Browsing by Author "Dowle, James"
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Item Open Access 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, MelissaThe 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.Item Open Access 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, MelissaThere 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.