Start of experiments in the aquatic mesocosm facility at the UBT
Researchers irrigate aquatic mesocosms with fluorescent microplastic particles on the UBT site. The experiment, led by Dr Benjamin Gilfedder, measures the transport and fate of the particles in bodies of water. In future, different types of plastic are to be analysed in order to develop methods to prevent the unwanted spread and pollution of the environment with microplastics. Prof. Dr Christian Laforsch emphasises the importance of mesocosms for collaborative research.
Silke Hammer (Technical Assistant at the Limnological Research Station), Prof. Dr Vadym Aizinger (Prof. for Numerical Methods of Partial Differential Equations), Dr Benjamin Gilfedder (Head of the Limnological Research Station), Anna-Maria Seiverth (HiWi, former BA student at the Brombach Lake experiment), Prof. Dr Christoph Thomas (Prof. for Micrometeorology), Dr Hassan Elagami (Limnological Research Station), Marco La Capra (PhD student of project group B03) (f.l.)
It is a clear, cold winter's day in mid-December when seven researchers with large metal watering cans are watering full water basins, aquatic mesocosms that were completed on the UBT site in 2023. However, the water that shimmers greenish against the light does not contain chemicals, but fluorescent microplastic particles.
"In the long-term experiment," explains Dr Gilfedder, Head of the Limnological Research Station, as he and his technical assistant Silke Hammer swirl the cans, "we measure the transport and fate of the particles and compare the results with the model calculations." So how long do microplastics remain in the water columns of lakes? For the previous experiments in Lake Brombach, the measurements deviated greatly from the model calculations, so the experiment is now being set up again in an artificial body of water, initially without the influence of living organisms.
The cross-faculty approach of the Collaborative Research Centre (CRC) 1357 Microplastics, which is funded by the German Research Foundation (DFG), is very clear, as in addition to Dr Benjamin Gilfedder, Professor Dr Christoph Thomas for micrometeorology and Professor Dr Vadym Aizinger for numerical methods of partial differential equations are also taking part. Together with Dr Hassan Elagami from the Limnological Research Station and doctoral students Marco La Capra and Bashir Ayinde, they are investigating the behaviour of microplastics in flowing waters and in the land surface-atmosphere system. The research team thus covers the full range of scientific expertise for transport processes at the air-water interface in field studies and modelling. For the experiment, a light green fluorescent, spherical plastic is used, which is stirred into the irrigation water as a powder with particle sizes of 1 - 5 micrometres. The researchers use their special fluorescence probes to monitor how the water sinks and continues to behave.
The experiment is to be continued after the winter so that the interactions with plankton organisms can then also be investigated in collaboration with Dr Matthias Schott from the Animal Ecology I working group. And more is also planned: in future, a wide range of plastic types with different surfaces and sizes will be investigated, including the production of precisely characterised PET fibres in the CRC 1357 Microplastics for further experiments. "All of this should help us to develop methods to prevent the further, unwanted spread and pollution of the environment with microplastics," explains Prof Dr Christian Laforsch, spokesperson for the Collaborative Research Centre Microplastics. He also emphasises the importance of the newly established mesocosms for collaborative research, which makes interdisciplinary cooperation possible in the first place.
