We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Significance of Hyporheic Exchange for Predicting Microplastic Fate in Rivers
AI summary Read the abstract
Researchers modeled the role of hyporheic exchange — water flow between rivers and streambed sediments — in driving microplastic delivery and retention in riverbeds, finding that this process significantly increases the rate at which small and positively buoyant microplastics are transported into streambed sediments. The study highlights hyporheic exchange as an underappreciated mechanism controlling microplastic fate in freshwater environments.
Microplastics are abundantly found in streambed sediments, including both small and low-density particles of neutral and positive buoyancy. Although the flow of water into streambed sediments (hyporheic exchange) has previously been shown to increase the rate of delivery of fine particles to the streambed, the influence of hyporheic exchange on microplastic fate in aquatic environments has not yet been assessed in detail. Here we evaluate the effects of hyporheic exchange on microplastics by calculating and comparing the rates of delivery of microplastics to streambed sediments by hyporheic exchange and gravitational settling for combinations of particle size and density most commonly found in streams. In a field stream study, we found that 23% of all microplastic combinations have a hyporheic exchange rate that is higher than their settling rate. This fraction was as high as 42% for microplastics composed of low-density polymers, such as polyethylene. We then expand these findings to consider a wide range of hydrodynamic conditions in rivers and demonstrate that hyporheic exchange is important for the transport and fate of particles that are <100 μm in diameter, irrespective of polymer type. Models that do not include hyporheic exchange are therefore likely to substantially underestimate the deposition, retention, and long-term accumulation of microplastics in streambed sediments.
More Papers Like This
The transport behaviour of microplastics in longitudinal mixing and hyporheic exchange under varied flow conditions
AI summary Read the abstract
Researchers studied how microplastics move through river systems, examining both downstream transport and how particles interact with riverbeds through hyporheic exchange. Understanding these transport behaviors helps predict where microplastics accumulate in river sediments.
Hyporheic exchange processes of pore-scale microplastics
AI summary Read the abstract
Researchers studied how microplastics move through the hyporheic zone, the region where river water mixes with groundwater beneath the streambed. They found that denser plastic particles sank through sediment pores toward groundwater, while lighter plastics rose to the surface, and both behaved differently from dissolved substances. These findings raise concerns that microplastics may be contaminating groundwater systems through processes that are not well captured by current water quality models.
Microplastic accumulation in riverbed sediment via hyporheic exchange from headwaters to mainstems
AI summary Read the abstract
Researchers developed a model showing that hyporheic exchange between river surface water and sediment causes long-term microplastic retention, with headwater residence times averaging 5 hours per kilometer but increasing to 7 years per kilometer during low-flow conditions.
Integrated numerical modeling of microplastic transport in fluvial systems
AI summary Read the abstract
This study developed an integrated numerical model for microplastic transport in rivers that accounts for both surface water flow and exchange with the hyporheic zone — the subsurface region where river water mixes with groundwater. Including hyporheic exchange improved predictions of microplastic storage and remobilization compared to surface-only models. The work helps explain why microplastics are often found at higher concentrations in river sediments than in the water column.
Microplastic transport in rivers and their hyporheic zone – combining modeling and experiment
AI summary Read the abstract
Researchers combined computational fluid dynamics (CFD) simulations with flume experiments to investigate the transport and fate of small polystyrene microplastic particles (1, 3, and 10 micrometres) in a rippled sandy streambed, including exchange into the hyporheic zone. Using a novel fluorescent MP detection system, they quantified how particle size and hydrodynamic conditions govern microplastic retention and hyporheic exchange in riverbed sediments.
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.