Practical isotopic analyzer for subsurface gases

Real-time, in-situ isotopic measurements of vadose-zone components are valuable within a multitude of disciplines to elucidate transport, phase transfer, and biogeochemical transformation processes in both natural and contaminated environments. Studies related to climate change, contaminant biodegradation and remediation, underground gas storage and disposal monitoring, and land management all benefit from isotopic measurement. Mesa Photonics is specifically interested in using stable isotopes in real-time to advance an innovative process-based method for vadose-zone assessment This project is a collaboration between Mesa Photonics and the Bureau of Economic Geology (BEG) at the University of Texas. Mesa will address the technical challenges of a new optical technique for rapid, continuous isotope ratio measurements in soil gas. BEG will perform microcosm laboratory studies to assess the range of isotopic analytical capabilities required to assess coupled biotic and abiotic transformations in the vadose zone. Co-dissolution of CO2 gas with soil carbonate and denitrification will be targeted for study. The stable isotopes of carbon, oxygen and nitrogen will be assessed to determine a preliminary range of isotopic fractionation that can be expected. Key aspects of an optical isotope analyzer will be tested to determine the expected performance capabilities of Phase II and commercial analyzers. Changes in stable isotope ratios of carbon, nitrogen and oxygen, during dissolution and/or denitrification will be measured by the University of Texas isotope laboratory and results compared with the capabilities demonstrated by the new optical isotope measurement method. Mesa Photonics and the University of Texas plan to develop a new scientific instrument that can aid understanding of soils and groundwater that are important to agriculture, hydrology, and climate. Commercial Application and Other Benefits: Commercial isotopic gas analyzers will be suitable for field studies including long-term continuous monitoring of gas isotope ratios. Instruments will be easily transported for field work, fully automated, self-calibrating, and will operate at low power. Direct measurement of isotopes of nitrogen and oxygen in soil gas is a new capability not found in competing commercial products. Installation and operating costs will be minimal. Multiple analyzers will be connected to a wireless network for data transfers and maintenance logging.