A review of microbial-environmental interactions recorded in Proterozoic carbonate-hosted chert.

The record of life during the Proterozoic is preserved by several different lithologies, but two in particular are linked both spatially and temporally: chert and carbonate. These lithologies capture a snapshot of dominantly peritidal environments during the Proterozoic. Early diagenetic chert preserves some of the most exceptional Proterozoic biosignatures in the form of microbial body fossils and mat textures.

Formation of Zerovalent Iron in Iron-Reducing Cultures of .

Methanogenic archaea have been shown to reduce iron from ferric [Fe(III)] to ferrous [Fe(II)] state, but minerals that form during iron reduction by different methanogens remain to be characterized. Here, we show that zerovalent iron (ZVI) minerals, ferrite [α-Fe(0)] and austenite [γ-Fe(0)], appear in the X-ray diffraction spectra minutes after the addition of ferrihydrite to the cultures of a methanogenic archaeon, (). cells and redox-active, nonenzymatic soluble organic compounds in organic-rich spent culture supernatants can promote the formation of ZVI; the latter compounds also likely stabilize ZVI.

Light-driven anaerobic microbial oxidation of manganese.

Oxygenic photosynthesis supplies organic carbon to the modern biosphere, but it is uncertain when this metabolism originated. It has previously been proposed that photosynthetic reaction centres capable of splitting water arose by about 3 billion years ago on the basis of the inferred presence of manganese oxides in Archaean sedimentary rocks. However, this assumes that manganese oxides can be produced only in the presence of molecular oxygen, reactive oxygen species or by high-potential photosynthetic reaction centres.

System-Wide Adaptations of Desulfovibrio alaskensis G20 to Phosphate-Limited Conditions.

The prevalence of lipids devoid of phosphorus suggests that the availability of phosphorus limits microbial growth and activity in many anoxic, stratified environments. To better understand the response of anaerobic bacteria to phosphate limitation and starvation, this study combines microscopic and lipid analyses with the measurements of fitness of pooled barcoded transposon mutants of the model sulfate reducing bacterium Desulfovibrio alaskensis G20. Phosphate-limited G20 has lower growth rates and replaces more than 90% of its membrane phospholipids by a mixture of monoglycosyl diacylglycerol (MGDG), glycuronic acid diacylglycerol (GADG) and ornithine lipids, lacks polyphosphate granules, and synthesizes other cellular inclusions.

Mercury methylation and demethylation in highly contaminated sediments from the Deûle River in Northern France using species-specific enriched stable isotopes.

The methylation-demethylation processes in sediments of the Deûle River were determined using well-established isotope experiments. For this purpose, species-specific isotopically enriched tracers in the form of inorganic mercury IHg ((199)Hg) and methylmercury MeHg (Me(201)Hg) were used to determine Hg dynamics in the Deûle River. Sediment cores were collected at two sampling locations chosen in the most polluted zone of the Deûle River (Northern France) in proximity of a Zn, Pb, Cu, and Ni smelter called "Metaleurop" that had closed in 2003.

Biogeochemical factors affecting the distribution, speciation, and transport of Hg species in the Deûle and Lys Rivers (Northern France).

The Deûle River is a highly polluted River by heavy metals caused by the historical discharges of ore minerals from the former ore smelter "Metaleurop." The potential mercury (Hg) pollution in the Deûle River implicates the importance of Hg distribution study in the river. As well as to configure the different biogeochemical factors that control the distribution and the potential transport of Hg to distant places.

Solid phase extraction of inorganic mercury using 5-phenylazo-8-hydroxyquinoline and determination by cold vapor atomic fluorescence spectroscopy in natural water samples.

8-Hydroxyquinoline (8-HQ) was chosen as a powerful ligand for Hg solid phase extraction. Among several chelating resins based on 8-HQ, 5-phenylazo-8-hydroxyquinoline (5Ph8HQ) is used for mercury extraction in which the adsorption dynamics were fully studied. It has been shown that Hg(II) is totally absorbed by 5Ph8HQ within the first 30 minutes of contact time with t 1/2 5 minutes, following Langmuir adsorption model.

Profile of trace metals accumulation in core sediment from Seine river estuary (docks basin).

The Seine is one of the most polluted rivers in Europe with respect to potentially harmful elements. It receives effluents from the upstream Paris urban and industrial area, and also local inputs from the heavily industrialized Rouen and Le Havre regions. The present study deals with this environmental topic and the concentrations of Cd, Ni, Pb, Hg, Zn and Cu were determined in sediment cores collected in the docks basin of Rouen harbour in 2008.

Preconcentration of total mercury from river water by anion exchange mechanism.

A simple and cheap analytical technique was developed for the measurement of total mercury in river water samples using inductively coupled plasma-mass spectrometry (ICP-MS). It is based on the direct complexation of mercury ions using iodide and a cationic surfactant in water for its subsequent solid-phase extraction. Mercury ions are retained on the silica phase as ion pairs in the presence of iodide ions and dodecyltrimethylammonium bromide.