Editorial: Natural and artificial radionuclides as tracers of ocean processes

The global oceans are a repository of radionuclides, both naturally occurring and anthropogenic, the latter originating predominantly from fallout from past atmospheric nuclear weapons tests, discharges from nuclear reprocessing plants and releases following accidents at nuclear facilities. The sources and physical and geochemical properties (e.g., radioactive half-life, solubility, particle reactivity and bioavailability) of these radionuclides vary broadly, giving rise to their use as radiotracers and providing a rich collection of tools for improving our understanding of ocean dynamics and processes. This Research Topic demonstrates how physical oceanographers and marine biogeochemists are currently moving beyond the state-of-the-art in the application of these radiotracers for increasing our knowledge of water circulation, particle cycling and fluxes, sedimentation processes, paleoceanography and more.
Even so, more comprehensive use of radionuclides as tracers in ocean science can be hindered by various factors, including instrumental limitations, complex and laborious analytical procedures, sparse observation data and methodological uncertainty. Looking forward, we also consider below ways in which these are already being overcome.