Séminaire “Effect of anthropogenic and climatic forcing on the metal contaminant cycle in the surface environments” par Gildas Ratié (LPG)

The biogeochemical cycles of metals have been profoundly disrupted by anthropogenic activities, particularly since the industrial revolution. These activities as well as the impacts linked to climate forcing are at the origin of significant flows and mobilization of metals, particularly towards soils and continental waters. Within the critical zone, soils act like sinks, particularly in wetlands with significant metal trapping capacities, acting as accumulator filters through their hydrological cycle (high water/low water) controlling biogeochemical processes. Climate models predict that the frequency, intensity and number of heavy precipitation events will increase as the global climate evolves. This state of affairs no longer makes it possible to precisely constrain the fate and source-sink balance of metals in the environment and consequently of the overall contributions from the continent to the oceans. Coupling of use of isotopic tracers and the study of the speciation of elements by X-ray spectroscopy on synchrotron, makes it possible to identify and finely quantify the process at the origin of the flows of metals between the different natural reservoirs.