Compound-specific isotope analysis (CSIA) is a specialized laboratory method that can provide direct evidence of biological degradation of chlorinated solvents in groundwater plumes. CSIA can also support assessment of the strength of other natural attenuation processes. However, CSIA data alone can be difficult to interpret, especially at sites with complex hydrogeology or release histories.

The popularity of CSIA has risen rapidly among project managers as one line of evidence supporting Monitored Natural Attenuation (MNA) remedies. The CSIA-RTM Guidance Document (link below) describes methods for collecting and interpreting CSIA data.

Simple data interpretation techniques described in the Guidance Document include carbon isotope mass balances, dual isotope plots and isotope ratio vs. fraction of contaminant remaining plots.

Additionally, the Guidance Document introduces a “Generation 3 MNA Analysis” where CSIA data and simple reactive transport models (RTMs) are combined in a new and novel way to strengthen interpretation of both CSIA and conventional analytical data. Generation 3 MNA analyses provide stronger, clearer evidence of the strength of attenuation processes for chlorinated solvent plumes.

Links below provide access to CSIA-RTM software for interpretation of CSIA data. The software installation and use is described in the Guidance Document and training slides located in Appendix C of the Guidance.

The CSIA-RTM model and guidance document have been funded by ESTCP as part of Project ER-201029.

How to Cite: ESTCP Project ER-201029. Environmental Security and Technology Certification Program, Arlington, Virginia

System Requirements

Windows 7 and above; 32 Bit Microsoft Office 2007 and above; Excel Application