A case study of contaminants on military ranges: Camp Edwards, Massachusetts, USA

Environmental monitoring of the Capo Frasca military training site (West Sardinia): Operability and environmental protection balanced plan

Military activities in training areas can contaminate soil and groundwater through different persistent pollutants. This article reports the design of the operating procedure to assess and monitor the environmental impact of training activities carried out at the Capo Frasca military firing range (PCF) on the west coast of Sardinia. The procedure includes two steps: (i) a baseline investigation of soil to detect the impact of previous training activities at PCF, and (ii) the development of a post-training monitoring plan. Results of the baseline investigations revealed that the activities conducted at PCF over many decades have not significantly affected the soil quality. Energetic compounds (ECs) were found below the limit of detection (LOD), and some low exceedances of the screening values (SVs) for Cd, Cu, and Ni were recorded in small areas that coincided with parts of two operational areas. A human health risk assessment (HHRA) identified no relevant issues. Results of baseline investigation allowed the planning of a light, noninvasive post-training monitoring plan based on two levels, L1 and L2, where L1 involves only manual sampling of topsoil (0-0.2 m). If L1 reveals contamination, a more in-depth and extensive L2 follow-up monitoring will be implemented. Results of post-training monitoring are not yet available. This environmental investigation protocol is intended to be a practical tool for regulatory provisions and is expected to be useful and effective for firing range management. This investigation also emphasized that, compared with the international state-of-the-art, environmental surveys in Italian military ranges require the improvement of ECs set to be analyzed, lowering EC LOD, and establishing ECs SVs. In Sardinia, many military areas, including PCF, are considered areas of significant natural interest. Therefore, it is deemed beneficial to move beyond HHRA and undertake the ecological risk assessment. Integr Environ Assess Manag 2024;20:2060-2075. © 2024 SETAC.

Movement of TNT and RDX from composition B detonation residues in solution and sediment during runoff

Energetics used in military exercises can potentially contaminate ground and surface waters. This study was conducted to evaluate the movement of Composition B, a formulation that includes TNT (2,4,6-trinitrotoluene), RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), and HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), in runoff. Mechanisms of transport we examined include movement of energetics dissolved in runoff, as particles and adsorbed to suspended sediment, and in infiltration. Rainfall simulations were conducted under controlled conditions with two rainfall rates (approximately 30 and 50 mm h-1), two soils with different infiltration capacities, and four energetic particle sizes (4.75-9.51 mm, 2.83-4.75 mm, 2-2.83 mm, and <2 mm). Particles remaining on the soil surface after rainfall were measured as well as energetics dissolved in runoff, in suspended sediment, and in infiltration. Greater concentrations of TNT than RDX and HMX were found dissolved in runoff due to its higher solubility and dissolution rates. We also found that particle transport in runoff increased with decrease in particle size. Smaller particle sizes also led to greater transport dissolved in solution. Relationships were found relating runoff and sediment yield to the transport of RDX and TNT. The results of this study allow improved prediction of Composition B transport in runoff and therefore its contamination potential.

Persistence of 2,4,6-triamino-1,3,5-trinitrobenzene in the environment

2,4,6-triamino-1,3,5-trinitrobenzene (TATB) is an Insensitive High Explosive (IHE) that is increasingly being used as a safer alternative to traditional energetic materials. However, the high thermal stability of TATB poses challenges for its disposal, particularly through existing open burning methods and its ability to remain in the environment for long period of time. Therefore, this study investigated the persistence of TATB in the environment by conducting small-scale experiments which were designed to examine the resistance of TATB to open burning and to assess unburnt residues. To evaluate the fate and transport of the unburnt materials in soil, laboratory-scale soil column transport studies were conducted to gauge the movement of TATB through soil. The results indicate that TATB exhibits a high resistance to burning, leaving unburnt materials that can persist in soil. The study emphasizes the importance of efficient disposal methods for explosives and highlights the need for further research to understand the environmental impact and toxicity of TATB.

Linear Free Energy Relationship for Predicting the Rate Constants of Munition Compound Reduction by the Fe(II)-Hematite and Fe(II)-Goethite Redox Couples

Abiotic reduction by iron minerals is arguably the most important fate process for munition compounds (MCs) in subsurface environments. No model currently exists that can predict the abiotic reduction rates of structurally diverse MCs by iron (oxyhydr)oxides. We performed batch experiments to measure the rate constants for the reduction of three classes of MCs (poly-nitroaromatics, nitramines, and azoles) by hematite or goethite in the presence of aqueous Fe2+. The surface area-normalized reduction rate constant (kSA) depended on the aqueous-phase one-electron reduction potential (EH1) of the MC and the thermodynamic state (i.e., pe and pH) of the iron oxide-Feaq2+ system. A linear free energy relationship (LFER), similar to that reported previously for nitrobenzene, successfully captures all MC reduction rate constants that span 6 orders of magnitude: log ( k S A ) = ( 1.12 ± 0.04 ) [ 0.53 E H 1 59 m V - ( p H + p e ) ] + ( 5.52 ± 0.23 ) . The finding that the rate constants of all the different classes of MCs can be described by a single LFER suggests that these structurally diverse nitro compounds are reduced by iron oxide-Feaq2+ couples through a common mechanism up to the rate-limiting step. Multiple mechanistic implications of the results are discussed. This study expands the applicability of the LFER model for predicting the reduction rates of legacy and emerging MCs and potentially other nitro compounds.

Impacts of calcium peroxide on phosphorus and tungsten releases from sediments

In this study, CaO₂ was used as a capping material to control the release of Phosphate (P) and tungsten (W) from the sediment due to its oxygen-releasing and oxidative properties. The results revealed significant decreases in SRP and soluble W concentrations after the addition of CaO₂. The mechanisms of P and W adsorption by CaO₂ were mainly chemisorption and ligand exchange mechanisms. In addition, the results showed significant increases in HCl-P and amorphous and poorly crystalline(oxyhydr)oxides bound W after the addition of CaO₂. The highest reduction rates of sediment SRP and soluble W release were 37 and 43%, respectively. Furthermore, CaO₂ can promote the redox of iron (Fe) and manganese (Mn). On the other hand, a significant positive correlation was observed between SRP/soluble W and soluble Fe (II) and between SRP/soluble W and soluble Mn, indicating that the effects of CaO₂ on Fe and Mn redox play a crucial role in controlling P and W releases from sediments. However, the redox of Fe plays a key role in controlling sediment P and W release. Therefore, CaO₂ addition can simultaneously inhibit sediment internal P and W release.

