Soil properties and organic matter transport
Earth surface dynamics following an experimental wildfire: subproject on soil properties and organic matter transport
Universität Göttingen, Institut für Geographie, AG Landscape Geoscience, Prof. Dr. Elisabeth Dietze , Lea V. DeutschSoil and contaminants after the fire
When a wildfire has been extinguished, the story is far from over for the soil: ash, charred material, and mobilized contaminants and nutrients alter its composition—often for years. Of particular relevance are polycyclic aromatic hydrocarbons (PAHs) and heavy metals, which are already enriched in the soil as a result of the Harz region’s historical mining legacy. As the coordinating working group for the overall project, the Landscape Geoscience Group brings together all soil and contaminant data from the burn sites. The controlled burn experiment in the Goslar FFR Lab is designed as a real-world laboratory: it complements our ongoing investigations at the uncontrolled burn site near the Grane Reservoir, where a fire occurred in June 2025 and where we have documented soil and surface changes since the event. While the site shows how an actual wildfire, without experimental control, affects material cycling, the controlled experiment enables us, for the first time, to investigate the specific effects of different fire-suppression strategies under comparable initial conditions. We systematically collect soil samples before the experiment, immediately afterwards, and after each of the following two winters. We analyse them for organic contaminants such as PAHs, as well as physical properties including susceptibility to erosion and water repellency. Our assessment also incorporates the heavy-metal concentrations measured in the same samples by the Chair of Physical Geography and Geoecology at RWTH Aachen University. This is the core of our analysis: we directly relate PAH and heavy-metal concentrations to the four fire-suppression strategies being tested. Does the use of wetting agents or fire retardants affect the extent to which—and the rate at which—contaminants are mobilized in the soil? And how does this influence soil erosion towards adjacent water bodies? In this way, we directly link soil chemistry to issues of water-resource and drinking-water protection, allowing us to identify which fire-suppression method places the least burden on people and the environment.
Burn site near the Grane Reservoir (June 2025) and sampling of burned soil
Fotos: Lea Deutsch
Projektleitung:
Prof. Dr. Elisabeth Dietze
Goldschmidtstraße 5, 37077 Göttingen
edietze@uni-goettingen.de