Relationship of surface changes to metal leaching from tungsten composite shot exposed to three different soil types

Physical changes that occur on the surface of fired shots due to firing and impact with soil may increase the dissolution of muniton metals. Increased metal dissolution could potentially increase metal transport and leaching, affecting metal concentrations in surface and groundwater. This research describes the relationship between the surface changes on fired tungsten–nickel–iron (94% W:2% Ni:4% Fe) composite shots and metals leaching from those shots. Tungsten composite shot was fired into, and aged in, three soil types (Silty Sand, Sandy Clay, and Silt) in mesoscale rainfall lysimeters to simulate live-fire conditions and subsequent interactions between the metals of the composite and soil. Leachate, runoff, and soil samples were collected from the lysimeters and analyzed for metal content. The shots were analyzed using scanning electron microscopy (SEM) to evaluate surface changes. SEM results indicated that a soil’s particle size distribution initially affected the amount of metal that was sheared from the surface of the fired W-composite shots. Shearing was greatest in soils with larger soil particles (sand and gravel); shearing was least in soils composed of small soil particles (fines). Increased metallic shearing from the shot’s surface was associated with increasedWdissolution, compared to controls, following a simulated 1 year soil aging

Bio-geochemical Factors that Affect RDX Degradation

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a secondary high explosive that has been identified as a contaminant of concern in groundwater and soil as a result of military training activities (Wani et al., 2002). Remediation technologies that have been proposed for use on these training ranges include in situ techniques. An obstacle to using in situ approaches for the treatment of RDX contaminated soils and groundwater is the lack of information concerning the biogeochemical factors that influence transformation. This research compares paired (biotic and poised abiotic systems) RDX degradation experiments in which Eh-pH conditions conducive to RDX degradation were established. Degradation of RDX under iron-reducing conditions was studied in biological and chemical systems. The redox conditions created by the biological systems were simulated by poised chemical systems in order to compare RDX transformation. The poised chemical systems used an iron-ligand complex to achieve the necessary Eh values for RDX degradation. RDX degraded in both biological and chemical systems and final reaction solutions from both systems were analyzed to determine which degradation pathway was followed. The results from this effort will expand the basic knowledge of energetic transformation over a range of biologically-induced conditions, by isolation of enzymatic pathways from abiotic redox mechanisms

Hydrated lime for metals immobilization and explosives transformation: Treatability study

Fragmentation grenades contain Composition B (RDX and TNT) within a steel shell casing. There is the potential for off-site migration of high explosives and metals from hand grenade training ranges by transport in surface water and subsurface transport in leachate. This treatability study used bench-scale columns and mesocosm-scale laboratory lysimeters to investigate the potential of hydrated lime as a soil amendment for in situ remediation of explosives and metals stabilization in hand grenade range soils. Compared to the unamended soil there was a 26–92% reduction of RDX in the leachate and runoff water from the lime treated soils and a 66–83% reduction of zinc in the leachate and runoff water samples; where the hand grenade range metals of concern were zinc, iron, and manganese. The amended soil was maintained at the target pH of greater than 10.5 for optimum explosives decomposition. The treatability study indicated a high potential of success for scale-up to an in situ field study