Hello, my name is David Bajnai (pronounciation: ˈdaːvid ˈbɒjnɒi). I am a research associate in geochemistry at the University of Cologne.
My scientific goals are to reconstruct accurate and precise seawater temperatures in geological times to learn about past (and future) climates. In my research, I focus on the stable isotope fractionations that happen during biomineralisation. The stable isotope composition of the fossil remains of marine calcifiers, e.g., belemnites and brachiopods, holds information on the surrounding water temperatures. By measuring this, palaeoceanographers can postulate how warm the oceans were millions of years ago. However, isotope fractionations, so-called vital effects, bias these temperature estimates. I am using the clumped isotope (∆47 and ∆48) and the triple oxygen isotope (∆17O) proxies to map these vital effects, correct for them, and thus determine unbiased, accurate temperature reconstructions.
2021-06-04: New article published in Paleoceanography and Paleoclimatology: Warm high-elevation mid-latitudes during the Miocene Climatic Optimum: Paleosol clumped isotope temperatures from the Northern Rocky Mountains, USA. Palaeosol carbonate ∆47 records from Montana and Idaho suggest stable (21±2 °C) continental temperatures over the Miocene Climatic Optimum (ca. 17–15 million years ago). Read the open access article here.
2021-06-02: New article published in Geophysical Research Letters: Devils Hole calcite was precipitated at ±1 °C stable aquifer temperatures during the last half million years. In this study, we investigated the Devils Hole caves that provide a reference oxygen isotope time series for North America. Dual clumped isotope thermometry (∆47 and ∆48) reveals that groundwater temperature did not change significantly in the last half-million years. Variations in the oxygen isotope composition of the deposited carbonates solely reflect variations in the oxygen isotope composition of the groundwater. Read the open access article here.
2021-05-13: Results from an in-progress study An experimental constraint on the oxygen isotope fractionation (18O/16O) between water and aqueous hydroxide ion will be presented at the Goldschmidt online conference on 7 July 2021. Read the abstract here.
2021-04-13: New article published in Geochemistry, Geophysics, Geosystems: InterCarb: A community effort to improve inter‐laboratory standardization of the carbonate clumped isotope thermometer using carbonate standards. This community effort, led by Stefano Bernasconi and involving 22 laboratories, provides consensus ∆47 values for carbonate standards and describes best practices for carbonate-based standardisation. Read the open access article here. Read the research spotlight here.
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