Barite formation in the ocean: Origin of amorphous and crystalline precipitates

We also thank editors and two anonymous reviewers for helpful comments that have significantly improved this contribution.Ocean export production is a key constituent in the global carbon cycle impacting climate. Past ocean export production is commonly estimated by means of barite and Barium proxies. However, the precise mechanisms underlying barite precipitation in the undersaturated marine water column are not fully understood. Here we present a detailed mineralogical and crystallographic analysis of barite from size-fractionated particulate material collected using multiple unit large volume in-situ filtration systems in the North Atlantic and the Southern Ocean. Our data suggest that marine barite forms from an initial amorphous phosphorus-rich phase that binds Ba, which evolves into barite crystals whereby phosphate groups are substituted by sulfate. Scanning electron microscopy observations also show the association of barite particles with organic matter aggregates and with extracellular polymeric substances (EPS). These results are consistent with experimental work showing that in bacterial biofilms Ba binds to phosphate groups in both cells and EPS, which promotes locally high concentrations of Ba leading to saturated microenvironments favoring barite precipitation. These results strongly suggest a similar precipitation mechanism in the ocean, which is consistent with the close link between bacterial production and abundance of Ba-rich particulates in the water column. We argue that EPS play a major role in mediating barite formation in the undersaturated oceanic water column; specifically, increased productivity and organic matter degradation in the mesopelagic zone would entail more extensive EPS production, thereby promoting Ba bioaccumulation and appropriate microenvironments for barite precipitation. This observation contributes toward better understanding of Ba proxies and their utility for reconstructing past ocean export productivity. This article is part of a special issue entitled: “Cycles of trace elements and isotopes in the ocean – GEOTRACES and beyond” - edited by Tim M. Conway, Tristan Horner, Yves Plancherel, and Aridane G. González.This study was supported by the European Regional Development Fund (ERDF) co-financed grants CGL2015-66830-R and CGL2017- 92600-EXP (MINECO Secretaría de Estado de Investigación, Desarrollo e Innovación, Spain), Research Group RNM-179 and BIO 103 (Consejería de Economía, Innovación, Ciencia y Empleo, Junta de Andalucía) and the University of Granada (Unidad Científica de Excelencia UCE-PP2016-05). We thank the Center for Scientific Instrumentation (CIC, University of Granada), the Warm Core Rings project, and NSF OCE- 0961660 for supporting sample collection during MV1101

Unlocking the bentonite microbial diversity and its implications in selenium bioreduction and biotransformation: Advances in deep geological repositories

Selenium, 79Se, is one of the most critical radionuclides in radioactive waste disposed in future deep geological repositories (DGRs). Here, we investigate the impact of bentonite microbial communities on the allotropic transformation of Se(IV) bioreduction products under DGR relevant conditions. In addition, Se amendmentdependent shifts in the bentonite microbial populations are assessed. Microcosms of water-saturated bentonites were spiked with a bacterial consortium, treated with selenite and incubated anaerobically for six months. A combination of X-Ray Absorption Spectroscopy, Electron Microscopy, and Raman Spectroscopy was used to track the allotropic changes of the Se bioreduction products. Interestingly, the color of bentonite shifted from orange to black in the selenite-treated microcosms. In the orange layers, amorphous or monoclinic Se(0) were identified, whilst black precipitates consisted of stable trigonal Se(0) form. Illumina DNA sequencing indicated the distribution of strains with Se(IV) reducing and Se(0) allotropic biotransformation potential, like Pseudomonas, Stenotrophomonas, Desulfosporosinus, and unclassified-Desulfuromonadaceae. The archaea Methanosarcina decreased its abundance in the presence of Se(IV), probably caused by this oxyanion toxicity. These findings provide an understanding of the bentonite microbial strategies involved in the immobilization of Se(IV) by reduction processes, and prove their implication in the allotropic biotransformation from amorphous to trigonal Se(0) under DGR relevant conditions.Spanish Government RTI2018.101548.B.I00 FPU 14/0426

Genesis and evolution of the San Manuel iron skarn deposit (Betic Cordillera, SW Spain)

