PLASTINEST – Physical processes of microPLASTics Transport IN macrotidal ESTuaries

PLASTINEST aims to elucidate on the transport, trapping and flushing dynamics of microplastics in macrotidal estuaries, deepening on their vertical dynamics, their variability from intratidal to seasonal time scales…

…the source-to-sink relationships, and the driver processes.

Achieving this progress requires an ambitious research strategy that combines laboratory experiments…

and the development of advanced (Lagrangian) numerical modelling.

Physical processes of microPLASTics Transport IN macrotidal ESTuaries

About the project

Macrotidal estuaries : major temporal or permanent sink of microplastics ?

Around three-quarters of plastic waste reported in the ocean are estimated to come from land-based sources, primarily via rivers and estuaries. However, not all plastic entering estuaries are flushed into the ocean. As fine sediments and particulate organic matter, microplastics may be trapped in estuaries forming regions of privileged accumulation. This trapping may be particularly significant in macrotidal estuaries characterized by significant landward residual fluxes of sediments.

However, compared to sediments, microplastics cover a larger spectrum of physical properties that can vary over time due to weathering and biofouling processes. Very little is known about the physical mechanisms of transfer and trapping of microplastics at the river-estuary-sea continuum…

WP 1. Microplastic vertical dynamics under hyperturbid conditions

This work package aims to describe the settling dynamics and the erodability of microplastics in hyperturbid environments from laboratory experiments.

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WP 2. Microplastic and hydrodynamics monitoring

The main goal of WP2 is to evaluate the spatio-temporal variability of microplastics and key physical parameters at the estuary scale from in-situ observations.

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WP 3. Process-based numerical modelling for the transport of microplastics

In WP3, numerical tools for the transport of microplastics are improved and implemented to the Gironde estuary in order to test hypotheses on transport dynamics and assess retrospective or prospective conditions.

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WP 4. Microplastic transport and drivers

In WP4, the three first WPs are combined to: (1) advance knowledge of microplastic transport at the estuary scale; (2) identify the relative contributions of the different physical and biochemical processes on microplastic dynamics; (3) understand the role of estuaries as sources and sinks of microplastics.

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WP 5. Management and knowledge transfer

WP 5 covers the project coordination, its financial and administrative management, and the dissemination of scientific knowledge to the scientific community, stakeholders and the general public.

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A case study

The Gironde estuary (SW France) is an ideal natural laboratory to achieve PLASTINEST’s objectives. It is one of the largest European estuaries, a major contributor of suspended particulate matter to the Bay of Biscay, and is characterized by strong sediment trapping.

PLASTINEST will cover three regions from the river to the ocean – the tidal river, the main estuary and the near-field plume – and will primarily focus on tidal and seasonal time scales.

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