Algal mediated intervention for the retrieval of emerging pollutants from aqueous media

Water is a crucial elemental contributor for all sectors; however, the agricultural sector alone accounts for 70% of the world's total water withdrawal. The anthropogenic activity from various industries including agriculture, textiles, plastics, leather, and defence has resulted in the release of contaminants into water systems, resulting harm to the ecosystem and biotic community. Algae-based organic pollutant removal uses several methods, such as biosorption, bioaccumulation, biotransformation, and biodegradation. The adsorption of methylene blue by algal species Chlamydomonas sp. showed a maximum adsorption capacity of 2744.5 mg/g with 96.13% removal efficiency; on the other hand, Isochrysis galbana demonstrated a maximum of 707 µg/g nonylphenol accumulation in the cell with 77% removal efficiency indicating the potential of algal systems as efficient retrieval system for organic contaminants. This paper is a compilation of detailed information about biosorption, bioaccumulation, biotransformation, biodegradation, and their mechanism, along with the genetic alteration of algal biomass. Where the genetic engineering and mutations on algae can be advantageously utilized for the enhancement of removal efficiency without any secondary toxicity.

Transport of insensitive munitions constituents, NTO, DNAN, RDX, and HMX in runoff and sediment under simulated rainfall

Insensitive munition constituents derived from residues of low order detonations and deposited on military training grounds present environmental risks. A series of rainfall simulation experiments on small soil plots examined the effect of precipitation, soil properties, and particle size on transport of IMX-104 munition components: NTO (3-nitro-1,2,4-triazol-5-one), DNAN (2,4-dinitroanisole), RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), and HMX (octahydro-1,3,5,7- tertranitro-1,3,5,7-tetrazocine). The primary pathways for rainfall driven transport were subsurface infiltration, off-site transport in solution, and transport in solid form including re-adsorption onto soil particles. The transport was solubility dependent with NTO moving mostly in solution, which was dominated by either runoff or infiltration depending on soil. DNAN, RDX, and HMX, were transported primarily in particulate form. The fine energetic fraction (<2 mm) showed the highest mobility, while the coarsest fraction (>4.75 mm) remained in-situ after rainfall. A simple linear model relating energetics transport with sediment yield and energetics particle size and was proposed. These findings provide the first comprehensive mass balance of munition constituents as affected by overland flow under rainfall. They improve our understanding of environmental fate of munitions, can further be used for predictive modelling, developing mitigation strategies, and regulatory compliance.

Russian-Ukrainian war impacts the total environment

The Russian-Ukrainian war triggered a tsunami that dramatically impacted the world economy, geopolitics, and food security. Due to the extreme humanitarian situation, the effects on the environment have been overlooked. However, due to the intense fighting, the impacts will be dramatic and produce an environmental disaster. The war is already affecting areas beyond Ukraine (explosions in Russia and Moldova territory). This discussion paper aims to shed light on the potential effect of this vast conflict on the ecosystems and their services. Although the war is still ongoing, there is evidence of severe air pollution and greenhouse gas emissions resulting from the intense fights. Also, warfare activities were conducted in the vicinity of the Zaporizhzhia nuclear power plant (the biggest in Europe) and Chernobyl, increasing the fear of radiation leaks. The biodiversity is being drastically affected due to intense deforestation and habitat destruction with potential implications for wildlife. Bombing, trench and tunnel excavations will likely negatively impact soil degradation and landscape morphology. This assumes particular importance since Ukraine has some of the most fertile soils globally (Chernozem), affecting food production. Water availability and quality are likely to be affected due to infrastructure destruction and the transport of pollutants to water reserves. The ecosystem services supplied will likely be strongly damaged since deforestation will decrease the capacity of the ecosystems to regulate air pollution or climate. Soil degradation will hamper food production, and landscape aesthetics, cultural heritage and social cohesion destruction drastically affects cultural services. Finally, the impacts on human health are already tremendous. However, it can be even higher due to exposure to high levels of contamination and sanitary conditions degradation. The war is still ongoing, and there is considerable uncertainty regarding the impacts. However, we may expect a dramatic effect on the total environment.

Development of an environmental hazard-based rating assessment for defence-related chemical compounds in ecological soil systems

Environmental hazard-based methods are commonly used to categorise the severity of chemical contamination to ecological soil systems, although a traffic-light approach (green, amber, red) has never been used to assess these consequences. A traffic light approach is an easy to interpretate data as it has a clear visual display which can provide an early warning approach for stakeholders to identify areas that require further investigation. This approach should be underpinned by extensive research data and systematic methods of development. However, the extent of reliable data available for specific chemicals can be limited and therefore decision making may rely on expert judgement. Therefore, in this study, an environmental hazard-based rating methodology was developed by combining the guidelines from the European Chemical Agency (ECHA) and the USEPA for Predicted Non-effect Concentration (PNEC) and Ecological Soil Screening Levels (Eco-SSL) for defence-related chemicals (2,4,6-trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazinane (RDX), cypermethrin, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS)). The developed hazard-based rating assessment was design to categorise the chemicals into low, medium and high environmental hazards priority to inform and ease the decision-making process for contaminated areas to ensure that sustainable operations are carried out.

Electrochemical Synthesis of High-Nitrogen Materials and Energetic Materials

Electrochemical synthesis is a valuable method for the preparation of molecules. It is innately eco-friendly, as potentially hazardous oxidation and reduction agents are replaced with electrochemical potentials. Electrochemistry is commonly applied globally in the synthesis of numerous chemicals, but the energetic materials field lags in this regard. In this review, we endeavor to cover the entire history of synthetic electrochemistry for the preparation of energetic materials and detail the electrochemical transformations of high-nitrogen materials that are relevant for the preparation of new energetic molecules. We hope this review serves as a starting point to inform those involved in synthetic energetic materials chemistry, and those interested in other applications of high-nitrogen molecules, about the environmentally friendly electrochemical methods available for such compounds.

