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Research Project: Understanding Ecological, Hydrological, and Erosion Processes in the Semiarid Southwest to Improve Watershed Management

Location: Southwest Watershed Research Center

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

item Polyakov, Viktor
item KADOYA, W - Us Army Corp Of Engineers (USACE)
item BEAL, S. - Us Army Corp Of Engineers (USACE)
item MOREHEAD, H. - University Of Arizona
item HUNT, E. - University Of Arizona
item CUBELLO, F. - University Of Arizona
item MEDING, S.M. - University Of Arizona
item DONTSOVA, K. - University Of Arizona

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/3/2023
Publication Date: 3/25/2023
Citation: Polyakov, V.O., Kadoya, W., Beal, S., Morehead, H., Hunt, E., Cubello, F., Meding, S., Dontsova, K. 2023. Transport of insensitive munitions constituents, NTO, DNAN, RDX, and HMX in runoff and sediment under simulated rainfall. Science of the Total Environment. 866. Article 161434.

Interpretive Summary: This work investigates pathways for movement and fate of munition energetic constituents on landscape. The energetics, derived from residues of low order detonations on military training grounds, present an environmental hazard. The study examined the effect of rainfall intensity and residue particle size on infiltration, runoff, erosion, and transport of IMX-104 constituents in runoff and infiltrating water. Movement of energetics in solution and suspended sediment, as well as change in contribution from both mechanisms over time were examined. The results will be useful for predictive modeling.

Technical Abstract: 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 modeling, developing mitigation strategies, and regulatory compliance.