Redox processes in pore water of anoxic sediments with shallow gas.

摘要: The Ria de Vigo (NW Spain) has a high organic matter content and rates of sedimentation. microbial degradation this led to shallow gas accumulations methane, currently distributed all along the ria. These peculiar characteristics favor development anoxic conditions that can determine dynamics iron manganese. In order study role played by manganese in processes take place sediments with gas, four gravity cores were retrieved November 2012. Methane was present two them, below 90cm inner zone 200cm, outer zone. Pore water collected analyzed for vertical profiles pH, sulfide, sulfate, concentrations. Sulfate concentrations decreased depth but never reached minimum detection limit. High sulfide measured cores. highest found methane lowest without methane. Concentrations maximum values upper layers sediment, decreasing depth, except where concentration increased strongly toward bottom sediment. areas reduction, sulfate reduction production coexist, showing traditional redox cascade is highly simplified suggesting may be involved cryptic sulfur cycle oxidation