Mineralization of RDX-derived nitrogen to N2 via denitrification in coastal marine sediments

Richard W. Smith, Craig Tobias, Penny Vlahos, Christopher Cooper, Mark Ballentine, Thivanka Ariyarathna, Stephen Fallis, Thomas J. Groshens

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a common constituent of military explosives. Despite RDX contamination at numerous U.S. military facilities and its mobility to aquatic systems, the fate of RDX in marine systems remains largely unknown. Here, we provide RDX mineralization pathways and rates in seawater and sediments, highlighting for the first time the importance of the denitrification pathway in determining the fate of RDX-derived N. 15N nitro group labeled RDX (15N-[RDX], 50 atom %) was spiked into a mesocosm simulating shallow marine conditions of coastal Long Island Sound, and the 15N enrichment of N215N2) was monitored via gas bench isotope ratio mass spectrometry (GB-IRMS) for 21 days. The 15N tracer data were used to model RDX mineralization within the context of the broader coastal marine N cycle using a multicompartment time-stepping model. Estimates of RDX mineralization rates based on the production and gas transfer of 15N2O and 15N2 ranged from 0.8 to 10.3 μmol d-1. After 22 days, 11% of the added RDX had undergone mineralization, and 29% of the total removed RDX-N was identified as N2. These results demonstrate the important consideration of sediment microbial communities in management strategies addressing cleanup of contaminated coastal sites by military explosives.

Original languageEnglish (US)
Pages (from-to)2180-2187
Number of pages8
JournalEnvironmental Science and Technology
Volume49
Issue number4
DOIs
StatePublished - Feb 17 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry

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