Researcher in geochemistry

The institut de physique du globe de Paris

A world-renowned geosciences organisation, the IPGP is associated with the CNRS and an integrated institute of the Université Paris Cité. Bringing together more than 500 people, the IPGP studies the Earth and the planets from the core to the most superficial fluid envelopes, through observation, experimentation and modelling.

The research aeras are structured through 4 main unifying themes: Interiors of the Earth and Planets, Natural Hazards, Earth System and Origins.

The IPGP is in charge of labelled observation services in volcanology, seismology, magnetism, gravimetry and erosion. And the IPGP’s permanent observatories monitor the four active French overseas volcanoes in Guadeloupe, Martinique, Réunion Island and Mayotte.

The IPGP hosts powerful computing resources and state-of-the-art experimental and analytical facilities and benefits from first-class technical support. The IPGP provides its students with geosciences training that combine observation, quantitative analysis and modelling, and that reflects the quality, richness and thematic diversity of the research conducted by the IPGP teams.

Team Department

The ACE team’s research focuses on the biogeochemical cycles of elements in the critical zone, particularly their evolution during the Anthropocene. The research questions addressed concern the speciation of heavy metals and organic contaminants (e.g., pesticides, pharmaceuticals, PFAS), their transport and transfer processes in natural compartments (soils, sediments, water, air), changes in their mobility and availability under the influence of anthropogenic forcing (including remediation processes), the behavior and fate of emerging contaminants such as manufactured or accidental nanoparticles in the environment, processes enabling the recovery of critical technological elements (TCEs) in the context of the circular economy and urban metabolism, whose biogeochemical cycles in the critical zone will be modified by their massive use in new technological applications.

Missions

The postdoctoral researcher will participate in the ANR Me-Thiol project led by the Institut de Physique du Globe de Paris, with potential collaborations with INSA Lyon, INRAE Bordeaux, and Géosciences Rennes. The project aims to better understand and describe the interactions between metals (Cd, Ag, Hg, Pt, Pd, Au) and thiol compounds present in natural waters and soils. Three mechanisms have been identified in the literature: metal complexation by thiol groups, metal reduction by these groups, and precipitation as metal sulfides. These three mechanisms will be studied through laboratory experiments conducted in an anaerobic chamber, with the resulting products analyzed using X-ray absorption spectroscopy (XAS) via synchrotron analysis. The results will be modeled using a combination of thermodynamic and kinetic models to be developed.

The postdoctoral fellow will also participate in the ANR REMAPE project, a collaborative initiative led by the Géosciences Rennes laboratory, in partnership with the ECOBIO laboratory and the Institut de Physique du Globe de Paris. The project aims to better understand and describe the dynamic interactions between contaminants and plants. Adopting a mechanistic approach, the project breaks with traditional descriptive approaches to contaminant transfer by seeking to quantify transfer and transformation processes in the rhizosphere under realistic and dynamic conditions. The successful candidate will be responsible for developing a geochemical speciation model that accounts for the impact of soil colloids on the speciation of key contaminants (As, Pb, Cu, Zn, etc.), based on an additive surface complexation model.

Activities

 More specifically, the postdoctoral fellow will be responsible for:

1) Conducting a review of the data available in the literature to support the development of a metal-thiol complexation model (acid-base titrations, complexation experiments, synchrotron data, etc.);

2) Conducting experiments in an anaerobic chamber for metals for which experimental data are lacking;

3) Submit funding proposals and analyze samples using XAS spectroscopy at the SOLEIL or ESRF synchrotrons;

4) Develop a thermodynamic model capable of accounting for metal complexation by thiol groups using the geochemical speciation software PHREEQC or Orchestra, which will implement the Model VII and/or Nica-Donnan models modified to account for thiol groups. Complexation constants will be determined for the following metals: Hg, Ag, and Cu;

5) Develop a kinetic model capable of accounting for the reduction kinetics of metals by thiol compounds in ionic or precipitated form.

6) Conduct a review of surface complexation models and available databases for contaminants that bind to colloidal phases (Fe/Al/Mn oxides, clays, organic matter);

7) Implement these models in geochemical speciation software (PHREEQC, Visual Minteq, or Orchestra);

8) Simulate the impact of physicochemical conditions (pH, Eh, solution composition) and colloidal composition on the speciation of contaminants, assuming an additive surface complexation model.

9) Communicate the results to the ACE team and project participants, as well as to the scientific community, through participation in Goldschmidt 2027 and by publishing scientific articles.

Expected Skills

> Expert in surface geochemistry, contaminants speciation

> Very strong expertise in geochemical speciation modeling

> Capability to communicate results (orally and by writing)

Obligations and risks

> Work on a computer.

> Experiments with toxic metals

Training and experience required

> PhD in Earth sciences with no more than 3 years experience.

How to apply

> CV and cover letter demonstrating clearly the very strong expertise in geochemical speciation modeling

> Deadlines for applications : August 27, 2026

> Contacts (2 contacts are required for the interview)

Rémi Marsac ()

Charlotte Catrouillet ()