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.

Investigating residue dissolution of insensitive high explosives in two sandy soil types: A predictive modelling approach.

The demand for munitions that are less likely to detonate accidentally has led to an increased use of Insensitive High Explosives (IHE), which contain substances like 2,4-dinitroanisole (DNAN) and 5-nitro-1,2,4-triazol-3-one (NTO). These substances have different properties compared to traditional explosives, and their potential environmental impact is not well understood. When these explosives are used in live-fire training exercises, their residues end up in the soil. It is important to determine how these residues dissolve and enter the soil. This study aimed to experimentally measure the rate at which an IHE formulation dissolves when exposed to rainwater with pH levels of 5.0 and 6.5, and to simulate how these residues dissolve and move through two different soil types. The dissolution rates were determined by conducting experiments in which IHE particles (30-60 mg) were exposed to water with varying pH levels and temperatures. The results showed that the dissolution rate of NTO did not vary with pH, while the dissolution rate of DNAN and RDX decreased with decreasing pH. Specifically, the dissolution rate of DNAN decreased from 18 ± 40 µg min-1 at pH 6.5 to 6 ± 4 µg min-1 at pH 5.0, while the dissolution rate of RDX decreased from 8 ± 4 to 3 ± 1 µg min-1. These findings were used to develop a stochastic model that successfully simulated the concentration of IHE in the leachate from soil columns over time. A sensitivity analysis revealed that while dissolution rates determined the amount of mass entering the soil, they did not significantly regulate the amount of mass that migrated through the soil and leached out of the soil columns.

Evaluating the effect of insensitive high explosive residues on soil using an environmental quality index (EQI) approach.

The environmental impact of Insensitive High Explosive (IHE) detonation residues to soil quality was assessed using a series of outdoor soil mesocosms. Two different soils were used including a pristine sandy soil and a land-degraded soil collected from a training range. Both soils were spiked with an IHE mixture comprised of 53 % NTO, 32 % DNAN and 15 % RDX at three different concentrations 15, 146 and 367 mg/kg respectively. The concentration levels were derived from approximate residues from 100 detonations over a 2 week training period. A set of five physico-chemical and biological indicators representative of the two soils were selected to develop environmental quality indexes (EQI). It was found that none of the concentrations tested for the pristine soil affected the chemical, biological and physical indicators, suggesting no decrease in soil quality. In contrast, the EQI for the degraded soil was reduced by 24 %, mainly due to a decrease in the chemical and biological components of the soil. Therefore, it is concluded that depending on the soil health status, IHE residues can have minor or severe consequences on soil health. Further studies are needed to determine the environmental impact of IHE on soil and water especially in the case where a larger number of detonations are more likely to be carried out on a training range.

Predicting the transport of 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO) in sandy and sandy loam soils.

There is a trend toward the use of Insensitive High Explosives (IHE) in both military and civil applications as they are intended to be less prone to accidental detonation compared to traditional explosive fills. This has driven the development of new explosive formulations containing different chemical compounds whose behaviour once they are released into the environment is not fully understood. To date, research into the toxicity and the persistence of IHE compounds in the environment is scarce and little has been described about how they interact with, or move through soil. In this work, the transport of two IHE constituents, 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO), through two soil types (sand and sandy loam) was simulated in GoldSim using a stochastic approach. The simulation outputs were validated by comparison to results from empirical soil column experiments. Sorption of the IHE constituents to the soil was the most significant factor in predicting when the contaminants eluted from the soil column. Sensitivity analysis demonstrated that variation in the matrix water partition coefficient (Kd) had the greatest influence when used to predict the IHE compounds transport. Kd was measured empirically and, as expected, it was low in sand for NTO (0.334 L kg-1) and DNAN (0.401 L kg-1), suggesting high mobility. While in sandy loam Kd for NTO (0.242 L kg-1) was similar to one obtained in sand, it was significantly higher for DNAN (9.128 L kg-1), explaining the high retention and adsorption in the sandy loam soil. The use of stochastic modelling to estimate IHE breakthrough concentrations could enable the uncertainty inherent in environmental systems to be embedded into simulations, thus increasing their representativeness. This study is the first step toward proactive management of IHE in the environment, and may support decision making for remediation and mitigation strategies in different environments.

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.

The use of a predictive threat analysis to propose revisions to existing risk assessments for precursor chemicals used in the manufacture of home-made explosives (HME).

