Browsing by Author "Gutierrez-Carazo, Encina"

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    Decision framework for the environmental management of explosive contaminated land
    (Elsevier, 2019-07-04) Ladyman, Melissa K.; Temple, Tracey J.; Piperakis, Michael; Fawcett-Hirst, William; Gutierrez-Carazo, Encina; Coulon, Frederic
    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.
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    Dissolution Rates of Chemical Components of an Insensitive High Explosive Formulation
    (Cranfield University, 2020-11-27 14:14) Gutierrez-Carazo, Encina
    The need of insensitive munition has driven the replacement of traditional explosives by Insensitive High Explosives (IHE), less sensitive to external stimuli. This new generation contains compounds such as 2,4-dinitroanisole (DNAN) and 5-nitro-1,2,4-triazol-3-one (NTO) that have different psyco-chemical properties, making them more labile and mobile through the environment. However, little is known about the persistence and toxicity of these chemicals once released in the environment and this raises the challenge on how they can be assessed for human exposure. Accelerated laboratory experiments such as soil columns or bottle flask have being addressing the problem, although they can be time consuming, expensive and results cannot be extrapolated to different environments. Computational modelling can help to overcome this issue, as it allows the simulation of fate and transport of explosive compounds in the environment under a different insight. Nevertheless, the simulations and predictions made with this approach are not representative enough and they require inputs that can only be obtained experimentally. Additionally, there are extra problems when assessing explosive impact in soil as it is a heterogeneous matrix and it varies over time and studied area. Therefore, the aim of this study is to develop a representative computational model to inform the fate, transport and persistence of IHE compounds in the environment. For that, GoldSim, a simulation software has been chosen due to its flexibly on modelling and due to the possibility of adding stochastic simulations, which are able to better understand and model uncertainties. The model will be used to assess environmental risks of explosives and to help remediation strategies.
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    Investigating residue dissolution of insensitive high explosives in two sandy soil types: a predictive modelling approach
    (Elsevier, 2023-09-15) Gutierrez-Carazo, Encina; Dowle, James; Coulon, Frederic; Temple, Tracey; Ladyman, Melissa
    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.
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    Investigation into the fate and transport of Insensitive High Explosives in sandy soils to inform the development of a computational simulation
    (Cranfield University, 2022-08) Gutierrez-Carazo, Encina; Ladyman, Melissa; Coulon, Frederic
    The use of less-sensitive energetic formulations for military training activities has driven the replacement of traditional explosive fills by a new generation known as Insensitive High Explosives (IHE). Due to their novelty, little is understood about their behaviour in the environment when deposited as part of a formulation, specifically how long they may persist and the likelihood of transport of significant concentrations to groundwater. However, it is impractical to empirically investigate the behaviour of IHE in all possible environmental conditions and scenarios, and as of yet, there is no single computational model that enables simulation of persistence of IHE in soil. Therefore, the aim of this thesis was to provide insight into the chemical behaviour of IHE to simulate their fate and transport in sandy soils. To achieve this, the key parameters governing IHE dissolution, transport through soil and degradation were identified, highlighting that the partitioning coefficient regulated IHE mobility through soil; rainwater pH modified IHE dissolution and soil temperature had a significant influence on IHE degradation. These parameters were used to develop a stochastic model able to simulate breakthrough times and concentrations in sandy soil environments. Comparison of simulated breakthrough concentrations of IHE to empirical soil columns proved that the model was able to representatively predict how IHE behaved in soil specifically concentration in leachate over time, which would be invaluable in evaluation of the environmental risks posed by IHE residues and to support soil remediation strategies in contaminated areas.
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    Persistence of 2,4,6-triamino-1,3,5-trinitrobenzene in the environment
    (Elsevier, 2023-10-13) Christian, Olivia; Spencer, Michael; Ladyman, Melissa; Persico, Federica; Gutierrez-Carazo, Encina; Kadansky, Evie; Temple, Tracey
    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.
