Reconstructing the climate of the earth's history

Paleothermometers have been known to science since the 1950s. By measuring the quantities of the stable oxygen isotopes ^16Oand ^18O, it is possible to reconstruct the temperatures at which an organism - for example a mussel - formed its shell from carbonate. The quantity of the respective isotope depends primarily on the water temperature in the ocean at that time. However, the thermometer has weaknesses: Depending on which organism incorporated the carbonate from the water, the quantities differ and make the temperature reconstruction unreliable. Later alteration processes also influence the result. Very high water temperatures of up to 70 degrees Celsius are calculated for the young Earth, i.e. for the time several billion years ago - although these are highly controversial results.

The rare third isotope

Prof. Dr. Daniel Herwartz therefore uses the third stable oxygen isotope ^17Ofor his measurements in the project "The kinetic oxygen cycle in chemical sediments". This isotope is very rare and its precise measurement is challenging. The combined measurement of all three oxygen isotopes can help to identify and correct errors in the conclusions of previous measurements. Herwartz also hopes to obtain information about the processes involved in the incorporation of the isotopes in the form of carbonates by various organisms. Which reactions took place? At what pH value? Through theoretical predictions, laboratory experiments and comparison with empirical data, he wants to work out individual processes in detail.