Effect of gypsum on transport of IMX‐104 constituents in overland flow under simulated rainfall

• Published in: Journal of environmental quality Vol. 54; no. 1; pp. 191 - 203
• Main Authors: Polyakov, Viktor, Beal, Samuel, Meding, Stephen Mercer, Dontsova, Katerina
• Format: Journal Article
• Language: English
• Published: United States John Wiley and Sons Inc 01.01.2025
• Subjects: Anisoles; Calcium Sulfate - chemistry; environmental quality; Explosive Agents; gypsum; loam soils; Models, Chemical; Nitro Compounds - analysis; organic matter; overland flow; photolysis; Rain; rainfall simulation; runoff; sediments; Soil - chemistry; Soil Pollutants - analysis; subsurface flow; Triazines; Triazoles - analysis; Water Movements
• ISSN: 0047-2425; 1537-2537; 1537-2537
• DOI: 10.1002/jeq2.20652

Residue of energetic formulations, which is deposited on military training grounds following incomplete detonation, poses biotic hazards. This residue can be transported off‐site, adsorb to soil clays and organic matter, transform or degrade, or taken up by plants and animals. Its harmful effects can be mitigated by localizing the energetics at the site of initial deposition using soil amendments and allowing them to bio‐ and photodegrade in situ. Small plots with coarse loamy soil were used to study the effect of gypsum (CaSO4·2H2O) on transport and redistribution under simulated rainfall of various sizes of insensitive munition explosive (IMX)‐104 particles, which consist of 3‐nitro‐1,2,4‐triazol‐5‐one (NTO), 2,4‐dinitroanisole (DNAN), hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX), and octahydro‐1,3,5,7‐tertranitro‐1,3,5,7‐tetrazocine (HMX). The addition of gypsum more than doubled infiltration and decreased sediment loss by 16% compared to the control. The post‐rainfall mass balance of IMX‐104 in the order from greater to smaller pools was as follows: (1) soil surface retention, (2) off‐site loss to overland flow, and (3) sub‐surface infiltration. Overall, the application of gypsum significantly decreased concentration and the total mass loss of dissolved DNAN, RDX, and HMX in surface runoff. In addition, gypsum significantly decreased (for NTO, DNAN, and HMX) or delayed (for NTO, DNAN, RDX, and HMX) the peak discharge of <2 mm particulate energetics. The infiltration of NTO in the gypsum treatment was fivefold greater than in the control. Moreover, DNAN and RDX were also present in infiltration, while in the gypsum‐free control none were found. Gypsum shifted the total mass balance of energetics toward subsurface flow. This study indicates that gypsum may decrease off‐site transport of energetic constituents in the soils that are subject to surface sealing. Core Ideas The study quantifies the effect of surface applied gypsum on transport of insensitive munition explosive (IMX)‐104 under artificial rainfall. The mobility of IMX‐104 energetics components is controlled by their solubility and particle size. Application of gypsum decreased concentration and the total mass of dissolved energetics in the surface runoff. Gypsum facilitated redistribution of mobilized energetics into the subsurface flow. Plain Language Summary This study investigates gypsum soil amendment as a method to diminish off‐site contamination by munition energetics. These energetics, originating from residues of low‐order detonations on military training grounds, are hazardous for the environment. This research examined mitigating effects of gypsum on rainfall‐driven transport of IMX‐104 components (NTO, DNAN, RDX, and HMX) including in runoff, infiltration, and sediment. The results have implications for risk assessment and land management.