Detection of Molecular High Explosives in Post‐detonation Residue: Environmental Persistence of Days to Months

This work demonstrated detection and persistence of trace molecular residue of chemical explosives from environmental samples collected several days, weeks, or months after large (820 and 13580 kg) detonations using atmospheric flow tube‐mass spectrometry (AFT‐MS). AFT‐MS enables detection of explosives at parts‐per‐quadrillion volume levels of vapor and sub‐picogram levels of residue. To better understand the persistence of high explosive residue in the environment post‐detonation, three studies are discussed from separate detonations that occurred at the Nevada National Security Site in Nevada, USA. In one study, surface soil samples were collected before scheduled detonations, 4 days after two 820 kg detonations of C‐4, and 3 weeks after the detonations. Eight of the 20 samples collected 4 days post‐detonation contained detectable amounts of RDX (∼40 to 1080 pg/g soil) and the locations correlated with the prevailing wind direction during the detonations. RDX concentration generally decreased a few weeks after the detonations, indicating potential RDX degradation or dispersion by wind. In a second study, dust was collected from air filters before and after a 13580 kg underground detonation of Comp B. RDX was detectable months after the detonation with the highest concentration observed at the sampling location closest to the detonation (∼70 m from the initially sealed cavity). In a third study, picogram quantities of residual RDX were detected from a sample of soil collected ∼6 months after detonation of small RDX‐based explosives. These studies demonstrate that explosive residue can remain in the environment for several months, albeit at trace picogram levels.