Mineral identity, natural organic matter, and repeated contaminant exposures do not affect the carbon and nitrogen isotope fractionation of 2,4-dinitroanisole during abiotic reduction

Matthew J. Berens, Bridget A. Ulrich, Jennifer H. Strehlau, Thomas B. Hofstetter, Bill Arnold

Research output: Contribution to journalArticle

Abstract

The recent development of insensitive munitions, such as 2,4-dinitroanisole (DNAN), as components of military explosives has generated concern for potential subsurface contamination and created a need to fully characterize their transformation processes. Compound specific isotope analysis (CSIA) has proven to be a useful means of assessing transformation pathways according to characteristic stable isotope fractionation patterns. The C and N isotope fractionation of DNAN associated with abiotic and enzymatic hydrolysis was recently assessed. The extent to which DNAN isotope fractionation will be affected by other potentially competing transformation pathways known for nitroaromatic compounds (e.g., reduction) and if previous knowledge can be extrapolated to other environmental matrices remains to be understood. Here, we investigated the C and N isotope fractionation and reaction rate constants of DNAN during abiotic reduction mediated by mineral-associated Fe(ii) species as a function of mineral type, natural organic matter presence, and repeated exposures to DNAN. Though rate constants varied, N and C apparent kinetic isotope effects (AKIEs) remained consistent across all experiments (averaged values of 15 N-AKIE = 1.0317 ± 0.0064 and 13 C-AKIE = 1.0008 ± 0.0005) and revealed significant 15 N- and minimal 13 C-enrichment in agreement with previous work on nitroaromatic compounds. Moreover, the observed fractionation was clearly distinct from trends for abiotic and enzymatic hydrolysis. This study provides a strengthened basis for the use of CSIA as a robust tool for monitoring DNAN degradation in complex environmental matrices as a component of future remediation efforts.

Original languageEnglish (US)
Pages (from-to)51-62
Number of pages12
JournalEnvironmental Science: Processes and Impacts
Volume21
Issue number1
DOIs
StatePublished - Jan 1 2019

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Nitrogen Isotopes
Carbon Isotopes
nitrogen isotope
Fractionation
Isotopes
Biological materials
Minerals
carbon isotope
fractionation
isotope
Impurities
organic matter
pollutant
mineral
Enzymatic hydrolysis
kinetics
hydrolysis
Kinetics
Rate constants
Hydrolysis

PubMed: MeSH publication types

  • Journal Article

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Mineral identity, natural organic matter, and repeated contaminant exposures do not affect the carbon and nitrogen isotope fractionation of 2,4-dinitroanisole during abiotic reduction. / Berens, Matthew J.; Ulrich, Bridget A.; Strehlau, Jennifer H.; Hofstetter, Thomas B.; Arnold, Bill.

In: Environmental Science: Processes and Impacts, Vol. 21, No. 1, 01.01.2019, p. 51-62.

Research output: Contribution to journalArticle

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