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Publisher's version (útgefin grein), Oldoinyo Lengai, located in the Gregory Rift in Tanzania, is a world-famous volcano owing to its uniqueness in producing natrocarbonatite melts and because of its extremely high CO2 flux. The volcano is constructed of highly peralkaline [PI = molar (Na2O + K2O)/Al2O3 > 2–3] nephelinite and phonolites, both of which likely coexisted with carbonate melt and a CO2-rich fluid before eruption. Results of a detailed melt inclusion study of the Oldoinyo Lengai nephelinite provide insights into the important role of degassing of CO2-rich vapor in the formation of natrocarbonatite and highly peralkaline nephelinites. Nepheline phenocrysts trapped primary melt inclusions at 750–800 °C, representing an evolved state of the magmas beneath Oldoinyo Lengai. Raman spectroscopy, heating-quenching experiments, low current EDS and EPMA analyses of quenched melt inclusions suggest that at this temperature, a dominantly natritess-normative, F-rich (7–14 wt%) carbonate melt and an extremely peralkaline (PI = 3.2–7.9), iron-rich nephelinite melt coexisted following degassing of a CO2 + H2O-vapor. We furthermore hypothesize that the degassing led to re-equilibration between the melt and liquid phases that remained and involved 1/ mixing between the residual (after degassing) alkali carbonate liquid and an F-rich carbonate melt and 2/ enrichment of the coexisting nephelinite melt in alkalis. We suggest that in the geological past similar processes were responsible for generating highly peralkaline silicate melts in continental rift tectonic settings worldwide., This study was financially supported by project NRDIO ( National Research, Development, and Innovation Office of Hungary ) K-119535 (to M. Berkesi and T. Guzmics) and by the Betta Üzletlánc Ltd. to Guzmics. In addition, M. Berkesi acknowledges to the ELTE Institutional Excellence Program (1783-3/2018/FEKUTSRAT) supported by the Hungarian Ministry of Human Capacities . We thank Toshiaki Tsunogae for his editorial handling, and Alan Cooper and an anonymous reviewer for their constructive comments that helped to improve the manuscript.

The influence of anthropogenic outdoor sources on the geochemical composition of house dust material in large cities is poorly understood. In this study, we investigate the magnetic signature and the concentrations of potentially toxic elements (PTEs) in randomly selected house dust samples from the metropolitan area of Athens, the most populated city in Greece. Environmental magnetic measurements, including isothermal remanent magnetization and thermomagnetism, indicated that the main magnetic mineral is coarse-grained low-coercivity magnetite. Detailed microscopic observations of the magnetically extracted material revealed the presence of three different kinds of Fe-rich particles deriving from both combustion-related and non-exhaust vehicular sources: irregularly-shaped grains and spherules of Fe-oxides, and particles consisting of metallic Fe. Further study of the morphology of single anthropogenic magnetic spherules (size > 30 μm) identified the presence of magnetite spherical particles, typically formed by industrial combustion processes. Enrichment factors (EFs) for the PTEs calculated against the Athens urban soil showed that the house dusts were very highly enriched in Cd, Cu, Zn and significantly enriched in Pb (median EF values of 34.1, 26.2, 25.4 and 10.3, respectively). The oral bioaccessibility of PTEs in the house dust, evaluated using a simulated gastric solution (0.4 M glycine), was in the order Pb > Zn > Mn > Cd > Ni > Cu > Cr > Fe. Concentrations of Pb increased with the house age. Principal component and cluster analysis demonstrated the close association of anthropogenic Cu, Pb and Zn with the magnetic susceptibility of the house dusts. We conclude that both traffic-related and industrial sources trigger the occurrence of magnetic Fe/PTEs- rich particles in house dust. These results reinforce the use of environmental magnetism determinations for assessing anthropogenic contamination of PTEs in the indoor environment in large cities.

