Stable Isotope Laboratory for Sediments and Water

In the laboratories for stable isotopes in sediments and water, the isotope ratios of the light elements nitrogen (N), carbon (C) and oxygen (O) in continental geoarchives such as lake sediments and speleothems as well as oxygen (O) and hydrogen (H) in precipitation and surface water are determined. This allows us to decipher changing environmental conditions and climate fluctuations in continental climate archives. For a better understanding of the archives, we use monitoring systems that record seasonal changes, the results of which can be transferred into the past.

Stable isotopes are non-radioactive nuclides of an element with the same number of protons and different numbers of neutrons and therefore different atomic masses. This results in different physical and chemical properties, which can lead to a shift in the isotope ratios in a substance (in our case organic matter, carbonate or water). The measured isotope ratios δ¹⁵N, δ¹³C, δ¹⁸O and δD form “fingerprints” of past environmental conditions and can thus indicate changes in precipitation, evaporation, temperatures, vegetation, nutrient input and organic productivity in our archives.

The shifts in isotope ratios in natural processes are often very small. These changes can be measured very precisely using isotope ratio mass spectrometers (IRMS) or laser spectroscopy (cavity ring down spectroscopy - CRDS).

We have presented key aspects of our work together with the Laboratory for Dendroclimatology using the example of oxygen isotopes here: "Vom Monitoring zum Klimaarchiv".