Lipid and PAH composition as indicators for conditions of thermal degradation

DFG WI 2810/9-1

From 01/2010 to 12/2011

Principal Investigator: Guido L.B. Wiesenberg

Lipids are main components of fresh plant biomass and organic matter in soils and sediments. Individual plants and plant groups carry a specific lipid distribution pattern which allows for their application as biomarkers. Thermal degradation of plant biomass i.e. during anthropogenic or wildfires shifts the distribution patterns depending on burning conditions. Therefore, burning conditions may be reconstructed based on patterns of primary lipidic components like alcohols and acids as well as their degradation products including aliphatic and polycyclic aromatic hydrocarbons (PAHs). Charred biomass incorporated in situ in soils and sediments will be subjected to biomarker analyses. Within an experiment the influence of temperature, duration, and oxygen availability during thermal degradation on modification of lipid distribution patterns of several plant species will be investigated. Experimental results are compared to recent and fossil soils and sediments containing charred biomass. Recent soils are selected due to frequent burning and well known burning history, whereas ancient soils are selected with a known burning history based on archaeological artefacts. The results of the project facilitate for the first time the reconstruction of fire conditions and vegetation in natural and anthropogenically modified ecosystems by means of lipid composition of charred materials from soils and sediments.