A cryptic sulfur cycle driven by iron in the methane zone of marine sediment (Aarhus Bay, Denmark)

摘要: Abstract Sulfate reduction and sulfur–iron geochemistry were studied in 5–6 m deep gravity cores of Holocene mud from Aarhus Bay (Denmark). A goal was to understand whether sulfate is generated by re-oxidation sulfide throughout the methane zones, which might explain abundance active reducers below main zone. penetrated down 130 cm where started build up concentration free peaked at 5.5 mM. Below this sulfate–methane transition, diffused downwards a sulfidization front 520 cm depth, dissolved iron, Fe2+, accumulated pore water. rates measured 35S-tracer incubations zone high due concentrations reactive organic matter. Within distinctly stimulated anaerobic oxidation methane. In below, remained positive “background”