Multiple stressors and pollutants
Freshwaters are used intensively by humans, meaning that they are exposed to a number of stressors. We explore the complex interrelations and impacts of the different stressors: How do nutrients and contaminants enter our surface waters, which factors play a central role in this process, and where are rivers and lakes in a particularly poor state? Nutrient inputs of nitrogen and phosphate, for example, may affect water quality, leading to algal blooms. It is often impossible to completely remove pharmaceuticals and biocides during wastewater treatment. They then end up in rivers and lakes, where they may affect the hormonal metabolism of fish and amphibians. Mining may lead to the contamination of adjacent freshwaters with potash and sulphate. Land use change, urbanisation, water control structures and the increasing use of artificial lighting at night (light pollution) exert additional pressure on our freshwaters. In our research, we acknowledge that use by humans is an important part of reality – only then can future-oriented solutions be developed.
Despite the increasing concern about the harmful effects of micro- and nanoplastics (MNPs), so far, there exist no harmonised guidelines for testing the ecotoxicity of MNPs. An international research team with IGB has now developed protocols to assess the toxicity of these substances in soil and aquatic ecosystems.
Time Series of Electrical Conductivity Fluctuations Give Insights Into Long-Term Solute Transport Dynamics of an Urban Stream
A solute transport model was applied to diurnal electrical conductivity fluctuations in a river to obtain long-term time series of transport metrics. The study showed that differences in transport metrics occur in adjacent river reaches and that mowing of macrophytes can increase the transient storage area.
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.
Multispecies assemblages and multiple stressors: synthesizing the state of experimental research in freshwaters
This is a review of multiple-stressor research in freshwaters, particularly studies that have experimentally manipulated multiple stressors and measured responses of multispecies assemblages. There is a gap between biotic interactions under multiple stressors and ecosystem recovery pathways after restoration, indicating a disconnect between multiple stressor research and environmental practice.
The authors analysed data from 14 lakes in the Berlin catchment area for the period 2000 to 2020. They found that if sulphate concentrations had not increased, there would be about 20 per cent more reeds in the sulphate-polluted lakes today.