Master’s 2 internship project on the influence of interannual variability in ocean circulation on the 3D distribution of microplastics

Visual description of subject

Context
Microplastics (MPs, <5 mm) are a pervasive pollutant found throughout the global ocean — from coastal zones to deep-sea trenches (Auta et al., 2017). Their transport and accumulation are strongly shaped by ocean circulation. Numerous modeling studies have investigated the physical processes driving MPs distribution in the ocean (Huck et al., 2022; Richon et al., 2022; van der Mheen et al., 2019). These studies revealed that processes such as Stokes drifts, convergence pathways and convective mixing influence the distribution of MPs and its partition between surface and sub-surface layers. However, the influence of interannual to decadal climate variability (e.g., ENSO, NAO, climate change) on MP distribution remains unexplored, despite emerging evidence of significant interactions (Goddijn-Murphy et al., 2025).

Objectives
This internship aims to investigate how interannual variability in ocean circulation influences the 3D global distribution of microplastics. Specifically, the student will:

Implement and run global ocean simulations with the NEMO/PISCES-PLASTIC model, developed by the host team;
Analyze simulation outputs (in NetCDF format) to quantify how varying climate conditions (past, present, and future) affect MP distribution patterns and accumulation zones.

Work Environment
The internship will take place at the Laboratoire d’Océanographie Physique et Spatiale (LOPS) in Brest, France for a duration of 6 months. The student will work with the NEMO/PISCES-PLASTIC global ocean model, which simulates the 3D transport of microplastics of different shapes and densities. The project is related to Anne Gaymard’s PhD on modeling the distribution and impacts of microplastics of various morphologies in the global ocean and will be co-supervised by Anne Gaymard, Thomas Gorgues, and Camille Richon.

Expected Outcomes
This internship will provide new insights into how interannual and decadal ocean variability modulates the transport and accumulation of microplastics. The results could improve our understanding of observed MP patterns and inform future projections under changing climate conditions.

Candidate Profile

Master’s 2 student in oceanography, climate sciences, environmental physics, or applied mathematics
Experience with numerical modeling, Python, and NetCDF data analysis
Strong interest in physical oceanography and climate variability

Contacts
Thomas Gorgues - thomas.gorgues[at]ird.fr Anne Gaymard - anne.gaymard[at]univ-brest.fr Camille Richon - camille.richon[at]univ-brest.fr

References
Auta.et al, 2017 Environment International 102, 165–176. https://doi.org/10.1016/j.envint.2017.02.013
Goddijn-Murphy et al., 2025. Marine Pollution Bulletin 212, 117528. https://doi.org/10.1016/j.marpolbul.2025.117528
Huck et al. 2022. Frontiers in Analytical Science 2. https://doi.org/10.3389/frans.2022.868515 Richon et al. 2022. Front. Mar. Sci. 9. https://doi.org/10.3389/fmars.2022.947309
van der Mheen et al. 2019. Journal of Geophysical Research: Oceans 124, 2571–2590 https://doi.org/10.1029/2018JC014806