A multi-disciplinary approach to delineate small scale interactions and couplings between hydrology and biogeochemistry in riparian wetlands.

FR 2858/2-1

In recent years, many studies have investigated the fundamental couplings between hydrology and biogeochemistry and researchers began to understand how feedback mechanisms between hydrology and biogeochemistry affect nutrient cycling (e.g. carbon or nitrogen) within terrestrial or stream ecosystems. However, a lot of knowledge gaps still exist, especially the relevance of interactions between hydrology and biogeochemistry on scales that are important to ecosystem functions and human interactions remains a challenging field of research. Especially for wetland ecosystems, the complex couplings between hydrology and biogeochemistry together with their potential influence on biogeochemical process patchiness, solute transformation and mobilization processes is only poorly understood. In order to really understand the fate of nutrients and solutes within wetland ecosystems, we need to focus on directly investigating the fundamental coupling mechanisms between static (e.g. soil properties, topographic patterns) and dynamic controls (e.g. surface and subsurface flow patterns, temperature and hydro-/biogeochemical boundary conditions) under field conditions. This will provide us important insights into how the spatial and temporal variations of biogeochemical activities in wetland systems are controlled by interactions between hydrological and biogeochemical processes and further will support us in developing reliable modeling frameworks. To improve our conceptual understanding about the nature of these interactions in wetland ecosystems, combined knowledge of physical hydrologists, experimental biogeochemists and numerical modelers along with novel research methods are necessary. Modern geophysical techniques like electrical resistivity tomography (ERT) or self potential measurements (SP) offer possibilities to directly investigating redox conditions, subsurface flow patterns and transport processes under field conditions without significantly affecting or altering the hydrological/biogeochemical characteristics of the system. Sate of the art ERT methods allow imaging of tracer solute migration in 2D/3D at markedly high spatial resolutions, information that subsequently can be used to investigate subsurface flow patterns and transport processes.

Objectives:

• Develop and apply novel and non-destructive field methods for a simultaneous investigation of physical controlled transport and biogeochemical controlled reaction processes in riparian wetlands.
• Improve our conceptual model understanding of how biogeochemical processes and hot spots in space and time are controlled by hydrological processes

DFG funding ID 279180939