Microplastic particles in lakes: CFD study of the variables affecting their spatiotemporal distributions

The issue of microplastic (MP) particle pollution has come increasingly into focus over the past decade. Specifically, freshwater environments, such as lakes, play an important role as a sink for these pollutants. Hence there is an increasing need for understanding the physical controls that govern microplastic distributions in lake systems. Numerical models are valuable tools to predict MP particle distributions in lakes over a range of physical conditions. In a temperate climate, the thermal stratification affects the physical properties of the lake water along the depth and dramatically interrupts the normal pace of settling of very small and light MP particles. To simulate MP distributions in a thermally stratified lake, which is influenced by wind and Coriolis forces as well, this study employs a hydrodynamic Eulerian lake model and a Lagrangian transport model implemented in the Delft3D software suite. MP distribution patterns are examined for elliptical-shaped lakes with constant and spatially variable bathymetries. Considering the predominant wind directions and the symmetry of the lake surface shape, points for instantaneous MP releases along the shoreline are deployed. The investigated scenarios will provide insights into microplastic distribution and accumulation patterns in lakes taking into consideration the different lake compartments (Epi-, Meta- and Hypolimnion) as well as sedimentation on the lakebed after one year of simulation. Also see: https://micro2022.sciencesconf.org/426006/document