Phys.org  May 17, 2023 In search for critical elements, polymetallic nodules at the deep abyssal seafloor are targeted for mining operations. Nodules efficiently scavenge and retain several naturally occurring uranium-series radioisotopes, which predominantly emit alpha radiation during decay. Researchers in Germany have presented new data on the activity concentrations of thorium-230, radium-226, and protactinium-231, as well as on the release of radon-222 in and from nodules from the NE Pacific Ocean. They demonstrated that the activity concentrations for several alpha emitters were often higher than at the surface of the nodules. The observed values could exceed current exemption levels by […]