M/F PhD position in marine biogeochemistry: CaCO3 dissolution in the deep sea
New
- FTC PhD student / Offer for thesis
- 36 months
- Doctorate
This offer is available in English version
This offer is open to people with a document recognizing their status as a disabled worker.
Offer at a glance
The Unit
Centre de Recherche et d'Enseignement des Géosciences de l'Environnement
Contract Type
FTC PhD student / Offer for thesis
Working hHours
Full Time
Workplace
13545 AIX EN PROVENCE
Contract Duration
36 months
Date of Hire
01/10/2026
Remuneration
2300 € gross monthly
Apply Application Deadline : 20 August 2026 23:59
Job Description
Thesis Subject
This PhD investigates the dissolution of calcium carbonate (CaCO3) in the deep sea, with a focus on the role of organic-matter degradation and microbial activity.
Your Work Environment
The goal is to follow CaCO3 shells (foraminifera, pteropods) from sinking particles to sediment formation, combining experiments (shell-scale respiration measurements, X-ray tomography, high-pressure reactor) with numerical modelling (COMSOL) to quantify and predict dissolution.
• Select and characterise biogenic shells (foraminifera, pteropods) from oceanographic cruises: inverted-microscope imaging, organic-matter localisation, X-ray tomography (CT-scan) before and after dissolution.
• Design and run CaCO3 dissolution experiments: O2 flux and pH measurements using microsensors (nano-respiration kit), varying organic-matter content and environmental conditions.
• Carry out high-pressure reactor experiments to reproduce different depths and study the effects of pressure, ocean acidification, shell quantity and organic-matter content on dissolution.
• Characterise the microbial communities associated with the shells (16S rRNA sequencing, exposure to deep-sea bacterial strains) and assess their role in CaCO3 dissolution, before and after pressurisation.
• Develop and run multiphysics numerical models in COMSOL (3D geometries from tomography, transport–reaction coupling) describing shell dissolution, from the individual scale to the sediment.
• Systematically compare simulations and experimental data to calibrate dissolution kinetics and improve prediction accuracy.
• Disseminate scientific results: writing papers, conference presentations, participation in field/sea campaigns and in the life of the team.
• Contribute to integrating the derived dissolution kinetics into a global ocean model (ECCO-Darwin-type sediment module) to quantify alkalinity generation and associated CO2 storage.
Compensation and benefits
Compensation
2300 € gross monthly
Annual leave and RTT
44 jours
Remote Working practice and compensation
Pratique et indemnisation du TT
Transport
Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€
About the offer
| Offer reference | UMR7330-CELPIN-021 |
|---|---|
| CN Section(s) / Research Area | Earth System: superficial envelopes |
| Relevant experience | 1 to 4 years |
About the CNRS
The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.
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