Redox issue of the journal Elements, coordinated by IPGP researchers

Knowledge of redox exchanges is essential for understanding the composition of our planet and its evolution, as well as the fundamental processes that occur in any natural chemical system, from the nucleus to the atmosphere, from magmatic systems to aquatic systems, from non-living to living. We are also familiar with many redox balances: combustion, rust and corrosion, respiration and photosynthesis.

At the Earth’s surface, almost all materials tend to oxidise when they come into contact with the atmosphere. Moreover, the phenomena associated with chemical alteration correspond to a set of oxidising processes that act collectively to consume atmospheric oxygen. This tendency is counterbalanced by biological processes, such as photosynthesis, which reduce CO2 and produce O2, allowing life to flourish on the Earth’s surface. The regulation of biological activity on Earth is now controlled by redox conditions, which determine whether and where specific metabolic pathways are thermodynamically most favourable.

Understanding redox balances is also important from a socio-economic point of view. They are fundamental to the development of metal deposits (by helping to control the mobility of metals in magmas and crustal fluids, right through to their deposition in future deposits). They can be used as indicators for environmental risk assessment, since they also play a fundamental role in the speciation of contaminants in our everyday environment. Finally, redox equilibria play a key role in processes that are essential in the steel, glass and cement industries, and in the development of new materials.