We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
A semi-analytical approach to characterize the effects of unsteadiness and dune migration on microplastics fate
Summary
Researchers developed a semi-analytical approach to model microplastic fate in streams, showing that unsteady flow conditions and migrating sand dunes significantly influence where microplastics are deposited and how long they remain in benthic and hyporheic zones.
Streams and rivers, together with their bed (i.e. benthic) and subsurface (i.e. hyporheic zone) environments represents the natural connectors between terrestrial and aquatic environments through which transport and transformation processes control the fate of a multitude of elements, including nutrients and contaminants, commonly produced by human activities. In recent years, particular attention was given to a new class of pollutants known as Contaminants of Emerging Concern (CECs) that include, among others, microplastics. Microplastics enter the streams and rivers after escaping degradation from wastewater treatment plants (WWTPs) and during the time they spend within the riverine environments they may have potential adverse effects on human and freshwater ecosystems. Among the different processes that affect their fate, burial within the streambed sediments is still the subject of current research; especially considering that under some hydrodynamics conditions small scale bedforms (i.e. dunes and ripples) can migrate causing hyporheic exchange to depend on both bedform migration, called turnover, and near-bed pressure gradients, called pumping. Here, we analyze the effects of turnover and pumping in sand-bedded streams with mobile dunes by proposing an analytical solution of the process. The proposed analytical solution allows us to determine: i) the pressure head distribution, ii) the velocity field and iii) the residence time distribution within a homogeneous stream bed sediment under transient conditions of the stream flows. The solution allows to characterize and quantify the penetration depth and the release (i.e. the resuspension process) of microplastics due to the trapping-releases successions as hyporheic pathways (connecting downwelling and upwelling zones) change in time.
Sign in to start a discussion.
More Papers Like This
Modeling microplastic deposition in sandy streams with moving bedforms
Researchers developed a coupled model combining improved mechanistic colloid attachment predictions with a bedform transport model to quantify microplastic deposition in sandy streams with moving dune bedforms, running numerical simulations to assess how streambed characteristics, flow conditions, and particle properties interact to control microplastic retention. The model addressed the poor predictive power of classical colloid filtration theory for microplastics by incorporating bedform dynamics into deposition calculations.
The role of pumping and turnover in controlling microplastics entrapment and release in sand-bed rivers
Researchers developed a mathematical framework to model how microplastics are trapped and released in sand-bed rivers through the combined effects of water flow and dune migration. The study found that dune movement substantially alters how microplastics are transported and buried in river sediments, with a nonlinear interplay between shallow rapid exchange and deep burial that depends on dune size and flow conditions.
Understanding how sediment movement affects microplastic deposition in sandy streambeds: A modeling study.
Researchers used a numerical model of flow and particle transport in moving streambed sediment to quantify how streambed motion affects microplastic deposition and accumulation, running simulations across streamwater velocities of 0.1-0.5 m/s and varying median grain sizes to examine MPs of all sizes and densities.
Microplastic deposition in streams under moving bedforms
Researchers conducted flume experiments to examine microplastic deposition in sandy streambeds under moving bedform conditions, finding that bedform migration and particle size both control whether microplastics are buried or remain in suspension, with implications for estimating MP residence times in river systems.
Integrated numerical modeling to quantify transport and fate of microplastics in the hyporheic zone
Researchers developed an integrated numerical model to simulate microplastic transport and retention in the hyporheic zone beneath streambeds, finding that particle size, density, and streambed morphology significantly influence microplastic infiltration dynamics.