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61,005 resultsShowing papers similar to Experimental study on the motion characteristics and critical hydraulic parameters of microplastics in a freshwater environment
ClearIncipient Motion of Exposed Microplastics in an Open-Channel Flow
Researchers experimentally determined the conditions needed to initiate microplastic movement in open-channel water flows, finding that standard sediment transport thresholds do not apply to microplastics and proposing a new predictive formula that reduces error from 55.6% to 12.3%.
Response of microplastic particles to turbulent flow: An experimental study
Using controlled flume experiments, researchers studied how turbulent flow conditions affect the transport and settling behavior of microplastic particles with varied shapes and densities, finding that turbulence intensity and particle morphology interacted to determine suspension and deposition patterns.
Investigating Microplastic Resuspension in Environmental flows: Experimental and Numerical Approaches
Researchers used combined experimental and numerical approaches to investigate the resuspension of microplastics from sediment beds in riverine flows, finding that turbulence intensity during high-flow events plays a key role in detaching MP particles embedded in multi-density granular sediment beds.
Effects of Particle Properties on the Settling and Rise Velocities of Microplastics in Freshwater under Laboratory Conditions
Physical experiments quantified the settling and rise velocities of ~500 microplastic particles of varying shapes, sizes, and densities under controlled laboratory conditions, finding velocities ranging from 0.39 cm/s (settling polyamide fibers) to 31.4 cm/s (rising expanded polystyrene), with standard sediment transport formulas inadequate for fibers. The study provides empirical data needed to improve models of microplastic transport in rivers and lakes.
Impact of the Reynolds Numbers on the Velocity of Floating Microplastics in Open Channels
Researchers experimentally tracked the motion of nearly spherical polyethylene, polypropylene, and polystyrene microplastics in open channel flow using video analysis, establishing quantitative relationships among Reynolds number, MP density, and floating velocity to better predict horizontal transport behavior.
Sediment-Water Interfaces as Traps and Sources of Microplastic Fragments and Microfibers─Insights from Stream Flume Experiments
Researchers used controlled stream flume experiments to study how microplastic fibers and fragments settle into riverbed sediments. They found that lower water flow speeds caused faster deposition, with the effect being strongest for fibers, and that traditional settling equations significantly underestimate how microplastics actually behave near the streambed. The findings improve our understanding of where and how microplastics accumulate in rivers.
Visualization of Buoyant MP motion in response to different flow velocities and bed types
Researchers visualized the movement of buoyant microplastic particles (lower density than water) in channels with different flow velocities and bed types. The experiments showed that these particles move along the water surface at velocities close to surface flow speed, making them highly mobile in rivers. This behavior helps explain why low-density microplastics like polyethylene are widely transported and dispersed in freshwater systems.
Coupled CFD-DEM modelling to assess settlement velocity and drag coefficient of microplastics
Researchers used computational fluid dynamics coupled with particle simulations to model how the size, shape, and density of microplastics affect their settling velocity and drag in water. Accurate physical models of microplastic behavior are essential for predicting where particles accumulate in rivers, lakes, and the ocean.
Microplastic and natural sediment in bed load saltation: Material does not dictate the fate
Researchers investigated how microplastics move as bed load in river flows and found that transport behavior in saltation was governed primarily by particle size, shape, and density rather than material composition, suggesting that microplastics follow similar transport mechanics as natural sediment.
Settling and rising velocities of environmentally weathered micro- and macroplastic particles
Researchers measured settling and rising velocities of environmentally weathered micro- and macroplastic particles collected from rivers, finding that existing predictive formulas developed for virgin pellets, fragments, and foams transferred reasonably well to weathered particles but were less accurate for films and larger macroplastics.
The role of biofilm and hydrodynamics on the fate of microplastic particles in rivers: an experimental study
Researchers conducted flume and field experiments to examine how biofilm formation and hydrodynamic conditions govern the fate of microplastic particles in rivers, investigating why some MP-polluted rivers crossing industrialized areas show no significant upstream-to-downstream concentration differences. The study identified biofilm-mediated density changes and turbulence as key factors controlling whether low-density MPs remain suspended or settle into sediments.
Plastic drift : Mapping the course of microplastic transport in turbulent riverine flows.
