Search

Magnetotactic bacteria(MTB) are ubiquitous prokaryotes that orient along magnetic field lines due to magnetosomes' biomineralization within the cell. These structures are ferrimagnetic organelles that impart a magnetic moment to the cell. To succeed in producing magnetosomes, MTB accumulate iron in(i) cytoplasm;(ii) magnetosomes; and(iii) nearby the organelle. It has already been estimated that a single MTB has an iron content of 10 to 100-fold higher than Escherichia coli. Phages are the most abundant entity in oceans and are known for controlling nutrient flow such as carbon and nitrogen by viral shunt and pump. The current work addresses the putative role of phages that infect MTB on the iron biogeochemical cycle. Can phage infection in MTB hosts cause a biogenic iron fertilization-like event in localized microenvironments? Are phages critical players in driving magnetosome biomineralization genes(BGs) horizontal transfer? Further investigation of those events, including frequency of occurrence, is necessary to fully comprehend MTB's effect on iron cycling in aqueous environments. [ABSTRACT FROM AUTHOR]

We applied field structural data and isotope geochemical (δ13C, δ18O and 87Sr/86Sr) analyses to understand the relationship among calcite veins, fault damage zones and carbonate host rocks in a thrust fault damage zone in the Achado quarry, Irecê Basin in the São Francisco Craton, NE Brazil. Our results reveal three hydrological packages with different rheological behaviours in a stratified carbonate succession. The upper package includes the Achado fault damage zone that is characterised by interlayered dolomitised grainstones and mudstones. These rocks display high positive δ13C values (10‰–13‰), negative δ18O values (mean −6.34‰) and radiogenic (87Sr/86Sr) isotope values (0.70885–0.71519). A second package is marked by a cataclastic brittle shear zone lateral parallel to dolograinstones bedding. These rocks show low to positive δ13C values (−3.41‰ to +8.85‰), more positive δ18O values (mean −3.73‰) and radiogenic (87Sr/86Sr) isotope values (0.71039–0.71373). The lower package is characterised by well‐preserved pristine limestone succession that shows δ13C values ranging between −0.46‰ and +3.17‰, mean δ18O = −5.41‰ and less radiogenic 87Sr/86Sr values (0.70762–0.70818). In contrast to the upper and intermediate packages, rocks from the lower one exhibit very low permeability and behaved as a seal for fluid migration. Fluid flow occurred several times during basin evolution, for example along syn‐rift fault damage zones, bedding‐parallel carbonate breccia, thrust faults, cataclastic shear zones, synorogenic conjugate shear fractures or joints and opening mode I fracture‐fill calcite veins. These fractures allowed pervasive fluid flow in the porous intermediate cataclastic shear zone where fluids flowed and formed veins, as diffuse fluid flow in randomly oriented fracture swarms, or channelised fluid flow in aligned fracture corridors. They record significant centimetre‐scale to km‐scale hydrological behaviour within carbonate layers. Most carbonates that are associated with veins, fault damage zones and hydraulic breccia were formed by fluids of the same origin with low δ13C (−6.0 to −2.0‰) and δ18O (−6.0 to −8.5‰) values, and more radiogenic 87Sr/86Sr values compared to the carbonate host rocks. [ABSTRACT FROM AUTHOR]

Anaerobic digestion has been widely applied for waste treatment, renewable energy generation and biofertilizer production. The biogas potential in Brazil is sizable, but the state of Rio de Janeiro is largely dependent on fossil fuels, and there is a lack of biogas potential assessments in the state. Thus, this study evaluated biomethane, electricity and biofertilizer potentials in the region. Three different scenarios of biomass supply were considered for four major biowaste streams: sewage sludge; cattle manure; sugarcane processing waste; and food waste. Biomethane generation from the assessed sources could reach 0.6–1.3 billion Nm3 year−1, corresponding to 1,768–3,961 GWh year−1 of electricity and 1.6–3.3 million Mg year−1 of biofertilizer. Cattle manure was responsible for 73–84% of the projected biomethane production, presenting an opportunity to reduce the significant emissions from livestock farming. The estimated biofertilizer production could meet the demands of the state, and the produced electricity could offset up to 10% of the demand. The gas grid could facilitate the distribution of upgraded biomethane, and 10–22% of the natural gas demand could be met. The findings of this work highlight the high potential for biogas generation in Rio de Janeiro, which is up to seven times larger than the current production. [ABSTRACT FROM AUTHOR]

Carbonates of the Salitre Formation, Irecê Basin, Brazil, have been the focus of extensive stratigraphic and structural studies for several decades. Besides hosting phosphorites deposits, these rocks are analogues to fractured and certified oil reservoirs, such as those of the Cretaceous pre-salt oil system offshore Brazil. The present study presents an integration of X-Ray Diffraction (XRD), Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMScan), Optical Petrography, Cathodoluminescence (CL), and Charge Contrast Imaging (CCI) data that allows a high-resolution characterization of the mineralogy within the carbonate units. In addition, we also present carbon and oxygen stable isotope data to identify possible origins of the associated fluids. The mineral characterization revealed that calcite (50–70%), quartz (20–30%) and dolomite (10–20%) are the main post-sedimentary mineral phases found in veins, vesicle structures and cement of the carbonate units. The mineral phases of veins were formed by the interaction with hydrothermal fluids, which had an important role in the dissolution, karstification, and remobilization of carbonate units. Isotopic analysis shows that δ13C and δ18O are more negative in veins and vesicles when compared to host rock, indicating that there is no effective isotopic exchange between the host rock and the filled structures and that these structures were filled with hydrothermal fluids from an external source. • Hydrothermal processes in carbonate sequences lead to hypogenic carstification. • The carbonate sequences of the Salitre Formation have structures filled with calcite, dolomite and quartz. • Isotopes of carbon and oxygen show that the veins and vesicles have a different signature than the embedding rock. • Fractures and faciological characteristics of carbonate sequences control the pervasive nature of hydrothermal fluids. • Mineralogical characterization shows dolomitization and dolomitic cementation processes. [ABSTRACT FROM AUTHOR]