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Updated: Jun 18, 2026
Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O
Published on: October 7, 2020
Quantifying RDX biodegradation in groundwater using delta15N isotope analysis
Anat Bernstein1, Eilon Adar, Zeev Ronen
1Zuckerberg Institute for Water Research, Department of Environmental Hydrology and Microbiology, Ben-Gurion University of the Negev, Sede Boqer Campus, 84990, Israel. anat.bernstein@helmholtz-muenchen.de
Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is naturally biodegraded in contaminated groundwater, with isotope analysis confirming up to 99.5% degradation. This study demonstrates isotope analysis as a viable method for tracking RDX biodegradation in aquifers.
Area of Science:
- Environmental Science
- Geochemistry
- Environmental Remediation
Background:
- Groundwater contamination by hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a significant environmental concern.
- Natural attenuation through biodegradation is a proposed remediation strategy for RDX-contaminated aquifers.
Purpose of the Study:
- To quantify the extent of RDX biodegradation in a contaminated aquifer using isotope analysis.
- To determine RDX biodegradation rates and half-lives under varying aquifer conditions.
- To assess the suitability of stable isotope fractionation analysis for monitoring RDX biodegradation.
Main Methods:
- Isotope analysis of RDX in groundwater samples collected along a 1.35-km contamination plume.
- Calculation of first-order biodegradation rates and half-lives based on degradation extents.
- Correlation of biodegradation rates with groundwater depth and geochemical data.
Main Results:
- RDX biodegradation reached up to 99.5% of the initial mass at 1.15-1.35 km downgradient.
- Average RDX biodegradation half-lives ranged from 4.4 to 31.2 years (aerobic/anaerobic) in the upper 15m.
- Degradation rates decreased with depth, with exceptionally low rates at the aquifer bottom.
- Aerobic biodegradation was suggested as the dominant attenuation process.
Conclusions:
- Stable isotope fractionation analysis is an effective tool for detecting and quantifying RDX biodegradation in situ.
- Natural biodegradation significantly reduces RDX concentrations in the contaminated aquifer.
- The findings support the use of natural attenuation for RDX-contaminated sites, with depth-dependent rates.
