Redox processes of carbon and sulfur in peat soil affected by water table fluctuations
Tobias Goldhammer (01/2006)
Support: Christian Blodau
Facing global change due to increasing CO2 concentrations in the atmosphere, improved knowledge of carbon releasing mechanisms is necessary, and the identification of sources and sinks is the crucial point to the budget-based approach. Their enormous amount of sequestrated carbon considered, the future behaviour of peatlands under changing environmental conditions might be of some relevance. However, understanding of carbon turnover processes in peat soils is far from being complete. This thesis is trying to deliver a small contribution to this complex of questions by investigating redox processes with carbon participation. Assuming that sulfur is the next important element in nutrient limitated peatland systems, the following hypothesis are being tested: 1. Anaerobic carbon mineralisation and methanogenesis are driven by an anaerobic sulfur cycle 2. Organic electron acceptors can function as a short time storage for redox equivalents 3. These two processes are affected by water table fluctuations, which lead to a change of the redox regime This is accomplished by a tree-fold approach: 1. Incubation experiments with field samples to identify pools and concentrations of redox species before and after the summer drainage 2. Lab-controlled simulation of a drying/rewetting cycle with peat substrate 3. In situ measurement of sulfate reduction, using a downscaled hydrogeological push-pull tracer technique All field work is done in Mer Bleue Bog, Canada. Laboratory work is done at Limnological Research Station, Department of Hydrology, University of Bayreuth.