Contamination characteristics of energetic compounds in soils of two different types of military demolition range in China

The pollution of energetic compounds (ECs) in military ranges has become the focus of worldwide attention. However, few studies on the contamination of ECs at Chinese military ranges have been reported to date. In this study, two different types of military demolition range in China, Dunhua (DH) and Taiyuan (TY), were investigated and the ECs in their soils were determined. 10 ECs were detected at both ranges. While all the contamination characteristics were distinct, 2,4,6-trinitrotoluene (TNT) was the most abundant contamination source in soils at DH range, with an average concentration of 1106 mg kg^-1 and a maximum concentration of 34,083 mg kg^-1. Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and two mono-amino degradation products of TNT were also found to have high concentrations, with potential ecological and human health risks. In contrast, the concentrations of ECs in soils of TY range were much lower. The content of RDX was most significant, with average and maximum concentrations of 7.8 and 158 mg kg^-1, respectively. However, the potential threat to human health of 2,4-dinitrotoluene and 2,6-dinitrotoluene in soils at both ranges should not be ignored. The differences in pollution characteristics of the ECs at DH and TY are closely related to the types and amounts of the munitions destroyed. Moreover, the spatial distribution of ECs at the demolition ranges was extremely heterogeneous, which may be attributed to the use of open burning / open detonation and the non-homogeneous composition of the munitions.

Removal of munition constituents in stormwater runoff: Screening of native and cationized cellulosic sorbents for removal of insensitive munition constituents NTO, DNAN, and NQ, and legacy munition constituents HMX, RDX, TNT, and perchlorate

Technologies are needed to address contamination with energetic compounds at military installations. This research developed and evaluated novel and sustainable materials that can be used to remove munition constituents (MC) from stormwater runoff. Initial work focused on 3-nitro-1,2,4-triazol-5-one (NTO), as it is both highly soluble and ionized at environmentally relevant pH values. Screening cellulosic materials indicated that cationized (CAT) versions of pine shavings (pine, henceforth) and burlap (jute) demonstrated >70% removal of NTO from artificial surface runoff. CAT materials also demonstrated >90% removal of the anionic propellant perchlorate. NTO removal (~80%) by CAT pine was similar across initial pH values from 4 to 8.5 S.U. An inverse relationship was observed between NTO removal and the concentration of the major anions chloride, nitrate, and sulfate due to competition for anion binding sites. Sorption isotherms were performed using a mixture of the three primary legacy explosives (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), hexahydro-1,3,5-trinitro-s-triazine (RDX), 2,4,6-trinitrotoluene (TNT)), the three insensitive MC (nitroguanidine (NQ), NTO, 2,4-dinitroanisole (DNAN)), and perchlorate. Isotherm results indicated that effective removal of both legacy and insensitive MC would best be achieved using a mixture of peat moss plus one or more of the cationized cellulosic materials.

Detection and toxicity modeling of anthraquinone dyes and chlorinated side products from a colored smoke pyrotechnic reaction

"Green" pyrotechnics seek to remove known environmental pollutants and health hazards from their formulations. This chemical engineering approach often focuses on maintaining performance effects upon replacement of objectionable ingredients, yet neglects the chemical products formed by the exothermic reaction. In this work, milligram quantities of a lab-scale pyrotechnic red smoke composition were functioned within a thermal probe for product identification by pyrolysis-gas chromatography-mass spectrometry. Thermally decomposed ingredients and new side product derivatives were identified at lower relative abundances to the intact organic dye (as the engineered sublimation product). Side products included chlorination of the organic dye donated by the chlorate oxidizer. Machine learning quantitative structure-activity relationship models computed impacts to health and environmental hazards. High to very high toxicities were predicted for inhalation, mutagenicity, developmental, and endocrine disruption for common military pyrotechnic dyes and their analogous chlorinated side products. These results underscore the need to revise objectives of "green" pyrotechnic engineering.

Perchlorate occurrence, sub-basin contribution and risk hotspots for drinking water sources in China based on industrial agglomeration method

Perchlorate is a persistent inorganic contaminant which has attracted wide attention because of its harmful effects on physical health. Despite the potential adverse effects to humans via drinking water, related research at the national scale in China are scarce. In this study, the occurrence of perchlorate in major river basins in China was investigated from 2009 to 2020. Generally, except for the Yangtze River Basin, perchlorate concentrations in the surface water of other river basins were low, ranging from < 0.01 to 8.53 μg/L. The results of a specialized field sampling and tracking program in the Yangtze River Basin in 2019 showed that the Xiangjiang River basin is the greatest contributor of perchlorate in the Yangtze River Basin, accounting for 58.63% of the total perchlorate input. Furthermore, based on correlation analysis between production enterprise information and measured concentrations in sampled sites, fireworks and explosives production industries were identified as the major sources of perchlorate contamination in surface water. The risk map showed that the central-southern part of China and the central part of Xinjiang province were risk hotspots for perchlorate contamination. The results gave insights into how to conduct more precise risk assessment and policy intervention towards prevention of perchlorate contamination.

Microbial diversity in a military impacted lagoon (Vieques, Puerto Rico) and description of "Candidatus Biekeibacterium resiliens" gen. nov., sp. nov. comprising a new bacterial family

The Anones Lagoon, located in the Island Municipality of Vieques, Puerto Rico (PR), received extensive bombing by the US Navy during military exercises for decades until 2003 when military activities ceased. Here, we employed shotgun metagenomic sequencing to investigate how microbial communities responded to pollution by heavy metals and explosives at this lagoon. Sediment samples (0-5 cm) from Anones were collected in 2005 and 2014 and compared to samples from two reference lagoons, i.e., Guaniquilla, Cabo Rojo (a natural reserve) and Condado, San Juan (PR's capital city). Consistent with low anthropogenic inputs, Guaniquilla exhibited the highest degree of diversity with a lower frequency of genes related to xenobiotics metabolism between the three lagoons. Notably, a clear shift was observed in Anones, with Euryarchaeota becoming enriched (9% of total) and a concomitant increase in community diversity, by about one order of magnitude, after almost 10 years without bombing activities. In contrast, genes associated with explosives biodegradation and heavy metal transformation significantly decreased in abundance in Anones 2014 (by 91.5%). Five unique metagenome-assembled genomes (MAGs) were recovered from the Anones 2005 sample that encoded genetic determinants implicated in biodegradation of contaminants, and we propose to name one of them as "Candidatus Biekeibacterium resiliens" gen. nov., sp. nov. within the Gammaproteobacteria class. Collectively, these results provide new insights into the natural attenuation of explosive contaminants by the benthic microbial communities of the Anones lagoon and provide a reference point for assessing other similarly impacted sites and associated bioremediation efforts.

