Quantification of post sedimentary root-derived carbon in loess using molecular proxies to improve paleoenvironmental reconstruction

Organic constitutents in loess-paleosol sequences are used to reconstruct paleovegetation and paleoenvironmental conditions in terrestrial ecosystems. The prerequisite of such studies implies the incorporation of organic matter only during sedimentation or during soil formation, whereby it is assumed that this derives only from aboveground biomass. Recent studies on rhizoliths (calcified roots) in loess indicate that substantial parts of organic carbon(Corg) can be derived from roots and have been incorporated postsedimentary.This implies also the probable overprint of 13C, 14C and the molecular composition of organic matter within these sequences.

In this research project, postsedimentary inputs of root-derived organic matter are investigated based on plant-derived lipids in dependance of plant species, depth and distant to the (former) roots. Therefore, rhizolith and loess samples from Central to Southeastern Europe will be investigated for their lipid molecular composition. By the help of dating techniques such as radiocarbon and OSL dating the overprint of organic matter in the terrestrial sediments will be validated. The relevant mechanisms influencing incorporation of root-derived Corg in proximal and distal areas wil be investigated under field and laboratory conditions by the help of molecular and isotope tracers. The final aim of the project is to suggest an approach for the correction of the quantification of biogenic origins in terrestrial sediments to improve paleoenvironmental reconstructions based on loess organic matter.

Figure 1: Picture of a rhizolith