The GEDI team (l’équipe de GEochimie Des Impacts) uses geochemistry (e.g. stable and radioactive isotopes, elemental composition) to investigate the impact of human activities on material transfers (e.g. sediment and soil particles along with contaminants/chemicals associated with these particles). Many nutrients and pollutants are strongly bound to fine particulate material. Therefore, it is important to understand material mobilization, transport, and storage within watersheds and oceanic water columns. Our research focuses on soil erosion, contamination of rivers, streams and watersheds; the fundamental transfer pathways of materials to the ocean.

The common theme of our team’s research is the development of novel tracing techniques to understand these fundamental transfer processes as well as quantify material flows. Our team samples contemporary soil, atmospheric deposition and suspended material. Further, we sample sediment cores from floodplains and lakes, in order to reconstruct the historical evolution of material transfers over time.

Word cloud based on the publication titles of the GEDI team members between 2010 and 2019

The GEDI team investigates stable and radioactive isotopic tracers along with major and trace elements in these samples with a wide range of analytical techniques such as ICP-MS, MC-ICP-MS and gamma spectrometry. Through these analyses, our team contributes significantly to the development of novel tracing approaches (e.g. U, Pa, Th, Sr, and their isotopes with the use of multi-collection mass spectrometry) necessary to thoroughly understand transfer processes. Accordingly, our facilities offer students and researchers access to multiple laboratories (including a clean room) and multiple analyses.

The GEDI team visiting the underground lab in Modane in June 2019

Our team conducts field work in different environments in France and around the world (e.g. Brazil, Mexico, Laos, Japan, France, New Caledonia) in order to improve our understanding of the material transfer processes. Accordingly, the GEDI team is involved in many national (e.g. ANR STREAMS and TECITEASY) and international projects (e.g. Franco-Japanese collaboration following the Fukushima accident) as well as being an important contributor to local the PIREN-Seine program (devoted to understanding transfer dynamics in the Seine River basin) since its inception (1989).