4,4'-Dinitrimino-5,5'-diamino-3,3'-azo-bis-1,2,4-triazole: A High-Performing Zwitterionic Energetic Material

Mixed acid nitration of electrochemically generated 4,4',5,5'-tetraamino-3,3'-azo-bis-1,2,4-triazole (TAABT) generated the novel energetic material 4,4'-dinitrimino-5,5'-diamino-3,3'-azo-bis-1,2,4-triazole (DNDAABT). Various energetic salts of DNDAABT were also prepared and characterized to confirm their structures and determine their explosive sensitivities and performances. The free acid of DNDAABT exists as a zwitterionic molecule that leads to a high-density material with predicted detonation parameters comparable to those of TKX-50 (bis(hydroxylammonium) 5,5'-bis(tetrazolate-1 N-oxide). Due to the insensitive nature of TAABT, it was predicted that DNDAABT would demonstrate remarkably low sensitivities for a primary N-nitramine. However, it was found that DNDAABT and all salts produced have primary explosive sensitivities, albeit with relatively high thermal stabilities for primary N-nitramines.

A review of treatment methods for insensitive high explosive contaminated wastewater

Insensitive high explosive materials (IHE) such as 3-nitro-1,2,4-triazol-5-one (NTO) and 2,4-dinitroanisole (DNAN) are increasingly being used in formulations of insensitive munitions alongside 1,3,5-trinitroperhydro-1,3,5-triazine (RDX). Load, assembly and packing (LAP) facilities that process munitions produce wastewater contaminated with IHE which must be treated before discharge. Some facilities can produce as much as 90,000 L of contaminated wastewater per day. In this review, methods of wastewater treatment are assessed in terms of their strengths, weaknesses, opportunities and threats for their use in production of IHE munitions including their limitations and how they could be applied to industrial scale LAP facilities. Adsorption is identified as a suitable treatment method, however the high solubility of NTO, up to 16.6 g.L-1 which is 180 times higher that of TNT, has the potential to exceed the adsorptive capacity of carbon adsorption systems. The key properties of the adsorptive materials along the selection of adsorption models are highlighted and recommendations on how the limitations of carbon adsorption systems for IHE wastewater can be overcome are offered, including the modification of carbons to increase adsorptive capacity or reduce costs.

Field trial demonstrating phytoremediation of the military explosive RDX by XplA/XplB-expressing switchgrass

The explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), a major component of munitions, is used extensively on military training ranges. As a result, widespread RDX pollution in groundwater and aquifers in the United States is now well documented. RDX is toxic, but its removal from training ranges is logistically challenging, lacking cost-effective and sustainable solutions. Previously, we have shown that thale cress (Arabidopsis thaliana) engineered to express two genes, xplA and xplB, encoding RDX-degrading enzymes from the soil bacterium Rhodococcus rhodochrous 11Y can break down this xenobiotic in laboratory studies. Here, we report the results of a 3-year field trial of XplA/XplB-expressing switchgrass (Panicum virgatum) conducted on three locations in a military site. Our data suggest that XplA/XplB switchgrass has in situ efficacy, with potential utility for detoxifying RDX on live-fire training ranges, munitions dumps and minefields.

Environmental impact of metals resulting from military training activities: A review

The deposition of metals into the environment as a result of military training activities remains a long-term concern for Defense organizations across the globe. Of particular concern for deposition and potential mobilization are antimony (Sb), arsenic (As), copper (Cu), lead (Pb), and tungsten (W), which are the focus of this review article. The fate, transport, and mobilization of these metals are complicated and depend on a variety of environmental factors that are often convoluted, heterogeneous, and site-dependent. While there have been many studies investigating contaminant mobilization on military training lands there exists a lack of cohesiveness surrounding the current state of knowledge for these five metals. The focus of this review article is to compile the current knowledge of the fate, transport, and ultimate risks presented by metals associated with different military training activities particularly as a result of small arms training activities, artillery/mortar ranges, battleruns, rocket ranges, and grenade courts. From there, we discuss emerging research results and finish with suggestions of where future research efforts and training range designs could be focused toward further reducing the deposition, limiting the migration, and decreasing risks presented by metals in the environment. Additionally, information presented here may offer insights into Sb, As, Cu, Pb, and W in other environmental settings.

Dietary exposure assessment to perchlorate in the Taiwanese population: A risk assessment based on the probabilistic approach

Perchlorate is an endocrine-disrupting chemical (EDC) that contaminate various foodstuffs. Exposure to perchlorate may cause severe health problems, mainly thyroid dysfunction. However, information on perchlorate contamination of consumer foods in Taiwan is limited. This study investigated perchlorate levels in 310 food samples belonging to 12 food groups collected from Taiwanese markets. A probabilistic risk assessment was conducted to assess the related exposure to Taiwanese people. Perchlorate was detected in 65% of the samples and high levels were identified in certain plant-origin, fruit, and processed food samples. A probabilistic approach was used to estimate daily dietary dose (Monte Carlo-estimated 95th percentile dietary exposure [MCS 95]) by using the Taiwan National Food Consumption database for 14 sex/age groups. The highest and lowest average daily doses (ADDs) were in the age groups of >65 years (MCS 95 = 3.60/3.90 [male/female] μg/kg bw/day) and 16-18 years (MCS 95 = 1.70/1.47 [M/F] μg/kg bw/day), respectively. The 95th percentile of the hazard index of exposure to perchlorate of all sex/age groups far exceeded the tolerable daily intake (0.3 μg/kg bw/day) and reference dose (0.7 μg/kg bw/day) set by the European Food Safety Authority and US EPA, respectively, but it was lower than the provisional maximum tolerable daily intake (10 μg/kg bw/day) suggested by the Joint FAO/WHO Expert Committee on Food Additives. The intake quantity and concentrations of perchlorate from vegetables, fruits, and whole grains are the critical contributors for the ADDs and integrated risk of dietary exposure to perchlorate. Long-term exposure through diets should be considered, instead of focusing on individual EDC during dietary risk assessment in specific populations. Furthermore, cumulative risks for exposure to multiple contaminants, particularly those causing thyroid adverse effects, may be higher than that from perchlorate exposure alone.

