Chromium exists in sediments in two oxidation states: Cr(III), which is relatively insoluble and nontoxic, and Cr(VI), which is much more soluble and toxic. Chromium(VI) is thermodynamically unstable in anoxic sediments, and acid-volatile sulfide (AVS) is formed only in anoxic sediments; therefore sediments with measurable AVS concentrations should not contain toxic Cr(VI). If this hypothesis h...

Microorganisms dominate most Antarctic marine ecosystems, in terms of biomass and taxonomic diversity, and play crucial role in ecosystem functioning due to their high metabolic plasticity. Admiralty Bay is the largest bay on King George Island (South Shetland Islands, Antarctic Peninsula) and a combination of hydro-oceanographic characteristics (bathymetry, sea ice and glacier melting, seasona...

Phosphate release from sediments hampers the remediation of aquatic systems from a eutrophic state. Microbial phosphatases in sediments release phosphorus during organic matter degradation. Despite the important role of phosphatase-expressing bacteria, the identity of these bacteria in sediments is largely unknown. We herein presented a culture-independent method to phylogenetically characteriz...

Fish farm sediments receive a large amount of organic matter from uneaten food and fecal material. This nutrient enrichment, or organic pollution, causes the accumulation of sulphide in the sediment from the action of sulphate-reducing bacteria (SRB). We investigated the effect of organic enrichment around coastal fish farms comparing the SRB community structure in these sediments. Sediment sam...

Phosphate release from sediments hampers the remediation of aquatic systems from a eutrophic state. Microbial phosphatases in sediments release phosphorus during organic matter degradation. Despite the important role of phosphatase-expressing bacteria, the identity of these bacteria in sediments is largely unknown. We herein presented a culture-independent method to phylogenetically characteriz...

Allochthonous and autochthonous organic matter deposited in benthic sediments are mineralized by microbial communities, resulting in release of nutrients to the water column. Lakes with different trophic states may have sediments with different carbon and nutrient concentration with consequently different microbial communities. Microbial diversity of surface sediments of three subtropical lakes...

We evaluated the depth-dependent geochemistry and microbiology of sediments that have developed via the microbially-mediated oxidation of Fe(II) dissolved in acid mine drainage (AMD), giving rise to a 8-10 cm deep "iron mound" that is composed primarily of Fe(III) (hydr)oxide phases. Chemical analyses of iron mound sediments indicated a zone of maximal Fe(III) reducing bacterial activity at a d...

Surface sediments were collected from various locations of the Mandovi estuary and the Marmugoa harbour. Sediments were analysed for organic carbon (OC), total lipids, n-alkanes concentration and composition. Concentrations of OC, total lipids and n-alkanes varied spatially and ranged from 1 to 2.5%, 176 to 1413 microg/g dry weight (dw) sediments, and 0.8 to 3.2 microg/g dw sediments of the Man...

Bacteria are the most abundant and active organisms in marine sediments and are critical for nutrient cycling and as a food source to many benthic and pelagic organisms. Bacteria are found both as free-living cells and as particle-associated cells, which can make investigations of these communities difficult. We found that common procedures for extracting bacteria from sediments leave the bacte...