Biogeochemistry of metals and metalloids

(G. Sarret, S. Guédron, A. Gourlan, L. Charlet, A. Fernandez-Martinez, B. Wild)

The biogeochemistry of metals and metalloids encompasses a wide range of topics, from the fate of metal contaminants in the environment to medical geology and paleoenvironmental reconstructions. This vast field of research aims to trace contaminants in environmental compartments, as well as using them as tracers of past contamination and climatic events. They can also be applied to pathologies, and hence to mitigation strategies and therapeutic treatments. This field of research requires strong interactions with other disciplines, notably toxicology and epidemiology, ecotoxicology, agronomy and archaeology.

The speciation of metals and metalloids (oligo-nutrients or contaminants), and its application to understanding their mobility, bioavailability, trophic transfer and toxicity, are links common to these areas of research. Another point of convergence is the use of isotopes as tracers of sources and processes. We use light isotopes, but also metal isotopes, taking advantage of the recent analytical development of multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), which enables us to measure very small isotopic shifts for metals such as Cu, Cd, Zn, etc... Synchrotron-based X-ray techniques are also used extensively to study the speciation of metals and metalloids, and their localization at micrometric or nanometric scales.