Insensitive munitions (IM) are being used on military training ranges along with traditional explosives. While research has provided knowledge about 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO), the behavior of these IM compounds in mixtures resulting from dissolution and phototransformation of IM and traditional explosives has not been extensively studied. In addition, the effect of climatic conditions on the release of DNAN and NTO from formulations has not been examined but is expected to be significant. The goal of this project is to obtain the data needed to predict the long-term potential of NTO and DNAN to contaminate soil, groundwater and surface water. This project is a continuation of SERDP project ER-2220 that studied dissolution of insensitive munitions under laboratory conditions and at one outdoor site, as well as NTO and DNAN adsorption and attenuation in a variety of soils. The research from this original effort will be extended under this project by examining the influence of climate on dissolution and phototransformation of IM and comparing results to the behavior of traditional munitions. Reactive soil components, such as organic matter, phyllosilicate clays, and iron oxides, will be examined to determine how they contribute to retention of NTO, DNAN, and other IM formulation constituents and what are mechanisms controlling their adsorption.
The objectives of the project will be met with the following tasks:
- Laboratory phototransformation studies to quantify the photolysis of sold DNAN and NTO, work that will allow scaling transformation rates for different climate conditions;
- Outdoor dissolution and phototransformation studies of IM formulations at several locations within an elevation gradient to evaluate the role of climate (rainfall amount and distribution and temperature) on extent of phototransformation;
- Batch adsorption studies using soil components to determine the role of reactive soil constituents in IM attenuation;
- Column transport studies using realistic mixtures of insensitive and traditional explosives with the added task to check if acidic solutions produced by IM formulations mobilize heavy metals in soils and if lime can prevent this;
- Numerical modeling, which will use the experimental results to predict the phototransformation, dissolution, and transport behavior of these compounds under a variety of climatic and soil conditions.
These tasks will allow quantification of solid IM particle phototransformation and dissolution as a function of climate, and characterization of adsorption, attenuation, and transport of released compounds.
Information obtained from this project will improve the ability to accurately predict the release and phototransformation of IM compounds in hot arid regions. It will also improve the understanding of the interaction of released compounds with soils, resulting in potential attenuation of these compounds and in changes in soil properties, such as increase in soil acidity and metal mobilization. Being able to predict what proportion of deposited energetic material is lost through photolysis and how much would enter soil and surface waters for different climatic conditions, as well as patterns of release in time, is essential for accurate estimation of the environmental impact of training exercises and combat activities. Since insensitive munitions result in larger percentages of rounds having low order detonations and larger fractions of unconsumed ordinance remaining post-explosion during blow-in-place procedures, predicting the fate of deposited material is even more critical. (Anticipated Project Completion - 12/2019)
Becher, J., S. Beal, S. Taylor, K. Dontsova, and D. Wilcox. 2019. Photo-transformation of Aqueous Nitroguanidine and 3-nitro-1,2,4-triazol-5-one: Emerging Munitions Compounds. Chemosphere, 228:418-426.