34 research outputs found
Iron Additions Reduce Sulfide Intrusion and Reverse Seagrass (Posidonia oceanica) Decline in Carbonate Sediments
Seasonal dynamics of microbial sulfate reduction in temperate intertidal surface sediments: controls by temperature and organic matter
Sulfate Reduction and Sulfur Cycles at Two Seagrass Beds Inhabited by Cold Affinity Zostera marina and Warm Affinity Halophila nipponica in Temperate Coastal Waters
Organic carbon accumulation and sulfate reduction rates in slope and basin sediments of the Ulleung Basin, East/Japan Sea
The Impact of Sediment and Carbon Fluxes on the Biogeochemistry of Methane and Sulfur in Littoral Baltic Sea Sediments (Himmerfjärden, Sweden)
Biological and chemical sulfide oxidation in a Beggiatoa inhabited marine sediment
The ecological niche of nitrate-storing Beggiatoa, and their contribution to the removal of sulfide were investigated in coastal sediment. With microsensors a clear suboxic zone of 2-10 cm thick was identified, where neither oxygen nor free sulfide was detectable. In this zone most of the Beggiatoa were found, where they oxidize sulfide with internally stored nitrate. The sulfide input into the suboxic zone was dominated by an upward sulfide flux from deeper sediment, whereas the local production in the suboxic zone was much smaller. Despite their abundance, the calculated sulfide-oxidizing capacity of the Beggiatoa could account for only a small fraction of the total sulfide removal in the sediment. Consequently, most of the sulfide flux into the suboxic layer must have been removed by chemical processes, mainly by precipitation with Fe2+ and oxidation by Fe(III), which was coupled with a pH increase. The free Fe2+ diffusing upwards was oxidized by Mn(IV), resulting in a strong pH decrease. The nitrate storage capacity allows Beggiatoa to migrate randomly up and down in anoxic sediments with an accumulated gliding distance of 4 m before running out of nitrate. We propose that the steep sulfide gradient and corresponding high sulfide flux, a typical characteristic of Beggiatoa habitats, is not needed for their metabolic performance, but rather used as a chemotactic cue by the highly motile filaments to avoid getting lost at depth in the sediment. Indeed sulfide is a repellent for Beggiatoa