GC-Py/C-,EA-,TC-IRMS

Isotope Ratio Mass Spectrometer for 2H, 13C, 15N and 18O bulk and compound-specific isotope analysis

19/07/2024 to 01/07/2028

The environmental sciences of the University of Tuebingen have a long-term track record of applying isotopes in ecosystem and paleoenvironmental studies. Recently, new isotope techniques appeared within biogeochemistry, which allow unprecedented insights into the relation of the biota and its abiotic environment, enabling us to study the interactions of the Biosphere and the Geosphere from smallest scales at mineral surfaces up to landscapes. Many of these new applications link biogeochemistry with plant or microbial ecology and look at specific processes at key geo-biosphere interfaces (rhizosphere, hyphosphere, detritusphere, microbial habitats, etc.). They either require highly flexible co-measurement of multiple isotopes (13C, 15N, 18O and 2H), and/or involve compound-specific isotope analysis (CSIA) of each of the four light isotopes in key substance classes. Both entails novel, state-of-the-art instrumentation, with a set of peripheries for different sample types and matrices, i.e. an elemental analyser (EA), a thermal conversion unit (TC), a gas chromatograph (GC) linked with- or without combustion (C) or pyrolysis (Py) unit to a sensitive isotope ratio mass spectrometer (IRMS). This will allow to measure solid samples for 13C and 15N simultaneously (EA-IRMS), 18O and 2H bulk isotope signature of solids and liquids (TC-IRMS), gases at high concentrations e.g. for 13C of CO2 (GC-IRMS), dissolved compounds for their 13C and 15N values (GC-C-IRMS) and even for their 2H and 18O signature (GC-Py-IRMS). This isotope portfolio paves in its combination the way for ground-breaking new research applications, e.g. by combining position-specific isotope labelling-based metabolic flux tracing with environmental thermodynamics, by evaluating the ecological potential of storage compounds buffering fluctuating environments, or the genetic potential of subsoil mycorrhiza for future sustainable agriculture. The applicants will develop new approaches to assess the role of viruses on ecosystem biogeochemistry, the impact of insect migration on ecosystem food webs and the bioeconomy of element trade at biogeochemical interfaces. New 2H- and 18O-based approaches, boosted by the implementation of compound-specific 18O analysis, will allow to assess the relevance of metabolic water for the soil microbiome under drought, the role of cata- and anabolism in the formation of soil organic matter and the contribution of O2-based oxidative processes to soil organic matter transformation.