Bjurböle L/LL4 ordinary chondrite was studied using scanning electron microscopy with energy dispersive spectroscopy, Raman spectroscopy, X-ray diffraction, magnetization measurements and Mössbauer spectroscopy. The phase composition and the relative iron fractions in the iron-bearing phases were determined. The unit cell parameters for olivine, orthopyroxene and clinopyroxene are similar to those observed in the other ordinary chondrites. The higher contents of forsterite and enstatite were detected by Raman spectroscopy. Magnetization measurements showed that the temperature of the ferrimagnetic-paramagnetic phase transition in chromite is around 57 K and the saturation magnetic moment is ~7 emu/g. The values of the 57Fe hyperfine parameters for all components in the Bjurböle Mössbauer spectrum were determined and related to the corresponding iron-bearing phases. The relative iron fractions in Bjurböle and the 57Fe hyperfine parameters of olivine, orthopyroxene and troilite were compared with the data obtained for the selected L and LL ordinary chondrites. The Fe2+ occupancies of the M1 and M2 sites in silicate crystals were determined using both X-ray diffraction and Mössbauer spectroscopy. Then, the temperatures of equilibrium cation distribution were determined, using two independent techniques, for olivine as 666 K and 850 K, respectively, and for orthopyroxene as 958 K and 1136 K, respectively. Implications of X-ray diffraction, magnetization measurements and Mössbauer spectroscopy data for the classification of the studied Bjurböle material indicate its composition being close to the LL group of ordinary chondrites. © 2020 Elsevier B.V. 783-3/2018/FEKUTSRAT; 115784, 115913, 134770; Fundação para a Ciência e a Tecnologia, FCT; Academy of Finland: 293975, 325806; Ministry of Education and Science of the Russian Federation, Minobrnauka: FEUZ-2020-0060; Ural Branch, Russian Academy of Sciences, UB RAS: АААА-А19-119071090011-6; Fundació Catalana de Trasplantament, FCT; Government Council on Grants, Russian Federation; Ural Federal University, UrFU; Ministry of Science and Higher Education of the Russian Federation This work was supported by the Ministry of Science and Higher Education of the Russian Federation, project № FEUZ-2020-0060, and Act 211 of the Government of the Russian Federation, contract № 02.A03.21.0006. The Coimbra Chemistry Centre (CQC; research unit UI0313/QUI/2020) is supported by the Portuguese Science Foundation (FCT) and COMPETE-UE. On behalf of two of us (Á.Sz. and Z.D.) this work was completed in the ELTE Excellence Programme (783-3/2018/FEKUTSRAT) supported by the Hungarian Ministry of Human Capacities. E.K. and Z.H. acknowledge NKFIH-OTKA (the grants № 115784, № 115913 and № 134770). M.G. acknowledges insightful discussions with Jarmo Moilanen and the Academy of Finland project № 325806 “Planetary spectrometry”. T.K. acknowledges the Academy of Finland project № 293975. The Zavaritsky Institute of Geology and Geochemistry of the Ural Branch of the Russian Academy of Sciences is supported by the Ministry of Science and Higher Education of the Russian Federation, project № АААА-А19-119071090011-6 (A.A.M.). This work was carried out within the Agreements of Cooperation between the Ural Federal University (Ekaterinburg) and the University of Coimbra (Coimbra) and between the Ural Federal University (Ekaterinburg) and the Eötvös Loránd University (Budapest). This work was supported by the Ministry of Science and Higher Education of the Russian Federation, project ? FEUZ-2020-0060, and Act 211 of the Government of the Russian Federation, contract ? 02.A03.21.0006. The Coimbra Chemistry Centre (CQC; research unit UI0313/QUI/2020) is supported by the Portuguese Science Foundation (FCT) and COMPETE-UE. On behalf of two of us (?.Sz. and Z.D.) this work was completed in the ELTE Excellence Programme (783-3/2018/FEKUTSRAT) supported by the Hungarian Ministry of Human Capacities. E.K. and Z.H. acknowledge NKFIH-OTKA (the grants ? 115784, ? 115913 and ? 134770). M.G. acknowledges insightful discussions with Jarmo Moilanen and the Academy of Finland project ? 325806 ?Planetary spectrometry?. T.K. acknowledges the Academy of Finland project ? 293975. The Zavaritsky Institute of Geology and Geochemistry of the Ural Branch of the Russian Academy of Sciences is supported by the Ministry of Science and Higher Education of the Russian Federation, project ? ????-?19-119071090011-6 (A.A.M.). This work was carried out within the Agreements of Cooperation between the Ural Federal University (Ekaterinburg) and the University of Coimbra (Coimbra) and between the Ural Federal University (Ekaterinburg) and the E?tv?s Lor?nd University (Budapest).

