We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Modeling the settling and resuspension of microplastics in rivers: Effect of particle properties and flow conditions
Summary
Researchers developed a mathematical model to simulate how microplastics of different shapes settle and resuspend in rivers, moving beyond the common assumption that all particles are spherical. They found that turbulence has a complex effect, sometimes keeping particles suspended longer and sometimes accelerating their settling, depending on flow conditions. The model reveals that particle shape significantly influences where microplastics end up in river systems.
Microplastics have numerous different shapes, affecting the fate and transport of these particles in the environment. However, theoretical models generally assume microplastics to be spherical. This study aims to develop a modeling approach that incorporates the shapes of microplastics to investigate the vertical transport of microplastics in rivers and simulate the effect of particle and flow characteristics on settling and resuspension. To achieve these aims, a mechanistic model was developed utilizing the mass-balance and hydrodynamic equations. Scenario analysis was implemented assigning different values to model parameters, such as bed shear stress, shape factor and particle size to simulate the effect of flow patterns and particle properties. The model outcomes revealed that the residence time of microplastics in the water column was longest in medium bed shear stress, whilst it was shortest in low bed shear stress. This suggests that the influence of turbulence is not unidirectional; it can both increase and decrease microplastic concentrations and residence time in the water column. According to the scenario analysis, the settling flux of microplastics was the highest for near-spherical particles and increased with the size of the particles, as well as with increasing bed shear stress. However, the resuspension of particles was primarily influenced by increasing bed shear stress, but the ranking of resuspension flux values for different shaped and sized microplastics exhibited alterations with changing flow patterns. Turbulent conditions predominantly influenced the resuspension of near-spheres and large microplastics. On the contrary, the settling of fibers and small microplastics were significantly influenced by changing flow patterns, whereas near-spheres and largest particles were least affected. The model results were sensitive to changes in shape factor developed for this model, therefore this parameter should be improved in future studies.
Sign in to start a discussion.
More Papers Like This
Settling velocity of irregularly shaped microplastics under steady and dynamic flow conditions
The settling velocities of irregularly shaped microplastics were measured under both still water and dynamic flow conditions, finding that shape strongly affected settling speed and that turbulence caused non-spherical particles to orient and settle differently than spheres, with implications for predicting microplastic vertical transport in rivers and coastal waters.
Modeling impacts of river hydrodynamics on fate and transport of microplastics in riverine environments
Researchers built a computer model to simulate how microplastics travel and transform in river systems, accounting for particle aggregation and breakage driven by water flow. They found that microplastics clump together significantly in the early stages after entering a river, which changes the size distribution of particles flowing downstream. The study suggests that river conditions play a major role in determining what size and form of microplastics eventually reach the ocean.
A Lagrangian Model for Microplastics Transport in Rivers
Researchers developed a Lagrangian computational model to simulate how microplastics are transported through river systems, accounting for particle buoyancy, turbulence, and settling behavior. The model provides a tool for predicting microplastic fate and accumulation in freshwater environments.
Settling velocity of microplastics in turbulent open-channel flow
Researchers studied how microplastic particles settle in turbulent river-like flow conditions compared to still water and developed a new formula to predict their behavior. They found that turbulence altered settling velocities by as much as 26% depending on particle properties, with larger, heavier particles being less influenced by water turbulence. The findings are important for building better models of how microplastics are transported and distributed in rivers and other flowing waterways.
Dispersal and transport of microplastic particles under different flow conditions in riverine ecosystem
Researchers developed a particle-tracking model combined with hydrodynamic simulation to study how microplastics travel through river systems under different water flow conditions. They found that flow speed, turbulence, and river channel features significantly influence where microplastics accumulate and how far they travel. The study provides a useful tool for predicting microplastic transport patterns and identifying pollution hotspots in river ecosystems.