We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Modeling microplastic transport and residence time in a tide-dominated Amazonian estuary: A case study in Guajará Bay – Pará, Brazil
AI summary Read the abstract
A hydrodynamic model of Guajará Bay in the Brazilian Amazon found that microplastics released by the Tamandaré River persist in the estuary for 8–32 days during the dry season and up to 72 days to fully exit the domain. Seasonal river discharge cycles drive dramatically different retention patterns, highlighting tidal estuaries as significant microplastic accumulation zones in the Amazon region.
This case study presents the first numerical simulation of surface microplastic transport in the Amazon region, using a hydrodynamic model coupled with a water quality model in Delft3D software. This research investigated the transport of microplastics released by the Tamandaré River into Guajará Bay waters (using observational data to parameterize released microplastics), together with an analysis of hydrodynamic transport timescales (i.e., renewal rate, age of continental water, and residence time). The renewal rate is the time it takes for the waters of the open boundary to wash the initial waters of the domain; the age of continental water corresponds to the lifetime (in days) of a water parcel from its entry at the fluvial boundary to control points; and residence time indicates how long a water parcel remains within a semi-closed estuarine body into which it was released. These indicators were analyzed jointly, enabling an integrated understanding of microplastic transport dynamics. The results show that the decrease in river discharge during the dry season increased the residence time and age of continental water, while reducing the renewal rate, prolonging the persistence of microplastics in Guajará Bay. During the wet season, the opposite pattern occurred. Seasonally, the residence time of Tamandaré River waters in the Bay varied from 8 to 32 days, requiring approximately 36 to 72 days to leave the domain. Although positive tidal asymmetry and marginal vegetation are common factors for plastic accumulation in estuarine environments, this study demonstrated that the morphological configuration (i.e., the slope of the bank relative to the channel and the riverbank bathymetry) was decisive for the local dispersal pattern. Two areas of temporary sinks were identified in this urban estuarine system: on the right bank of Guajará Bay (BG1) and on the right bank of the mouth of the Guamá River (RG).
More Papers Like This
Size-dependent microplastics transport in a sediment rich environment
AI summary Read the abstract
Researchers developed a two-dimensional depth-averaged numerical model to simulate size-dependent microplastic transport in sediment-rich estuarine environments, incorporating cohesive and non-cohesive sediment classes to capture how tidal deposition and resuspension cycles govern microplastic fate.
Physical drivers of transport, dispersion and trapping of microplastics in a macrotidal, hyper-turbid fluvial–estuarine system: A modelling approach
AI summary Read the abstract
Estuaries — where rivers meet the ocean — act like traps for microplastics, with tides, sediment, and shoreline interactions causing much of this plastic pollution to get stuck rather than flushed out to sea. This matters because these are often the same waters used for fishing and shellfish harvesting, meaning trapped microplastics may build up in local food sources over time rather than dispersing and diluting in the open ocean.
Transport et piégeage des microplastiques dans un estuaire fortement turbide et dominé par la marée
AI summary Read the abstract
A Lagrangian numerical model of the Gironde estuary found that shoreline beaching-refloating dynamics dominate transport of buoyant microplastics, while resuspension and vertical mixing control denser particles. This mechanistic understanding of estuarine microplastic trapping is critical for accurate risk assessment, as estuaries act as major retention zones where microplastics accumulate before reaching coastal marine environments.
Macroplastic fate and transport in an Amazonian Estuarine System: A Lagrangian Modelling Approach
AI summary Read the abstract
Scientists used computer models to track how large plastic waste travels from the city of Belém, Brazil through rivers and waterways to the ocean. They found that plastic pollution gets stuck in certain areas during low water periods but moves quickly to the ocean during high water periods, creating pollution hotspots near the city. This research helps identify where plastic waste accumulates so communities can better target cleanup efforts and prevent this pollution from reaching the ocean and potentially entering our food chain.
Exposing estuarine regions as microplastic traps: modeling transport pathways and accumulation hotspots in the Minho Estuary (Portugal-Spain)
AI summary Read the abstract
Researchers combined field sampling with a Lagrangian particle tracking model in the Minho Estuary to map how river discharge and tidal cycles control microplastic transport, identifying persistent accumulation hotspots and determining the conditions under which the estuary shifts between acting as a source versus a sink for ocean-bound microplastics.
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.