The GEochimie Des Impacts (GEDI) team is interested in studying the influence of anthropogenic activities on the transfer of matter (particles, carbon and contaminants associated with particles) on continental surfaces using geochemical tools (stable and radioactive isotopic tracers, elemental tracers). Novel alternative tracers have been added to this conventional suite of tracers (colour, infrared spectroscopy, environmental DNA, etc.). Many nutrients and pollutants have a strong affinity for particles, and their transfer or storage in watercourses is largely governed by dissolved-particle exchanges and linked to the fate of fine particles. The impacts studied include soil erosion, river contamination and sediment fluxes across catchments. The common points between the studies tackled by the different members of the team are the development of dating and tracing methodologies for studying transfer processes and the quantification of material fluxes, using the data obtained to test and feed different types of hydrological and transfer models for particles and associated pollutants.
Study areas
To achieve these objectives, case studies are carried out in different environments in France, both in mainland France and overseas (Martinique, Mayotte, etc.), as well as around the world (Brazil, Uruguay, Argentina, Laos, Japan) in order to improve our overall understanding of these transfer processes and their response to global change. The team is involved in numerous national and regional projects (e.g. pollution of the Seine through the PIREN-Seine programme, Chantier Notre-Dame following the cathedral fire that took place in 2019, ANR ANTIMONY, ANR TRAJECTOIRE, ANR DECACLIM, EC2CO HISTORIFEUX, LESELAM) and international projects (e.g. French-Swiss project AVATAR, DinBuam, International Research Project MITATE Lab Post-Fukushima Studies, International Research Project CELESTE Lab).
Our projects page gives more details on some of them.
The team’s expertise, acquired through numerous field campaigns, ranges from the characterisation of contemporary sources of fine particles through the collection of soil, atmospheric fallout and suspended matter, to the study of historical evolution through the reconnaissance and coring of overflow plains, ponds and lakes, veritable archives of catchment areas.
Methods
The team has the required skills to analyse radioactive tracers and trace elements in the environment using a wide range of techniques, such as ICP-QMS, MC-ICP-MS and gamma spectrometry, and has access to dedicated chemistry laboratories including a clean room.