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    Predicting the Fate and Transport of Insensitive High Explosives in Soils
    (Cranfield University, 2020-01-09 15:50) Gutierrez-Carazo, Encina
    A great deal of studies on the environmental fate and transport of legacy explosives such as cyclotrimethylenetrinitramine (RDX), 2,4,6-trinitrotoluene (TNT) and 1,3,5,7-tetranitro-1,3,5,7-tetrazoctane (HMX) has been conducted. However, less is known about the behaviour of Insensitive High Explosive (IHE) constituents being brought into military service such as 2,4-dinitroanisole (DNAN) and 5-nitro-1,2,4-triazol-3-one (NTO) in soil and water environmental compartments. Typically fate and transport of explosives are often performed under controlled laboratory conditions. However, experimental data are often limited to a particular soil type under specific climatic conditions (i.e. pH, soil saturation, temperature), which are not always representative of genuine environments. For example, several studies have addressed the dissolution mechanisms of energetic compounds on soil surfaces; many, however, have addressed dissolution of individual IHE without considering formulations with multiple constituents. Such results may have limited applicability for dissolution of residues on soils at impact zones or firing ranges because IHE often contain mixtures of energetic materials e.g. DNAN, RDX, and NTO, as well as small quantities of other chemicals such as stabilisers, which may alter physico-chemical properties compared to the pure compound. Therefore, computational modelling software is increasingly being used as an additional tool to simulate real scenarios. However, models are limited by the quality of the empirical data used to predict the temporal and spatial behaviour e.g. rate of transport of IHE to an aquifer. This is a particular problem for the prediction of the behaviour of IHE in the environment where key experimental data has not been obtained for a wide variety of soils and environments, and whose compounds are frequently investigated in isolation even though they are used in combination in IHE formulations. Therefore, the aim of this study is to review and assess two predictive models including GoldSim Simulation Software and Hydrus-1D for a representative range of soil-IHE combinations, and to develop a standardised method for the prediction of the behaviour of IHE in the environment. To date the GoldSim simulations have been compared to soil columns under controlled laboratory conditions to estimate the accuracy of the model developed. GoldSim was initially chosen due to its flexibility, which enabled the use of experimentally determined empirical data for specific soil types and IHE constituents. Initial comparisons were undertaken with DNAN and a simple quartz sand medium to determine which empirical data gave the most accurate predictions e.g. soil adsorption coefficient, degradation rates and solubility. The comparisons will be extended to include mixtures of IHE constituents in a variety of soil types e.g. sandy, loamy, and silty under various climatic conditions.
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    ItemOpen Access
    Predicting the Fate and Transport of Insensitive High Explosives in Soils
    (Cranfield University, 2020-01-07 16:30) Gutierrez-Carazo, Encina
    A great deal of studies on the environmental fate and transport of legacy explosives such as cyclotrimethylenetrinitramine (RDX), 2,4,6-trinitrotoluene (TNT) and 1,3,5,7-tetranitro-1,3,5,7-tetrazoctane (HMX) has been conducted. However, less is known about the behaviour of Insensitive High Explosive (IHE) constituents being brought into military service such as 2,4-dinitroanisole (DNAN) and 5-nitro-1,2,4-triazol-3-one (NTO) in soil and water environmental compartments. Typically fate and transport of explosives are often performed under controlled laboratory conditions. However, experimental data are often limited to a particular soil type under specific climatic conditions (i.e. pH, soil saturation, temperature), which are not always representative of genuine environments. For example, several studies have addressed the dissolution mechanisms of energetic compounds on soil surfaces; many, however, have addressed dissolution of individual IHE without considering formulations with multiple constituents. Such results may have limited applicability for dissolution of residues on soils at impact zones or firing ranges because IHE often contain mixtures of energetic materials e.g. DNAN, RDX, and NTO, as well as small quantities of other chemicals such as stabilisers, which may alter physico-chemical properties compared to the pure compound. Therefore, computational modelling software is increasingly being used as an additional tool to simulate real scenarios. However, models are limited by the quality of the empirical data used to predict the temporal and spatial behaviour e.g. rate of transport of IHE to an aquifer. This is a particular problem for the prediction of the behaviour of IHE in the environment where key experimental data has not been obtained for a wide variety of soils and environments, and whose compounds are frequently investigated in isolation even though they are used in combination in IHE formulations. Therefore, the aim of this study is to review and assess two predictive models including GoldSim Simulation Software and Hydrus-1D for a representative range of soil-IHE combinations, and to develop a standardised method for the prediction of the behaviour of IHE in the environment. To date the GoldSim simulations have been compared to soil columns under controlled laboratory conditions to estimate the accuracy of the model developed. GoldSim was initially chosen due to its flexibility, which enabled the use of experimentally determined empirical data for specific soil types and IHE constituents. Initial comparisons were undertaken with DNAN and a simple quartz sand medium to determine which empirical data gave the most accurate predictions e.g. soil adsorption coefficient, degradation rates and solubility. The comparisons will be extended to include mixtures of IHE constituents in a variety of soil types e.g. sandy, loamy, and silty under various climatic conditions.
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    Predicting the transport of 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO) in sandy and sandy loam soils
    (Elsevier, 2022-11-21) Gutierrez-Carazo, Encina; Dowle, James; Coulon, Frederic; Temple, Tracey; Ladyman, Melissa
    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.
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    Structure of an Insensitive High Explosive formulation under a microscope
    (Cranfield University, 2020-11-27 10:07) Gutierrez-Carazo, Encina
    IMX-104 is an Insensitive High Explosive containing a mixture of 3-Nitro-1,2,4-triazol-5-one (NTO), 2,4- dinitroanisole (DNAN) and cyclotrimethylenetrinitramine (RDX). Due to its novelty, little is known about its potential toxicity and persistence in the environment and which has raised questions regarding its behaviour.Small flakes were placed under a Leica DM LM microscope to observe their microscopic structure and investigate the formulation process. The picture was taken using a ten times lense (10x) and reflected light. The scale shows the size of the flakes (in mm) and the fragments in focus were approximately 70 µm.