Where does hydrogen in the deep sea come from? An international team led by the University of Bremen addressed this question and discovered an unexpected process occurring beneath the sparsely studied hydrothermal fields at extremely slow-spreading mid-ocean ridges that could play an important role. Particularly at sites where liquids circulate through sediments. Samples from the Jøtul Hydrothermal Field off Norway were analyzed for the study. The findings have been published in the professional journal Communications Earth & Environment.