Aquatic biogeochemistry

Lead: M. Sc. Lena Heinrich

Waterbodies are havens of biodiversity, drinking water reservoirs for humans, are used for navigation or for recreation. On the other hand, the high pressure of use puts a strain on water bodies. Again and again, these pressures become apparent, for example, through fish kills, as in 2022 on the Oder or in 1986 on the Rhine. If bathing waters have to be closed due to algae or blue-green algae blooms, like Lake Tegel in Berlin in 2021, or if drinking water production is restricted as a result, like Tai Hu Lake west of Shanghai in 2007, this is perceived as a social crisis. The European Water Framework Directive for the protection of water bodies has been in force since 2000. The acute death of aquatic organisms or their slow disappearance often has biochemical and physical causes. Be it a lack of oxygen at the bottom of water bodies, overloading with nutrients or the discharge of waste water that is too warm. The causes of poor water quality are manifold and often due to human activities. This is where the research activities of our working group come in. We analyse the presence or absence of certain minerals, such as iron phosphate (vivianite), iron sulphides (e.g. pyrite) or oxides (e.g. lepidocrocite), in water sediments or the presence of dissolved substances such as iron (Fe²⁺), sulphur (S^2-, SO₄^2-) or chloride (Cl^-) in water and investigate their influence on the quality status of water bodies. With the help of multi-sensor systems such as the mobile Biofish, with which water quality can be mapped three-dimensionally, or the Biolift, which profiles water quality over depth, the dynamics of physical, chemical and biological conditions in water bodies are determined. In combination with weather data, algal blooms can be modelled, for example. Specifically, we work on, among other things

redox-sensitive processes in water bodies and their sediments,
mechanisms of algal blooms,
pollutant loads in water bodies,
properties of subhydric soil types of stillwaters,
development of concepts for monitoring the quality of water bodies.