A Conceptual Model of Fate and Transport Processes for RDX Deposited to Surface Soils of North American Active Demolition Sites

Lapointe, Marie-Claude; Martel, Richard; Diaz, Emmanuela

doi:10.2134/jeq2017.02.0069

Cited by 10 publications

(4 citation statements)

References 80 publications

(107 reference statements)

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“…To our knowledge, NTO has not been released to surface waters, but this would likely occur at dilute concentrations, similar to RDX being detected in surface waters near demolition sites (up to 3 μg/L or 0.02 μM). 33 Compared to naturally present reactive species and scavengers in environmental waters, production of singlet oxygen (from NTO selfsensitization) and hydroxyl radicals (from NTO-derived nitrite and nitrate) is expected to be negligible at environmentally relevant NTO concentrations. For example, in our experimental setup (10 μM NTO), singlet oxygen is predicted to have an initial (maximum) steady-state concentration of 1.8 × 10 −13 M and contribute a pseudo-first-order reaction rate of 2.1 × 10 −5 min −1 (∼0.5% of the observed rate) using eqs 2 and 3 adapted to NTO rates and concentrations.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Photolysis of 3-Nitro-1,2,4-triazol-5-one: Mechanisms and Products

Schroer

Londono

et al. 2023

ACS EST Water

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Insensitive munitions formulations that include 3-nitro-1,2,4-triazol-5-one (NTO) are replacing traditional explosive compounds. While these new formulations have superior safety characteristics, the compounds have greater environmental mobility, raising concern over potential contamination and cleanup of training and manufacturing facilities. Here, we examine the mechanisms and products of NTO photolysis in simulated sunlight to further inform NTO degradation in sunlit surface waters. We demonstrate that NTO produces singlet oxygen and that dissolved oxygen increases the NTO photolysis rate in deionized water. The rate of NTO photolysis is independent of concentration and decreases slightly in the presence of Suwannee River Natural Organic Matter. The apparent quantum yield of NTO generally decreases as pH increases, ranging from 2.0 × 10–5 at pH 12 to 1.3 × 10–3 at pH 2. Bimolecular reaction rate constants for NTO with singlet oxygen and hydroxyl radical were measured to be (1.95 ± 0.15) × 106 and (3.28 ± 0.23) × 1010 M–1 s–1, respectively. Major photolysis reaction products were ammonium, nitrite, and nitrate, with nitrite produced in nearly stoichiometric yield upon the reaction of NTO with singlet oxygen. Environmental half-lives are predicted to span from 1.1 to 5.7 days. Taken together, these data enhance our understanding of NTO photolysis under environmentally relevant conditions.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Photolysis of 3-Nitro-1,2,4-triazol-5-one: Mechanisms and Products

Schroer

Londono

et al. 2023

ACS EST Water

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“…The cyclic nitramines hexahydro-1,3,5-trinitro-1,3,5-triazine (commonly called RDX), octogen (HMX), and hexanitrohexaazaisowurtzitane (CL-20) are compounds found in military grade explosives and propel- lants. Contamination of these cyclic nitramines in soil and groundwater is concerning due to their toxicity and potential carcinogenicity [3][4][5][6][7][8]. Biotic and abiotic degradation of cyclic nitramines often produce linear nitramine byproducts.…”

Section: Introductionmentioning

confidence: 99%

Activity assays of NnlA homologs suggest the natural product N-nitroglycine is degraded by diverse bacteria

Strickland,

Martinez Rodriguez,

Holland

et al. 2024

Beilstein J. Org. Chem.

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Linear nitramines (R–N(R′)NO2; R′ = H or alkyl) are toxic compounds, some with environmental relevance, while others are rare natural product nitramines. One of these natural product nitramines is N-nitroglycine (NNG), which is produced by some Streptomyces strains and exhibits antibiotic activity towards Gram-negative bacteria. An NNG degrading heme enzyme, called NnlA, has recently been discovered in the genome of Variovorax sp. strain JS1663 (Vs NnlA). Evidence is presented that NnlA and therefore, NNG degradation activity is widespread. To achieve this objective, we characterized and tested the NNG degradation activity of five Vs NnlA homologs originating from bacteria spanning several classes and isolated from geographically distinct locations. E. coli transformants containing all five homologs converted NNG to nitrite. Four of these five homologs were isolated and characterized. Each isolated homolog exhibited similar oligomerization and heme occupancy as Vs NnlA. Reduction of this heme was shown to be required for NnlA activity in each homolog, and each homolog degraded NNG to glyoxylate, NO2− and NH4+ in accordance with observations of Vs NnlA. It was also shown that NnlA cannot degrade the NNG analog 2-nitroaminoethanol. The combined data strongly suggest that NnlA enzymes specifically degrade NNG and are found in diverse bacteria and environments. These results imply that NNG is also produced in diverse environments and NnlA may act as a detoxification enzyme to protect bacteria from exposure to NNG.

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“…Originally patented for medical use in 1899, mass production of 1,3,5-trinitro-1,3,5-triazine (RDX) began, and its properties became fully understood during World War II (Anderson, 2010, Akhavan, 2004. Since then the manufacture and use of this toxic compound (Robidoux et al, 2002, Talmage et al, 1999 in munitions has contaminated soils, surface waters, and groundwater, particularly at military training ranges (Clausen et al, 2004, Hewitt et al, 2005, Albano et al, 2010, Lapointe et al, 2017.…”

Section: Introductionmentioning

confidence: 99%