Researchers conducted laboratory experiments tracking the 3D trajectories of 24 negatively buoyant microplastic particles spanning a range of sizes, shapes, and densities in turbulent open channel flow, generating 720 trajectories to evaluate how well conventional sediment transport models apply to microplastics. Results revealed that the inherent variability in microplastic physical properties challenges direct application of sediment transport concepts to microplastic fate prediction in rivers.
Mobility and retention of microplastic fibers and irregular plastic fragments in fluvial systems: an experimental flume study
Researchers conducted experimental flume studies to compare the mobility and retention of microplastic fibres and irregularly shaped plastic fragments in fluvial systems. The study found that particle shape strongly influences transport behaviour, with fibres exhibiting greater mobility and distinct retention patterns compared to irregular fragments, highlighting the need to move beyond spherical particle models in microplastic transport research.
Experimental study on parameterizing microplastic-sediment aggregation
Researchers conducted laboratory flocculation experiments to parameterize microplastic-sediment aggregation, testing fibers, fragments, and spheres of varying sizes and densities to characterize how microplastics and sediment form flocs with enhanced settling velocity, with the goal of improving numerical transport models of microplastic fate in rivers and estuaries.
Study of the influence of fluvial dynamics on the distribution and transport of microplastics.
Researchers studied how fluvial dynamics including flow velocity, turbulence, and river geomorphology influence the distribution and transport of microplastics in river systems. River hydrodynamics were found to be major determinants of where microplastics accumulate and how far they travel, with implications for predicting contamination patterns in river catchments.
The curious case of microplastic settling velocity within suspended sediment
Researchers investigated the settling velocity of microplastics within suspended sediment in freshwater environments, aiming to better characterize the transport dynamics of these persistent pollutants through the water column. Their analysis highlighted that microplastic settling behavior is complex and context-dependent, complicating predictions of temporal and spatial distribution in rivers.
Study of the influence of fluvial dynamics on the distribution and transport of microplastics.
Researchers studied how fluvial dynamics, including water flow, turbulence, and river morphology, influence microplastic distribution and transport in a river system. The study found that hydrological conditions strongly control where microplastics deposit and how they move through the watershed.
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.
Contribution to the study of the dislodgment conditions of spheroids from a surface in fluid flow
Researchers used theoretical fluid mechanics to derive the critical conditions under which prolate and oblate spheroidal particles resting on a surface are dislodged by fluid flow. They found that a rolling mode always occurs first, and that asperity geometry acts as a pivot point governing critical dislodgment conditions, with relevance to understanding how microplastic particles are mobilized in flowing water.
Settling Velocities of Small Microplastic Fragments and Fibers
Researchers precisely measured the settling speeds of over 4,000 small microplastic particles in water and found that existing prediction models designed for larger microplastics do not work well for these tiny fragments and fibers. The settling speed depends on each particle's size, density, and shape, with the smallest particles sinking extremely slowly. Understanding how quickly microplastics settle in water is important because it determines how far they travel and how long they remain available to be consumed by aquatic organisms that humans may eventually eat.
Microplastic Pathways: Investigating Vertical and Horizontal Movement from Riverine Environments to Oceans
Researchers investigated the vertical and horizontal movement of microplastics in riverine systems en route to the ocean, examining how physical MP characteristics and hydrodynamic conditions govern whether particles settle near riverbeds or float at the surface, and how both gravity-driven and flow-driven transport contribute to their ultimate fate.
Settling velocity of submillimeter microplastic fibers in still water
The settling velocity of 519 submillimeter microplastic fibers (300-600 micrometers long) was measured in still water, finding that settling rates vary considerably by fiber length and orientation, informing models of microplastic fiber transport and deposition in aquatic systems.
Plastic drift : Mapping the course of microplastic transport in turbulent riverine flows.
Researchers investigated the transport dynamics of 24 negatively buoyant microplastic particles across a spectrum of sizes, shapes, and densities using a 3D particle tracking system in turbulent open channel flow, generating 720 trajectories. They found that particle shape was the dominant determinant of transport behavior, with fibers tending to remain near the water surface at lower forward velocities while spheres stayed closer to the bed with higher forward velocities.
AQuantitative Relationshipbetween Settling and Wettabilityfor Weathered Microplastics in Aquatic Systems
Researchers quantified the relationship between surface wettability and settling velocity for weathered microplastics in aquatic systems, demonstrating that wettability-driven microscale changes at the particle-water interface modify drag forces and thus govern the transport and fate of submillimeter plastic particles.