The School of Geography, Earth and Environmental Sciences organises a regular series of research seminars throughout the academic year to which everyone is welcome to attend. Speakers - both external and internal to the University - will talk on topics related to all aspects of Earth Sciences.
Today's speaker is Dr Sabine Lengger, Lecturer in Chemistry from the School of Geography, Earth and Environmental Sciences.
Lipids (fats) of organisms can be preserved over geological timescales. Over time, they often lose specific aspects of their structures. Notwithstanding, their presence and distribution in geological samples can give astonishing amounts of information about the paleoenvironment at the time of deposition. An example is the TEX86 proxy using preserved membrane lipids of microorganisms to reconstruct sea surface temperatures. Another is the use of bacterial lipids called hopanes to constrain processes involving methane.
Some of the causal relationships between environmental conditions and proxies, however, are not completely understood, and could lead to biased paleoreconstructions. An example for this are e.g. discrepancies between TEX86 and other paleotemperature proxies during Oceanic Anoxic Events. Studying modern biogeochemical processes involving the lipid-producing organisms can help us to better constrain potential bias affecting organic proxies and paleoclimate reconstruction. For this, the analysis of the biological form of the lipid molecules, containing high amounts of additional information, can give valuable insights. However, these can sometimes pose substantial analytical challenges. Here, I will discuss organic proxies, how we can use new methods for the analysis of biolipids, insights gained for paleoreconstructions, and how novel methods can reveal their stable isotopic composition, with a particular focus on paleotemperature proxies and the methane cycle.