A time series investigation of the stability of nitramine and nitroaromatic explosives in surface water samples at ambient temperature

Abstract

We investigated the fate of nitramine and nitroaromatic explosives compounds in surface water to determine how surface water biogeochemistry affects the stability of explosives compounds. Five river water samples and 18.2 MOmega deionized water were spiked with 10 explosives compounds and the samples were held at ambient temperatures (20 degrees C) for 85 d. Surface water represented three rivers with a range of total organic carbon concentrations and two rivers draining glacial watersheds with minimal organic carbon but high suspended solids. 18.2 MOmega deionized water exhibited no explosives transformation. Nitroaromatic compound loss from solution was generally: tetryl>1,3,5-TNB>TNT>1,3-DNB>2,4-DNT. The HMX, RDX, 2,6-DNT, 2ADNT, and 4ADNT concentrations remained somewhat stable over time. The surface water with the highest total organic carbon concentration exhibited the most dramatic nitroaromatic loss from solution with tetryl, 1,3,5-TNB and TNT concentrations decreasing to below detection within 10d. The two water samples with high suspended solid loads exhibited substantial nitroaromatic explosives loss which could be attributable to adsorption onto fresh mineral surfaces and/or enhanced microbiologic biotransformation on mineral surfaces. An identical set of six water samples was spiked with explosives and acidified with sodium bisulfate to a pH of 2. Acidification maintained stable explosives concentrations in most of the water samples for the entire 85 d. Our results suggest sampling campaigns for explosives in surface water must account for biogeochemical characteristics. Acidification of samples with sodium bisulfate immediately following collection is a robust way to preserve nitroaromatic compound concentrations even at ambient temperature for up to three months.

Desorption of nitramine and nitroaromatic explosive residues from soils detonated under controlled conditions

“…At considerably lower initial concentrations (i.e., 2-3 ppm) than the samples in the present study, RDX was lost from solution in batches created by spiking explosive compounds into the same three soils investigated here [16]. In the present study, RDX (and HMX) appear to be stable in solution in all three batches.…”

“…3). However, in deionized water, with an absence of biogeochemical surfaces, TNT does not undergo transformation [ [16]; the present study]. The 2ADNT, 4ADNT, and 1,3,5-TNB were not detected in the Composition B used to detonate our soils.…”

“…The location information, soil mineralogy, major-and traceelement chemical composition, and grain-size distribution of our three soil samples were presented in an earlier study [16], but are briefly summarized here. The three soil types detonated in the present study were extracted from river banks, represent soils that are thousands of years old, and likely were not previously exposed to soot or other potentially interfering chemical compounds.…”

“…However, uptake onto soil particle surfaces and transformation of explosive compounds depend strongly on soil and water biogeochemical parameters [4,[8][9][10][11][12][13][14][15]. It has recently been shown that nitramine and nitroaromatic compounds exhibit greater transformation rates in aqueous solutions in the presence of fractured soil particles than in weathered soils [16]. This may be attributable to enhanced electron-reduction transformation in the presence of fresh, reactive mineral particle surfaces and/or to the presence of an active microbiological regime on fresh soil particle surfaces.…”

Transformation Products of Emerging Organic Compounds as Future Groundwater and Drinking Water Contaminants

“…TNT is photo-degraded to 1,3,5-trinitrobenzene (TNB) and biotransforms to 2-amino-4,6-dinitrotoluene (2-ADNT) and 4-amino-2,6-dinitrotoluene (4-ADNT) (Douglas et al, 2009). Some of the metabolite products of TNT and DNT, particularly partially reduced aminonitrobenzenes, are equally or even more toxic than the parent compounds (Sunahara et al, 1998).…”