High Sensitive Methane Sensor for Real-time Measurements of Methane Isotopes

Determination of isotopologue ratios are a critical tool in plant, microbial and ecosystem ecology, hydrology, biogeochemistry studies, and interrogation of environmental remediation. In addition, the most abundant elements utilized and exchanged by plants, microbes and ecosystems are carbon (C), hydrogen (H), oxygen (O) and nitrogen (N), all of which have naturally occurring stable isotope forms that can be used as natural tracers for understanding plant and microbial activities and cycling of carbon and nitrogen between soil, plants, and the atmosphere. In particular, real-time high sensitivity measurements of methane (CH4) concentrations in air and in the ground with the ability to detect the isotopic ratio and concentration (ppm) at a number of points within a spatial-region of 100m would be extremely valuable for a variety of applications. Amethyst Research will team with Appalachian Laboratory at the University of Maryland to deploy this methane isotope measurement system for measurements of methane fluxes in forest soils in New England and agricultural soils in eastern Maryland. Isotopic analysis of the CH4 within the soil and the air above would allow an understanding of the net effect of fractionation caused by methanotrophic and methanogenic bacteria in the soil. The low power automated sensor will be equipped with multiple senor heads that can be placed above or underground. These sensors will be connected to the main controller box via fiber optic array. Amethyst’s methane sensor will be based on a previously developed and proven field portable sensor for CO2 isotopic measurement that uses infrared absorption spectroscopy. This system will be modified for CH4 isotopic analysis. In the Phase I program Amethyst Research will design the field portable measurement system for methane isotope measurements and optimize all of the components to be able to detect methane at <1ppm levels and determine the isotopic ratios to 1 part per mil resolution. Commercial Application and Other Benefits: This detection system will be invaluable for real time measurements of soil methane for a variety of research applications. Once the system in built and proven it could also be used to detect methane leaks in buried pipe lines and less expensive, non-isotopic, systems could be built to detect leaks in above ground applications. By changing the laser source wavelength this system can be used to measure other gases.