We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Transport and Retention of Microplastics in Gravelly Riverbed Sediments: A Polymer-Specific Column-Scale Study
AI summary Read the abstract
Lab experiments passed water through columns of gravel sediment to see how four types of plastic fragments moved through it. Most plastic particles stayed in the top 10 to 15 cm of gravel, with denser plastics like PET and PVC moving less deep than lighter polystyrene, suggesting particle density affects how far microplastics travel into riverbeds.
Abstract Microplastic particles (MPs) are ubiquitous in aquatic environments, with rivers playing a key role in transporting them from terrestrial sources to marine systems. Field studies indicate that MPs can be transferred from surface water into riverbed sediments and groundwater, often showing polymer-specific patterns, yet the processes governing transport and retention remain poorly understood. Here, we investigated vertical, polymer-specific mobility in gravel (d10/d50/d90 = 5.60:6.60:7.80 mm) sediment columns under environmentally relevant hydraulic conditions simulating bank filtration. Reference MP fragments (178 ± 140 μm)─irregular, secondary, nonspherical particles─of polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and polyvinyl chloride (PVC) with densities of ρPP = 0.9, ρPS = 1.04, ρPET = 1.35, and ρPVC = 1.39 g cm–3 were applied individually, and the sediment was sampled at multiple depths up to 50 cm for MP detection. Subsequent analysis revealed that most MPs were retained within the upper 10–15 cm of the sediment, with a decreasing vertical mobility into greater depths following the order PET > PVC > PS. These findings indicate a relevant role of density in MP retention at low to medium flow velocities of 1.5–16 m d–1. Overall, the results provide mechanistic insight into polymer-specific MP transport and retention in gravelly riverine sediments.
More Papers Like This
Transport and retention of micro-polystyrene in coarse riverbed sediments: effects of flow velocity, particle and sediment sizes
AI summary Read the abstract
Researchers conducted column experiments to investigate how polystyrene microplastic fragments are transported and retained in coarse riverbed sediments under different flow conditions. They found that most particles were captured in the upper 15-20 centimeters of sediment, but smaller fragments between 100-500 micrometers could penetrate to depths of at least 50 centimeters. The study suggests that riverbeds can act as both temporary sinks and long-term retention sites for microplastics, slowing their transport from streams to oceans.
Hydrodynamic controls on vertical transport and retention of microplastic particles in subsurface sediments
AI summary Read the abstract
Lab columns filled with gravel tested how two plastic types (polyethylene and polystyrene) move through sediment under different water flow patterns. Steady and pulsed water flow carried microplastics deeper and faster than single bursts, with smaller particles moving earlier and over half of particles staying trapped in the top 10 centimeters of sediment.
Subsurface transport of microplastics in riverine sediment: Impacts of different rain events and particle density
AI summary Read the abstract
Microplastics added to the surface of riverbed gravel columns gradually migrate deeper into the sediment as rain events accumulate, especially through repeated wet-dry cycles. Both polystyrene (denser than water) and polyethylene (less dense) particles traveled deeper over time, with smaller, less hydrophobic particles moving farthest. This shows that riverine sediment is not just a permanent sink for microplastics but can also funnel them downward into groundwater aquifers and subsurface habitats.
Investigations on microplastic infiltration within natural riverbed sediments
AI summary Read the abstract
Researchers used laboratory flume experiments to investigate how sediment grain size affects the infiltration of four types of microplastics (PET spheres, PET ellipsoids, polystyrene fragments, and polyamide fibers) into riverbed sediments. Sediment particle size, microplastic shape, and density were key factors controlling how deeply microplastics penetrate into the hyporheic zone.
Assessing the Behavior of Microplastics in Fluvial Systems: Infiltration and Retention Dynamics in Streambed Sediments
AI summary Read the abstract
Scientists used laboratory river-bed simulations to study how microplastics move from surface water down into streambed sediments. Smaller particles (1 micrometer) penetrated deeper into the sediment than larger ones, and higher water flow pushed more particles downward. This research helps explain how microplastics accumulate in river beds, which serve as both drinking water sources and habitats for aquatic organisms.
Research digests by email
When a large batch of papers lands in the Atlas, we read through it and send a short write-up of what stood out.