Our group uses the distribution and stable isotopic composition of biologically-produced organic molecules that accumulate in the environment to study climatic and ecological changes in the recent geologic past, and to determine how human activities influence these systems today. We make particular use of compound-specific hydrogen isotope ratios of lipid biomarkers. The large natural variability in these lipid hydrogen isotope ratios facilitates their use as proxies for diverse processes, and they encode information about climate, ecology, and metabolism. We work to improve our mechanistic understanding of the controls on the stable isotope distribution of biomarkers and other organic geological proxies, and apply these tools to answer questions about past changes and modern carbon cycling. 

New paper:Central European Hydroclimate Since the Younger Dryas Inferred from Vegetation‐Corrected Sedimentary Plant Wax δ²H Values

Plant wax hydrogen isotopes are an important and commonly used tool for reconstructing past hydroclimate from lake sediments. However, the isotopic composition of waxes can be impacted by both changing climate and changing vegetation sources. In this study, led by Organic Geochemistry PhD student Ricardo Santos, and recently published in Paleoceanography and Paleoclimatology, we tested different methods to correct sedimentary plant wax hydrogen isotope values for changes in vegetation source. We showed that in central Europe, a simple correction using the relative abundance of different plant waxes allows us to isolate changes in past precipitation hydrogen isotopes. This approach will facilitate improved reconstructions of past hydroclimate change from lake sediments throughout Europe. 

Link zur Publikation: https://doi.org/10.1029/2025PA005401

01 Oct, 2025 Welcome Elena! Elena Jovanovska started today as an Ambizione Fellow, hosted by the Organic Geochemistry group and co-hosted by the Animal Diversity and Evolution group. Elena’s project will investigate the evolutionary processes of adaptive radiation and the associated key innovations underlying rapid diversification in a unique assemblage of single-celled siliceous diatoms from the genus Diploneis inhabiting Lake Tanganyika, East Africa. 

15 Sept, 2025. Welcome Kelly! Kelly Tragash has just joined the Organic Geochemistry group as a PhD student. Kelly will work on soil mesocosms and soil cores from the Swiss Canopy Crane II site to improve our understanding of how soil microbes respond to drought, and the implications for carbon cycling in soils. 

7 Sept - 11 Sept, 2025: Members of the Organic Geochemistry group traveled to Porto, Portugal to attend the 32nd International Meeting on Organic Geochemistry. Group members presented data from lakes in Switzerland, New York state, and the tropical South Pacific, as well as the first results from our bacterial co-cultures. PhD student Antonia Klatt was recognized for her excellent talk with a student presentation award. Congratulations Antonia!