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Investigating the Fate of Nitroaromatic (TNT) and Nitramine (RDX and HMX) Explosives in Fractured and Pristine Soils
Author(s) -
Douglas Thomas A.,
Walsh Marianne E.,
McGrath Christian J.,
Weiss Charles A.
Publication year - 2009
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2008.0477
Subject(s) - trinitrotoluene , soil water , slurry , explosive material , environmental chemistry , detonation , chemistry , materials science , chemical engineering , mineralogy , environmental science , soil science , composite material , organic chemistry , engineering
Explosives compounds, known toxins, are loaded to soils on military training ranges predominantly during explosives detonation events that likely fracture soil particles. This study was conducted to investigate the fate of explosives compounds in aqueous slurries containing fractured and pristine soil particles. Three soils were crushed with a piston to emulate detonation‐induced fracturing. X‐ray diffraction, energy‐dispersive X‐ray spectrometry, gas adsorption surface area measurements, and scanning electron microscopy were used to quantify and image pristine and fractured soil particles. Aqueous batches were prepared by spiking soils with solutions containing 2,4,6‐trinitrotoluene (TNT), hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX), octahydro 1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX), and 2,4‐dinitrotoluene (2,4‐DNT). Samples were collected over 92 d and the concentrations of the spiked explosives compounds and TNT transformation products 2‐amino‐4,6‐dinitrotoluene (2ADNT) and 4‐amino‐2,6‐dinitrotoluene (4ADNT) were measured. Our results suggest soil mineralogical and geochemical compositions were not changed during piston‐induced fracturing but morphological differences were evident with fractured soils exhibiting more angular surfaces, more fine grained particles, and some microfracturing that is not visible in the pristine samples. TNT, 2,4‐DNT, RDX, and HMX exhibited greater analyte loss over time in batch solutions containing fractured soil particles compared to their pristine counterparts. 2ADNT and 4ADNT exhibited greater concentrations in slurries containing pristine soils than in slurries containing fractured soils. Explosives compound transformation is greater in the presence of fractured soil particles than in the presence of pristine soil particles. Our results imply fractured soil particles promote explosive compound transformation and/or explosives compounds have a greater affinity for adsorption to fractured soil particle surfaces.