PhD position: Microplastic Dynamics in a macrotidal hyper-turbid estuary

Supervisors: Isabel Jalón-Rojas (; Damien Sous (; Aldo Sottolichio (

Start Date: November or December 2022

Duration: 3-years contract, already 100% funded (ANR JCJC PLASTINEST)

Host Institution: EPOC laboratory, University of Bordeaux

Salary: 23,7 € (gross) / year


Plastic pollution is recognised as one of the most critical anthropogenic issues in aquatic environments worldwide. At the land-ocean interface, estuaries are privileged pathways of plastic. However, not all plastic entering estuaries are flushed into the ocean. We can hypothesize that, as fine sediments and particulate organic matter, microplastics may be trapped in estuaries forming regions of privileged accumulation (Defontaine et al., 2021). This trapping may be particularly significant in macrotidal hyper-turbid estuaries characterized by important landward residual currents (Buchard et al, 2018; Jalón-Rojas et a 2021) and conditions that may favor the flocculation of microplastics and cohesive sediments. Therefore, macrotidal estuaries may be a major sink of microplastics. However, very little is known about the physical mechanisms of transfer and trapping of microplastics at the river-estuary-sea continuum.

The objective of this is to make fundamental progress in understanding the transport, trapping and dispersion of microplastics in estuaries dominated by tides. The successful candidate will elucidate on major research questions such as

(1) the effect of different physical processes on the transport of microplastics at different estuarine regions;

(2) the formation of  Estuarine MicroPlastic Maxima (EMPM) in macrotidal estuaries in relation to the particle physical properties (density, size and shape) and physical drivers;

(3) the fluxes of microplastics entering the estuary and flushed to the ocean and sources-to-sink relationships.

(4) the role of macrotidal estuaries as source and sink of microplastics,  which will ultimately contribute to quantifying the distribution and budget of Microplastics at the land-ocean interface.

The Gironde-Garonne fluvial-estuarine system (SW France) will serve as a natural laboratory to achieve this challenge. 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 (Jalón-Rojas et al., 2015; 2021). The methodology will combine high-frequency multisite in-situ observations of both microplastics and physical parameters and advanced numerical modelling (Jalón-Rojas et al., 2019; Baudena et al., 2022). The thesis will benefit from improved model parameterizations developed in the context of PLASTINEST, strong international collaborations, citizen science data, and exchange with local associations and authorities.


Baudena, A., Ser-Giacomi, E., Jalón-Rojas, I., Galgani, F., Pedrotti, M.L., 2022. The streaming of plastic in the Mediterranean Sea. Nature Communications, 13, 2981.

Defontaine, S., Sous, D., Tesan, J., Monperrus, M., Lenoble, V., Lanceleur, L., 2020. Microplastics in a salt-wedge estuary: Vertical structure and tidal dynamics. Marine Pollution Bulletin 160, 111688.

Burchard, H., Schuttelaars, H.M., Ralston, D.K., 2018. Sediment trapping in estuaries. Annual review of marine science 10, 371–395.

Jalón-Rojas, I., Dijkstra, Y., Schuttelaars, H., Brouwer, R., Schmidt, S., Sottolichio, A., 2021. Multidecadal Evolution of the Turbidity Maximum Zone in a Macrotidal River Under Climate and Anthropogenic Pressures. Journal of Geophysical Research: Oceans 126, e2020JC016273.

Jalón-Rojas, I., Schmidt, S., Sottolichio, A., 2015. Turbidity in the fluvial Gironde Estuary (southwest France) based on 10-year continuous monitoring: sensitivity to hydrological conditions. Hydrology and Earth System Sciences 19, 2805–2819.

Jalón-Rojas, I., Wang, X.H., Fredj, E., 2019a. A 3D numerical model to track marine plastic debris (TrackMPD): sensitivity of microplastic trajectories and fates to particle dynamical properties and physical processes. Marine Pollution Bulletin 141, 256–272.


Microplastic, transport, estuary, physical processes, source to sink, modelling


This work will be funded by project PLASTINEST (ANR JCJC 2022-2025) which involves EPOC, UPPA, CEREMA, PPRIME, and many international collaborations. This project will also fund the functioning of the PhD work (computing facilities, workshop and conferences, publication fees, …). A long stay abroad (typically 1 month to 3 months) is planned during the PhD (e.g. at University of Granada, Spain), in order to acquire new methodologies and reinforce collaboration with international researchers. The student will be employed by the University of Bordeaux.


We seek highly motivated candidates with:

  • MSc degree in Physical Oceanography, Environmental Physics, Marine Science, Fluid Mechanics, or a closely related discipline with a strong background in Hydrodynamics;
  • Technical abilities in scientific programming (e.g Matlab, Python)
  • A training experience in data analysis and numerical modelling will be appreciated
  • Proven affinity with coastal physical oceanography (desirable);

The selected candidate should, if possible, have also the following qualities: autonomy, scientific curiosity, and open-mindedness. She/he should have if possible excellent teamwork, writing and communication skills.


The PhD contract is for a period of 3 years, with a starting date in November 2022. Applicants should send by email to Isabel Jalón-Rojas (, Damien Sous ( and Aldo Sottolichio ( the documents listed below before 12 September 2022.

  • Letter of motivation
  • CV
  • Master’s grades
  • Contact details of 2 referees
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