RDX degradation by chemical oxidation using calcium peroxide in bench scale sludge systems

The ability of calcium peroxide (CaO₂) to degrade hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in contaminated soil slurries using CaO₂-based modified Fenton oxidation was investigated. Results showed that increasing the CaO₂ dose increased degradation rates of RDX and pH. RDX concentrations decreased to below detection after 18 h with 2 M and 2.5 M CaO₂, after 30 h with 1.5 M CaO₂, after 54 h with 1 M CaO₂, but 0.1 M CaO₂ achieved no significant RDX removal. Increasing the soil organic matter content decreased the rate and extent of RDX degradation. RDX degradation products 4-nitro-2,4-diazabutanal (NDAB) and methylenedinitramine (MEDINA) were quantified, and the greater accumulation of NDAB than MEDINA suggests denitration of RDX was the most likely initial degradation step. Isotopic ratios for nitrogen and oxygen associated with RDX oxidation are also consistent with either nitrification of NH₄⁺ from soil or precipitation. Existing technologies merely only extract energetics from soils for treatment ex situ, whereas the approach introduced herein destroys RDX in situ with a one-step application.

Decision Framework for the environmental management of explosive contaminated land

The environmental risks from explosive manufacturing and testing activities are usually evaluated using a qualitative process such as environmental impact prioritisation as recommended by legislation and guidance. However, standard environmental management system (EMS) guidance rarely provides detailed information on how to objectively assess the significance of the environmental impacts based on a rational scientific evidence. Quantitative exposure and eco-toxicity assessments are frequently used in combination with environmental threshold limit guidelines, but these omit important environmental impacts such as physical damage to land, nuisance and contribution to climate change. These impacts are particularly relevant to the explosives industry where noise nuisance and physical damage are given high priority. In addition, contamination from explosive compositions may comprise mixtures of multiple legacy and new generation explosives such as 1,3,5-trinitro-1,3,5-triazinane (RDX), 2,4,6-trinitrotoluene (TNT), 5-nitro-1,2,4-triazol-3-one (NTO), 2,4-dinitroanisole (DNAN) and nitroguandine (NQ), which may have combined impacts not captured by conventional eco-toxicity assessments. Further, threshold limits for energetic materials in soil and water have not been established for most nations. Additionally, in the explosive industry wider concerns such as legislative compliance and stakeholder concerns may help to provide a more broadly applicable assessment of environmental impact. Therefore in this study a novel decision framework was developed to integrate empirical data with business risks to enable rational decision making for the environmental management of explosive manufacturing facilities. The application of the framework was illustrated using three case studies from the explosive manufacturing industry to demonstrate how the framework can be used to justify environmental management decision making. By linking the environmental impacts to business risks, we demonstrate that manufacturers are able to assess a wide spectrum of issues that might not be identified in the initial environmental assessment such as non-toxic pollution incidents, breaches in legislation and stakeholder perceptions.

The combined effect of phytostabilization and different amendments on remediation of soils from post-military areas

Army bases and battle fields are areas of high pollution due to the chemicals released there. Soils in these areas suffer from these uses of the land, and ecosystem services are affected. Although, in the 20th century, the production of bombs and the locations of battle fields and army bases were widespread, there is little research on the impact of war on nature. Moreover, there is a need to rehabilitate the disturbed soils. The contents and ecological risks of Cu, Ni, Cd, Pb, Zn, and Cr in the topsoil from a post-military area (north-eastern Poland) were investigated. In addition, a vegetation experiment was performed with the technique of aided phytostabilization on soils from the study area. The novelty of this study is the assessment of the usefulness of soil amendments (chalcedonite, limestone, activated carbon) in heavy metal (HM) phytostabilization in contaminated soils from post-military areas. Soil samples were also examined for pollution quantification indicators, including the index of geoaccumulation (I_geo), contamination factor (CF), and degree of contamination, and subjected to the Ostracodtoxkit test. The mean contents of the tested HMs were higher than those stipulated in soil environmental quality standards. The highest I_geo (7.38) and CF (346) values were those of Cr and Zn, respectively. The highest increase in soil pH was observed after the application of limestone to the soil. The greatest reduction in Cu, Ni, and Cd contents was caused by addition of limestone. The contents of HMs in Festuca rubra were higher in its roots than in its above-ground parts.

Manipulating redox conditions to enhance in situ bioremediation of RDX in groundwater at a contaminated site

Surficial application of waste glycerol (WG) for enhanced bioremediation was tested in situ at an old military range site to address hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) contaminated groundwater. This treatment was effective in inducing strong reducing conditions (range: -4 to -205 mV) and increasing the concentrations of organic carbon (from 10 to 729 mg/L) and fatty acids (from 0 to 940 mg/L) concomitantly with a decrease in RDX concentrations (range: 17 to 143 μg/L) to below detection limits (0.1 μg/L) in 2 of the 3 monitoring wells (MWs) evaluated. None of these changes were observed in the control MW. RDX disappeared without the detection of any common anaerobic nitroso degradation intermediates, with the exception of one MW where the concentration of organics did not significantly increase (range: 10 to 20 mg/L), suggesting the conditions were not favourable for biodegradation. Ecotoxicological analysis suggested that the use of WG may have some dose-related deleterious effects on different soil and aquatic receptors. Analysis of the microbial community composition, using 16S rRNA gene amplicon sequences, which provided insight into whether the process design had selected for and stimulated the optimal microbial populations, indicated co-existence of numerous Operational Taxonomic Units (OTUs) belonging to groups known to be capable of RDX degradation under anaerobic conditions, with a positive link between Geobacter spp. enrichment and the presence of RDX nitroso metabolites. Overall, the results from this field test show that this treatment process can provide an effective long-term, semi-passive remediation option for RDX contaminated groundwater.