Author(s): Bali, E; Guðfinnsson, GH; Aradi, LE; Szabo, A; Szabo, C; Zierenberg, R; Diamond, LW; Pettke, T; Friðleifsson, G | Abstract: The ∼4500-m-deep Iceland Deep Drilling Project (IDDP) borehole IDDP-2 in Iceland penetrated the root of an active seawater-recharged hydrothermal system below the Mid-Atlantic Ridge. As direct sampling of pristine free fluid was impossible, we used fluid inclusions to constrain the in situ conditions and fluid composition at the bottom of the hydrothermal convection cell. The fluid temperature is ∼600 °C, and its pressure is near-hydrostatic (∼45 MPa). The fluid exists as two separate phases: an H2O-rich vapor (with an enthalpy of ∼59.4 kJ/mol) and an Fe-K–rich brine containing 2000 μg/g Cu, 3.5 μg/g Ag, 1.4 μg/g U, and 0.14 μg/g Au. Occasionally, the fluid inclusions coexist with rhyolite melt inclusions. These findings indicate that the borehole intersected high-energy steam, which is valuable for energy production, and discovered a potentially ore-forming brine. We suggest that similar fluids circulate deep beneath mid-ocean ridges worldwide and form volcanogenic massive sulfide Cu-Zn-Au-Ag ore deposits.

Based on the well-known excellent adsorbent ability of chicken eggshells, the adsorptive capacity and mechanism of Remazol Brilliant Violet-5R (RBV-5R) dye by eggshell was investigated. Exploiting the high surface-area-to-volume ratio and porous structure of this natural adsorbent, the developed procedure showed to be useful for the efficient adsorption of RBV-5R dye from contaminated water. The protocol was thoroughly optimized by investigating the effect of the dye concentration, biomass-contaminated water ratio, particle size of the adsorbent, pH and temperature, as they are key factors in the efficiency of the dye removal process. The eggshell material was characterized by different types of microscopy techniques (stereo, polarization, SEM) as well as elemental analysis (element distribution mapping, EDX), Raman spectroscopy and BET-surface density measurements. EDX, FTIR and Raman spectroscopy proved the presence of the adsorbed dye on the surface of the biomaterial. It was shown that under optimal conditions, the environmentally friendly and inexpensive eggshell could be a reliable adsorbent for Remazol dye removal from wastewater.

The aim of this study was to determine both ‘water’ contents (as OH− and H2O) and δD values of several clinopyroxene samples from alkaline basalts. These parameters were first obtained from five clinopyroxene samples using both the classical ‘off-line’ vacuum extraction technique and the ‘on-line’ high-temperature pyrolysis technique. Blanks measured with the ‘on-line’ gas extraction techniques were low enough to prevent any contamination by atmospheric water vapour. The comparison of data has revealed that our ‘on-line’ procedure is more effective for the extraction of ‘water’ from clinopyroxenes and, consequently, this ‘on-line’ technique was applied to ten additional clinopyroxene samples. Sample δD values cover a similar range from −95 to −45 ‰ (VSMOW) regardless of the studied locations, whereas the total ‘water’ content varies from ~115 to ~2570 ppm. The structural hydroxyl content of clinopyroxene samples measured by micro-FTIR spectrometry varies from ~0 to 476 ppm expressed in molecular water equivalent. The total ‘water’ concentrations determined by mass spectrometry differ considerably from structural hydroxyl contents constrained by micro-FTIR, thus indicating that considerable proportion of the ‘water’ may be present in (nano)-inclusions. The structural hydroxyl concentration—apart from clinopyroxenes separated from amphibole clinopyroxenite xenoliths—correlates positively with the δD values of clinopyroxene megacrysts for each locality, indicating that structurally bond hydrogen in clinopyroxenes may have δD values higher than molecular water in inclusions. This implies that there may be a significant hydrogen isotope fractionation for structural hydroxyl during crystallization of clinopyroxene, while for molecular water there may be no or only negligible isotope fractionation.