The emerging use of 2,4-dinitroanisole (DNAN) in insensitive munitions formulations has caused concern for future contamination of subsurface environments, generating significant interest in understanding and identifying its transformation processes. Similar to other nitroaromatic contaminants, DNAN can be reduced by microbes and abiotically by dissolved and mineral-bound reductants to the corresponding aromatic amines, which are highly susceptible for oxidative transformation. However, in contrast to structurally similar compounds, biodegradation of DNAN under aerobic conditions is initiated through an O-demethylation reaction leading to 2,4-dinitrophenol as the main product. Assessing the numerous enzymatic and abiotic reactions that can be in involved in the transformation of DNAN and its degradation products is therefore a major challenge.  Compound-specific stable isotope analysis (CSIA) offers a promising strategy for distinguishing between those degradation processes without an explicit need to monitor the concentration dynamics. Over the recent years, we have characterized the mechanisms and isotope effects of the relevant oxidative, reductive, and hydrolytic transformation pathways. Our results show that the combined evaluation of carbon and nitrogen isotope fractionation of DNAN and its transformation products reveals the identity of the bonds being broken and thus offers robust evidence for the monitoring of chemical and biological processes in natural and engineered systems.

Compound-specific isotope analysis reveals the transformation processes of the insensitive munition component 2,4-dintroanisole and its reaction products

2019 Spring National Meeting

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