High throughput quantification of the functional genes associated with RDX biodegradation using the SmartChip real-time PCR system

The explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a contaminant at many military sites. RDX bioremediation as a clean-up approach has been gaining popularity because of cost benefits compared to other methods. RDX biodegradation has primarily been linked to six functional genes (diaA, nfsI, pnrB, xenA, xenB, xplA). However, current methods for gene quantification have the risk of false negative results because of low theoretical primer coverage. To address this, the current study designed new primer sets using the EcoFunPrimer tool based on sequences collected by the Functional Gene Pipeline and Repository and these were verified based on residues and motifs. The primers were also designed to be compatible with the SmartChip Real-Time PCR system, a massively parallel singleplex PCR platform (high throughput qPCR), that enables quantitative gene analysis using 5,184 simultaneous reactions on a single chip with low volumes of reagents. This allows multiple genes and/or multiple primer sets for a single gene to be used with multiple samples. Following primer design, the six genes were quantified in RDX-contaminated groundwater (before and after biostimulation), RDX-contaminated sediment, and uncontaminated samples. The final 49 newly designed primer sets improved upon the theoretical coverage of published primer sets, and this corresponded to more detections in the environmental samples. All genes, except diaA, were detected in the environmental samples, with xenA and xenB being the most predominant. In the sediment samples, nfsI was the only gene detected. The new approach provides a more comprehensive tool for understanding RDX biodegradation potential at contaminated sites.

The effect of soil type on the extraction of insensitive high explosive constituents using four conventional methods

Explosive contamination is commonly found at military and manufacturing sites (Hewitt et al., 2005; Clausen et al., 2004; Walsh et al., 2013). Under current environmental legislation the extent of the contamination must be characterized by soil sampling and subsequent separation of the explosive contaminants from the soil matrix by extraction to enable chemical analysis and quantification (Dean, 2009). It is essential that the extraction method can consistently recover explosive residue from a variety of soil types i.e. all materials that have not degraded or irreversibly bound to the matrix, so that any resultant risk is not underestimated. In this study, five different soil types with a range of organic content, particle size and pH, were spiked with a mixture of RDX, DNAN, NQ and NTO at 50 mg/kg and were extracted using one of four one-step extraction methods: stirring, shaking, sonication, and accelerated solvent extraction (ASE). Analysis of the extraction efficiencies of the four methods found that they were broadly successful for the extraction of all IHE constituents from all five soils (an average of 84% ± 14% recovery across 80 extractions). However, soils with high organic content (Total Organic Content (TOC) ≥ 2%) were found to significantly affect extraction efficiency and reproducibility. NTO and DNAN were the least consistent in extraction efficiency with poorest recovery of NTO as low as 37% ± 2%. Of the four tested methods shaking was found to be the most reproducible, though less efficient than stirring (64%-91%). ASE was found to have the most variable results for extraction of IHE constituents suggesting that ASE was the most affected by the different soil types. Therefore, it is recommended that the efficiency and reproducibility of the selected extraction method should be validated by extracting known concentrations of the IHE from the soil of interest and that any required correction factors are reported.

Right on target: using plants and microbes to remediate explosives

While the immediate effect of explosives in armed conflicts is frequently in the public eye, until recently, the insidious, longer-term corollaries of these toxic compounds in the environment have gone largely unnoticed. Now, increased public awareness and concern are factors behind calls for more effective remediation solutions to these global pollutants. Scientists have been working on bioremediation projects in this area for several decades, characterizing genes, biochemical detoxification pathways, and field-applicable plant species. This review covers the progress made in understanding the fundamental biochemistry behind the detoxification of explosives, including new shock-insensitive explosive compounds; how field-relevant plant species have been characterized and genetically engineered; and the major roles that endophytic and rhizospheric microorganisms play in the detoxification of organic pollutants such as explosives.

Ecotoxicity of 2,4-dinitrotoluene to cold tolerant plant species in a sub-Arctic soil

Decades of live-fire training exercises have left millions of acres of military training lands contaminated with various munitions constituents such as dinitrotoluene. Those that pose a threat to higher organisms due to their toxicity and mobility in the soil are of particular concern. Plants aid in the biodegradation and phytoextraction of contaminants, and site-specific ecotoxicity determinations are critical to inform effective remediation strategy. These ecotoxicity determinations are lacking in cold-adapted plants and would be very informative for contaminated training lands in cold regions. Therefore, we conducted a phytotoxicity study to determine the median effective concentration (EC₅₀) of 2,4-dinitrotoluene (2,4-DNT) to four native Alaskan plant species in a sub-Arctic soil at two different temperatures. Plant species investigated were white spruce (Picea glauca), field locoweed (Oxytropis campestris), bluejoint grass (Calamagrostis canadensis), and Jacob's ladder (Polemonium pulcherrimum). Seedling emergence, fresh plant mass, and dry plant mass were used to model plant response to 2,4-DNT contamination. White spruce was most tolerant to 2,4-DNT contamination (EC₅₀ = 130.8 mg kg^-1) and field locoweed was least tolerant (EC₅₀ = 0.38 mg kg^-1). In general, Arctic plant species were more vulnerable to 2,4-DNT when compared to plant types native to temperate or tropical regions.

Worldwide occurrence and origin of perchlorate ion in waters: A review

Perchlorate (ClO₄^-) is a persistent water soluble oxyanion of growing environmental interest. Perchlorate contamination can be a health concern due to its ability to disrupt the use of iodine by the thyroid gland and the production of metabolic hormones. Its widespread presence in surface water and groundwater makes the aquatic environment a potential source of perchlorate exposure. However, the amount of published data on perchlorate origins and water contamination worldwide remains spatially limited. Here, we present an overview of research on perchlorate origins and occurrences in water, and the methodology to distinguish the different perchlorate sources based on isotope analysis. All published ranges of isotopic content in perchlorate from different sources are presented, including naturally occurring and man-made perchlorate source types, as well as the effects of isotope fractionation that accompanies biodegradation processes. An example of a case study in France is presented to emphasize the need for further research on this topic.

