DBU Stipendium
The Alkanol Alternative Development
of a new climate proxy based on
substance-specific δ18O
isotope analyses of n-alkanol
lipid biomarkers
From 2015
Scholarship holder: Johnnes Hepp
Supervisors: Dr Michael Zech, Prof. Dr Bruno Glaser
Cooperation partners: Prof. Dr Roland Zech, Dr Christoph Mayr
The extreme weather conditions caused by anthropogenic climate change are considered to be the most serious problems facing humanity in the future. In addition, human development and, above all, cultural history have always been closely linked to natural climate fluctuations, which underlines the great interest in and relevance of climate research.
Loess palaeosol sequences are among the valuable climate archives that document Quaternary climate change in the past. However, the methods used to date to reconstruct climate history allow only limited quantitative conclusions to be drawn from these widely distributed archives. In recent decades, oxygen isotopes (δ18O) have become one of the most important quantitative climate proxies, which have been successfully applied to ice cores, stalagmites and tree rings, among other things. However, its application to many terrestrial climate archives is sometimes hampered by a lack of analytical methods. For example, it has not yet been possible to extract cellulose or hemicellulose-derived sugar biomarkers for δ18O analyses from loess palaeosol sequences. The development, validation and application of substance-specific δ18O analysis on n-alkanols therefore represents an innovative and promising alternative or extremely valuable addition to the methods available to date.
Therefore, this doctoral project aims to (i) develop methods for substance-specific δ18On-alkanol measurements using GC-Py-IRMS coupling; (ii) clarify whether plant wax-derived n-alkanols reflect the δ18O isotopy of leaf water; (iii) attempt to robustly determine the biosynthesis fractionation factor for δ18O of n-alkanols; (iv) apply the substance-specific d18On-alkanol method to a C-poor and carbonate-rich loess palaeosol sequence. To validate the δ18On-alkanol approach, existing sample material from a climate chamber study or transect study can be used. The subsequent application is carried out on loess palaeosol samples from the Crvenka profile (northern Serbia; province of Vojvodina), providing a unique opportunity to create a δ18On-alkanol record for continental Europe dating back approximately 140,000 years. The doctoral project thus makes a highly innovative and valuable analytical contribution to environmental and climate research at the climate-plant-soil interface.