Laser-based analyzer for detection of 12C/13C and H/D in methane

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Methane aside of carbon dioxide is the important greenhouse gas in the context of current climatic change. Methane concentrations in the atmosphere are currently rising; however, the natural and anthropogenic methane sources and their drivers have so far not been fully resolved. A dual laser methane analyser for the abundance of carbon-13 and deuterium in methane is to be established at the central laboratory of the Institute of Landscape Ecology, University of Münster, to address the methane cycle and fluxes in sediments, soils, coastal, and freshwater wetlands. The use of both stable isotopes of carbon and hydrogen will enable us to disentangle different methanogenic pathways and trace methane oxidation in these highly relevant ecosystems. We aim i) to understand controls of the methane cycle under varying redox conditions, ii) to study its link to nitrogen fixation, iii) to study effects of wetland restoration iv) to address plant-microbe interactions in the wetland rhizospheres, v) to study methane cycling in thawing permafrost landscapes, and vi) to study methane uptake by oxidation in upland soils. The requested system is thus to be used for atmospheric samples of ambient concentrations (2-10 ppm) and for gas samples from incubations or in-situ samples from soils and sediments at elevated concentrations up to 2.5 % methane by volume. To this end, the system will be equipped with an automated inlet system to adjust the concentrations of samples to the measurement range of the instrument. Alternatively, the instrument will be capable of tracking changes in real-time by analyzing gas in a flow through mode at very short response times in order to be used along with automated gas flux chamber systems or mesocosm setups with constant flux measurements in the laboratory. Moreover, a weather-proof, temperature-controlled enclosure will allow field operation of the instrument and its direct connection to existing gas flux chamber systems on-site. The vacuum pumping system of the instrument will have safety features to protect the laser-optics in case of power failures and have a low power consumption for operation under suboptimal power supply in the field. The system will be mainly operated by the Ecohydrology and Biogeochemistry group, in cooperation with the Rhizosphere Biogeochemistry group and the Soil Ecology and Land Use group, but generally be open to all users in the central laboratory of the institute and beyond. Access is organized using a web-based system to schedule measurement times. As only limited amounts of data are generated, data can be stored on institutional servers with regular backups and can be made publicly available along with publications, codes or research compendia on common or on university-owned open-access platforms.