Reconstructing Changes in Regional Hydrology during the Holocene employing Novel Stable Isotope and Molecular Proxies

• Applicant: Professor Dr. Dirk Sachse
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: from 2009 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 104302536

The timing and magnitude of the response of the continental hydrological cycle to global climate changes is still not well understood. Especially abrupt climatic change during the Holocene is often most severely expressed through changes in hydrology on the continents. Knowledge of these processes and it’s causes however, is essential, when trying to predict the consequences of anthropogenic climate change on hydrological processes. Differences in regional responses of the terrestrial hydrological system are largely unknown due to a lack of direct hydrological proxies and paleoclimate records. A promising new paleohydrological proxy, the hydrogen isotopic composition of individual lipid biomarkers, has been emerging in the last years, which is capable of enhancing our knowledge about changes in hydrology over the continents. Therefore, I propose to establish an Emmy Noether Research Group with the following aims: (1) Advance and refine the use of lipid biomarker hydrogen isotope measurement as a paleohydrological proxy for terrestrial ecosystems through comprehensive calibration studies. Through studies on plants under controlled greenhouse conditions as well as of plants and soils along steep (natural) hydrological gradients, we will be able to understand the factors influencing the hydrogen isotopic composition of terrestrial plant derived lipids – apart from the source water isotopic composition. This work will fully establish the use of lipid biomarker hydrogen isotopes as a viable paleohydrological proxy for terrestrial ecosystems. (2) Obtain high-resolution records of changes in precipitation, plant evapotranspiration and atmospheric circulation throughout the Holocene from temperate, arid and highly seasonal climatic regimes. By applying compound-specific isotope analysis to excellent continental climate archives, maar lakes, throughout the Holocene we will be able to determine the timing and magnitude of regional hydrological changes. We will compare the response of this new proxy to changes in hydrology for different climate mean states (temperate, arid and monsoonal climate regimes). Special emphasis will be placed on the nature and timing of precipitation and evapotranspiration changes during abrupt climate transitions, such as the Younger Dryas in Central Europe. Our work will also provide better constraints on variations in precipitation as a consequence of changing monsoonal patterns in the Tropics, a region which will most harshly effected by changing hydrology through anthropogenic climate change. The outcome of the work proposed here will significantly enhance our knowledge about changes in continental paleohydrology throughout the Holocene as well as establish the use of a new paleohydrological proxy within the paleoclimate community.

• DFG Programme: Independent Junior Research Groups
• Major Instrumentation: Accelerated Solvent Extraction System + Zubehör (6 Ektraktionszellen Kit) ; GC-FID/MSD System
• Instrumentation Group: 1310 Extraktionsgeräte, Verteilungsapparaturen ; 1700 Massenspektrometer