The concept of redox conditions is widely applied in the studies of modern and ancient aquatic systems. It is based on the availability of free oxygen (oxic, suboxic, anoxic conditions) and free hydrogen sulfide (euxinic conditions) within a defined water mass, e.g. a lake or ocean basin. Redox conditions exert a fundamental control on many natural processes, e.g.the number and species of organisms, the availability and recycling of essential nutrients like Fe and P, the degradation and preservation of organic matter, and even the evolution of life.

Because they are of such importance in the natural environment, redox conditions and their variability in modern and ancient aquatic systems are intensively studied. In the sedimentary record, redox changes are documented by e.g. the abundance and assemblage of benthic organisms and trace fossils, the degree of bioturbation or lamination, the morphology of pyrite framboids, specific biomarkers, enrichments or depletions of trace metals, Fe and P species, and signatures of traditional (e.g. S, N) and non-traditional (e.g. Cr, Fe, Mo, U) stable isotopes.

The aim of this session is to bring together scientists that study the redox conditions of aquatic systems, their biogeochemical causes and consequences, and the development and limitations of redox proxies. This includes investigations of Precambrian to modern lacustrine and marine sedimentary systems, biogeochemical laboratory experiments, and computer modeling. We welcome contributions that apply (ideally in combination) biological, micro- and macro-paleontological, sedimentological, organic and inorganic geochemical methods and data. We specifically encourage submissions that bridge the gap between modern observations and sedimentary proxy records.