Influence of microplastics on grassland plants

, Cornelsen Hanna.

So far, the fate of freshwater and marine systems has been in the focus of societal and scientific attention with manifold negative effects of microplastics identified for aquatic biota. On the contrary, the characteristics of these contaminants in terrestrial ecosystems have not been dealt with in depth. Especially our knowledge on dynamics of microplastics in agricultural soils and crops is fragmentary. Agroecosystems are areas of high human influence, providing manifold input routes for microplastic particles. Potential pathways are agricultural practices like fertilization by sewage sludge, the usage of plastic mulching or irrigation with contaminated water. Beside these, littering behaviour, runoff from surrounding areas and aerial deposition are further entry points. Considerable parts of the global agricultural area are covered by grassland that is providing essential functions for lifestock and fodder supply, and thus also food production. Therefore, it is important to determine the so far unclear consequences of microplastics' presence for grassland soil and plants. In the initial stage of plant performance, potential effects of stressors can be observed more detailed. Therefore, the aim of this research was to investigate the influence of different forms of microplastics particularly on the germination process of grassland species. We assessed different sets of germination trials under laboratory conditions, using annual ryegrass (Lolium multiflorum Lam.var. westerwoldicum) as a model plant. We chose polyvinylchloride (PVC) and particles derived from truck tyres for simulation of common primary and secondary microplastics. Seeds were grown on moisturized filter paper in petri dishes with different amounts of microplastics. After a predefined growth period, above- and belowground biomass of the seedlings was separately analysed. Dried shoot material was analysed for d13C as an indicator of drought stress using an isotope ratio mass spectrometer (IRMS), and dried roots were analysed with a scanning instrument. Results will be shown and discussed.

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