A Short Course on Stable Isotope Approaches for Determining the Fate and Distinguishing Sources of Contaminants at DoD Sites

Objective

The key technical objective of this technology transfer effort was to develop and present training that provides practical information and guidance concerning the application of stable isotope technology for environmental remediation and forensic applications at Department of Defense (DoD) sites. The primary audience for this training is DoD Remedial Project Managers (RPMs) and environmental scientists as well as state and federal regulators and environmental consultants working at DoD facilities. The training was presented online and in person through a number of different venues. One of the training sessions is available on YouTube and is embedded below.

Technical Approach

Stable isotope analysis, and particularly compound-specific stable isotope analysis (CSIA), is a very powerful and useful tool that continues to be improved through fundamental and applied research. Stable isotopes have been demonstrated to be effective at helping detect, understand, and quantify biological and abiotic degradation of chemicals of concern at DoD sites, such as chlorinated volatile organic compounds (cVOCs), propellants, explosives, and fuel additives, among others. Stable isotope analysis is now ready to be applied more broadly throughout the DoD environmental remediation community. An important feature of stable isotope technology is that it can distinguish changes in chemical concentration due to degradative processes, as these cause isotope fractionation, from those caused by nondestructive processes such as dilution, dispersion, and sorption. This has led to two primary applications that have received SERDP and ESTCP attention to date, the use of isotopes to document degradation of chemicals of concern in the field, and the use of isotopes to trace these sources in complex environments.

Results

This short course provided training on the use of CSIA and covered the following topics:

Fundamentals of CSIA
Applications
- Documenting cVOC degradation
  - Parent cVOCs
  - Daughter products
- Source Discrimination - vapor intrusion
- Other chemicals of concern
  - 1,4-Dioxane
  - 1,2-Dibromoethane
  - Perchlorate

Project Summary

Benefits

Stable isotope methods can help address many questions for RPMs at military sites (e.g., monitored natural attenuation assessment, source delineation, determining field degradation rates), and there are commercial, academic, and/or government laboratories (based on isotope and compound) that can perform the requisite analyses. However, these methods are presently underutilized. This training provides DoD RPMs as well as consultants and regulators, with a practical background on the applications of stable isotopes at DoD sites. Ideally, this knowledge will lead to increased and appropriate use of this technology at field sites to improve cost efficiency of future monitoring and remediation applications. (Project Completion - 2021)