The transport of tyre wear particles in rivers, with a focus on settling and resuspension

There is increasing research into Tyre and Road Wear Particles (TRWPs), including quantifying their generation, environmental sampling and the development of methods to better extract and analyse these samples. However, there is currently a lack of research which looks into the fate and transport of these particles through pathways in the environment, and no research which looks to find or quantify these particles in groundwater. This research investigates how TRWPs are transported through the environment and in aquatic ecosystems, with a particular focus on settling and resuspension in rivers, in comparison with more extensively studied, 'traditional', microplastics. There are few published studies which perform standard density characterisation on TRWPs. As such, we present initial characterisation data of TRWP density, zeta potential and heavy metal concentration, determined using gas pycnometry, a DLS zetasizer and ICP-MS. We also present data from research on tyre wear content in bioswales, and of the settling and dispersion rates of tyre wear particles in a stationary, settled system. These settling rates were conducted in a settling box and show the effects of interaction between multiple particles on their settling. These settling experiments in a settling box lead on to mesocosm flume experiments which will be conducted to show settling and resuspension rates of tyre wear particles in comparison with more 'traditional' microplastics. This will test our hypothesis that, due to their unique characteristics, the transport of TRWPs through catchments cannot be predicted using models developed for 'traditional' MPs. We present the methodology for these flume experiments and the subsequent analysis. Also see: https://micro2024.sciencesconf.org/558833/document