SGER: High-Resolution, In Situ Measurements of Metabolic Gas Profiles in Sediments

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The ability to measure concentrations of metabolic gases, such as CO2 CH4, O2, H2 and others, can provide insights into biogeochemical processes associated with soils or sediments. Measurement of these metabolic gases with high resolution is limited both by the difficulty of sampling porewaters from sediments and by disturbances caused by porewater sampling. This research project will measure volatile gases in situ using a battery-operated portable mass spectrometer and a small semi- permeable probe. The basic portable mass spectrometer has already been developed. The present research will focus on development of a suitable probe that can be directly inserted into sediments, as well as augmentation of the mass spectrometer itself. The system will be tested in peatland sediments where distributions and gradients of methane, oxygen, carbon dioxide are important for understanding the mechanisms of trace gas exchange with the atmosphere. The proposed system, because it is based on a mass spectrometer, also has the potential to support in situ stable isotope enrichment studies.