in elemental compositions between the two lignins indicated that alkali lignin should have more sites (O- and S-containing functionalities) for H-bonding. The BET surface area and calculated total pore volume of alkali lignin were almost 10 times greater than that of organosolv lignin suggesting that alkali lignin should provide more sites for sorption. 31P NMR showed that organosolv lignin contains more phenolic -OH groups than alkali lignin, i.e., 70% and 45%, respectively. The variations in the type of OH groups between the two lignins might have affected the strength of H-bonding between DNAN and the type of lignin used.

An important R and D effort was dedicated to the characterization of ranges and training areas and to the study of the environmental fate and the ecotoxicological impacts of munitions constituents in the last 20 years in Canada and the United States. Major environmental issues were identified, and the sources of munitions constituents in training ranges are better understood. Protocols were developed for collecting representative soil samples and their effective processing. In the last years, a large effort was dedicated to the measurement of the mass of munitions constituents deposited both at target impact areas and at firing positions, which led to a good estimation of source terms of contaminants. In Canadian ranges and training areas, efforts were also dedicated to characterize both surface and subsurface aquifers and geology, and detailed hydrogeological and geological mapping. All the data acquired over the last years have been used to build hazards and vulnerability maps, which can be combined to draw risk maps that represent great assets from a risk-management perspective. The next step is the development of environmentally sound solutions that will sustain military training and maintain force readiness. In order to achieve that goal, efforts are committed to the modification of actual live-firing activities to minimize their environmental adverse impacts. Finally, Canada is aiming at developing greener and insensitive munitions that will ease the environmental pressure. This paper is a summary of what has been done in North America toward understanding and minimizing the environmental footprint of munitions.

Live fire military training involves the detonation of explosive warheads on training ranges. The purpose of this experiment is to evaluate the hydrogeological changes to the vadose zone caused by military training with high explosive ammunition. In particular, this study investigates artillery ammunition which penetrates underground prior to exploding, either by design or by defective fuze mechanisms. A 105 mm artillery round was detonated 2.6 m underground, and hydraulic conductivity measurements were taken before and after the explosion. A total of 114 hydraulic conductivity measurements were obtained within a radius of 3 m from the detonation point, at four different depths and at three different time periods separated by 18 months. This data was used to produce a three dimensional numerical model of the soil affected by the exploding artillery round. This model was then used to investigate potential changes to aquifer recharge and contaminant transport caused by the detonating round. The results indicate that an exploding artillery round can strongly affect the hydraulic conductivity in the vadose zone, increasing it locally by over an order of magnitude. These variations, however, appear to cause relatively small changes to both local groundwater recharge and contaminant transport. © 2013 Elsevier B.V. All rights reserved.

Nitroglycerin (NG) is widely used for the production of explosives and solid propellants, and is a soil contaminant of concern at some military training ranges. NG phytotoxicity data reported in the literature cannot be applied directly to development of ecotoxicological benchmarks for plant exposures in soil because they were determined in studies using hydroponic media, cell cultures, and transgenic plants. Toxicities of NG in the present studies were evaluated for alfalfa (Medicago sativa), barnyard grass (Echinochloa crusgalli), and ryegrass (Lolium perenne) exposed to NG in Sassafras sandy loam soil. Uptake and degradation of NG were also evaluated in ryegrass. The median effective concentration values for shoot growth ranged from 40 to 231 mg kg- 1 in studies with NG freshly amended in soil, and from 23 to 185 mg kg- 1 in studies with NG weathered-and-aged in soil. Weathering-and-aging NG in soil did not significantly affect the toxicity based on 95 percent confidence intervals for either seedling emergence or plant growth endpoints. Uptake studies revealed that NG was not accumulated in ryegrass but was transformed into dinitroglycerin in the soil and roots, and was subsequently translocated into the ryegrass shoots. The highest bioconcentration factors for dinitroglycerin of 685 and 40 were determined for roots and shoots, respectively. Results of these studies will improve our understanding of toxicity and bioconcentration of NG in terrestrial plants and will contribute to ecological risk assessment of NG-contaminated sites.

2,4-Dinitroanisole (DNAN) is a low sensitive melt-cast chemical being tested by the Military Industry as a replacement for 2,4,6-trinitrotoluene (TNT) in explosive formulations. Little is known about the fate of DNAN and its transformation products in the natural environment. Here we report aerobic biotransformation of DNAN in artificially contaminated soil microcosms. DNAN was completely transformed in 8 days in soil slurries supplemented with carbon and nitrogen sources. DNAN was completely transformed in 34 days in slurries supplemented with carbons alone and persisted in unamended microcosms. A strain of Bacillus (named 13G) that transformed DNAN by co-metabolism was isolated from the soil. HPLC and LC-MS analyses of cell-free and resting cell assays of Bacillus 13G with DNAN showed the formation of 2-amino-4-nitroanisole as the major end-product via the intermediary formation of the arylnitroso (ArNO) and arylhydroxylamino (ArNHOH) derivatives, indicating regioselective reduction of the ortho-nitro group. A series of secondary reactions involving ArNO and ArNHOH gave the corresponding azoxy- and azo-dimers. Acetylated and demethylated products were identified. Overall, this paper provides the evidence of fast DNAN transformation by the indigenous microbial populations of an amended soil with no history of contamination with explosives and a first insight into the aerobic metabolism of DNAN by the soil isolate Bacillus 13G.

Triethylene glycol dinitrate (TEGDN) is an energetic plasticizer presently used in the synthesis of new insensitiveformulations. However, little is known about its environmental fate and impact. In the present study, wemeasured several environmental physicochemical parameters that are necessary to predict the fate and impact ofthe chemical in the environment. High solubility of TEGDN in water (7,430mg L1 at 25 8C), its low log Kowvalue (0.79), and low Kd values (0.09-0.78 L kg1) suggest that TEGDN will be very mobile in soils. We alsoinvestigated the kinetics and mechanisms of several degradation processes likely to occur in the environment.Hydrolysis and degradation in sterile soils were found to be very slow. No significant biological transformationwas detected after 3-month incubation in soils under aerobic conditions. Photolysis was the fastest process totake place with a rate of 0.049 day1 (t1/2¼14 days) and 0.031 day1 (t1/2¼22 days) at 258C in the dissolved ordry form, respectively. Nitrate, formaldehyde, and formate were the major photoproducts. Glyoxal, glycolaldehyde,and polycondensation products were also observed in the absence of water.