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Environmental Health - Toxic Substances

Toxics Program Remediation Activities

RDX Biodegradation Assessment

  • Site Characterization
  • Natural Attenuation Evaluation

Naval Submarine Base Bangor, Washington


Naval Facilities Engineering Command, U.S. Navy

Technology Natural Attenuation
Contaminants RDX (Royal Demolition eXplosive, hexahydro-1,3,5-trinitro-1,3,5-triazine)

RDX concentrations, redox conditions, and HCO3- concentrations in the shallow aquifer at Site A, Operable Unit 1, NSB Bangor during May 2002. RDX concentrations, redox conditions, and HCO3- concentrations in the shallow aquifer at Site A, Operable Unit 1, NSB Bangor during May 2002.
(Click on image to enlarge)

USGS scientists partnered with the U.S. Navy's Naval Facilities Engineering Command to evaluate a plume of RDX (Royal Demolition eXplosive) contamination, and to assess the potential for the natural attenuation of RDX at the Naval Submarine Base (NSB) Bangor, Washington. Field and laboratory experiments were conducted to assess:

  • The potential contribution of microbial RDX degradation to observed decreases in RDX concentrations in the contaminant plume at NSB Bangor – Laboratory experiments involved the use of radiochemically labeled RDX (carbon 14) in microcosms under oxic (with oxygen) and anoxic (without oxygen) conditions. Quantitative polymerase chain reaction (Q-PCR) was used to identify the types of bacteria active in the microcosm studies. Greater than 85 percent of 14C-RDX converted to radioactive carbon dioxide ( 14CO 2) was observed in the microcosms under native, manganese-reducing, anoxic conditions. The results indicate that microbial degradation of RDX may contribute to natural attenuation of RDX in metal-reducing aquifer systems.
  • Characterization of redox conditions and identification of RDX transformation products – Field experiments involved the characterization of ambient redox conditions in ground water and analyses of water samples for possible RDX transformation products. Although metal-reducing redox conditions were identified, ground-water chemistry data overall did not clearly indicate RDX degradation (see above site . The unique intermediate degradation products hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX), hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX) were not detected in any ground-water sample, but those compounds were also not detected in the laboratory experiments (see above). The non-unique RDX mineralization products CO 2 and N 2O were elevated in many wells within and down-gradient from the RDX plume. There was a clear depression in RDX concentrations in the center of the plume, possibly due to RDX degradation, although those results may reflect that the wells are screened in a finer-grained and relatively stagnant portion of the shallow aquifer.
More Information
  • Paul M. Bradley, USGS, South Carolina Water Science Center,
  • Richard S. Dinicola, USGS, Washington Water Science Center,
Links Information on Natural Attenuation from the Toxics Program

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