About this issue
On the background of his own studies of the sulfur cycle over the past forty years, Bo Barker Jørgensen discusses important aspects of the microbiology and geochemistry of sulfur transformations in the seabed. Mixed with anecdotes, he reminisces how the field developed, with exciting discoveries and occasional failures. There is particular focus on experimental approaches and their use to understand sulfate reduction, sulfide oxidation, and disproportionation. Interactions with the methane cycle and with general mineralisation processes are described, and the information provided by stable sulfur isotopes is discussed. The final sections analyse global aspects and future perspectives of the sulfur cycle.