Author(s): Hojung You; Rafael Omar Tinoco

Linked Author(s): Hojung You

Keywords: Microparticle; Obstacle configuration; PIV; PTV

Abstract: The recent increase in use of surgical facial masks and PPE has magnified microplastic pollution in natural waters. When plastics are degraded into smaller particles, they are easily absorbed and transported onto various ecosystems. Since freshwaters transport a majority of plastics from the land to the sea, with accumulated plastics causing detrimental effect on aquatic biota along the way, we seek to develop an efficient microplastic management strategy by thoroughly understanding the transport mechanism of such particulate matter in water. Common obstacles in freshwater such as branches, logs and hydraulic structures are identified as local hotspots of microplastics. Hydrodynamic analysis of these locations provides a more efficient approach to capture and redirect plastics in freshwater ecosystems by predicting particle behaviors at different flow conditions. As an effort to identify flow characteristics creating hotspots of particles, we analyze the transport of neutrally buoyant particles when obstacles are installed in various configurations in a laboratory setting. The transport mechanisms of particles are analyzed depending on obstacles’ dimensions and the spacing between neighboring obstacles when flow obstructions are located: (a) on the bed, and (b) at the free surface. We conducted experiments on a closed-loop racetrack flume, using Particle Tracking Velocimetry (PTV) to track the transport of neutrally buoyant particles and Particle Image Velocimetry (PIV) to identify specific mean and turbulent conditions that determine particle retention or redirection. The spatial and temporal analysis of two-dimensional velocity fields yields valuable information on flow-structure-particle interactions and their response to changing hydrodynamic conditions due to different obstacle configuration. We expect current study to provide an efficient microplastic management strategy in freshwater ecosystem based on the : 1) prediction of plastic accumulation zones for monitoring or their removal in streams, and 2) effective design of artificial traps to target specific plastic materials without affecting transport of stream organisms.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022349

Year: 2022