Aktuelle Projekte der ORCAS Gruppe (nur englisch)

EURYI European Young Investigator Award (10/2006-04/2012)

The overall goals of the proposed project are to explore the formation of biospheric climate-relevant volatile organic compounds (VOCs) and to study their life-cycle utilising a stable isotope approach. The group will focus mainly on the three simple gases, methane, chloromethane and bromomethane but other C1 VOCs such as iodomethane, chloroform and bromoform which also play a role in atmospheric chemistry will also be of interest. Particular emphasis will be given to the fact that biospheric emissions of these gases are expected to drastically change in the 21st century as a response to global change. Climate feedbacks in the past will also be considered. After having identified and quantified all the major sources and having established the environmental parameters that control the fluxes of biospheric C1 VOCs we will apply numerical models of different complexity to simulate past and future scenarios of the atmospheric burden of these atmospherically important compounds. This will enhance our understanding of the life-cycle of C1 VOCs in the past, present and future and consequently provide insight into possible feedback mechanisms in the biosphere-atmosphere system. A multi-interdisciplinary approach requiring the interaction of several disciplines including geochemistry, biochemistry, analytical chemistry and atmospheric- chemistry and physics is envisaged to realise the aims of the project.

Area of interest: salt lakes in Southern Russia; Picture: F. Keppler, MPI for Chemistry

HALOPROC Natural Halogenation Processes in the Environment (04/2008-01/2014)

Although it has recently become more evident that terrestrial ecosystems play an important role in production, consumption and emission of volatile halogenated compounds, they are still very poorly characterized. A potentially powerful tool in the investigation of the lifecycle of halomethanes is the use of stable isotope ratios. Variations in the carbon isotope composition of compounds, produced and destroyed in the global carbon cycle, are often used successfully to investigate biogeochemical cycles and global source-sink relationships, as well as the underlying mechanisms. The objective of the proposed research activities as part of the DFG research unit HALOPROC is to further explore the formation of environmentally-relevant halomethanes such as chloromethane, bromomethane, iodomethane, chloroform and bromoform; and to study their biogeochemical cycles utilising a stable isotope approach. Stable isotope values of volatile halogenated compounds will be measured from a series of samples collected in semi-arid areas of South Russia. Laboratory investigations of several environmental parameters influencing the emissions of halocarbons will be conducted. Furthermore, a series of laboratory experiments with varying degrees of complexity will be conducted to gain more information about the underlying mechanisms involved in halocarbon formation.

For more information, see Website Natural Halogenation Processes

ISOTOPE-BIOGAS (01/2007-)

Newly developed analytical instruments that are based on Laser Absorption Spectroscopy will be applied to measure the stable carbon isotope values of methane and carbon dioxide during anaerobic digestion (in biogas reactors). For quality control values will be compared with those measured by Continuous-Flow Isotope Ratio Mass Spectrometry. Furthermore, stable carbon isotope labeling experiments of organic compounds will be applied in batch experiments to identify important reaction pathways. The project is conducted in cooperation with the Bayerische Landesanstalt für Landwirtschaft (LFL).

Pattern of stable hydrogen isotopes in precipitation over Europe

ISOTOPE-TRACE (03/2008-)

Stable hydrogen isotope analysis is emerging as a powerful tool in global climate research. Thus variations in stable hydrogen isotope values of water in ice cores are being used to reconstruct past climatic temperature fluctuations. Furthermore, stable hydrogen isotope values of wood in the annual growth rings of trees can provide the information necessary to reconstruct past climates and to assist ecophysiological research. Compound specific stable hydrogen isotope values of biomarkers accumulated in sediments are increasingly employed as paleoclimatic and paleohydrological proxies. This project aims to test if methoxyl groups (from lignin and pectin) of biomaterial can serve as a tool in assisting not only with the constraint of the geographical origin of biomaterial (e.g. wood and potatoes) but also with paleoclimate, food authenticity and forensic investigations.

Is the stable hydrogen isotope pattern in precipitation retained in methoxyl groups of tree rings? Can it be used for paleoclimate studies of trees and sediments?