(Dept. 1) Ecohydrology and Biogeochemistry
The interactions within and between green water (in terrestrial systems) and blue water (lakes, rivers, and subsurface aquifers) affect in complex ways the habitats for organisms and the reactive transport of abiotic components. Aquatic and terrestrial systems are coupled at multiple spatio-temporal scales. The overall goal of the Department of Ecohydrology and Biogeochemistry is to understand the ecohydrological and biogeochemical processes of these connected land- and waterscapes in natural, rural and urban environments. Therefore, our research projects focus on the following core topics:
- Interactions of landscape-freshwater ecosystems
- Physical and biogeochemical drivers under global change
- Water security in disturbed and urban systems
In our research, we integrate different modelling approaches with data collected in field studies, in large-scale manipulation studies, by long-term monitoring and in laboratory experiments. We study ecohydrological and biogeochemical processes using a variety of tracer techniques, particularly stable isotopes, and by measuring naturally dissolved solutes, conservative geogenic ions, trace organic matter, and nutrients. In doing so, we combine basic research with application aspects and aim to record and model the effects of climate and land use changes. With its laboratory infrastructure and expertise in the fields of inorganic and organic analysis as well as isotope measurement, the department performs a central function for the entire institute. To achieve our research goal, we combine our professional expertise from the research disciplines of hydrology, geochemistry, aquatic physics, ecology, environmental engineering, and geography.
Geochemical focusing and burial of sedimentary iron, manganese, and phosphorus during lake eutrophication
From the distribution of manganese, iron and phosphorus within sediment cores from 11 water depths of Lake Arendsee, changes in the trophic state and oxygen conditions could be reconstructed. The redox-controlled geochemical focussing induced authigenic vivianite formation under oligo-mesotrophic conditions about 100 years ago, resulting locally in strongly increased burial phosphorus deposition.
Spatial variability of radon production rates in an alluvial aquifer affects travel time estimates of groundwater originating from a losing stream
Radon in surface water is mostly used to localise and quantify groundwater discharge. The study presents the opposite approach and use radon to estimate travel times of infiltrated surface water in the aquifer. The spatial heterogeneity of radon production rates complicates this approach, but the problems can be overcome by additionally considering temperature and hydraulic heads.
Estimates of water partitioning in complex urban landscapes with isotope-aided ecohydrological modelling
The authors used isotopes in an ecohydrological model to estimate evapotranspiration (ET) from the landscape of Berlin. This resolved components of ET and quantified transpiration, soil evaporation and evaporation of vegetation-intercepted water. Transpiration from tree-covered areas dominates; with ~80% of ET for urban cooling coming from woodland green spaces covering ~25% of the urban area.
Functional multi-scale integration of agricultural nitrogen-budgets into catchment water quality modeling
Using field-experimental data, crop N uptake responses to fertilizer management were parsimoniously conceptualized and integrated into a catchment diffuse-N model. The improved catchment modeling further facilitated integration with agricultural budget-based assessments.
Divergent roles of iron and aluminum in sediment organic matter association at the terrestrial–aquatic interface
The authors hypothesized that the variation in sediment redox and pH regime govern how iron (Fe) a.aluminum (Al) interact with organic matter (OM) in near-surface mineral sediments.The reactive monomeric Al preferably binds with organic ligands from less-decomposed OM under acidic and anoxic conditions. Low-crystallinity Fe formed under oxic conditions binds with more microbially-processed OM.