The San Manuel magnesian skarn is an iron deposit hosted in dolomitic marbles from a tectonic slice imbricated within the Ronda peridotites, in the westernmost part of the Betic Cordillera, Spain. According to the dominant mineral assemblage, the skarn is subdivided into three different zones, (1) forsterite ± calcite skarn, (2) calcite ± chlorite ± serpentine skarn, and (3) Ca-amphibole skarn. The main ore in the skarn is a ∼ 2.5 m thick, massive ore body situated in the middle of the sequence. In this paper, we firstly report a comprehensive major to trace element composition, texture, microstructure, and mineralogy characterization for zoned magnesioferrite-magnetite grains of the San Manuel deposit using a combination of (1) laser ablation inductively coupled plasma mass spectrometer, (2) focused ion beam combined with transmission electron microscopy, and (3) electron back-scattered diffraction. We have defined four different magnesioferrite-magnetite generations. A complete sequence of zoning includes cores of magnesioferrite (Mag-1; MgO up to 10.6 wt%) overprinted by three successive generations of magnetite, namely Mag-2, Mag-3, Mag-4. Mag-2 (MgO < 4 wt%), hosts composite forsterite ± calcite ± chlorite inclusions, consistently with high Si, Ca, and Sr (average: 8204 ppm, 8980 ppm, and 49 ppm respectively) contents detected by in situ laser ablation inductively coupled plasma (LA-ICP-MS). Mag-3 replacing former Mag-1 and Mag-2 includes nanometric spinel and gahnite exsolutions detected by focused ion beam combined with a transmission electron microscope (FIB-TEM), which is consistent with its high Al, Ti, V, and Ga (average: 5073 ppm, 368 ppm, and 20 ppm, respectively) trace element concentration. Mag-4 is the Fe-richest magnetite (up to 94.16 wt% FeO) forming the outermost rims in magnetite grains, and exhibiting the lowest total trace element contents. Approaches in temperature estimations employing magnetite-spinel exsolutions in Mag-3 suggest that the minimum temperature of the prograde stage reached temperatures below 700 °C, whereas Mag-4 should be formed during the retrograde stage. Magnetite microstructure studied by electron backscatter diffraction (EBSD) suggests Mag-4 formation under fluid-assisted dynamic conditions, which is consistent with the tectonic evolution of the emplacement. We propose that the San Manuel deposit formed by pulsed hydrothermal fluids derived from anatexis of crustal rocks during peridotite emplacement, promoting re-equilibration processes that led to the magnesioferrite-magnetite zoning.This study was funded by the Spanish project RTI2018-099157-A-I00, granted by the “Ministerio de Ciencia, Innovación y Universidades”, the grant PRE2019-088262 “Ayudas para contratos predoctorales para la formación de doctors” (FPI), defrayed by the “Ministerio de Ciencia, Innovación y Universidades. The Mexican research program “CONACYT-Ciencia Básica” A1-S-14574 is also thanked for proving additional funding for standards employed in LA-ICP-MS analysis. J.M. González-Jímenez also acknowledge funding provided by the Ramón y Cajal Fellowship RYC-2015-17596. We would like to thank X. Llovet from “Serveis Cientifico-Técnics” (CCiTUB) of the Universidad de Barcelona for his invaluable assistance with the electron probe micro-analyzer, and to C. Ortega-Obregón from the “Laboratorio de Estudios Isotópicos of the Centro de Geociencias” (UNAM, Mexico) for his help with the LA-ICP-MS analyses on magnetite. Moreover, we would like to express our gratitude to I. Sánchez from the “Centro de Instrumentación Científica “(CIC-UGR) for her supporting of the scanning electron microscope. The authors would like to acknowledge the use of “Servicio General de Apoyo a la Investigación-SAI, Universidad de Zaragoza”, particularly the help of C. Gallego and L. Casado Zueras from the “Advanced Microscopy Laboratory” (LMA) for their careful preparation of the EBSD maps and FIB samples, respectively

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Autoantibodies against type I IFNs in patients with critical influenza pneumonia

In an international cohort of 279 patients with hypoxemic influenza pneumonia, we identified 13 patients (4.6%) with autoantibodies neutralizing IFN-alpha and/or -omega, which were previously reported to underlie 15% cases of life-threatening COVID-19 pneumonia and one third of severe adverse reactions to live-attenuated yellow fever vaccine. Autoantibodies neutralizing type I interferons (IFNs) can underlie critical COVID-19 pneumonia and yellow fever vaccine disease. We report here on 13 patients harboring autoantibodies neutralizing IFN-alpha 2 alone (five patients) or with IFN-omega (eight patients) from a cohort of 279 patients (4.7%) aged 6-73 yr with critical influenza pneumonia. Nine and four patients had antibodies neutralizing high and low concentrations, respectively, of IFN-alpha 2, and six and two patients had antibodies neutralizing high and low concentrations, respectively, of IFN-omega. The patients' autoantibodies increased influenza A virus replication in both A549 cells and reconstituted human airway epithelia. The prevalence of these antibodies was significantly higher than that in the general population for patients 70 yr of age (3.1 vs. 4.4%, P = 0.68). The risk of critical influenza was highest in patients with antibodies neutralizing high concentrations of both IFN-alpha 2 and IFN-omega (OR = 11.7, P = 1.3 x 10(-5)), especially those <70 yr old (OR = 139.9, P = 3.1 x 10(-10)). We also identified 10 patients in additional influenza patient cohorts. Autoantibodies neutralizing type I IFNs account for similar to 5% of cases of life-threatening influenza pneumonia in patients <70 yr old

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Quantitative EDX Analysis in TEM. Practical Development, Limitations and Standards

Principles and methods of EDX microanalysis in transmission electron microscopy are presented. Absorption and fluorescence corrections are not carried out in TEM, as real thickness of the sample in the precise analysis point is unknown, but very small. Therefore it is assumed that the effect of such corrections should be minimum. Small thickness guarantees a lack of spread of electrons to larger areas than the spot size used, which means the possibility of very high spatial resolution chemical analyses. In relation to electron microprobe or scanning electron microscope, microanalysis in TEM presents the advantage of minimum size of analysis spot, but its drawback is its lower analytical quality. As the excited volume is an unknown figure, microanalysis in TEM always produces relative results, that is, only the ratios of concentrations among the various elements can be measured but not their absolute concentrations. This is an intrinsic limitation of the method

Mineralogía y geoquímica de las pegmatitas de Sierra Albarrana (provincia de Córdoba)

Tesis Universidad de Granada. Departamento de Mineralogía y Petrologí

Textural and chemical relationships between chlorite and berthierine in metamorphic nodules enclosed in granitic pegmatites of Sierra Albarrana (SW. Spain)

Reseña de la comunicación presentada en el 16th General Meeting of the International Mineralogical Association (Pisa, Italia, 4-9 septiembre 1994)Chlorite and berthierine occur through alteration of cordierite within nodules that are enclaves of metamorphic rocks texturally and mineralogically transformed by the Sierra Albarrana pegmatites during their empalcemente. The coexistence of both phyllosilicates, in some cases at lattice level, allows us to study their stability relationships and to compare their chemical compositions by mens of powder X-ray difraction, electron microprobe and analytical high resolution transmission electron microscopy.Peer reviewe