Title: Studies on the geochemical behavior of metals at redox interfaces

ABSTRACT

Natural redox boundaries such as hydromorphic soils and aquatic sediments are dynamic environments, with spatial and temporal heterogeneities known to impact the speciation/availability of major and trace elements, and their role as essential nutrients or toxic contaminants.

This seminar will present collaborative field and laboratory studies conducted at the Institute of Mineralogy, Physics of Materials and Cosmochemistry (Sorbonne University), the French Institute for Radiation Protection and Nuclear Safety, the Department of Environmental Geosciences (University of Vienna), and Argonne National Laboratory. It will address uranium behavior in a uranium mining-impacted wetland; zinc oxide nanoparticles transformation in lacustrine sediments; and iron redox-biogeochemistry in coastal soils located along upland to shoreline gradients. In particular, the power of X-ray absorption spectroscopy, X-ray fluorescence, and electron microscopy techniques for determining elemental speciation and distribution at the atomic and microscopic scales will be highlighted. Combined with additional mineralogical and chemical analyses, this information provides an improved understanding of the (bio)geochemical processes involved in the scavenging and/or mobilization of metals, which is crucial to predict their fate in natural and engineered environments.

BIO

Dr. Lucie Stetten is a researcher at Argonne National Laboratory in the Bioscience Division. She received her PhD in 2018 in Environmental Geochemistry and Mineralogy from Sorbonne University (Paris, France). Her research focuses on the biogeochemical cycles of major and trace elements in aquatic and terrestrial environments. She is particularly interested in the study of abiotic and biotic processes at solid-solution interfaces affecting the fate of contaminants and nutrients. Her research relies on synchrotron-based techniques such as X-ray absorption spectroscopy and X-ray Fluorescence, as well as Electron Microscopy to determine elemental speciation and distribution at the micro and molecular scales.