Detection of hexahydro-1,3-5-trinitro-1,3,5-triazine (RDX) with a microbial sensor

Explosives such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) are common contaminants found in soil and groundwater at military facilities worldwide, but large-scale monitoring of these contaminants at low concentrations is difficult. Biosensors that incorporate aptamers with high affinity and specificity for a target are a novel way of detecting these compounds. This work describes novel riboswitch-based biosensors for detecting RDX. The performance of the RDX riboswitch was characterized in Escherichia coli using a range of RDX concentrations from 0-44 μmol l^-1. Fluorescence was induced at RDX concentrations as low as 0.44 μmol l^-1. The presence of 4.4 μmol l^-1 RDX induced an 8-fold increase in fluorescence and higher concentrations did not induce a statistically significant increase in response.

In situ pilot test for bioremediation of energetic compound-contaminated soil at a former military demolition range site

Bioremediation was performed in situ at a former military range site to assess the performance of native bacteria in degrading hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and 2,4-dinitrotoluene (2,4-DNT). The fate of these pollutants in soil and soil pore water was investigated as influenced by waste glycerol amendment to the soil. Following waste glycerol application, there was an accumulation of organic carbon that promoted microbial activity, converting organic carbon into acetate and propionate, which are intermediate compounds in anaerobic processes. This augmentation of anaerobic activity strongly correlated to a noticeable reduction in RDX concentrations in the amended soil. Changes in concentrations of RDX in pore water were similar to those observed in the soil suggesting that RDX leaching from the soil matrix, and treatment with waste glycerol, contributed to the enhanced removal of RDX from the water and soil. This was not the case with 2,4-DNT, which was neither found in pore water nor affected by the waste glycerol treatment. Results from saturated conditions and Synthetic Precipitation Leaching Procedure testing, to investigate the environmental fate of 2,4-DNT, indicated that 2,4-DNT found on site was relatively inert and was likely to remain in its current state on the site.

Applying Incremental Sampling Methodology to Soils Containing Heterogeneously Distributed Metallic Residues to Improve Risk Analysis

This study compares conventional grab sampling to incremental sampling methodology (ISM) to characterize metal contamination at a military small-arms-range. Grab sample results had large variances, positively skewed non-normal distributions, extreme outliers, and poor agreement between duplicate samples even when samples were co-located within tens of centimeters of each other. The extreme outliers strongly influenced the grab sample means for the primary contaminants lead (Pb) and antinomy (Sb). In contrast, median and mean metal concentrations were similar for the ISM samples. ISM significantly reduced measurement uncertainty of estimates of the mean, increasing data quality (e.g., for environmental risk assessments) with fewer samples (e.g., decreasing total project costs). Based on Monte Carlo resampling simulations, grab sampling resulted in highly variable means and upper confidence limits of the mean relative to ISM.

Leaching of propellant compounds from munition residues may be controlled by sorption to nitrocellulose

Sustainable management of military ranges requires effective assessment of surface mobility and leaching potential of propellant compounds (PCs). Previous studies have focused mostly on PCs' dissolution from fired residues and their sorption to soil components. This work investigated the potential role of nitrocellulose, a major component in propellants, in the binding of PCs to propellant residues. Sorption isotherms of military grade nitrocellulose for dissolved nitroglycerine (NG) or 2,4-dinitrotoluene (2,4-DNT) was measured in batch experiments and were determined to be S_NG=10^2.39(±0.05)C_NG^{0.916(±0.032)} and S_2,4-DNT=10^3.08(±0.01)C_2,4-DNT^{0.668(±0.010)} (S and C in mg/kg_{nitrocellulose} and mg/L_wat, respectively). Solid-to-water partitioning for NG and 2,4-DNT was 100 times greater in propellant residues than in typical military ranges soils. Since nitrocellulose can sorb NG and 2,4-DNT up to 23 and 5% of its mass, respectively, it can slow down, through retarded diffusion, the leaching of PCs from fired residues over the typical composition ranges of common propellants. The slow leaching of PCs from propellant grains in column studies can be better interpreted by considering their sorptive interaction with nitrocellulose in addition to dissolution kinetics. With nitrocellulose as the carrying matrix, residue-bound PCs may migrate farther and persist longer in subsurface environment.

Effects of Military activity and habitat quality on DNA damage and oxidative stress in the largest population of the Federally threatened gopher tortoise

Department of Defense lands are essential for providing important habitat for threatened, endangered, and at-risk species (TER-S). However, there is little information on the effects of military-related contaminants on TER-S on these lands in field situations. Thus, this study examined genotoxicity and oxidative stress in gopher tortoises (Gopherus polyphemus) on Camp Shelby, MS-the largest known population of this species, which is listed as an "endangered species" in Mississippi and a "threatened species" by the U.S. government. Blood was collected from tortoises at 19 different sites on the base with different levels of habitat quality (high-quality and low-quality habitat) and military activity (high, low, and no military activity). Oxidative stress was quantified as lipid peroxidation and GSSG/GSH ratios, while DNA damage was determined using flow cytometry. Our results suggest that: (1) for tortoises residing in low-quality habitats, oxidative stress and DNA damage increased with increasing military activity, while in high-quality habitats, oxidative stress and DNA damage decreased with increasing military activity; (2) in the absence of military activity, tortoises in high-quality habitat had higher levels of oxidative stress and DNA damage than those in low-quality habitat, and (3) there were interactions between military activity, habitat quality, and landuse in terms of the amount of observable DNA damage and oxidative stress. In particular, on high-quality habitat, tortoises from areas with high levels of military activity had lower levels of oxidative stress and DNA damage biomarkers than on reference sites. This may represent a compensatory or hormetic response. Conversely, on low-quality habitats, the level of oxidative stress and DNA damage was lower on the reference sites. Thus, tortoises on higher-quality habitats may have a greater capacity for compensatory responses. In terms of management implications, it is suggested that low quality habitats should be a higher priority for remediation, and lower priority for conducting military activities.

