Oxygen is essential for the development of higher life. However, it was hardly present in the oceans of the young Earth.
Oxygen is essential for the development of higher life. However, it was hardly present in the oceans of the young Earth. It was not until the evolution of photosynthetic bacteria that the oceans saw a significant increase in oxygen levels. By measuring tungsten isotope composition, an international research team with the participation of scientists from the University of Cologne’s Institute of Geology and Mineralogy has now laid the foundation for a more precise determination of the development of oxygen levels in the early oceans over time. Prospectively, they expect more precise insights into the evolution of life. In cooperation with scientists from ETH Zurich, the Universities of Bern and Tübingen, and the Leibniz Institute for Baltic Sea Research Warnemünde (IOW), geologists led by Dr Florian Kurzweil at the University of Cologne analysed the chemical element tungsten, which could act as an indicator element for oxygen, in today’s seawater. The results have been published in the Proceedings of the National Academy of Sciences (PNAS) under the title ‘Redox control on the tungsten isotope composition of seawater’. The research is part of the German Research Foundation’s priority programme ‘Building a Habitable Earth’.
Tungsten is present only in very small amounts in the oceans, making it difficult to accurately determine its concentration. It is even more difficult to determine the abundance of individual tungsten isotopes in seawater. Isotopes of an element have the same number of protons, but different numbers of neutrons. Hence, there are heavy tungsten isotopes with many neutrons and lighter tungsten isotopes with fewer neutrons. The analytical methods developed at the University of Cologne enable the most precise measurement of relative tungsten isotope abundances currently available worldwide.
Read more at University of Cologne
Image: With the research vessel Elisabeth Mann Borgese, the research team set out to collect seawater samples in the Baltic Sea. The geologists hope to gain insights into the oxygen content of the early oceans by determining tungsten isotopes in ancient sediment samples. (Credit: Leibniz Institute for Baltic Sea Research Warnemünde (IOW))
