Selected publications

Persistent, mobile and toxic (PMT) substances pose a threat to water supplies and aquatic ecosystems. This review article presents our current knowledge on PMT substances in urban stormwater and identifies future research needs for improved stormwater monitoring and management.

The authors conducted monthly UAV flights for 2 years in a riparian wetland in Germany. Such multi-flight-based classification outperformed single-flight-based ones, providing a picture of vegetation community evolution. Apart from contributing to an evidence base for wetland management, such multi-flight UAV vegetation mapping could provide fundamental insights into their landscape ecohydrology.

The authors analysed a data set of 66-yr streamwater quality,  21-yr of groundwater quality and 31-yr streamflow nested from the heavily urbanized Panke catchment in Berlin. The upstream parts showed a flow regime most sensitive to changes in hydroclimatic conditions, downstream sites are more influenced by wastewater effluents, urban storm drains and inter-basin transfers for flood alleviation.

As the hyporheic zone of rivers can be very heterogeneous already at cm-scales, the authors developed an experimental setup to preset short and shallow hyporheic flow paths in the field and to sample pore water. In this experimental setup, the authors were able to study the attenuation of 18 different trace organic compounds wherein the majority were attenuated within the short oxic sections.

Using seasonal, large scale synoptic sampling of stable water isotopes and tritium along the Spree allowed to assess water cycling, storage and losses. The Spree is heavily regulated and drought-sensitive due to high evapotranspiration losses. Such insights are important to adjust water management strategies.

Long-term stream nitrate nitrogen concentrations and concentration-discharge were investigated along the Spree revealing significant heterogeneity in both variables. The upstream parts and winter seasons showed the most serious pollution. Concentrations and relationships are also likely to respond strongly to future droughts, leading to challenges for future land and water management.

This study investigated the mobilisation and transport of particle-associated organic contaminants and their cytotoxicity in a river during storm events. Cytotoxicity determined in cell-based bioassays correlated linearly with total suspended solids concentration in a river, demonstrating that particle-associated contaminant mixtures can strongly affect river water quality during rain events.

The study investigated the impact of streamwater flow velocities and the resulting bedform migration on the CO2 production in streambeds. State-of-the-art 2-dimensional imaging techniques reveal the CO2 distribution in the streambed, an increasing CO2 production in the upper sediment and a decreasing hydrological exchange with deeper sediment layers, with increasing flow velocities.