A Conceptual Model of Fate and Transport Processes for RDX Deposited to Surface Soils of North American Active Demolition Sites

The use of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) as an energetic material (EM) in ammunition constituents such as detonators, primers, mines, and rocket boosters and in plastic explosives has led to an international warning on possible soil, surface water, and groundwater contamination on military training sites. In Canada, the demolition sites of range training areas are known to be the second most contaminated sites by EM residues in terms of their concentrations in soil after anti-tank ranges. This research proposes a conceptual model of the presence of RDX at the field scale at demolition sites according to previous soil and water characterization studies. This model illustrates the origin of RDX contamination, the main RDX transport pathways and processes, and the main threatened receptors. This conceptual model is of importance to visualize and understand RDX's environmental fate and behavior and to ultimately enable the production of a detailed quantitative model that can help to manage those RDX-contaminated sites.

Studying Water Quality Using Socio-Environmental Synthesis Approach: A Case Study in Baltimore’s Watershed

While almost 87% of the world’s population now has access to an improved drinking water source, the risk of water pollution remains, often due to environmental factors such as increasing urbanization and industrialization. Last year, as the country watched the tragic Flint, Michigan tap water quality deterioration unfold, the issue was brought closer to home: How good is Baltimore’s water system? Baltimore’s water source is primarily surface water, which feeds into the Liberty, Loch Raven and Prettyboy reservoirs. The Socio-Environmental Synthesis (SES) approach was used to investigate the factors that contribute to water quality impairment. SES is a research method that integrates existing knowledge and data from natural and social sciences to advance understanding of socio-environmental systems. The study found out that while the quality of the drinking water is generally good, there is a growing concern with the quality of water in the watersheds. The high levels of nitrate-nitrogen and increased concentrations of carbon dioxide are especially alarming. The high levels of Biological Oxygen Demand are also good indicators of the intensity of agriculture and urbanization in the watersheds. This study believes that maximizing the current watershed conservation and restoration efforts would reduce the treatment costs and safeguard the urban water supplies.

Evaluation of Biostimulation and Bioaugmentation To Stimulate Hexahydro-1,3,5-trinitro-1,3,5,-triazine Degradation in an Aerobic Groundwater Aquifer

Hexahydro-1,3,5-trinitro-1,3,5,-triazine (RDX) is a toxic and mobile groundwater contaminant common to military sites. This study compared in situ RDX degradation rates following bioaugmentation with Gordonia sp. strain KTR9 (henceforth KTR9) to rates under biostimulation conditions in an RDX-contaminated aquifer in Umatilla, OR. Bioaugmentation was achieved by injecting site groundwater (6000 L) amended with KTR9 cells (10(8) cells mL(-1)) and low carbon substrate concentrations (<1 mM fructose) into site wells. Biostimulation (no added cells) was performed by injecting groundwater amended with low (<1 mM fructose) or high (>15 mM fructose) carbon substrate concentrations in an effort to stimulate aerobic or anaerobic microbial activity, respectively. Single-well push-pull tests were conducted to measure RDX degradation rates for each treatment. Average rate coefficients were 1.2 day(-1) for bioaugmentation and 0.7 day(-1) for high carbon biostimulation; rate coefficients for low carbon biostimulation were not significantly different from zero (p values ≥0.060). Our results suggest that bioaugmentation with KTR9 is a feasible strategy for in situ biodegradation of RDX and, at this site, is capable of achieving RDX concentration reductions comparable to those obtained by high carbon biostimulation while requiring ~97% less fructose. Bioaugmentation has potential to minimize substrate quantities and associated costs, as well as secondary groundwater quality impacts associated with anaerobic biostimulation processes (e.g., hydrogen sulfide, methane production) during full-scale RDX remediation.

Relating Carbon and Nitrogen Isotope Effects to Reaction Mechanisms during Aerobic or Anaerobic Degradation of RDX (Hexahydro-1,3,5-Trinitro-1,3,5-Triazine) by Pure Bacterial Cultures

Kinetic isotopic fractionation of carbon and nitrogen during RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) biodegradation was investigated with pure bacterial cultures under aerobic and anaerobic conditions. Relatively large bulk enrichments in (15)N were observed during biodegradation of RDX via anaerobic ring cleavage (ε(15)N = -12.7‰ ± 0.8‰) and anaerobic nitro reduction (ε(15)N = -9.9‰ ± 0.7‰), in comparison to smaller effects during biodegradation via aerobic denitration (ε(15)N = -2.4‰ ± 0.2‰). (13)C enrichment was negligible during aerobic RDX biodegradation (ε(13)C = -0.8‰ ± 0.5‰) but larger during anaerobic degradation (ε(13)C = -4.0‰ ± 0.8‰), with modest variability among genera. Dual-isotope ε(13)C/ε(15)N analyses indicated that the three biodegradation pathways could be distinguished isotopically from each other and from abiotic degradation mechanisms. Compared to the initial RDX bulk δ(15)N value of +9‰, δ(15)N values of the NO2 (-) released from RDX ranged from -7‰ to +2‰ during aerobic biodegradation and from -42‰ to -24‰ during anaerobic biodegradation. Numerical reaction models indicated that N isotope effects of NO2 (-) production were much larger than, but systematically related to, the bulk RDX N isotope effects with different bacteria. Apparent intrinsic ε(15)N-NO2 (-) values were consistent with an initial denitration pathway in the aerobic experiments and more complex processes of NO2 (-) formation associated with anaerobic ring cleavage. These results indicate the potential for isotopic analysis of residual RDX for the differentiation of degradation pathways and indicate that further efforts to examine the isotopic composition of potential RDX degradation products (e.g., NOx) in the environment are warranted.

IMPORTANCE

This work provides the first systematic evaluation of the isotopic fractionation of carbon and nitrogen in the organic explosive RDX during degradation by different pathways. It also provides data on the isotopic effects observed in the nitrite produced during RDX biodegradation. Both of these results could lead to better understanding of the fate of RDX in the environment and help improve monitoring and remediation technologies.