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Mechanistic insights into the pore-scale transport and retention of microplastics: bridging physical and geochemical controls
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Scientists modeled how tiny plastic particles move through underground soil and rock to figure out what makes them get trapped versus flow into groundwater supplies. They found that warmer water and certain narrow, twisty underground pathways cause more microplastics to get stuck—sometimes more than doubling how much sticks around—while faster-flowing water lets more particles slip through toward drinking water sources. This matters because it helps predict when and where groundwater (a major source of drinking water) is more vulnerable to microplastic contamination, especially as climate change warms groundwater temperatures.
Porous media with constricted throats and heterogeneous surfaces dictate microplastic transport and retention within the soil-groundwater continuum; however, the multifaceted mechanisms governing their subsurface accumulation remain poorly understood. This study quantifies microplastic migration pathways, adsorption hotspots, and breakthrough dynamics in aquifers using a high-resolution pore-scale Lagrangian framework that couples hydrodynamic drag, Brownian motion, dielectrophoretic (DEP) forces, and surface adsorption. Our results demonstrate that while Brownian perturbations fundamentally drive particle-wall collisions, DEP forces and minerals with high surface charge magnitudes serve as deterministic geochemical controls on particle immobilization. We show that geometric singularities, such as narrow throats and sharp bends, act as permanent retention hotspots regardless of bulk porosity. A non-monotonic size effect was identified, where particles of an intermediate size (3 µm) exhibited the highest maximum velocity. Environmental forcing significantly modulates these processes: warming groundwater (0 °C to 25 °C) enhances Brownian-driven filtration, more than doubling the retention capacity from 1.2% to 2.65%. Conversely, higher inlet velocities intensify hydrodynamic drag and confine trajectories to preferential flow paths, thereby suppressing dispersive adsorption. Furthermore, pore-network architecture (diagonal vs. transverse flow) can shift the aquifer's role from a transport conduit to a long-term pollutant sink. By bridging the gap between microscopic physical forces and geochemical controls, this study provides a mechanistic tool to assess the vulnerability of groundwater resources and informs long-term subsurface risk management.
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How soil moisture and flow regime drive microplastic transport in the vadose zone: insight from modelling and column experiments
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Scientists studied how tiny plastic particles move through soil toward underground water sources that we use for drinking water. They found that plastic particles travel very differently depending on how wet or dry the soil is - sometimes getting trapped, other times moving quickly through the ground. This research helps us better understand how microplastics might contaminate our groundwater supplies, which is important for protecting drinking water quality.
Microplastics transport in subsurface environments: Mechanisms and multi-scale modeling
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Tiny plastic particles are seeping through soil into groundwater—the same water many of us drink—and this review of existing research shows scientists still struggle to predict exactly how they move underground. Because these particles behave differently than the chemicals or germs we usually track in water, current safety models may miss how far and fast they travel, which matters since they can carry other pollutants along with them. Better tracking models, which the researchers propose building, could eventually help protect drinking water supplies from this hidden contamination.
Effects of co-present mineral colloids on the transport of microplastics in porous media: The key role of hydrochemical and hydrodynamic conditions
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Scientists studied how tiny plastic particles (microplastics) move through soil and sand when mixed with natural clay particles. They found that the combination of different clay types and water conditions can either help microplastics travel further underground or trap them in place. This research helps us better understand how microplastics might contaminate groundwater sources that provide our drinking water.
Enhanced mobility and dynamic retention of nanoplastics in mineral coated porous media.
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Scientists studied how tiny plastic particles move through different types of soil and sand that might be found in groundwater systems. They discovered that these nanoplastics travel much farther and faster through soil than previously thought, especially when water flows quickly. This matters because it suggests that plastic pollution from things like food packaging and cosmetics could spread more widely through our drinking water sources than we realized.
The Effect of Polymer Type and Particle Concentration on Microplastic Transport Mechanisms in Saturated Porous Media
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Scientists studied how tiny plastic particles move through soil and groundwater by testing different types of plastics at various concentrations. They found that the amount and type of plastic affects how far these particles travel underground, and that bacteria growing on the plastic surfaces can change how they move through soil. This research helps us better understand how microplastics might contaminate our drinking water sources and food supply.
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When a large batch of papers lands in the Atlas, we read through it and send a short write-up of what stood out.