Stable and non-traditional isotopes
Stable isotope geochemistry is concerned with the measurement and interpretation of mass-dependent enrichments or depletions of the stable isotopes of an element (e.g. 18O relative to 16O). Stable isotope fractionation results from equilibrium isotope exchange or kinetic isotope separation mechanisms.
In earth sciences, stable isotopes are applied as natural tracers, e.g. to elucidate sources and their relative contributions in water masses and for process identification (e.g. involvement of microbes). Furthermore, because stable isotope partitioning depends on temperature, stable isotopes can be used as paleothermometers.
In the last fifty years stable isotope geochemistry was traditionally concerned with a few light elements (mainly H, C, N, O, S). From the seventies onwards, double-spike thermal ionization mass spectrometry was used to unravel mass-dependent variations in heavier elements such as Cd, Ca, Cr, Fe, and Se. Following the advent of multiple-collector inductively coupled plasma - mass spectrometry (MC-ICP-MS), within only a few years papers reported measurements of a wide range of „non-traditional“ stable isotopes, including Li, B, Mg, Si, Ca, Ti, Fe, Cu, Zn, Ge, Se, Mo, Cd, Sn, Sb and even Hg and Tl. Problems that are addressed include many different aspects of natural sciences, such as climate change, formation of the solar system or medical research. However, most "non-traditional" stable isotope systems are still in their infancy and the fractionation behavior is little studied. The stable isotope variations in nature and experiments do not always exceed the analytical reproducibilities by much. Furthermore in the laboratory, analytical artifacts and frustration may be easily produced. Think positive! There is much room for improvement and progress in the future.
Currently, we focus on the analyses of the stable isotope compositions of the earth-alkaline elements Ca, Mg and Sr for applications in marine geochemistry.
Showcase Projects
- ArcheGeo - Coralline sclerosponges as archives for geochemical and climatological proxies
- CARLA - The role of high and low temperature oceanic crust alteration on the marine calcium budget
- MAGISO - Magnesium Isotopes (d26Mg) as proxies for biogenic and abiogenic calcification and for the chemical evolution of Phanerozoic oceans
- SENECA - The dependence of strontium isotope fractionation (d88Sr) during temperature controlled precipitation of calcium carbonate
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