Coastal waters worldwide suffer from increased eutrophication and seasonal bottom water hypoxia. Here, we assess the dynamics of iron (Fe), manganese (Mn), and phosphorus (P) in sediments of the eutrophic, brackish Gulf of Finland populated by cable bacteria. At sites where bottom waters are oxic in spring, surface enrichments of Fe and Mn oxides and high abundances of cable bacteria were observed in sediments upon sampling in...

Continental shelves are a major source of iron (Fe) and manganese (Mn) to marine waters. Here, we investigate controls on benthic release of Fe and Mn and the impact on the water column in the Baltic Sea. We find high in situ benthic release rates of dissolved Fe and Mn at seasonally hypoxic sites (bottom water oxygen between 0–63 μ mol L −1 ) receiving high inputs of organic matter. We find that benthic Fe and Mn release is s...

The dissolution rates of diatom frustules, phytoliths, two diatomaceous lake sediments, a siliceous ooze from the Southern Ocean, a diatomite deposit, and a synthetic amorphous silica were measured in flow‐through reactors supplied with either seawater or freshwater. Although the rates varied by more than one order of magnitude among the different siliceous materials, for any given solid the rate was systematically higher in s...