PhD defense of Luna Cartayrade

Abstract: What is selenium (Se)? Where does it come from? The third chalcogen element, Se, has essential properties in biological systems, from mammals to plants. Interest in selenium grew when its vital properties were confirmed, leading to an increase of studies on its presence and distribution across the globe. We first thought Se concentration to be confined to soil and water, but recent discovery on its presence in precipitations led research to grow an interest in the possibility of Se cycling across the atmosphere. In my work, I aim to shed light on the transformations of the main emitted Se species, driven by HO^• radical, the atmospheric scavenger. I provide key thermodynamic data about the five most emitted gaseous species, and scrutinize how three of them are transformed by HO^•, using computational tools. This study is anchored into a broader scheme, where multiple teams, experiments and computations are synergistically working side by side to build our understanding of Se atmospheric cycle.