As a result of the unabated growth in plastic usage worldwide, the presence of microplastics in marine and freshwater environments has steadily increased over the last few decades, raising concerns about the potential impacts on aquatic ecosystems and human health. Although most research has focused on marine environments, freshwater systems are equally vulnerable to microplastic pollution. Understanding the fate and transport of microplastics I river systems can provide important clues for designing pollution control strategies and improving the quality of water bodies. This study investigates the applicability of existing model formulations for representing transport, deposition and resuspension of microplastics in river systems during low and high flows with an application to a real case study. The model simulations rely on the software HEC-RAS for hydrodynamic modelling of river flows, and on a custom-made MATLAB code for modelling microplastics transport processes. The model is applied to the network of the rivers Irwell and Mersey in the Greater Manchester area. Simulations are performed before and during the Boxing Day flood event of 2015 to analyse the change in microplastics concentrations induced by different flow conditions. Significant changes are observed in the distribution of microplastics in the river sediments as they are flushed downstream during the flood event, and good agreement is found between the model results and the experimental data of Hurley et al. (2019). However, some limitations are found in the ability of the model to represent the transport of buoyant microplastics, which highlight gaps in the current understanding of microplastics transport processes. Full model validation is also limited by the scarcity of empirical data in field and laboratory settings. Despite the limitations, the model presented in this study can be a useful tool for understanding the migration of microplastics and their accumulation in river systems. By doing so, the model can help decision makers develop best catchment management practices and identify appropriate strategies for removing microplastics from river sediments or directly from the source.
- Microplastic transport and deposition
- Numerical particle transport model
- River Irwell and Mersey,
- Hydrodynamic model
MODELLING THE TRANSPORT AND DEPOSITION OF MICROPLASTICS IN RIVER SYSTEMS
Bhagat, N. (Author). 31 Dec 2023
Student thesis: Master of Philosophy