New H₂O Isotope Spectrometer Opens Unique Insights into Exotic Components of the Global Water Cycle

The research group studies chemical sediments such as carbonates, sulfates, and phosphates. These minerals precipitate from water and incorporate its isotopic “fingerprint,” plus a temperature-dependent component. These signatures allow researchers to reconstruct the environmental and climatic conditions under which the minerals formed, sometimes millions of years ago.

Water isotopes fractionate due to processes such as evaporation, condensation, and precipitation. Lighter isotopes preferentially enter the gas phase, creating characteristic patterns in rain and snow that can be compared globally. As a result, water isotopes are powerful tracers of the global water cycle and past climate variability. Ice cores preserve such isotopic signals and represent some of the most important archives of Earth’s climate over the past approximately one million years.

In most natural processes, isotopes fractionate according to their mass. An important exception occurs during ozone formation, where mass-independent processes lead to an enrichment of rare isotopes in ozone and a negative ¹⁷O anomaly in atmospheric oxygen. This signature is transferred to water through respiration and metabolic processes and can therefore be detected in the body water of humans and animals, as well as in teeth and bones. Fossil dinosaur tooth enamel thus provides insights into the composition of the ancient atmosphere.

So-called metabolic water produced within organisms, also plays an important role today. For insects living in deserts, it can constitute a major part of their water balance. In potato shoots, the influence of atmospheric oxygen is likewise clearly detectable. In microorganisms like E. coli, a high proportion of metabolic water in cells is observed during phases of rapid growth.

Daniel Herwartz and his team focus on these rather exotic components of the water cycle and aim to fundamentally understand how the ¹⁷O anomaly is transferred from the atmosphere to H₂O and subsequently into geological archives. Their work combines studies of modern systems with investigations of geological archives from deep time.

With the installation of the CRDS analyser, the research group now has a powerful tool for analysing water from organic materials as well as crystal-bound water. The group looks forward to exploring new research questions together with national and international partners and advancing isotope analytics into previously inaccessible areas. The new instrument represents not only a technological advance but also a gateway to entirely new insights into the role of water in nature, the environment, and living systems. Additional instruments enabling ¹⁷O analyses in carbonates are planned for installation in the coming year.