Improvised explosive devices (IEDs) have generated over 137,000 civilian casualties in the past decade, more than any other explosive weapon system in the same period with a far-reaching impact on personal security freedoms across 50 affected countries. The aim of this paper is to consolidate existing risk management processes to control the availability of chemical precursors used in the manufacture of home-made explosives (HME) and to recommend global standards for market regulations in their composition, sale and use. This will be achieved by assessing the current regional regulations for three common chemical precursors (hydrogen peroxide, ammonium nitrate and potassium chlorate), and proposing a risk management process to identify key precursor chemicals that require greater control.

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.

Adsorption behaviour of 1,3,5-trinitroperhydro-1,3,5-triazine, 2,4-dinitroanisole and 3-nitro-1,2,4-triazol-5-one on commercial activated carbons.

Insensitive high explosives are increasingly being used to replace more sensitive formulations, however large quantities of environmentally hazardous wastewater are generated from loading, assembling and packing processes. Currently, there is limited literature regarding the treatment of wastewater contaminated with these hazardous insensitive high explosive materials such as 1,3,5-trinitroperhydro- 1,3,5-triazine (RDX), 2,4-dinitoranisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO). The preferred method of explosive wastewater treatment is adsorption by activated carbon, usually through treatment columns or fluidised beds that are simple to operate and cost effective. The aim of this research was to assess whether commercially available activated carbons would be suitable and economically viable to treat explosive wastewater containing RDX, DNAN and NTO. Bottle point tests were used to determine adsorption capacity and adsorption kinetics for the individual insensitive high explosives with three different activated carbons. Equilibrium data were fitted to the Langmuir, Freundlich and Temkin isotherms to determine the mechanisms of adsorption. Six hour bottle point tests for a mixture of the three insensitive high explosive constituents were used to consider possible preferential adsorption. As expected, RDX and DNAN were adsorbed at concentrations up to 40 mg.L-1 and 150 mg.L-1 respectively by the activated carbons tested, demonstrating the viability of treatment by adsorption. However, at the high concentrations of NTO expected in wastewater (1400 mg.L-1) activated carbons were rapidly saturated, suggesting that treatment of NTO contaminated wastewater would require prohibitively large quantities of activated carbon compared to RDX and DNAN.

Ozonation of diesel-fuel contaminated sand and the implications for remediation end-points.

In this study, we investigate specifically the influence of soil grain size and water content on the degradation of n-alkane fractions and the formation of aldehydes and carboxylic acid during ozonation. 15 g of quartz sand spiked with diesel (25 g kg(-1)) were exposed to ozone for 20 h at concentrations of 10, 30 and 50 mg L(-1), respectively. Results indicated that ozonation of the n-alkanes in fine grain size sand (0.15-0.25 mm) was 1.2 times faster than coarse sand due to higher surface contact area between O3 and sand particles. Soil moisture below 18% w/w did not influence the ozonation efficiency. In contrast the ozonation led to an increase of acidity of the sand samples (pH=3.0) after 20 h treatment. This was due to the formation of carboxylic acid. Formaldehyde, one of the key by-products of ozonation, was always <13 mg kg(-1) after the treatment which is below the industrial soil clean-up target level. While the aldehydes and carboxylic acid further reacted with O3 and their ozonation rate were slower than those of the alkanes suggesting that the hydroxylated by-products accumulated in the sand during the process. Overall the findings demonstrated that not only the alkanes but also aldehydes and carboxylic acid should be considered when defining remediation end-points.

The spatial distribution of postblast RDX residue: forensic implications.

Locating exactly where trace explosive residue samples should be sought during sample collection at bomb scenes is not specified in the published literature or guidelines; in this area, it is generally acknowledged that forensic practices are based on tradition rather than evidence. This study investigated patterns in the spatial distribution of postblast 1,3,5-trinitro-1,3,5-triazocyclohexane residue from a series of unconfined detonations, over a range of sampling sites, and at two different detonation heights. The amount of residue recovered from the sites decreased as a function of distance from the center of the explosion. [Correction added after online publication 27 December 2012: In the preceding sentence, "increased" was corrected to "decreased" to agree with the conclusion of the article.] As the height of the detonations increased, more residues were found from all sampling sites. The findings of this empirical study have a number of important practical implications including determining where residue samples are best sought at crime scenes.