title: (Bio)transformation of 2,4-dinitroanisole (DNAN) in soils.
abstract: Recent studies have begun to assess the environmental fate and toxicity of 2,4-dinitroanisole (DNAN), an insensitive munition compound of interest to defense agencies. Aerobic and anaerobic DNAN biotransformation in soils was evaluated in this study. Under aerobic conditions, there was little evidence of transformation; most observed removal was attributed to adsorption and subsequent slow chemical reactions. Under anaerobic conditions, DNAN was reductively (bio)transformed and the rate of the transformation was positively correlated with soil organic carbon (OC) up to a threshold of 2.07% OC. H2 addition enhanced the nitroreduction rate compared to endogenous treatments lacking H2. Heat-killed treatments provided rates similar to the endogenous treatment, suggesting that abiotic factors play a role in DNAN reduction. Ten (bio)transformation products were detected by high-resolution mass spectrometry. The proposed transformation pathway involves reduction of DNAN to aromatic amines, with putative reactive nitroso-intermediates coupling with the amines to form azo dimers. Secondary reactions include N-alkyl substitution, O-demethylation (sometimes followed by dehydroxylation), and removal of an N-containing group. Globally, our results suggest that the main reaction DNAN undergoes in anaerobic soils is nitroreduction to 2-methoxy-5-nitroaniline (MENA) and 2,4-diaminoanisole (DAAN), followed by anaerobic coupling reactions yielding azo-dimers. The dimers were subsequently subject to further (bio)transformations.
authors.affiliation: Department of Chemical and Environmental Engineering, University of Arizona, P.O. Box 210011, Tucson, AZ 85721, USA. Electronic address: olivarec@email.arizona.edu.
authors.forename: Christopher I
authors.initials: CI
authors.lastname: Olivares
authors.affiliation: Department of Soil, Water & Environmental Science, University of Arizona, P.O. Box 210011, Tucson, AZ 85721, USA; Department of Chemistry & Biochemistry, University of Arizona, P.O. Box 210011, Tucson, AZ 85721, USA.
authors.forename: Leif
authors.initials: L
authors.lastname: Abrell
authors.affiliation: Department of Soil, Water & Environmental Science, University of Arizona, P.O. Box 210011, Tucson, AZ 85721, USA.
authors.forename: Raju
authors.initials: R
authors.lastname: Khatiwada
authors.affiliation: Department of Soil, Water & Environmental Science, University of Arizona, P.O. Box 210011, Tucson, AZ 85721, USA.
authors.forename: Jon
authors.initials: J
authors.lastname: Chorover
authors.affiliation: Department of Chemical and Environmental Engineering, University of Arizona, P.O. Box 210011, Tucson, AZ 85721, USA.
authors.forename: Reyes
authors.initials: R
authors.lastname: Sierra-Alvarez
authors.affiliation: Department of Chemical and Environmental Engineering, University of Arizona, P.O. Box 210011, Tucson, AZ 85721, USA.
authors.forename: Jim A
authors.initials: JA
authors.lastname: Field
mesh_terms: D000693:Anaerobiosis; D000840:Anisoles / Q000378:metabolism*; D001711:Biotransformation; D002244:Carbon / Q000378:metabolism; D053834:Explosive Agents / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D010084:Oxidation-Reduction; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*
chemical_list: D000840:Anisoles; D053834:Explosive Agents; D012989:Soil Pollutants; C539360:2,4-dinitroanisole; D002244:Carbon; D007501:Iron
keywords: 2,4-Dinitroanisole; Biodegradation; Insensitive munitions; Nitroaromatics; Soil