Lab worker's hands using a machine

Compound-Specific Isotope Analysis (CSIA)

A tool in your toolbox to optimize characterization and quantification of in situ degradation at contaminated sites.

SiREM has added compound-specific isotope analysis, or CSIA to our portfolio of advanced tools for forensics and to help optimize remediation of contaminated sites.

With CSIA, stable isotope ratios in compounds of concern from elements such as carbon, hydrogen, oxygen, nitrogen, chlorine, and sulfur can be traced back to specific origins. This can help identify sources of compounds of concern, a process often called fingerprinting.

CSIA differentiates bond breaking degradative processes such as biotic and abiotic degradation, from non-bond breaking processes such as dilution, sorption and volatilization. CSIA is therefore extremely useful in understanding if contaminant mass is actually declining or if it is simply be sequestered, diluted or transferred to a different medium.

CSIA can help you understand if a compound is degrading through both biological processes and non-biological (abiotic) processes, this information can be provides robust multiple lines of evidence for monitored natural attenuation.

When CSIA is combined with SiREM’s other molecular biological tools, such as Gene-Trac® Testing and advanced Analytical Testing, and is incorporated into treatability studies, it can greatly enhance our understanding of potential sources, help choose the most effective remediation strategy, and accurately measure progress.

CSIA testing can help you accomplish the following:

  • Confirm contaminant degradation processes by diffeentiating from non-degradative losses.

  • Distinguish between contaminant sources.

  • Understand if there was more than one source of contaminants at the site.

  • Form strong conclusions about how a compound is degrading.

  • Measure progress at a site that is being remediated.

  • Decide whether monitored natural attenuation is a viable remedy for a site.

Trace stable isotope ratios of elements back to specific origins

  • Carbon
  • Hydrogen
  • Oxygen
  • Nitrogen
  • Chlorine
  • Sulfur

How It Works

CSIA assesses stable isotopes—atoms of an element that have the same number of protons but different numbers of neutrons. For example, the light form of carbon has 6 neutrons (12C, 6 protons and 6 neutrons) and the heavy form has 7 neutrons (13C, with 6 protons and 7 neutrons).

In nature, stable isotopes occur in a relatively constant ratio, for example 13C is around 1% of all carbon. This ratio is called the isotope signature. Because degradation processes favor molecules containing light isotopes, molecules with heavy isotopes become selectively enriched during degradation. This leads to a subtle, but measurable, shift in the isotope signature. Because other processes, like dilution, dispersion, and sorption do not cause this shift, proof of degradation can be established through measuring changes in isotopic signatures over time.

Learn more by watching our CSIA webinar >

Stable isotopes are light and heavy atoms of the same element.

Degradation of a compound can lead to a subtle, but easily measurable, shift in this isotope signature.

Want to know more?

Contact us today, we would be happy to discuss with you.

CSIA Strategic Partnership

SiREM is proud to offer CSIA services through our strategic partnership with Isodetect GmbH of Leipzig, Germany. Isodetect offers isotope analytical services and scientific expertise to clients around the work who are working in groundwater remediation, the oil and gas industry, and environmental monitoring. Isodetect holds key knowledge and intellectual property for natural attenuation monitoring, source identification and in situ remediation at contaminated sites. Isodetect’s services include CSIA, stable isotope probing (SIP), in situ microcosms (BACTRAPs®), laboratory microcosm studies, metabolite analysis, Gene-Trac® testing (qPCR), and gas chromatography-mass spectrometry (GC-MS) screening.